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TREATMENT OF SURFACE WATER AND
MUNICIPAL WASTEWATER BY
HYBRID CERAMIC MICROFILTRATION SYSTEMS
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management Examination Committee: Prof. C. Visvanathan (Chairperson) Dr. Preeda Parkpian Dr. Thammarat Koottatep Nationality: Vietnamese Previous Degree: Bachelor of Engineering in Environmental Technology Hanoi University of Technology, Vietnam Scholarship Donor: Ministry of Education and Training (MOET), Vietnam - AIT Asian Institute of Technology School of Environment, Resources and Development First of all, I would like to express my deep gratitude and appreciation to my advisor and chairman of the examination committee, Prof. C. Visvanathan, for his valuable advice, suggestions and continuous encouragement for a successful study. Prof. C. Visvanathan's kindness, invaluable help, and scientifically and effectively working ways will be always in my memory. I would like to send my sincere thanks to the examination committee members, Dr. Preeda Parkpian and Dr. Thammarat Koottatep for their helpful comments and kind suggestions on this research. I would like to express my deep gratitude and profound thanks to Prof. Yoshimasa Watanabe, Hokkaido University and Dr. Hitoshi Yonekawa, NGK Ltd., Japan, for giving me an invaluable research opportunity by providing the pilot system. Sincere thanks are due to Prof. Akira Yuasa, Gifu University, Japan who provided me the particle counter for micro-particle measurement of the research. My grateful thanks and appreciations are surely sent to Mr. Bui Xuan Thanh, AIT doctoral student, for his kindness, encouragement and suggestions during the research. I am very grateful to Prof. Dang Kim Chi, Deputy Director of Institute for Environmental Science and Technology (INEST), Hanoi University of Technology (HUT), Hanoi, Vietnam, for her continually invaluable encouragement. The useful experiences and scientifically working methods, which I had learnt during my work under her advice before I became an AIT student, strongly helped me to conduct successfully this research. I would like to express my sincerest gratitude to Mr. Le Ngoc Cau, AIT Center in Vietnam (AITCV) for his invaluable help and encouragement, which made my hope of studying at the AIT come true. His kindness is one of the most important and nicest things forever engraved in my mind. Moreover, I would like to thank the Ministry of Education and Training (MOET), Vietnamese Government, for granting the scholarship for my study at AIT. I am also honest to thank the lecturers and staff of Environmental Engineering Program for their support during my study at the AIT. Sincere thanks are due to all my good friends at the AIT for their friendship and help. And last, but not the least, I would like to express my deepest and heartfelt thankfulness to my parents and family members, and to my betrothed - Phuong N.T.H, for their invaluable encouragements and sacrifices given to me during my master study at the AIT. There is no word that can express completely and perfectly my deepest gratitude to them. This work and my AIT master degree are dedicated to them. Abstract
Concerns of limitations of conventional technologies for surface water treatment and reuse potentials of municipal wastewater have led to increased interest in membrane technologies. One of the most attractive membrane materials in the water and wastewater works nowadays that has been researched and developed is ceramic membrane. The ceramic membrane has many advantages for overcoming problems generated from conventional water and waste treatment systems. This research was conducted with hybrid ceramic microfiltration (CMF) systems in which pre-treatment processes were used to enhance the micro-filtration, in the ambient conditions of the tropical region. Feed waters for the pilot systems were synthetic water, surface water, and municipal wastewater. It was found out that the hybrid ceramic microfiltration systems were very attractive on surface water treatment. When combined with pre-treatment coagulation-flocculation, the hybrid ceramic microfiltration removed highly almost all of pollutants including microbial pathogens. Suspended solid, total coliform, and fecal coliform, were removed completely in all direct and hybrid CMF systems. Giardia and Cryptosporidium removal efficiency of 99.77% and 99.92 % was achieved in poly aluminum chloride (PACl) + CMF hybrid system and powder activated carbon (PAC) + PACl + CMF hybrid systems, respectively. The highest TOC and DOC removals were more than 80 % with the PACl + PAC + CMF hybrid system. Permeate of the hybrid systems was very good for portable water. Furthermore, the research also investigated that ceramic membrane could be applied attractively in municipal wastewater treatment. The highest pollutants removal rates were achieved in the PACl + CMF hybrid system. BOD and COD were removed at 67 % and 63 %, respectively. Total coliform and fecal coliform were removed completely. Almost all of measured parameters of permeate in the hybrid systems met standards for reuse activities such as irrigation and other agricultural purposes. Table of Contents
Chapter Title
Acknowledgements Table of Contents List of Abbreviations Objectives of the study Scopes of the study Literature Review Surface water and reclamation of municipal wastewater 2.1.1 Important of surface water 2.1.2 Contaminations of surface water 2.1.3 Reclamation of municipal wastewater 2.2 Conventional technologies for surface water treatment 2.2.1 A typically conventional technology for surface water 2.2.2 Advantages and disadvantages of conventional 2.3 Membrane technologies for surface water treatment 15 2.3.1 Background on membrane filtration 2.3.2 Advantages and disadvantages of membrane filtration 2.4 Ceramic microfiltration for surface water treatment 2.4.1 Development of ceramic microfiltration 2.4.2 Enhanced microfiltration for surface water treatment 2.5 Membrane technology for municipal wastewater reclamation 2.6 Advantages of hybrid ceramic membrane filtration 3.2.1 Feed water 3.2.2 Hybrid ceramic microfiltration system 3.2.3 Chemicals preparation for experiment 3.3 Experimental set-up 3.4 Overall experiment 3.5 Operational conditions 3.6 Chemical cleaning procedure for ceramic membrane 3.6.1 Chemical cleaning procedure for normal clogging 3.6.2 Chemical cleaning procedure for serious clogging 3.7 Monitoring and analyzing methods 3.7.1 Monitored and analyzed parameters 3.7.2 Jar test for optimization of coagulant dosage 3.7.3 Determination of micro-particles, giardia and 3.7.4 Determination of total and dissolved organic carbon 4.1 Results of pre-experiments 4.1.1 Preparation of synthetic water 4.2 Experimental run with synthetic water 4.2.1 Result and discussion 4.2.2 Conclusion 4.3 Experimental runs with surface water 4.3.1 Scenario 1: Direct ceramic microfiltration 4.3.2 Scenario 2: Coagulation-flocculation and CMF 4.3.3 Scenario 3: Adsorption, coagulation-flocculation, and 4.3.4 Comparison of results 4.4 Experimental runs with municipal wastewater 4.4.1 Scenario 1: Direct ceramic microfiltration 4.4.2 Scenario 2: Coagulation-flocculation and CMF 4.4.3 Comparison of results 4.5 Operational problems and solutions Conclusions and Recommendations 5.2 Recommendations for future studies List of Tables
Major concerns on quality of surface water Municipal wastewater reuse and applications of conventional technologies for surface water treatment 2.4 Classification Advantages and limitations of membrane filtration Major characteristics of synthetic water Major characteristics of AIT pond water Major characteristics of AIT wastewater Specifications of coagulation unit Specifications of ceramic membrane unit Specifications of backwash unit Specifications of sub-units of the CMF pilot Experimental se-up for different operational scenarios Major operation conditions of the CMF system Parameters for monitoring and analyzing Concentration and dosage of coagulation for Jar test TMP recovery by chemical cleaning Quality of treated water and standards TMP recovery by chemical cleaning Quality of treated wastewater and standards for reusing activities Operational problems and solutions for the dead-end CMF system List of Figures
Figure Title
Water distributions in the world The alum coagulation diagram that defines the mechanism of coagulation based on pH and alum dose A graph illustrating the benefit of tanks in series for flocculation Schematic of a conventional water treatment plant Application size range of membrane filtration process Dead-end membrane filtration and its configuration for tubular CM Cross-flow membrane filtration Correlation between TMP and micro-particle concentration Schematic of partial restorations of transmembrane flux or pressure by backwashing and chemical cleaning of MF membranes Structure of ceramic NGK membrane Diagram of the system set-up 3.2 Microfiltration Equipment and illustrated flow diagram of backwash process Coagulant preparation procedure of 1%citric acid solution Procedure to preparation of 0.05M H2SO4 solution Simplified flow diagram of microfiltration system for operational Technical diagram for the operational scenarios Working principle of particle counter MLC-7P Experimental set-up of particle counter MLC-7P Variation of turbidity with Kaolin clay concentration Variations of turbidity and pH of supernatant with coagulant dosage Variations of TOC and color of supernatant with PAC dosage Variations of turbidity and pH of supernatant with coagulant dosage Variations of turbidity and pH of supernatant with coagulant dosage Variations of TOC and color of supernatant with PAC dosage Variation of turbidity and pH of supernatant with coagulant dosage Variations of TMP and turbidity of feed water with period of Variations of TMP and turbidity of feed water with period of Changes of TOC and TOC removal efficiency with period of Changes of DOC and DOC removal with period of treatment Variation of Fe with period of treatment Micro-particles of feed and permeate water and removal efficiency Changes of TMP and turbidity of feed water with period of Changes of turbidity with period of treatment Changes of TOC and TOC removal efficiency with period of Changes of DOC and DOC removal efficiency with period of Change of number of micro-particle with period of treatment of run Change of number of micro-particle with period of treatment of run Changes of TMP, turbidity of feed water and period of treatment Change of turbidity with period of treatment TOC and TOC removal rate with period of treatment DOC and DOC removal rate with period of treatment Number of micro-particle and period of treatment of run 1 Number of micro-particle and period of treatment of run 2 Changes of TMP and turbidity of feed water with period of Relationship between turbidity and period of treatment TOC and TOC removal rate with period of treatment DOC and DOC removal rate with period of treatment Number of micro-particle and period of treatment of the PAC + PACl + CMF hybrid system Changes of TMP with filtration time Recovery of TMP by each time of backwashing Comparison among scenarios on removals of major pollutants Changes of TMP and turbidity of feed water with period of Changes of turbidity of feed water and permeate with time Number of micro-particle and period of treatment of the direct CMF Removals of pollutants by the direct CMF system Changes of TMP and turbidity of feed water with period of Changes of turbidity of feed water and permeate with time Number of micro-particle and period of treatment of the PACl + CMF hybrid system Removals of pollutants by the PACl + CMF hybrid system Changes of TMP with filtration time Recovery of TMP by each time of backwashing Comparison among scenarios on removals of major pollutants List of Abbreviations
Asian Institute of Technology American Public Health Association Biochemical Oxygen Demand BW Backwashing CMF Ceramic Crypto Cryptosporidium COD Chemical Oxygen Demand Disinfection By-Products Dissolved Organic Carbon EPA Environmental Protection Agency (United State) Extracellular Polymetric Substance MF Microfiltration MWW Municipal MWWT Municipal Wastwater Treatment ND None NF Nanofiltration NOM Natural Organic Matter UF Ultrafiltration NTU Nephelometric Turbidity Unit Safe Drinking Water Act THMs Trihalomethanes TOC Total organic carbon Total Suspended Solid Powdered Activated Carbon Poly Aluminum Chloride Programmable Logic Controller PN Protein POC Particulate Polyvinyl Chloride World Health Organization Chapter 1
1.1 Background

The shortage of ground water sources having good quality necessitates a need for the better
surface water treatment for drinking water. Conventionally, water treatment technologies
for surface water treatment were based on conventional physico-chemical processes
including coagulation, flocculation, sand filtration, disinfection, and etc. Although these
technologies have been used for along time but they have been showing some problems
such as the low organic removal, wasteful chemicals, large area requirement, especially
low pathogens removal efficiency.
The reality mentioned as above needs alternatives in term of economic, engineering and
transferring technology aspects for a higher quality of treated water from surface water.
Membrane technologies have advantages for overcoming the problems generated from
conventional water treatment systems. One kind of membrane filters widely applied for
surface water treatment by hybrid system is ceramic membrane filter. Although it has been
developed in recent years, ceramic microfiltration is being known as a good solution for
surface water treatment due to its advantages on turbidity, total organic carbon, and
especially micro particles removal. When combined with pre-treatment processes such as
chlorination, adsorption by powdered activated carbon (PAC) and coagulation, the
membrane filtration has a high rate on removing pollutants in surface water as 98.8 –
99.9% for turbidity and 96-99.8% for micro particles of 1-50 µm (Yuasa, et al., 2006).
There is a great potential for application of the ceramic membrane technology in
developing countries. However, the operation of the new technology is usually depended
on the specific characteristics of surface water sources taken and other local factors such as
temperature, pH, turbidities, etc. Therefore, the study was conducted with a hybrid ceramic
microfiltration (CMF) system, which is the combination of chlorination, PAC adsorption,
coagulation process and microfiltration using ceramic membrane, in the ambient
conditions. The study was implemented with different operational scenarios and different
feed water qualities.
Furthermore, the ceramic membrane also can be applied in municipal wastewater (MWW)
treatment for reuse activities. However, literatures and information on the development of
ceramic microfiltration for reusing municipal wastewater are very limited. The functions of
ozonation, PAC adsorption and coagulation-flocculation can be effectively contributed to
CMF system for reusing municipal wastewater. Therefore, it is possible to investigate the
important effect of a hybrid CMF system for municipal wastewater treatment for reuse.
Comparisons among scenarios were pointed out clearly, and problems related to dead-end
ceramic microfiltration were investigated. Beside, comparisons between the quality of
treated water or wastewater and standards or guidelines were also conducted. The study
created good recommendations in transferring advanced technology for the treatment of
surface water and domestic wastewater as well. In addition, starting results allowed having
good directions for continually ongoing researches in the ceramic membrane filtration.
1.2 Objectives of the study
The objectives of the study are the followings:
1. Evaluate efficiency of the hybrid ceramic microfiltration system on surface water treatment for potable water with aspects of removal of physical, chemical and biological pollutants, in which efficiencies of removing natural organic mater and pathogens (bacteria and protozoa) are the most important interests. 2. Investigate potential and evaluate efficiency of the ceramic membrane technology on municipal wastewater treatment for reuse activities. 3. Investigate operational problems related to dead-end filtration for surface water treatment and municipal wastewater reclamation by the hybrid ceramic microfiltration technology in the tropical condition.
1.3 Scope of the study
The study served as both experimental and practical types in which the practical aspect was the dominant expectation. The study was carried in pilot scale including two stages: 1. Stage 1: Research with synthetic water. The aim of this stage is to: - Find out any problem generated while operating and solution for solving it - Optimize the system for next stage from experiences in this stage - Evaluate, analyze, and recommend gained results 2. Stage 2: Research with surface water (AIT pond water) and municipal wastewater (AIT wastewater) The aim of this stage is to get the real result on treatment of surface water and municipal wastewater by the hybrid ceramic microfiltration system. The stage pointed out much useful information for evaluations of removing pollutants and comparisons with standards for differently use activities of treated water and wastewater. In addition, requirements were also investigated to enhance the system when transferring the technology to the reality. Chapter 2
Literature Review

2.1 Surface water and reclamation of municipal wastewater
2.1.1 Importance of surface water
Nowadays, the rapid growths of population and industrialization in the world lead to a big
increase in water consumption. In Thailand, industrial growth of 8 to 10% per year requires
a lot of water supply, estimated that industries consume water of 800 km3/year. In addition,
agriculture needs about 2,800 km3 /year. Thailand has ground water consumption of 8.99
km3 /year, while surface water available of 199 km3 /year, this points out the need of using
surface water as the main water supply source to satisfy economic development of the
country (Aim, 2007).
In a larger view, figure 2.1 shows in detail all available water sources and limited amount
of surface water in the world. The consideration that sea water occupies 96% of 1.386
million km3 of total water in the world. In addition, 68.7 % of total fresh water is existed in
ice; 30% is ground water; surface water sources such as rivers and lakes have total volume
of 93.100 km3 or 1% of total water of the world. Although surface water has a small
amount compared with other water sources, it is the main source for daily human activities.
Water in the world Fresh surface water Figure 2.1 Water distributions in the world (Gleick, 1996)
Between 1900 and 1995, the world water use increased by a factor of six – more than double the rate of population growth during the same period. The world population is projected to increase from the current six billion or so to 8.3 billion in 2025. The result is already evident in the competition for water for agricultural, domestic and industrial purposes. Growing tensions over water resources are becoming a potentially explosive
source of conflict. Many predict that wars of the next century will be over water, not oil or
politics (Schonfeldt, 1999).
2.1.2 Contaminations of surface water

Microbial contamination (pathogens):

Microorganisms present in water supplies can cause immediate and serious health
problems. Infections by bacteria, viruses, and protozoa usually cause gastrointestinal
distress; however, some, such as the bacteria Vibrio cholerae, can result in death. There is
a vast number of pathogenic organisms exist, and water suppliers cannot feasibly monitor
for all of them. Therefore, they monitor for indicator organisms instead. The total coliform
group of bacteria is the most common indicator. Unfortunately, some pathogens (e.g.,
viruses and protozoa) are more resistant to conventional water treatment processes than are
total coliforms.
Protozoa cysts are the largest pathogens in drinking water, and are responsible for many of
the waterborne diseases. Protozoa cysts range is size from 2 to 15 µm, but can squeeze
through smaller openings. In order to insure cyst filtration, filters with an absolute pore
size of l µm or less should be used. The two most common protozoa pathogens are Giardia
Zamblia
(Giardia) and Cryptosporidium (Crypto). Both organisms have caused numerous
deaths in recent years in the U.S. and Canada, the deaths occurring in the young and
elderly, and the sick and immune compromised. Many deaths were a result of more than
one of these conditions. Neither disease is likely to be fatal to a healthy adult, even if
untreated. Outside of the US.and other developed countries, protozoa are responsible for
many cases of amoebic dysentery, but so far this has not been a problem in the U.S., due to
the application of more advanced wastewater treatment technologies. This could change
during a survival situation. Tests have found Giardia and/or Crypto in up to 5 % of vertical
wells and 26% of springs in the U.S (American Water Works Association, 1999).
Bacteria are smaller than protozoa and are responsible for many diseases, such as typhoid
fever, cholera, diarrhea, and dysentery. Pathogenic bacteria range in size from 0.2 to 0.6
µm, and a 0.2 µm filter is necessary to prevent transmission. Contamination of water
supplies by bacteria is blamed for the cholera epidemics, which devastate undeveloped
countries from time to time. Even in the U.S., E. coli is frequently found to contaminated
water supplies. Fomately, E. coli is relatively harmless as pathogens go, and the problem
isn't so much with E. coli found, but the fear that other bacteria may have contaminated the
water as well. Never the less, dehydration from diarrhea caused by E. coli has resulted in
fatalities. One of hundreds of strains of the bacterium Escherichia coli, E. coli 0157:H7 is
an emerging cause of food borne and waterborne illness. Although most strains of E. coli
are harmless and live in the intestines of healthy humans and animals, this strain produces
a powerful toxin and can cause severe illness. E. coli 0157:H7 was first recognized as a
cause of illness during an outbreak in 1982 traced to contaminated hamburgers. Since then,
most infections are believed to have come from eating undercooked ground beef. However,
some have been waterborne. The presence of E. coli in water is a strong indication of
recent sewage or animal waste contamination. Sewage may contain many types of disease-
causing organisms. Since E. coli comes from human and animal wastes, it most often
enters drinking water sources via rainfalls, snow melts, or other types of precipitation, E.
coli may be washed into creeks, rivers, streams, lakes, or groundwater. When these waters
are used as sources of drinking water and the water is not treated or inadequately treated, E. coli may end up in drinking water. E. coli 0157:H7 is one of hundreds of strains of the bacterium E. coli. Although most strains are harmless and live in the intestines of healthy humans and animals, this strain produces a powerful toxin and can cause severe illness. Infection often causes severe bloody diarrhea and abdominal cramps; sometimes the infection causes non-bloody diarrhea (American Water Works Association, 1999). Frequently, no fever is present. It should be noted that these symptoms are common to a variety of diseases, and may be caused by sources other than contaminated drinking water. In some people, particularly children under 5 years of age and the elderly, the infection can also cause a complication, called hemolytic uremic syndrome, in which the red blood cells are destroyed and the kidneys fail. About 2%-7% of infections lead to this complication. In the U.S. hemolytic uremic syndrome is the principal cause of acute kidney failure in children, and most cases of hemolytic uremic syndrome are caused by E. coli 0157:H7. Hemolytic uremic syndrome is a life-threatening condition usually treated in an intensive care unit. Blood transfusions and kidney dialysis are often required. With intensive care, the death rate for hemolytic uremic syndrome is 3 %-5%. Symptoms usually appear within 2 to 4 days, but can take up to 8 days. Most people recover without antibiotics or other specific treatment in 5-10 days. There is no evidence that antibiotics improve the course of disease, and it is thought that treatment with some antibiotics may precipitate kidney complications. Antidiarrheal agents, such as loperamide (Imodium), should also be avoided. The most common methods of treating water contaminated with E. coli is by using chlorine, ultra-violet light, or ozone, all of which act to kill or inactivate E. coli. Systems, using surface water sources, are required to disinfect to ensure that all bacterial contamination is inactivated, such as E. coli. Systems using ground water sources are not required to disinfect, although many of them do. According to EPA regulations, a system that operates at least 60 days per year, and serves 25 people or more or has 15 or more service connections, is regulated as a public water system under the Safe Drinking Water Act (SDWA). If a system is not a public water system as defined by EPA's regulations, it is not regulated under the SDWA, although it may be regulated by state or local authorities. Under the SDWA, EPA requires public water systems to monitor for coliform bacteria. Systems analyze first for total coliform, because this test is faster to produce results. Any time that a sample is positive for total coliform, the same sample must be analyzed for either fecal coliform or E. coli. Both are indicators of contamination with animal waste or human sewage. The largest public water systems (serving millions of people) must take at least 480 samples per month. Smaller systems must take at least five samples a month, unless the state has conducted a sanitary survey - a survey in which a state inspector examines system components and ensures they will protect public health - at the system within the last five years (American Water Works Association, 1999). Viruses are the second most problematic pathogen, behind protozoa. As with protozoa, most waterborne viral diseases don't present a lethal hazard to a healthy adult. Waterborne pathogenic viruses range in size from 0.020-0.030 pm (American Water Works Association, 1999), and are too small to be filtered out by a mechanical filter. All waterborne enteric viruses affecting humans occur solely in humans, thus animal waste doesn't present much of a viral threat. At the present viruses don't present a major hazard to people drinking surface water in the U.S., but thls could change in a survival situation as the level of human sanitation is reduced. Viruses do tend to show up even in remote areas, so a case can be made for eliminating them now. Chemical contamination:
Inorganic contaminants:

Toxic metals and other inorganic compounds contaminate water supplies from both
human-made and natural sources. Nitrates, common in groundwaters, cause
methemoglobinemia or "blue-baby syndrome" in infants. Fluoride, added by many water
suppliers in small doses to prevent tooth decay, causes a weakening of the bones called
skeletal fluorosis at concentrations above 4 mg/L. Radon, a naturally occurring
radionuclide, may cause lung cancer from long-term exposures in the air after being
released from water.

Organic contaminants:

Water can be contaminated by a number of organic compounds, such as chloroform,
gasoline, pesticides, and herbicides from a variety of industrial and agricultural operations
or applications. One exception is when the aquifer is located in limestone. Not only will
water flow faster through limestone, but the rock is prone to forming vertical channels or
sinkholes that will rapidly allow contamination from surface water. Surface water may
show great variations in chemical contamination levels due to differences in rainfall,
seasonal crop cultivation, or industrial effluent levels. Also, some hydrocarbons (the
chlorinated hydrocarbons in particular) form a type of contaminant that is especially
troublesome.
Total organic carbon (TOC) is a measure of the dissolved and particulate material related
to the formation of disinfection by-products. Certain naturally occurring organic
substances (particularly humic and fulvic acids) react with chlorine to form these by-
products. Natural organic matter (NOM) consists of naturally occurring organic material
derived from decaying organic matter and dead organisms. Other portions of TOC are
derived from domestic and industrial activities that include wastewater discharge,
agricultural and urban runoff, and leachate discharge.
Humic substances are typically the major component of NOM in water supplies. They are
derived from soil and are also produced within natural water and sediments by chemical
and biological processes such as the decomposition of vegetation. Humic substances are
anionic polyelectrolytes of low to moderate molecular weight, and their charge is primarily
caused by carboxyl and phenolic groups. They have both aromatic and aliphatic
components and can be surface active; they are refractive and can persist for centuries or
longer. Humic substances are defined operationally by the methods used to extract them
from water or soil. Typically, they are divided into the more soluble fulvic acids (FAs) and
the less soluble humic acids (HAs), with FAs predominating in most waters (Christman,
1983). The concentration of NOM in water is typically expressed using the amount of
organic carbon. Organic carbon that passes through a 0.45 µm pore-size membrane filter is
defined as dissolved organic carbon (DOC), and the amount that does not is known as
particulate organic carbon (POC).Total organic carbon (TOC) is the sum of DOC and POC.
The DOC of lakes ranges from 2 mg/L or less (oligotrophic lakes) to 10 mg/L (eutrophic
lakes) (Thurman, 1985).The DOC of small, upland streams will typically fall in the range 1
to 3 mg/L; the DOC of major rivers ranges from 2 to 10 mg/L. The highest DOC
concentrations (10 to 60 mg/L) are found in wetlands (bogs, marshes, and swamps). The
DOC concentration in upland lakes has been shown to be directly related to the percentage
of the total watershed area that is near-shore wetlands (Driscoll et al., 1994). The median
raw water TOC concentration for U.S. plants treating surface water is approximately 4
mg/L (Krasner, 1996).
Aesthetic aspects of water quality:

Color and turbidity:

Inorganic metals such as iron and organic compounds such as NOM cause color. In
addition to being aesthetically undesirable, color in the form of NOM is a precursor to the
formation of disinfection by-products (DBPs), which may cause cancer. Turbidity is the
cloudiness of water and is determined by measuring the amount of light scattered by
suspended particles in water. The unit of turbidity is the nephelometric turbidity unit
(NTU). Although not a direct threat to health, turbidity decreases the efficiency of
disinfection, and particles that cause turbidity can transport harmful chemicals through a
treatment plant.

Taste and odor:

Zinc, copper, iron, and manganese can be detected by taste at concentrations of 1 mg/L.
Hydrogen sulfide, a common contaminant in groundwaters, is detectable at concentrations
of 100 ng/L. Many tastes and odors in surface waters result from biological activity of
filamentous bacteria and blue-green algae. They produce geosmin and methylisoborneol,
which cause an earthy or musty smell. Both are detected at concentrations of 10 ng/L
(Arnold, 1990).

Alkalinity:

Alkalinity is a measure of the buffering capacity of water. Alkalinity determines the
magnitude of pH changes during coagulation and affects the solubility of calcium
carbonate in the distribution system. In natural waters the carbonate system dominates
alkalinity. In such systems, bicarbonate (HCO -
3 ), carbonate (CO3 ), and hydroxide (OH-) ions are the major species of alkalinity. • Temperature and pH: Temperature and pH affect coagulation, disinfection, and corrosion control. Equilibrium constants and reaction rates vary with temperature. The hydrogen ion concentration, measured as pH, is an important chemical species in these processes. Furthermore, the density and viscosity of water vary with temperature; thus, it is an important variable in the design of mixing, flocculation, sedimentation, and filtration process units. Table 2.1 Major concerns on quality of surface water (American Water Works Association (1999), WHO (2008))
Effects on water supplier Solids, turbidity Domestic sewage, urban and agricultural runoff, Hinder water treatment process. Reduce treatment effectiveness. construction activity Shield microorganism against disinfectants. Reduce reservoir Septic system leachate, wastewater plant discharge, Nitrates that may be toxic to infants and unborn fetuses. lawn and road runoff, animal feedlots, agricultural Accelerates eutrophication: high levels of algae; dissolved oxygen lands, eroded landscapes, landfill leachate, rainfall deficiencies. Increase algae activity. High color and turbidity. (especially nitrogen) Disinfection by-product formation. Taste and odor problems Natural organic matter Naturally occurring; wetlands in the watershed tend to Influence nutrient availability. Mobilize hydrophobic organics. increase concentrations Disinfection by-product formation Synthetic organic Domestic and industrial activities, spills and leaks, Adverse impacts on human health and aquatic life. wastewater discharges, agricultural and urban runoff, leachate, wastewater treatment and transmission Coliform bacteria Domestic sewage from wastewater discharges, sewers, Fecal coliform are indicators of warm-blooded animal fecal septic systems, urban runoff, animal farms and contamination that pose a threat to human health grazing, waterfowl droppings, land application of animal wastes Cryptosporidium and Eggs are shed through feces, where they can enter Causes acute short-term infection, chronic diarrhea, intestinal illness lakes, reservoirs and other sources of drinking water Fecal-Oral, Water, & possibly respiratory secretions. May become severe in children and immune compromised Industrial activities and wastewater, runoff Adverse effect to aquatic life and public health Taste and Odor: industrial chemicals, algae Aesthetic problems Reduce public confidence in water supply safety metabolites, NOM, urea Color: metals, NOM, algae, AOC, Turbidity: solids and algae, Staining: Metals Agriculture, lawn care, industrial sites, roads and Toxic to humans and aquatic life parking lots, wastewater 2.1.3 Reclamation of municipal wastewater
Wastewater reuse presents a promising solution to the growing pressure on water resources.
However, wastewater reuse implementation faces obstacles that include insufficient public
acceptance, technical, economic and hygienic risks and further uncertainties caused by a
lack of awareness, accepted standards, uniform guidelines and legislation. So far, there are
no supra-national regulations on water reuse in Europe and further development is slowed
by lack of widely accepted standards, e.g. in terms of required water quality, treatment
technology and distribution system design and operation (Wintgens et al., 2004).
Treatment technology encompasses a vast number of options and membrane processes are
regarded as key elements of advanced wastewater reclamation and reuse schemes and are
included in a number of prominent schemes world-wide, e.g. for artificial groundwater
recharge, indirect potable reuse as well as for industrial process water production. For dual
reticulation purposes in urban areas two types of systems have been built, a centralized
type of treatment with dual membrane processes, including e.g. microfiltration (MF) and
reverse osmosis (RO), and small-scale systems using membrane bioreactors.
Reclamation and reuse of municipal wastewater is a very common practice worldwide
(Bixio et al., 2004). By reclaiming wastewater, the circulation of water through the natural
water cycle can be short-circuited, such that a contribution to human water needs is made
and the environmental impact thereof limited. Furthermore, a main characteristic of
reclaimed wastewater is that its "production" is relatively constant during the year, due to
its source being dependent not on rainfall, but on the production of municipal sewage.
Thus, reclaimed water can increase the reliability of a water supply, comprising as it does,
a further source of water. Similarly, recycled water can be viewed as an independent
source of water capable of increasing the reliability of a water supply (Anderson et al.,
2002). This opportunity has to date been used in various countries using a range of
technologies for different water applications.
Reclamation technologies of the treatment can be classified as secondary, tertiary or
quaternary level. The wastewater reclamation refers to the treatment or processing of water
to make it fit for reuse, which is defined as any kind of beneficial use of reclaimed water
(Lens et al., 2002). A number of definitions require further details; secondary treatment -
here also including nutrient removal - is characteristic of restricted agricultural irrigation
(i.e. for food crops not consumed uncooked) and for some industrial applications such as
industrial cooling (except for the food industry). Additional filtration/disinfection steps
(tertiary treatment) are applied for unrestricted agricultural or landscape irrigation as well
as for process water in some industrial applications. Quaternary treatment is defined here
as a treatment producing a quality comparable to drinking water - often involving a "dual
membrane" step to meet unrestricted residential uses and industrial applications requiring
ultrapure water. Table 2.2 lists the main categories of municipal wastewater reuse
applications (listed in order of decreasing projected volume of use).
Conventionally treated wastewater contains a wide range of contaminants from suspended
solids to the smallest of inorganic salts. Many of these are known or suspected to be
detrimental to various reuse applications. Microorganisms represent the most common
threat to the reuse of waste water, due the large concentration of potentially infectious
species that routinely are present in the effluent of waste water from secondary treatment
plants.
Table 2.2 Municipal wastewater reuse and applications (Metcalf& Eddy, 1991)
Categories Reuse Agricultural irrigation Crop irrigation; Commercial nurseries Landscape irrigation Park; Golf course; Residential Industrial recycling and reuse Cooling; Boiler feed; Process water Groundwater recharge Groundwater replenishment; Salt water intrusion control Lakes and ponds; Streamflow augmentation; Fisheries Non-potable urban uses Fire protection; Air conditioning; Toilet flushing Blending in water supply reservoir; Pipe to pipe water supply
2.2 Conventional technologies for surface water treatment
2.2.1 A typically conventional technology for surface water treatment
Figure 2.4 shows conventional treatment processes in surface water treatment plant. After
being withdrawn from a source (lake or river), raw water is a suspension of small, stable
colloidal particles whose motions are governed by molecular diffusion. In coagulation
these particles are destabilized by the addition of a coagulant during rapid mixing.
Flocculation promotes the collisions of these unstable particles to produce larger particles
called flocs. In sedimentation, these flocs settle under the force of gravity. The particles
that do not settle are removed during filtration. A disinfectant such as chlorine is then
added, and, after a certain amount of contact time, the treated water is distributed to
consumers. Direct filtration plants omit the sedimentation and occasionally the flocculation
processes. These plants are suitable for raw waters with low to moderate turbidities and
low color. The following sections describe the underlying theory and design of each of the
major processes: coagulation, sedimentation, filtration, and disinfection.

Coagulation:

Coagulation is the process of adding chemicals to water to make dissolved and suspended
particles bind together and form larger particles that will settle out of the water as floc. It is
a safe and effective form of water treatment used by many cities to treat drinking water.
Coagulation improves the quality of water by reducing the amount of organic compounds,
iron and manganese, colour, and suspended particles
In coagulation, small particles combine into larger particles. Coagulation consists of three
separate and sequential processes: coagulant formation, particle destabilization, and
interparticle collisions. The first two steps occur during rapid mixing, whereas the third
occurs during flocculation. In natural waters, particles (from 10 nm to 100 µm in size) are
stable, because they have a negative surface charge (Amirtharajah, 1999).

Mechanisms of destabilization:

The possible mechanisms of particle destabilization are double layer compression, polymer
bridging, charge neutralization, and sweep coagulation. In water treatment the last two
mechanisms predominate; however, when organic polymers are used as coagulants,
polymer bridging can occur. In charge neutralization the positively charged coagulant,
either the hydrolysis species of a metal salt (alum or ferric chloride) or polyelectrolytes,
adsorbs onto the surface of the negatively charged particles. As a result, the particles have
no net surface charge and are effectively destabilized. In sweep coagulation a metal salt is
added in concentrations sufficiently high to cause the precipitation of a metal hydroxide
(e.g., aluminum hydroxide). The particles are enmeshed in the precipitate, and it "sweeps"
the particles out of the water as it forms and settles.

With metal salt coagulants, the mechanism of coagulation is determined by the coagulant
dose and the pH of the equilibrated solution. The most common coagulant is alum
[Al2(SO4)3.14.3 H2O] . The alum coagulation diagram, shown in figure 2.3, indicates the
regions where each mechanism dominates. A similar diagram exists for ferric chloride
(Amirtharajah and O' Melia, 1990).
Figure 2.2 The alum coagulation diagram that defines the mechanism of coagulation based
on pH and alum dose (Amirtharajah et al., 1982.). At a fundamental level the rapid-mixing unit provides encounters between molecules and particles in the source water and the coagulant species. These encounters are controlled by the hydrodynamic parameters and geometry of the mixer, molecular properties of the source water, and the kinetics of the coagulation reactions. Research indicates that coagulation by sweep coagulation is insensitive to mixing intensity. Although its applicability is questionable on theoretical grounds, the G-value is widely used to represent mixing intensity in both rapid mix and flocculation units. The G-value is computed as the following equation. where G is the velocity gradient (s-1), P is the net power input to the water (W), µ is the
dynamic viscosity of water (Ns/m2), V is the mixing volume (m3), ε is the rate of energy
dissipation per mass of fluid (W/kg), and ν is the kinematic viscosity (m2/s) Mixing time, t,
is an important design parameter, and it can vary from less than one second in some in-line
mixers to over a minute in back-mix reactors. In general, short times (< 1 s) are desired for
the charge neutralization mechanism and longer times (10 to 30 s) for sweep coagulation.

Flocculation:

In flocculation, physical processes transform smaller particles into larger aggregates or
flocs. Interparticle collisions cause the formation of flocs, and increased mixing with
increased velocity gradients accelerates this process. However, if the mixing intensity is
too vigorous, turbulent shear forces will cause flocs to break up. Studies of the kinetics of
flocculation (Argaman and Kaufman, 1970) indicate that a minimum time exists below
which no flocculation occurs regardless of mixing intensity and that using tanks in series
significantly reduces the overall time required for the same degree of flocculation. Figure
2.3 illustrates these two conclusions. In current designs, G-values are tapered from one
tank to the next with the highest G-value in the first tank and decreasing in each successive
compartment. G-values are between 60 and 10 s-1, and total detention times are close to 20
minutes.



Figure 2.3 A graph illustrating the benefit of tanks in series for flocculation
(Argaman et al., 1970) Sedimentation:

During sedimentation, gravity removes the flocs produced during the preceding
flocculation process. These flocs continue to aggregate as they settle, and, as a result,
experimental techniques are required to describe their settling behavior. Rectangular
sedimentation basins are the most common in water treatment practice. Designs are based
on the overflow rate, which is the flow rate divided by the surface area. The overflow rate
indicates the settling velocity of the discrete (non-flocculant) particles that are removed
with 100% efficiency. Typical overflow rates are 1.25 to 2.5 m/h. Plate and tube settlers
are often added to the last two thirds of a basin to increase the overflow rate.

Disinfection by chlorine
Rapid mixing tank Flocculation tank Flow dividing tank Coagulation, flocculation
Primary Pump station Sedimentation tank Rapid Sand Filter t Sand filtrati ank
Back washing water Treated water reservoir Back washed water To distribution pipe Release to the river Alum dosing tank Alum dosing pump To landfill
Secondary Pump station Figure 2.4 Schematic of a conventional water treatment plant
Filtration:

The most common filters are dual-media filters, in which water flows by gravity through a
porous bed of two layers of granular media. The top layer is anthracite coal, and the bottom
layer is sand. Filters are operated until one of two criteria is exceeded the effluent turbidity
standard or the allowable head loss through the filter. The filters are cleaned by
backwashing to remove the particles that have been collected on the filter media. The
removal of particles in a dual-media filter occurs within the pores of the filter and is
mediated by transport mechanisms that carry small particles across fluid streamlines to
distances close to the filter grains (also called collectors). When particles are very close to
the collectors, short-range surface forces cause the collector to capture the particle.
The dominant transport mechanisms in water filtration are diffusion and sedimentation.
Diffusion is transport resulting from random Brownian motion by bombardment of the
particle by molecules of water. Diffusion is increasingly important for particles less than 1
µm in size. Sedimentation is due to the force of gravity and the associated settling velocity
of the particle, which causes it to cross streamlines and reach the collector. This
mechanism becomes increasingly important for particles greater than 1 µm in size (for a
size range of 5 to 25 µm). The combination of these two mechanisms results in a minimum
net transport efficiency for a size of approximately 1 µm. It is interesting to extrapolate this
result to two important microbial contaminants. Cysts of Giardia lamblia, with dimensions
of 10 to 15 µm, are probably removed by the sedimentation mechanism, whereas
Cryptosporidium, with a dimension close to 3 to 5 µm, is probably close to the minimum
net transport efficiency. Unfortunately, a theory of filtration that is sufficiently general and
predictive does not yet exist. Therefore, designers must rely on empirical evidence from
pilot-scale tests for guidance.
Disinfection:

A variety of disinfectants are available in water treatment, including chlorine, chloramines,
chlorine dioxide, and ozone. However, chlorine is the most common disinfectant in almost
all of developing countries. Chlorine gas is added to water to form hypochlorous acid
(HOCl). At pHs between 6 and 9, HOCl dissociates to form the hypochlorite ion (OCl-)
and hydrogen ion (H+). HOCl has the greatest disinfection power. The extent of
disinfection in a water treatment plant is determined by computing CT values, where C is
the concentration of disinfectant and T is the contact time between disinfectant and water.
The CT value required varies with chlorine concentration, pH, and temperature. Although
increasing the CT value may provide a large factor of safety against microbial
contamination, disinfection causes the formation of disinfection by-products (DBPs),
which are suspected carcinogens. DBPs result from reactions between disinfectants and
NOM, which is ubiquitous in natural waters. The most common DBPs from chlorine are
the THMs: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.

2.2.2 Advantages and disadvantages of the conventional technologies

Major advantages and disadvantages of the conventional technologies for surface water treatment are given in table 2.3. The most noticeable limitations of the technologies are low pathogens removal efficiency. High level of DOC after the treatment of highly DOC contaminated water sources may cause taste, odor and color. In addition, low DOC removal leading to potentials of creating harmful substances from conventional disinfection. DOC is one precursor contributing to generation of disinfection by-products, THMs, in the chlorine disinfection. Table 2.3 Advantages and disadvantages of conventional technology for surface water
treatment

Advantages Disadvantages Simple and easy operation Low capital cost due to cheap Produce disinfection by-products causing cancer building materials Suitable for pure surface water Low pathogens removal rate sources Low natural organic mater removal rate Low maintenance and operation Large area requirement cost, low cost of water supply, Water containing a high level of DOC may cause taste, odor and color suitable for weakly developing problems and sand filtration can not effectively remove DOC Not sufficient for high quality requirement of water supplies in developed countries
2.3 Membrane technologies for treatment of surface water and municipal wastewater
2.3.1 Background on membrane filtration
Type of membrane filtration process:

The classification of membrane process can be based on different aspects such as driving
force, membrane type and configuration, and removal capacities. For application on
drinking water industry, membrane processes are used for desalting, softening, dissolved
organics and color removal, turbidity and pathogens removal. Although the membrane
technologies for water treatment become commercially available more than 25 years ago,
they are experiencing rapid development and improvements.
Based on the driving force used to promote the water treatment, membrane process can be
classified as pressure, electrical voltage, tem pressure, concentration gradient, and
combinations types. Actually, commercially available and commonly used membrane
processes for water treatment are pressure-driven and electrically driven membrane
processes in which pressure-driven process is more commonly used and popular.
Based on pore size, the pressure-driven membranes are classified into four different types:
revere osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF).
The classification of membranes is presented in table 2.4.

Table 2.4 Classification of membranes
Membrane Driving Membrane material Ceramic, Polysulfone, Ceramic, Polysulfone, Polyvinylidenedifluoride, hollow Cellulose acetate thin spiral wound, plate-and-frame Cellulose acetate thin Solution/diffusion wound, plate-and-frame Solution/diffusion Cellulose acetate thin spiral wound, plate-and-frame Sources: (Stephenson et al., 2000 and Wagner, 2001) The applications of membranes depend on their specific types. Figure 2.5 presents major applications of the respective types of membranes. Figure 2.5 Application size range of membrane filtration process (Scott and Huges, 1996)
Based on configurations of operating a filtration process, membrane processes can be classified into two types as the followings: • Dead-end filtration: The most basic form of filtration is dead-end filtration. The complete feed flow is forced through the membrane and the filtered matter is accumulated on the surface of the membrane. The dead-end filtration is a batch process as accumulated matter on the filter decreases the filtration capacity, due to clogging. A next process step to remove the accumulated matter is required. Dead-end filtration can be a very useful technique for concentrating compounds. Figure 2.6 Dead-end mode and its configuration for tubular ceramic membrane
Cross-flow filtration:
With cross-flow filtration a constant turbulent flow along the membrane surface prevents
the accumulation of matter on the membrane surface. The membranes used in this process
are commonly tubes with a membrane layer on the inside wall of the tube. The feed flow
through the membrane tube has an elevated pressure as driving force for the filtration
process and a high flow speed to create turbulent conditions. The process is referred to as
"cross-flow", because the feed flow and filtration flow direction have a 90 degrees angle.
Cross-flow filtration is an excellent way to filter liquids with a high concentration of
filterable matter.

Figure 2.7 Cross-flow membrane filtration
Permeate flux:

The capital and operating costs of membrane systems typically scale directly as a function
of the membrane permeate flux. Where it is possible to move more water across a unit area
of membrane per time unit, less membrane area will be required to provide for the design
flow. This results in a lower cost for membrane modules, peripheral piping and pumps,
monitoring equipment, skids, foundations, and buildings. The cost of replacing membranes
as reflected in the membrane life is often the single largest component of operating cost.
By reducing the amounts of membrane area to be replaced, a higher permeate flux also
corresponds to a lower operating cost. Thus, permeate flux and the factors that influence it
are central considerations in determining membrane performance and cost.

Transmembrane pressure (TMP):

Transmembrane pressure (TMP) is defined as the difference between the average
feed/concentrate pressure and the permeate pressure. It is effectively the driving force
associated with any given flux for low-pressure membranes. The TMP of the membrane
system is an overall indication of the feed-pressure requirement and it is used with the flux
to assess membrane fouling (WEF Press, 2006).
It was investigated that there is a correlation between micro-particle concentration and
TMP of ceramic membrane filtration. Recently, researchers have been researched on a
hybrid ceramic microfiltration using the effluent from a conventional rapid sand filtration
process as the feed water. A clear relationship between micro-particale concentration and
TMP was pointed out. It would suggest a significant effect of the flocculation on the
filterability in the monolith channel. The micro-particles, larger than 1 µm in the shear
field, are subjected to a lift force such as the lateral migration and shear-induced diffusion
which are proportional to square and cubic power of the equivalent particle diameter,
respectively (Watanabe et al., 2007).

Figure 2.8 Correlation between TMP and micro-particle concentration (Watanabe et al., 2007)
Membrane fouling:

If membrane separations are to be economical, high fluxes are required. Unfortunately,
most membrane separations exhibit flux decline as a result of fouling. Fouling may be
defined as the deposition of matter on or in the membrane such that the membrane
performance is altered. During the flow of a clean liquid through a porous layer, the
resistance is constant and the flow rate is constant for a given pressure difference. But
when the liquid contains suspended particles, the resistance of the porous layer will
progressively increase as the particles accumulate on it, resulting a corresponding drop
in the permeate rate at a constant pressure drop. Although fouling is very complicated, it
can be classified into two types (Davis, 1992):
(1) Internal membrane fouling: The attachment of material within the internal pore structure of the membrane or directly to the membrane surface due to adsorption, precipitation, pore plugging, particulate adhesion, etc. (2) External cake fouling: The formation of a atagnant cake layer of the membrane surface due to concentration polarization as the material being filtered is carried to the membrane by permeate flow and is then rejected by the membrane. Based on fouling materials, membrane fouling can be distinguished by four types: (1) Inorganic fouling/scaling is caused by the accumulation of inorganic precipitates such as metal hydroxides, and "scales" on membrane surface or within pore structure. Precipitates are formed when the concentration of chemical species exceeding their saturation concentrations. (2) Particle/colloids fouling in most cases, particles and colloids do not really foul the membrane because the flux decline caused by their accumulation on the membrane surface is largely reversible by hydraulic cleaning measures such as backwash and air scrubbing. A rare case of irreversible fouling by particles and colloids is that they have smaller size relative to membrane pore size. Therefore, those particles and colloids can enter and be trapped within the membrane structure matrix, and not easily be cleaned by hydraulic cleaning. (3) Microbial fouling: The formation of biofilms on membrane surfaces. Once bacteria attach to the membrane, they start to multiple and produce extracellular polymetric substances (EPS) to form a viscous, slimy, hydrated gel. EPS typically consists of heteropolysaccharides and have high negative charge density. This gel structure protects bacterial cells from hydraulic shearing and from chemical attacks of biocides such as chlorine (Syed et al., 2000). (4) Organic fouling: Organic fouling is profound in membrane filtration with source water containing relatively high natural organic matters (NOM). Surface water (lake, river) typically contains higher NOM than ground water, with exceptions. For source water high in NOM, organic fouling is believed to be the most significant factor contributed to flux decline (Mallevialle et al., 1996; Lahoussine et al, 1990).
Membrane cleaning:


Fouling including irreversible and reversible fouling is the major disadvantage of
membrane filtration. Two main techniques, backwashing and chemical cleaning, are
developed for overcoming fouling problems.
Membrane backwashing: Backwashing of the membrane is a common technique used with low-pressure, hollow-fiber membranes to maintain the design operating flux of the system. Backwashing removes the layer of contaminants retained on the feed side of the membrane that have accumulated during the previous operating cycle. This fouling layer presents additional hydraulic resistance to fluid flow across the membrane. To overcome this additional resistance, elevated TMPs are required, which results in increased operating costs. The frequency of backwashing events should be optimized to maintain low TMPs throughout normal operating cycles. Because filtrate production stops when a unit is backwashed, increasing the frequency or duration of backwashes reduces the net daily production of water. Further, most systems require filtrate for all or a portion of the backwash water so that the use of increased volumes of backwash water reduces the overall recovery of water. When the total daily backwash time and volume exceed the design values, overall system production will drop below design (WEF Press, 2006). • Membrane chemical cleaning: Regular backwashing is very effective in removing a significant portion of contaminants retained on the feed side of the membrane. However, a fraction of these contaminants remains on the surface of or embedded in the membrane. Periodic chemical cleaning will be required to recover a portion of the productivity not recovered by normal backwashing subsequences. Chemical cleaning procedures vary with membrane manufacturer, membrane configuration, membrane material, type of suspected foulant, and degree of fouling. Procedures for chemical cleaning range from a prolonged backwashing cycle enhanced by chemical addition to extended periods of immersion in a chemical bath. Chemicals typically used in chemical cleanings include acids, bases, and surfactants. Chlorine and chloramines-resistant membrane may also be disinfected through the addition of free or combined chlorine residuals. Before addition of any chemical to the membrane system, compatibility and recommended concentrations must be verified by manufacturer. Flux Irreversible
fouling

Backwashing
Chemical
cleaning
Chemical
cleaning

Backwashing
Figure 2.9 Schematic of partial restorations of transmembrane pressure by backwashing
and chemical cleaning of MF membranes (Mallevialle et al, 1996)
2.3.2 Advantages and disadvantages of membrane filtration

Table 2.5 presents major advantages and disadvantages of membrane technology in
practical situations. The noticeable advantages of the membranes are that they overcome
many limitations of conventional technologies in water and wastewater works. The major
disadvantage of membranes is fouling problem.

Table 2.5 Advantages and limitations of membrane filtration
Advantages Disadvantages High pathogens removal rate High capital cost High natural organic mater removal rate (when Complicated operation enhanced by pre-treatment) Small area requirement (compact) Skilled and trained human power requirement Save chemical utilization Pressure limitations Low energy consumption (low membrane pressure) Problems related to fouling
2.4 Ceramic microfiltration for surface water treatment

2.4.1 Development of the ceramic microfiltration for surface water treatment
Overcoming some problems generated from conventional water treatment system, the
membrane technology has been being known as the good alternative. Membrane
technologies have been developed in the recent decades. One of type of membrane material
is ceramic. Ceramic membranes are made of mainly metal oxides like aluminum oxide α-
Al2O3 and γ- Al2O3, titanium dioxide TiO2, zirconium dioxide ZrO2, silicon dioxide SiO2,
silicon carbide SiC, etc. By improvement of prescriptions, development of new concepts,
use of new technologies like nanotechnology and increase of the production of ceramic
membrane there is an enormous development. For large scale water treatment, the ceramic
microfiltration is very interesting as pre-treatment step in the production of drinking water
from surface water (Doeke et al., 2006)
Ceramic membrane has been applied in drinking water treatment for approximately 20
years (Milton et al., 2006). Although the ceramic membrane have just introduced since
1990s in Japan, it was applied effectively in the reality. Based on the mechanisms of the
operation, as other membrane technologies, the ceramic membrane can be dived into two
types: cross flow and dead-end. In the world, almost all of developed countries (USA,
Norway, Turkey, etc.) use the cross flow technology. However, Japan uses not only this
kind of ceramic membrane but also researched and designed many dead-end ceramic
membrane system. This makes Japan be well-known in this technology.
a) b)
Figure 2.10
Ceramic membrane products: a) Ceramic membrane element; b) The structure
of ceramic membrane (Milton et al., 2006 and http://www.jiuwu.com, 2007)
Figure 2.11 Structure of ceramic NGK membrane (NGK Insulators, Ltd., Japan, 2007)

2.4.2 Enhanced ceramic microfiltration for surface water treatment
Ceramic microfiltration is enhanced by coagulation:

Recent researches show that the hybrid coagulation/membrane system for water treatment
has many advantages in term of the good quality of treated water: independence from the
quality of raw water, organic matter removal including microbiological removal,
particulates removal, etc. Beside, it also introduces other important advantages for
feasibility in transferring technology such as fully automatic operation, small area
requirement, and flexibility in system enlargement. In addition, this advanced technology
helps to improve and stabilize both polymeric and membrane operation performance.
Andre Lerch, et al. (2004) conducted a study to determine the optimum conditions in
coagulation for a hybrid system in which unit test was built. This pilot is a combination of
a Jar test and a membrane filtration. The optimum conditions for coagulation of different
coagulants such as dosage of coagulant, PH and energy consumption in the combination
with the membrane were evaluated in the aspect of the influence on membrane operation
performance. The experiment shows that the best coagulant dosage is 1.5 – 2 mg/L as Al3+
and 20 mg/L as PACl and the maximum permeability for the coagulated/flocculated Ruhr
River Water is 80 L/m2.h. The results were also mentioned as turbidity and particle
removal versus time. A very high efficiency in turbidity removal (the turbidity of the
filtrate is less than 0.004 NTU while this of feed water is more than 1 NTU), and 4 log
removal rate in the size rang of bacteria was confirmed by this experiment. Based on the
experiments, there are some recommendations for enhanced operation were proposed such
as: overcoming the fouling by base chemical enhanced backwashing after normal
backwashing and acid chemical enhanced backwashing, the design of mixing tank is
important to distribute well coagulation for a better efficiency, the dosage of coagulation is
also very important and need to be adjusted for removing organic pollutants better.
On the other hand, the influence of pH on coagulation/flocculation used for enhancing
microfiltration was investigated by Meyn et al., 2006. The study has evaluated the
removal of natural organic matter (NOM) and color of surface water as functions of
coagulant dosage and the pH. In each train of the plant a different coagulant dosage as
applied and kept constant for a period of the experiments. Polyaluminum chloride (PACl)
was dosed in 5, 3 and 2 mg Al/L respectively. The pH value is fixed for one week of the
experiment that mean the pilot was running with constant conditions for the duration of
one week foe each examined pH value. Mixing conditions were constant during all
experiments. A rapid mixing was applied at 192 rpm with the hydraulic retention time
(HRT) of raw water of 6.7 minutes, and then a slow mixing is conducted at the speed of 53
rpm and the HRT of 20 minutes. The ceramic membrane used was operated in dead-end,
inside-ouside mode with a pore size of 0.1 µm. The study pointed out that DOC removal
greater than 80% at a pH value of 5.7 and dosage of 3.2 mg Al/L could achieved. DOC
removal rate was achieved only at 50% if the dosage down to 2 mg Al/L at optimum pH
value (Meyn et al., 2006).

Not only affecting to the pollutants removal rate, coagulation and flocculation conditions
have had effects to the operation of the ceramic membrane. A lower pH range results in a
higher rate of increase in TMP, but less TMP recovery after a hydraulic backwash.
However, this problem dose not matter once a chemical cleaning could recover most of the
membrane performance. Whereas, a higher pH resulted in a lower rate of TMP increase,
but better TMP recovery that was at low pH (Milton et al., 2006).

Ceramic microfiltration is enhanced by powdered activated carbon (PAC) adsorption:

Further more, researches also pointed out the high removal rate of organic carbon by
ceramic membrane enhanced by powered activated carbon (PAC). PAC added improves
the efficiency of ceramic membrane. The turbidity also was improved by PAC added and
shown that the satisfied removal with PAC addition less then 50 mg/L. Effects of PAC size
to performance of the pilot were evaluated: PAC with the size of 1µm has higher removal
rate in comparison with this of 10µm. And only 1/3 of PAC with size of 1µm is good
enough to have the equivalent removal rate of PAC of 10µm. (Kanto et al., 2000).
In addition, researchers recently showed that the hybrid adsorption-membrane filtration
processes are getting more attention because of its advantages such as high throughputs
and low energy cost (Takizawa, et al, 2006). In order to get fully utilized adsorption
capacity, a noble hybrid powdered activated carbon combined with ceramic microfiltration
membranes (PAC-MF) was developed for advanced water treatment (Khan et al., 2002). A
high concentration, i.e. 20 g/L, of PAC was suspended in the membrane separation reactor
in order to maintain high DOC removal rates. In the previous study, a pilot-scale PAC-MF
system had been operated for one year without withdrawal and replacement of PAC with
an average DOC removal rate of about 80 percent (Kim et al., 2006; Oh et al., 2006). PAC
cake layer fouling, however, was found to be a major problem while other types of
membrane fouling, such as adsorption of organics on the membrane and membrane pore
blocking, were significantly reduced because of very high removal rates of organic matter
and metals from raw water (Zhao et al., 2005). The prevention of cake-layer formation was
found to be very important to operate this process without replacement of PAC and
membrane chemical cleaning. The effectiveness of air-scouring and backwashing on the
prevention of cake-layer fouling was investigated using two PAC-MF pilot plants with
different sizes of PAC. It was confirmed in previous experiments that the other kinds of
resistance, e.g. pore blocking, were significantly lower than the PAC cake resistance
(Takizawa, et al, 2006). Khan et al. (2002) conducted hybrid PAC-MF experiments, and
revealed that PAC particle sizes decrease with time due to particle breakage caused by
severe collision and friction, facilitating the cake formation.

Three factors affecting the membrane fouling in a hybrid PAC-membrane processes were
previously reported; namely, natural organic matter, metal ions and particulate matter.
Vernhet et al.(1997) reported that membrane pore blocking and cake layer may be caused
by polar interaction and electrostatic forces between the membrane and PAC. Multivalent
metals, such as Ca2+, Mg2+, Fe3+, electrostatically attract and neutralize the negative
charges of PAC particles and membrane surfaces, forming intra- and intermolecular
interaction with organic molecules by bridging free functional groups, thus promoting
aggregation and deposition of PAC cake layer (Yiantsios et al., 2001; Yuan et al., 1999).
Fan et al. (2001) found that natural organic matter hardly adsorbable to PAC because of
larger molecular weight (MW) or its hydrophilic nature may cause membrane fouling.
Suspended solids, especially colloids and fine particles, are adsorbed not only on PAC, but
on and within membrane surface, causing membrane pore blocking and cake layer (Pienta
et al., 1998).

Ceramic microfiltration is enhanced by chemical backwashing (ECBW):

Although ceramic membrane filtration is already combined with pretreatments such as
coagulation and PAC, the irreversible fouling still can not be eliminated completely. This
reality requires a backwashing process. The strength of backwashing is very important to
overcome fouling. With the same flux, shorter interval of backwashing makes a higher
transmembrane pressure recovery (TMP). In addition, if the volume of water used for
backwashing per unit of membrane surface area increase, TMP recovery will be increased.
Using backwashing enhanced by acid, the volume required of backwashing water is
reduced and the TMP was reached at high value (TMP = 99.2% in comparison with 98.5 %
of normal backwashing) (Yonekawa et al., 2006).

In conclusion, the effectiveness of ceramic membrane filtration can be enhanced by
pretreatment such as coagulation, PAC as well as by chemical backwashing. When
enhanced, the hybrid ceramic membrane filtration will satisfy quality of treated water and
technical conditions for operation.

2.5 Membrane technology for municipal wastewater reclamation
Membrane processes are regarded as key elements of advanced wastewater reclamation
and reuse schemes and are implemented in a number of prominent schemes world-wide
including artificial groundwater recharge, indirect potable reuse as well as industrial
process water production.

There is a clear trend for new larger scale plants to use dual membrane processes and
MBRs. Currently, membranes are applied to the treatment municipal wastewater mainly in
MBRs and in MF/UF filtration of effluent, eventually followed by RO. An alternative to
the "end of- pipe" treatment is the application of MBRs as a straight combination of
biological treatment processes and biomass retention by MF or UF membranes. MF and
UF employed in tertiary wastewater treatment are dedicated to remove suspended solids,
organic matter, and for disinfection, recovering a high quality final effluent with various
possible uses. MF and UF technologies both in effluent filtration as well as in MBRs are
also suitable as pretreatment to NF or RO. Such physical barrier processes are attractive in
wastewater treatment because any technology employed must be able to produce reused
water of uniform quality, regardless of the normally wide variation in the concentrations or
physicochemical properties of the wastewater influent (Metcalf & Eddy; Adin & Asano; E. Alonso et al., 1991, 1998, 2002) and the absence of chemicals addition is of economic and ecological benefit. Conductivity and dissolved oxygen content remain unaffected by both MF and UF treatment. The decolouration due to UF is more noticeable than that due to MF. Elimination of detergent and phenol concentrations of 40% were achieved by filtration. Fe, Zn, AI, Cr, Cu and Mn can also be significantly eliminated by filtration, not only by direct precipitation as hydroxides or phosphates, but also through association of metals to suspended matter and macromolecules. It has been reported that microbial pollution is totally eliminated by MF and UF, explicable due to bacterial sizes being higher than pore the field of wastewater treatment, UF cannot be considered a complete barrier to bacteria. Positive coliform results were obtained when membrane systems were operating. The passage of bacteria across membranes may be attributable to the following: imperfections in the membrane surface; degradation of the membrane by bacterial enzymes or other materials; or inferior packing of membrane modules or elements. Another possible reason for the detection of bacteria in membrane filtrate is the introduction of bacteria from exterior sources such as contamination of the permeate tank. Also, because nutrients are not eliminated from the water, re-emergence is best avoided through a disinfection process (Bourgeous et al., 2001). MF and UF are effective in eliminating many wastewater contaminants associated with suspended matter. Elimination of viruses and nematodes accompanies to some extent removal of suspended matter. It has been demonstrated that viruses (28 nm) can be effectively retained by a (0.2 µm nominal pore size) MF membrane. Virus retention is enhanced at lower TMP, in the presence of shear and in the presence of biomass/turbidity. The latter both provides extra surface area for adsorptive removal and forms a secondary filter-cake layer on the membrane. Coupled with powdered activated carbon (PAC), UF can be used to treat water contaminated by dissolved organic matter and micro-pollutants. In PAC-membrane processes, PAC is added to the recirculation loop of the membrane systems. Contaminants (including natural disinfection byproduct precursors) are adsorbed onto the activated carbon particles, which are then separated from water by either UF or MF (Zhou & Smith, 2002). Because the quality of wastewater influent to MF and UF processes has a high influence on final effluent quality, permeated water might be suitable for unrestricted irrigation purposes, as it is high in nutrients (N and P practically insensitive to filtration), low micro-pollutant and microorganics content, and exhibits favourable inorganic ratios (Alonso et al., 2002). MF may provide significant cost savings and water quality improvement when replacing conventional lime pre-treatment for RO (Lazarova et al., 2003). In addition, MF can reduce microbial contamination and thereby reduce the rate at which fouling and biofilm formation occurs in subsequent RO. Although are unlikely to pass through an RO membrane, leakage is possible (via glue strips or permeate seals) in spiral-wound elements. Thus, there is an incentive for virus removal at the pretreatment stage. Use of capillary membranes as a pre-treatment for RO feed has enabled operation of cellulose acetate membranes at lower feed pressure and the production of water of lower salinity (Wilf & Ait, 2000). Anti-scalant addition is intended to minimize chemical precipitation on the RO membrane surface. It has also been reported as deemed necessary that MF effluent be dosed with suiphuric acid for pH adjustment to minimize hydrolysis of cellulose acetate
RO membranes. It is not uncommon for RO membranes in water reclamation applications
to experience an average annual flux decline of 25-30%, even with frequent membrane
cleanings. It should be noted that membrane rejection properties are susceptible to change
after cleaning.
2.6 Advantages of hybrid ceramic membrane filtration
Compared with normal traditional filters and polymer or organic membranes, ceramic
membrane filters has many unique advantages as the followings (Doeke et al, 2006):
- Excellent resistance to acid/alkaline and oxidation chemicals - Solvent stability - High permeate production at relative low pressure - High thermal stability - Fine separability with narrow pore size distribution - Excellent mechanical and abrasive resistance - Extremely long work life compared with polymeric membrane - High recoveries - Hydrophilic membrane surface - Easy to be cleaned and sanitized with short backwash interval (with air flush) chemical cleaning When a ceramic membrane filtration is enhanced by pre-treatment processes such as PAC adsorption and coagulation-flocculation, the system is called as a hybrid ceramic microfiltration. Not only the hybrid ceramic microfiltration has all above advantages of a ceramic membrane, but also it has some other special things such as very high quality of permeate, prolonged filtration cycle by reducing biological and colloidal fouling, etc. Although the ceramic membrane can be applied in both surface water treatment and municipal wastewater reclamation, literatures on practical situations are very limited. In addition, in many papers they researched only on some specific feed waters with limited scenarios. The functions of PAC adsorption and coagulation-flocculation combined with CMF should be clarified more deeply, especially in ambient conditions. Based on gaps of recent researches and the need of application of the advanced technology, the study was conducted to contribute to achievement of a hybrid CMF system for treating surface water and reusing municipal wastewater. In conclusion, it was completely possible and important to investigate more attractive roles of a hybrid CMF system in the field of water and wastewater works. Chapter 3
Methodology
3.1 Introduction

Based on the literature review and realities requirements, this study was conducted with
ceramic membrane pilot in which dead-end mode of the microfiltration was used. The
microfiltration using CMF would be enhanced by pre-treatment processes such as
coagulation and adsorption depending on specifically operational scenario. The CMF pilot
has major units that were made in Japan and almost all of processes of the pilot are
controlled automatically. The study was divided into main stages including different
experiments. Materials, experimental set–up, monitoring, and analytical methods are
expressed in this chapter.

3.2 Materials
Materials for the study consist mainly of three parts, namely: (1) feed water including
synthetic water, surface water, and municipal wastewater; (2) chemicals for operation and
analysis and; (3) hybrid ceramic membrane filtration system.

3.2.1 Feed water

The study was carried out in two stages. The first stage was studied with synthetic water.
Meanwhile, surface water (AIT pond water) and municipal wastewater (AIT wastewater)
were used for the second stage.
Synthetic water:

Real surface water and wastewater have a variety of different components including
inorganic and organic matters. This may causes many operational problems to the pilot
system during experiments with these feed water sources. And, it is not easy to find out
ways for solving operational problems within a limited time. Therefore, a buffer studying
stage with synthetic water should be conducted before deploying any experiment with real
surface water and municipal wastewater sources. The objective of this stage was to find out
operationally generated problems of the CMF system and overcoming solutions. In addtion,
by doing the first stage, it was very useful for next stage with surface water and municipal
wastewater in terms of skilled working, time saving, problem avoiding and other
experiences as well.
To achieve the mentioned objectives of the stage, characteristics of synthetic water were
ensured for getting intermediate lessons. The useful conclusions from this experiment
would be applied to avoid possible problems in treatment of surface water and municipal
wastewater. Therefore, the synthetic water should have a similar characteristic on major
components. The major components were not only pollutants interested in evaluating
removal rate, but also elements could affect negatively to the treatment process. In addition,
this similarity is not only about constitution but also on range of concentration of typical
parameters. In the experiment, synthetic water was prepared using tap water and Kaoline
clay. Compositions of the synthetic water were the followings:
Table 3.1 Major characteristics of synthetic water
Micro-particle, 5-15 µm Count/mL 33,100 – 339,040
Surface water (AIT pond water):

The AIT pond water was used as a surface water source for the study. The pond water was
pretreated by a raw mesh screen, and then stored in a storage tank. This feed water was
taken and analyzed to find out components before and during all experimental runs. The
following table gives major characteristics of the AIT pond water used in the study.
Table 3.2 Major characteristics of AIT pond water
Micro-particle, 5-15 µm Count/mL 1,230 – 11,448 Municipal wastewater (AIT wastewater):

The domestic wastewater of AIT campus was used as a municipal wastewater source for
the study. The municipal wastewater was also pretreated by a raw mesh screen before
stored in the feed tank of the CMF system. Characteristics of the wastewater were analyzed
in laboratory to find out components before and during every experiment The followings
are major characteristics of AIT wastewater used in the study.
Table 3.3 Major characteristics of AIT wastewater
3.2.2 Hybrid ceramic microfiltration system

System set-up:

Main material of the study was a hybrid ceramic microfiltration system in which pre-
coagulation process was combined to enhance efficiency of ceramic membrane filtration.
In addition, backwashing equipment was an important unit accompanied to automatically
clean fouling inside the channels of the membrane. Other sub-equipment such as feeding
tank, chemical tanks, pumps, pressure gauge, and etc. were units constituting the pilot as
well. The hybrid ceramic mirofiltration system is expressed in the figure 3.1 and figure 3.2.
Raw water was pumped to the system by a primary pump. After screened by the mesh
screen, it came to the feed tank. Other pre-treatment processes could be used depending on
each detailed experimental run. The raw water was continually pumped to the coagulation
unit. In this unit, coagulant poly aluminum chloride (PACl) was supplied with an optimum
dosage determined by the Jar test in part 3.7.2. After coagulated, raw water was pumped
through flocculation tube before coming to the ceramic membrane. Inside the flocculation
tube, flocculation occurred and the process helps to enhance pollutant removal efficiency
of ceramic membrane filtration process. Coagulated - flocculated raw water then was
transferred to inlet channels of the ceramic membrane, filtrate went to the pressurized tank
before coming out to the filtrate tank. Backwashing process was operated automatically
after each two hours (in synthetic and surface water treatment) or 40 minutes (in
wastewater treatment) of filtration for reducing fouling. The backwashing process was
conducted at 500 kPa using filtrate enhanced by NaClO. After that, air flushing at 200 Kpa
was conducted also. Chemical cleaning process was done to overcome irreversible fouling
when the transmembrane pressure (TMP) reached 100 to 120 kPa.
RAW WATER SOURCE CERAMIC MEM
FLOCCULATION TUBE COAGULATION TANK BACKWASH WASTEWATER
CERAMIC MEMBRANE
L. A. Tuan
Prof. C.Visvanathan FILTRATION SYSTEM (CMF)
Date: 18/06/2007 SYSTEM SET-UP
ASIAN INSTITUTE OF TECHNOLOGY
FIGURE 3.1
Figure 3.1 Diagram of the system set-up
Pressurized tank Ceramic membrane filter Coagulation unit Feed raw water tank Flocculation tube Figure 3.2 Microfiltration system
Each of equipment of the CMF system has some fixed specifications and functions in the treatment process. The followings are descriptions and specifications on major units of the Coagulation unit:
Coagulant feeding pipe
Level sensor
Impeller
Storage section
Figure 3.3 Coagulation unit
The coagulation unit severed as a pre-treatment process for enhancing pollutants removal rate, especially for removing more effectively natural organic matter in raw water. Effectiveness of the coagulation process depends upon some factors such as pH, coagulant type, and coagulant dosage. With a range of raw water is nearly neutral, and used coagulant is PACl, the coagulant dosage was the most important factor affecting to the pre- treatment process. Therefore, jar test was conducted frequently to find out optimum dosage for coagulation process, and this is expressed more clearly in part 3.7.2. The coagulation unit was a rectangular tank including two compartments. The first compartment was to store raw water and equalize its flow rate, so it had an inlet pipe and two over flow drains. This compartment ensures the flow rate supplied to the next compartment (mixing section) was always stable. The coagulant PACl was added into the mixing section. The followings are some specifications of the coagulation unit: Table 3.4 Specifications of the coagulation unit (NGK Insulators, Ltd.)
Storage tank volume Coagulant dosing rate Determined by Jart test Retention time in mixing tank When flux is 1.2 m3/m2/d Coagulation mixing speed Designed range: 300 – 450 rpm

Ceramic membrane filter module:

Being known as a feature unique to Japan, the most advanced dead-end type monolith
ceramic membrane filtration system was developed in the early 1990s, and then it has been introduced in water purification since 1996. Nowadays, the type of ceramic membrane has been applied in more than thirty water treatment plants in Japan (Kanto, et al., 2000). Almost studies on membrane technologies for surface water treatment in Japan were conducted with ceramic membrane filtration. Likewise, in this study ceramic membrane module was the most important unit of the pilot and it was operated at dead-end mode. In the study, ceramic membrane filter was fixed by a module casing (a stainless steel tube). The ceramic membrane has the pore size of 0.1 µm and it was installed vertically. The ceramic membrane has 55 channels and each channel has inner diameter of 2.5 mm. Raw water come into these channels and filtrate went outside. Raw water was pumped in the up flow from the bottom end of the ceramic membrane. Filtrate comes out from the upper end, concentrate flow is discharged downward through backwashing process after every two hours of filtration. When the membrane got fouling at 100-120 kPa of TMP, it was taken out from the module casing to carry out chemical cleaning process. Figure 3.4 is to describe more detail on structure of the ceramic membrane module, and specifications of the membrane are expressed in the table 3.4. Figure 3.4 Ceramic membrane module
Table 3.5 Specifications of ceramic membrane unit (NGK Insulators, Ltd.)
Monolith (multi-channel) Dead-end mode, inside-outside flow Dimension: D x H D: outer diameter, H: length Nominal pore size Effective surface area Filtration flow rate (backwash interval)

Backwashing equipment:

Backwash was an important process to overcome fouling of the CMF system. It helps to
limit the continuous accumulation of solids on the surface membrane area. Although the backwash process could be implemented manually or automatically, in this study, manual backwashing is used only in optional case and special cases such as after a few days that membrane filtration equipment has not been operated. The normal backwash process was carried out automatically using pressurized air combined with pressurized liquid. The backwash equipment includes two main parts: air compressor and pressurizing tank. The of operation of the process can be divided into two different stages, one is backwashing using pressurized filtrate combined with air in the pressurizing tank and another one is blow- down using pressurized air only. The maximum pressure of backwash was fixed as 500kPa and this one of blow-down was 200kPa. Pressure and flow of liquid and air were controlled by automatic valves. Filtrate
Pressurized tank
Air compressor
Figure 3.5 Equipment and illustrated flow diagram of backwash process
Table 3.6 Specifications of backwash unit (NGK Insulators, Ltd.)
AC100V, 50Hz, 200W, 0.69 MPa (Max.) Stainless steel, fixed interval 2 hours pressure 500 kPa pressure 200 kPa

Other equipment:

Other equipment such as feeding tank, chemical tanks, pumps, pressure gauge, and etc. are
expressed in terms of their functions and technical characteristics as the following table.
Table 3.7 Specifications of sub-units of the CMF pilot (NGK Insulators, Ltd.)
Specification Material Removal of raw material of Vertical flow direction raw water source Storage of raw water Supplies pre-coagulated AC100 V, 50 Hz, 20 W, 38 water to the ceramic L/min (max.), 1 MPa Supplies coagulant for AC100 V, 50 Hz, 20 W, coagulation process 38l/min (max.), 1 MPa Supplies chlorine solution AC100 V, 50 Hz, 20 W, 38l/min (max.), 1 MPa To feedback information on Electrode rod type level for automatically controlling the operation To indicate flow rate of Float type, 50-500 ml/min Poly-amid To indicate TMP of the Maximum level of 200 kPa Others: coagulant Sub-units of the system tank, chlorine tank, filtrate tank, PAC tank, control panel, valves, etc.
3.2.3 Chemicals preparation for experiment
Chemical agents for coagulation process:

Coagulant for experiment was Poly Aluminum Chloride (PACl). The efficiency of
coagulation is highly affected by dilution and dosage of coagulant. With the commercial
PACl solution 10%, the maximum efficiency of coagulation would be achieved at dilution
factor of 100 times (NGK Insulator, Ltd. Japan, 2006). For the experiment, dilution and
dosage of coagulant were calculated and prepared carefully, and then setting up dosing
pump was taken care as well. After preparing 25 liters of coagulant PACl solution by
diluting the initially commercial product 100 times, the prepared PACl solution was used
within one week at the optimum dosage that had been being determined by Jar test.

Coagulant dosage:
As above, after diluted 100 times, the prepared coagulant solution had concentration of 1.0
g/L (1000 mg/L). The prepared coagulant solution was added into coagulation tank by a
dosing pump, and the calculation for setting-up the pump and at what level is as the
following:
- PACl dosage that would be used is x mg/L (determined from Jar test, part 3.7.2). - 1 m L of the prepared coagulant solution had 10 mg PACl. - Flow rate of permeate: Q2 = 150 ml/min. - Q1 (mL/min) is the flow rate of PACl added in order to get the above Q1*C1 = Q2*C2 ⇒ Q1 *1000 mg/L = 150 ml/min *x mg/L ⇒ Q1 = 150*x/1000 (ml/min)
In short, with coagulant concentration of 1000 mg/L and dosage of x mg/L, the flow rate of
dosing pump needed is Q1 (was calculated as above), and then pump configuration (with
stroke length of 80) would be set to have the pump flow rate of Q1.

Procedure for coagulant preparation:

The procedure for coagulant preparation was as the following, and the prepared coagulant
solution was used within one week after preparation.
De-ionized water (DW) of 20 liters Storage tank with volume of 25 L Thoroughly mixing Fill DW up to 25 liters Thoroughly mixing 25 L of prepared coagulant Figure 3.6 Procedure for coagulant preparation

Chemical agents for chemical enhanced backwashing process:

In the study, NaClO solution was used for enhancement of backwasing. The followings are
about preparation of the solution for the process.

Choosing dosage for the pump:

- The NaClO x % solution has 1000*x mg of PACl in each liter - NaClO dosage that will be used is 10 mg/L. - Flow rate of permeate: Q2 = 150 ml/min. - Q1 (mL/min) is flow rate of NaClO added in order to get the above concentration: Q1*C1 = Q2*C2 ⇒ Q1 *1000*x mg/L = 150 ml/min *10 mg/L ⇒ Q1 = 1500/(1000*x) = y (ml/min) Based on the relationship between flow rate and stroke rate of the pump that was fixed by the producer, y = 5 (ml/min) was chosen with the stroke rate of 50. Therefore, x = 0.03, and it is needed to prepare NaClO 0.03 % solution. NaOCl solution 0.03%: Prepare one liter NaOCl solution 0.03% (300 mg/L) from a commercial NaOCl solution 10% (100,000 mg/L) by following equation: C1*V1 = C2*V2 ⇒ V1 (L) * 100,000 (mg/L) = 300 (mg/L) * 1 (L) ⇒ V1 = 0.003 L = 3 mL.
⇒ To prepare NaOCl solution 0.03%, take 3 mL of commercial NaOCl solution 10% and
adding distilled water (DW) up to one liter to have one liter of NaOCl solution 0.03%.
⇒ For operation of the pilot, taking 75 mL of commercial NaOCl solution 10% and adding
distilled water up to 25 liters to have 25 liters of NaOCl solution 0.03%.

Chemicals preparation for chemical cleaning process of the membrane:

When the ceramic membrane filter was fouled in which the pressure gauge indicated at 100
- 120 kPa, it was required to take out the ceramic membrane for chemical cleaning process.
To do the process, a preparation for chemical solutions was carried out before conducting
soaking. The followings are procedures for preparing needed solutions:

Preparation of citric acid solution 1%:

Weigh 10 gram of dried citric acid Dissolve by DW in a 250 mL flask Dilute up to 1 liter using DW in a volumetric tank of 1 L One liter of citric acid 1% Figure 3.7 Procedure for preparation of 1%citric acid solution
NaOCl solution 0.3%: Preparing one liter NaOCl solution 0.3% (3000 mg/L) from commercial NaOCl solution 10% (100,000 mg/L) by following equation: C1*V1 = C2*V2 ⇒ V1 (L) * 100,000 (mg/L) = 3000 (mg/L) * 1 (L) ⇒ V1 = 0.03 L = 30 mL. ⇒ Taking 30 mL of commercial NaOCl solution 10% and adding distilled water up to one liter to have one liter NaOCl solution 0.3%. H2SO4 solution 0.05M, pH = 1.5: Preparing H2SO4 solution 0.05M from H2SO4 solution of 96% by using calculation: H2SO4 solution 96%: 960 gram H2SO4 in one liter of the solution ⇒ 960/98 = 9.796 mole H2SO4 in 1000 milliliters of the solution ⇒ 0.05 mole of H2SO4 in 0.05x1000/9.796 = 5.1 mL H2SO4 solution 96%. Procedure for preparation of the solution was as the following figure: Place 200 mL DW into volume metric tank of 1 liter Pilpet 5.1 mL H2SO4 solution 96% and put it into the tank that already Dilute up to 1 liter using DW in the volumetric tank of 1 liter One liter 0.05M H2SO4 solution Figure 3.8 Procedure to preparation of 0.05M H2SO4 solution


3.3 Experimental set-up

To achieve the proposed objectives of the study, three seniors were used for setting-up
experiment as table 3.8. Parameters shown in table 3.9 were monitored and analyzed.
Simplified flow diagrams and technical diagrams of the scenarios are drawn in figures 3.9
and 3.10.
Table 3.8 Experimental set-up for differently operational scenarios
Operational scenarios Operational descriptions Scenario 1:
Direct CMF and backwashing To evaluate the direct filtration of Raw water comes to the ceramic membrane filter directly. This scenario is very important to enhanced by NaClO. Chemical the ceramic membrane and Filtrate goes to the filtrate tank. Back washing interval of 2 evaluate non-enhanced CMF cleaning by citric acid solution compare results gained between the hours (in synthetic and surface water treatment) or 40 minutes system (not hybrid CMF system) 1% (for 24 hrs) and NaClO scenario and other scenarios. To (in municipal wastewater treatment) was set up automatically. on removing pollutants and it is 0.3% (four 24 hrs) investigate operational problems The backwashing enhanced using NaClO with dosage of 10 the basis to propose whether a and ways to overcome them. mg/L (in synthetic and surface water treatment) or 15 mg/L hybrid system is necessary. (in MWW). When TMP reached at 100-120 kPa, CMF fouling would be solved by chemical cleaning process. Scenario 2:
Coagulation and Flocculation + To evaluate effectives of a hybrid Raw water goes to the coagulation unit. PACl coagulant is Coagulation and flocculation help CMF. Backwashing enhanced CMF system where the CMF added at an optimum dosage (determined from Jart test) under to enhance effectively system on by NaClO. Chemical cleaning system was enhanced by mixing condition of 400 rpm. After coagulation, coagulated pollutants removal, especially by citric acid solution 1% (for coagulation and flocculation water goes through flocculation tube for forming bigger size organic matters. 24 hrs) and NaClO 0.3% (four process. To investigate the of flocs, and then it comes to the CMF. After 2 hours (SWT) effectiveness of the coagulation or 40 minutes (in MWWT) of filtration, backwashing using and flocculation on the filtrate water enhanced by NaClO dosage of 10 mg/L (in SWT) or 15 mg/L (in MWWT) and air-blow was operated automatically. Chemical cleaning process were conducted when TMP reached at 100 – 120 kPa. Scenario 3:
PAC adsorption + Coagulation To investigate effects of pre- Raw water has been firstly pre-treated by PAC adsorption, and Pre-treatment by PAC is to and Flocculation + CMF. treatment by PAC adsorption then it goes to the coagulation unit using PACl coagulant. enhance organic removal rate, Backwashing enhanced by beside coagulation and flocculation Coagulated-raw water goes through flocculation tube, and especially remained DOC that NaClO. Chemical cleaning by processes. then comes to the CMF. Filtrate goes to the filtrate tank. After could not removed by coagulation citric acid solution 1% (for 24 2 hours (in SFT) or 40 minutes (in MWWT) of filtration, and flocculation processes. After hrs) and NaClO 0.3% (four 24 backwashing by filtrate water enhanced by 10 mg/L (in SWT) adsorbing DOC, PAC would be or 15 mg/L NaClO (in MWWT) and air-blow were operated coagulated together with other automatically. Chemical cleaning process was conducted pollutants and removed by CMF. when TMP reached at 100 – 120 kPa. Pressurized
Air Compressor
Raw water source
Mesh screen
Raw Water Tank
PACl (2, 3)
CERAMIC MEM
Pre-sedimentation tank
(For MWWT only)
Backwash
Storage and Coagulation Tank
Flocculation Tube
Figure 3.9 Simplified flow diagram of the CMF system for the operational scenarios:
PACl (2, 3): coagulant PACl is used for scenarios 2 and 3; PAC (3): powered activated carbon is used for the scenario 3 Raw water source RAW WATER TANK
COAGULANT TANK
CERAMIC MEM
Pre-sedimentation tank
(For MWWT only)
CHLORINE TANK
COAGULATION UNIT
CONCENTRATE
CERAMIC MEMBRANE
L. A. Tuan
Prof. C.Visvanathan FILTRATION SYSTEM (CMF)
- Scenario 1: Adsorption (PAC) and coagulation-flocculation (PACl) processes were not included Date: 08/08/2007 - Scenario 2: No adsorption process included ASIAN INSTITUTE OF TECHNOLOGY
- Scenario 3: All processes were included as the full figure SCENARIOS
Figure 3.10
Figure 3.10 Technical diagram for the operational scenarios


3.4 Overall experiment
The experiment of the study was divided into two main stages: the first stage was carried
out with synthetic water and; the second stage was conducted using AIT pond water and
AIT wastewater as the raw water sources. Major objectives of the first stage were to find
out problems generated while operating and solution for solving them as well as for getting
skilled work and analysis in the laboratory. Beside, inter-evaluations and optimization of
the system would be achieved for experiment runs in the second stage. The second stage
was the main part of the study and all results gained from the stage allowed us to have an
actual evaluation of the system on the treatment of surface water and municipal wastewater.
Each scenario of real waters was repeated for two cycles of membrane fouling.
Scenarior 1: Direct ceramic microfiltration
Monitoring, sampling Analysis Evaluations, recommendations Chemical cleaning Inter-evaluation on efficiency and lesson for optimization of operation, membrane cleaning AIT pond water
Scenarior 1: Direct CMF
Monitoring, sampling Analysis Evaluations, recommendations Chemical cleaning Scenarior 2: Coagulation-flocculation + CMF
Monitoring, sampling Analysis Chemical cleaning Scenario 3: PAC + Coagulation-flocculation + CMF
Monitoring, sampling Analysis Evaluations, recommendations Chemical cleaning AIT wastewater
Scenarios 1 and 2
Final evaluation, comparisons,
Figure 3.11 Overall experiment
3.5 Operational conditions

All equipment of the ceramic membrane systems were designed for indoor use only, with
electricity power of 220V. To achieve the best results on operation, major operation
conditions were set in ranges as recommended by producer. In addition, based on previous
researches on this type of the membrane, the operation was carried out in some specific
conditions to get high efficiency of water treatment. In short, main operation conditions are
expressed in the following table:
Table 3.9 Major operational conditions of the CMF system
Effective membrane area Membrane filtration rate 0.2m3/day (150 ml/min) Filtration time (backwash interval) Backwash pressure Blow-down pressure Coagulant dosing rate Determined by jar test Coagulation Mixing Speed
3.6 Chemical cleaning procedure for the membrane

3.6.1 Chemical cleaning procedure for normal clogging

Regular backwashing is very effective for removing a significant portion of contaminants
retained on the feed channels of membrane. However, a faction of contaminants remains
persistently on the surface or embedded inside the membrane, so a periodic chemical
cleanings would be required to overcome fouling not recovered during normal
backwashing sequences. Chemical cleaning procedure varies with membrane manufacturer,
membrane configuration, membrane material, type of suspected foulant, and degree of
foulant (WEF Press, 2006). The following is the procedure for chemical cleaning of the
study:
- Take out the ceramic membrane from the system - Soak the ceramic membrane 1% in citric acid solution for 24 hours - Take out the ceramic membrane and rinse it with tap water - Take out the membrane and dip in 0.3% NaOCl solution for 24 hrs - Take out the membrane and wash it by tap water - Use air flow pressurized by external air compressor to push out remained foulants. - If the ceramic membrane was already cleaned, fix it in the system and observe the recovery on transmembrane pressure (TMP).
3.6.2 Chemical cleaning procedure for serious clogging

In cases that fouling was solved by the chemical cleaning procedure for normal clogging as
above, a chemical cleaning process could be used as the following:
- Soak the Ceramic membrane H2SO4 solution 0.05M, pH = 1.5 - Soaking time is around six to twenty four hours, depending upon the fouling status - Take out the membrane and wash it by tap water - Use air flow pressurized by external air compressor to push remained solid out. - Fix the ceramic membrane in the system and observe TMP recovery.
3.7 Monitoring and analyzing methods

3.7.1 Monitored and analyzed parameters

All measurements were based on standard methods for examination of water and
wastewater and the frequency, methods, and sampling location for analyzing were
depended on specific parameters. Detail monitoring and analyzing for the hybrid CMF
system are expressed in table 3.10.
Table 3.10 Parameters for monitoring and analyzing
Sampling location Methods/analyzing Shimazu TOC-5000 Shimazu TOC-5000 absorption Oxidizing spectrophotomer (AAS) agents, PO - heavy metals, Nitrite spectrophotomer (AAS) Z-8230 absorption Chloride, spectrophotomer (AAS) Organic Z-8230 spectrophotomer (AAS) Z-8230 Chromate, ferric, sulfite Particle counter MLC-7P Giardia & Cryptosporidium Jart test equipment
Note:

- (a): Wash and sterilize the filtrate side before sampling.
- Feed: water in raw water tank
- Filtrate: sampling directly in filtrate after ceramic membrane filtration
- Examinations base on Standard methods for the examination of water and wastewater (APHA, 1998).

3.7.2 Jar test for optimization of coagulant-flocculation

Jar test ws conducted twice a run to verify the optimum dose of coagulant. According to
the given PACl solution concentration is 10%. The dilution factor is very important to
achieve effectiveness of coagulation, with PACl coagulant at optimum dosage, the highest
effectiveness of coagulation is achieved at dilution factor of 100 times (NGK Insulators,
Ltd.). After diluted 100 times as calculated above, the PACl solution has concentration of
1000 mg/L or 1000 mg/1000 mL.
⇒ 1 mg of PACl in 1 mL of the diluted solution, the concentration and dosage respectively
that were used for Jar test are the followings:
Table 3.11 Concentration and dosage of coagulation for Jar test
Concentration of PACl (mg/l) Dosage
Adding coagulant as above into 1000 mL of water and operating jart test as the following procedure: - Rapid mixing at 125 rpm for 1-2 minutes - Slow mixing at 30 – 40 rpm for 20 minutes - Settling for 30 minutes 3.7.3 Determination of micro-particles, Giadia and Cryptosporidium (protozoa)

As mentioned in the chapter 2, protozoa are the microbial pathogens in water and waste
water works, and they have size ranges are from 2 to 15 µm. In these pathogens, Giadia
and Cryptosporidium are the most common protozoa pathogens with the body size of 5 to
15 µm (American Water Works Association, 1999). The two major pathogens were
measured relatively using micro-particle counter machine MLC-7P (made in Japan). The
size range of particles that can be measured by the counter was 1 to 25µm.
Sample flow 50 mL/min
Figure 3.12 Working principle of particle counter MLC-7P


a. Set-up equipment:

Particle counter
Sample container Calibration container Figure 3.13 Experimental set-up of particle counter MLC-7P
b. Sample preparation:

• Filter sample using screen with pore size of 53 µm; • Dilute sample if necessary; • Check all connections correctly (refer to the figure 3.13). c. Calibration and measurement:

Calibration:

• Open tap water valve and wait until having in overflow gate of the filtrate tank for • Switch on the main power and the pump of the particle counter; • Open the flow valve to the maximum value to eliminate air bubble in the tubes; • Adjust the flow rate to 50 mL/min; • Press the "confirm" button in the function buttons; • Wait until the machine is stabilized when umber of particle of the filtered water is near zero (or less than 50).
Sample measurement:

• When machine is stable, put inlet tube into the filtered sample container instantly. • Open the flow valve to the maximum value to eliminate air bubble for few minutes; • Adjust the flow rate to 50 mL/min; • Switch on the printer; • After getting five repetitive results; • Change to the next sample if any; • After measurement, deep the inlet tube to the calibration container to clean the instrument for 5-10 minutes; switch off the pump and the main power. Note: the measurement is not correctly done if particles in sample are too highly
concentrated. Measurement limit of this machine is 10,000 (alarm level). Results over
measurement limit are not reliable. In this case, sample should be diluted using filtered
water of micro-filter 1µm.
3.7.4 Determination of total and dissolved organic carbon (TOC and DOC)
Both total organic carbon (TOC) and dissolved organic carbon (DOC) were determined.
TOC and DOC are very important in detecting contaminants included in water. DOC is
defined as organic carbon remaining after 0.45 µm filtration, the DOC is determined by
TOC analyzer (Jarusuthirak, et al. 2007). TOC is an important parameter because of its
possible effects on the environment, human health, and TOC is of interest in the field of
potable water purification due to disinfection of byproducts. In addition, normally surface
water and wastewater are contaminated with organic compound, so TOC removal is the
most important factor to evaluate efficiency of the ceramic membrane filtration system on
treatment of surface water and wastewater. Especially, when enhanced with other process
such as pre-coagulation and adsorption using powered activated carbon, the efficiency of a
hybrid ceramic microfiltration on TOC removal was very high. The TOC and DOC
parameters were analyzed using Shimazu TOC-5000 machine.
Chapter 4
Results and Discussions
The study was implemented in two stages as mentioned in the chapter 3. In more detail, in
terms of experimental works, the results of the study could be divided into four parts: pre-
experiments in which operational conditions such as preparation of synthetic water and
results of jar test for the pilot were found out, and experimental results with synthetic water,
surface water, and municipal wastewater respectively. Therefore, the experimental results
and discussions of the study are also arranged in four parts. In addition, the investigation of
operational problems generated during study of the dead-end ceramic microfiltration
system and solutions are presented in the fifth section of this chapter.

4.1 Results of pre-experiments

4.1.1 Preparation of synthetic water
The synthetic water was prepared from tap water (in the ambient lab of EEM, AIT) and
Kaolin clay. Composition of tap water and detailed data of the preparation are presented in
tables B.1 and B.2, appendix B, and the graphical results are shown in figure 4.1.
Concentration of Kaolin clay (mg/L) Figure 4.1 Variation of turbidity with Kaolin clay concentration
Based on turbidities of real water sources that would be used for the pilot (AIT pond water and AIT wastewater) and the relationship drawn in figure 4.1, synthetic water was prepared in three different levels of turbidity as the followings: - Turbidity level 1 (low turbidity, slightly higher than maximum turbidity of AIT Pond water): Turbidity of 40 NTU with Kaolin clay concentration of 55 mg/L - Turbidity level 2 (average turbidity as minimum turbidity of AIT wastewater): Turbidity of 80 NTU with Kaolin clay concentration of 95 mg/L - Turbidity level 3 (high turbidity, higher than maximum turbidity of AIT wastewater):
Turbidity of 120 NTU with Kaolin clay concentration of 137 mg/L
4.1.2 Jar test

a. Jar test for surface water (AIT pond water)
Jar test with coagulation-flocculation process by PACl:
Figure 4.2 is graphical result of the jar test and table B.3, appendix B, presents the detailed
results.
PACl Dosage (mg/L) Figure 4.2 Variations of turbidity and pH of supernatant with coagulant dosage
In terms of turbidity removal, optimum dosage of PACl was 15 mg/L, turbidity was 0.39
NTU and TOC was 2.55 mg/L. In terms of TOC removal, it was found out that optimum
dosage of PACl was 20 mg/L, turbidity is 1.67 NTU and TOC is 2.29 mg/L. Because
turbidity is not an issue with CMF (when running with synthetic water, turbidity removal
of direct ceramic microfiltration was very high: turbidity of permeate was always around
0.065 NTU compared with 40, 80, or 120 NTU of feed) and the major purpose of the
experiment was to remove TOC as high as possible, the selected optimum coagulant
dosage was 20 mg PACl/L (equal to 2 mg/L as Al3+), and pH of supernatant was at 6.3.
This selected optimum dosage was used for experimental scenario of the hybrid CMF
system enhanced by coagulation-flocculation with AIT pond water.
Jar test with adsorption process by PAC:
The quality of supernatant was analyzed, and the figure 4.3 shows the main results for
choosing PAC dosage, and table B.4 (appendix B) presents the detailed resuts.
TOC removal of PAC adsorption was quite low. With the dosage of 50 mg/L, TOC
removal rate was 31% (remained TOC is 7.5 mg/L compared with 10.8 mg/L of TOC of
AIT pond water). Remained TOC decreased slowly with the increase of PAC dosage and until PAC dosage of 250 mg/L, TOC reduction of 55.56 % (TOC remained is 6 mg/L). Although PAC dosage was increased from 50 mg/L to 250 mg/L, the removals of color and TOC were not increased notably. This changing tendency of efficiency of the PAC adsorption can be explained clearly that PAC can adsorb only small molecules of organic matters and therefore it could not remove all TOC in very small dissolved form (DOC). Because PAC was used to enhance coagulation-flocculation process in terms of TOC removal and also help to reduce fouling. The combination among the above results of jar test, economic aspect of using PAC, and literature review made a decision to choose the dosage of PAC of 20 mg/L. In this point, although 13.9% of TOC was removed by PAC, it was expected that the remained TOC would be removed more effectively by accumulation of PAC inside membrane during filtering and coagulation-flocculation process followed. PAC Dosage (mg/L) Figure 4.3 Variations of TOC and color of supernatant with PAC dosage
Jar test with the combination of adsorption and coagulation-flocculation processes:

As selected in the jar test with PAC adsorption, PAC dosage of 20 mg/L was used for
enhancement of TOC removal of the hybrid CMF system. Thus, in this combined jar test,
all beakers were supplied with the same PAC absorbent dosage of 20 mg/L and only PACl
coagulant dosage was altered.
Graphical result of this jar test is presented in figure 4.4, and table B.5 (appendix B) shows
analyzed data in more detail. The graphical result shows that remaining TOC and turbidity
of supernatant were decreased rapidly with the increase of PACl dosage from 0-20 mg/L.
After the point of 20 mg/L PACl, the TOC and turbidity removal were not changed notably
and the remaining values were almost kept at the same values compared with those at
PACl dosage of 20 mg/L. Beside, with increase of PACl, pH was degreased, and in
practical situation we do not want to have a too low pH after coagulation-flocculation to
avoid possible metallic corrosion of equipment. Therefore, the optimum coagulant dosage
chosen is 20 mg PACl/L (2 mg/L as Al3+), with TOC removal of 56% (remaining TOC of
4.27 mg/L), and pH of supernatant was at 6.97.
In conclusion, selected adsorbent and coagulant dosages were 20 mg/L PAC and 20mg/L PACl, and used for experimental scenario of the hybrid CMF system enhanced by adsorption and coagulation-flocculation with AIT pond water. PACl Dosage (mg/L) Figure 4.4 Variations of turbidity and pH of supernatant with coagulant dosage


b. Jar test for municipal waste water (AIT wastewater)

Jar test with coagulation-flocculation process by PACl:

PACl Dosage (mg/L) Figure 4.5 Variations of turbidity and pH of supernatant with coagulant dosage
The results are presented on the above graph, and numerical results are given in table B.6, appendix B. The optimum dosage of PACl was chosen as 20 mg/L. In this point, the lowest remaining concentrations of TOC and turbidity of supernatant were achieved, and at pH of 6.8. • Jar test with adsorption process by PAC:

The quality of supernatant was analyzed, and the figure 4.6 shows the main results for
choosing PAC dosage. Table B.7, appendix B, presents detailed results .
PAC Dosage (mg/L) Figure 4.6 Variations of TOC and color of supernatant with PAC dosage
When PAC dosage increased, the TOC removal also was increased. However, from 30 to 50 mg/L of PAC dosage, the TOC removal rate was not increased rapidly. In addition, when used in the CMF system, PAC not only enhances coagulation-flocculation process in terms of TOC removal, but it also helps to reduce fouling of the ceramic membrane. The combination among the above results of jar test, economic aspect of using PAC, and literature review made a decision to choose the dosage of PAC of 30 mg/L. In this point, 26 % of TOC was removed by PAC and it was expected that the remained TOC would be removed more effectively by accumulation of PAC inside membrane during filtering and the combined coagulation-flocculation process. • Jar test with the combination of adsorption and coagulation-flocculation processes:
In the combined jar test, all beakers were supplied with the same PAC absorbent dosage of
30 mg/L and only PACl coagulant dosage was altered.
Figure 4.7 presents graphical result of the jar test, and table B.8 (appendix B) shows
analyzed data in more detail. The graphical result shows that remaining TOC and turbidity
of supernatant were decreased rapidly with the increase of PACl dosage from 0 to 20 mg/L.
After the point of 20 mg/L PACl, the TOC and turbidity removal were slightly decreased
and the remaining values were higher than the TOC and turbidity values at PACl dosage of
20 mg/L. Beside, with increase of PACl, the pH was decreased, and in practical situation it
is unwanted to have a too low pH after coagulation-flocculation due to possible metallic corrosion of equipment. Therefore, the optimum coagulant dosage chosen is 20 mg PACl/L (2 mg/L as Al3+), with TOC removal of 52.4 % (remaining TOC of 4.52 mg/L), and pH of supernatant was at 6.63. In conclusion, selected adsorbent and coagulant dosages were 30 mg/L PAC and 20mg/L PACl, and used for experimental scenario of the hybrid CMF system enhanced by adsorption and coagulation-flocculation with AIT wastewater. PACl Dosage (mg/L) Figure 4.7 Variation of turbidity and pH of supernatant with coagulant dosage
4.2 Experimental run with synthetic water

In this experiment, prepared synthetic water was used as feed water for the pilot. The pilot
system was set-up and operated with the scenario 1 as mentioned in the chapter 3.
4.2.1 Results and discussions
a. Transmembrane pressure (TMP)

Figure 4.8 gives changes of TMP and turbidity of feed water with filtration time. The TMP was being increased day by day until the 11th day of the operation. After adding chlorine using NaClO with dosage of 10 mg/L, the TMP was decreased, and then after 17 days of treatment TMP was at 43 kPa. It was expected that the CMF would have to be cleaned by chemical cleaning in which TMP of 100 kPa. Due to the decrease of TMP after adding NaClO to backwashing, it was decided to increase the turbidity of feed water up to 80 NTU but the TMP still was going down to 30 kPa. After turbidity of feed water was increased to 120 NTU, the TMP was increased slightly but it was kept almost at the constant TMP of 40 kPa. The characteristic of feed water was inorganic, and the foulants here almost are inorganic particles (kaolin clay), so the membrane was easily cleaned by BW, and TMP was recovered highly. Start adding NaClO into BW Increasing turbidity of feed water Period of treatment (days) Figure 4.8 Variations of TMP and turbidity of feed water with period of treatment
b. Performance of the system in terms of turbidity removal
Figure 4.9 shows graphical changes of turbidities with time duration of the operation.
(Refer to table B.11, appendix B, for detailed data).
Period of treatment (days) Figure 4.9 Changes of turbidity, turbidity removal with filtration time
The turbidity of permeate was very low (less than 0.1 NTU) even that of feed water was
very high (40, 80, and 120 NTU). Although turbidity of the feed water was increased from
40 NTU to around 80 NTU and then up to around 120 NTU, the turbidity of the permeate
was kept constantly. Therefore, the efficiency of the direct CMF system for the synthetic
water treatment in terms of turbidity removal was dependent from the turbidity of feed
water. The log removal of turbidity was from 2.56 – 3.28 and the removal rate was 99.73 –
99. 95%. The most visible evidence explaining clearly such a high performance is that
kaolin clay had the size range from 100- 235 µm and it was easily removed by the ceramic
membrane with pore size of 1 µm.
c. Observations of pH, temperature and conductivity

The numerical results of all the parameters are given in table B.9, appendix B. The pH of
feed water and permeate water were neutral from 6.9 to 8. Because NaClO was added into
permeate (for enhancing backwashing process), the remaining NaClO made a slightly
higher pH of the permeate compared with that of the feed water. Figure B.4, appendix B,
presents this difference in detail.
The temperature of permeate was always higher than the temperature of feed water, but the
difference was not remarkable (0.1 – 1.5 oC). The increase of temperature of water after
filtered can be caused by the effect of friction when feed water passed to the so small pores
of the membrane. The changes of the temperature are presented in figure B.5, appendix B.
At the beginning stage, in which feed water has turbidity of 40 NTU, conductivity of
permeate were little smaller than that of the feed water (conductivity of the synthetic water
was around 47 – 51 µS/cm meanwhile this of the permeate was 47 – 50 µS/cm). But after
adding NaClO into filtrate tank (for enhancement of backwashing), the conductivity of the
permeate was increased and higher than that of the feed water. The phenomena could be
explained by the existing of ions released from NaClO compound. The variety of
conductivity is shown in the figure B.6, appendix B.

d. Performance in terms of TOC removal
Figure 4.10 presnts the results on TOC removal efficiency and TOC concentrations in the
feed water and the permeate. (Refer to table B.12, appendix B, for more detail).
Period of treatment (days) Figure 4.10 Changes of TOC and TOC removal efficiency with period of treatment
TOC of the synthetic water was from 1.43 to 3.79 mg/L, and permeate had lower TOC
(1.12 – 2.08 mg/L). The TOC efficiency of the direct CMF system for the synthetic water
treatment in terms was relatively low, from 38 to 57 %. It pointed out that without pre-
treatments for enhancement of TOC removal such as coagulation-flocculation, adsorption,
and etc., the experimental scenario could not remove effectively TOC. All most al of
removed TOC here was particles (DOC may be adsorbed in kaolin clay particles), and the
remained TOC was colloidal form that passed through the pores of the ceramic membrane.

e. Performance in terms of DOC removal
DOC removal efficiency, DOC concentrations of the feed water and the permeate are
shown in figure 4.11. (Refer to table B.12, appendix B, for more detailed information).
Period of treatment (days) Figure 4.11 Changes of DOC and DOC removal with period of treatment

DOC of the synthetic water was low (1.07 – 1.859 mg/L), and permeate had lower DOC
concentration (0.78 – 1.18 mg/L). The DOC removal efficiency of the direct CMF system
for the synthetic water treatment was low, from 20 to 43 %. The reason explaining this low
performance is the same as the above mentioned discussion for the TOC removal.

f. Performance in terms of total Fe removal

Period of treatment (days) Figure 4.12 Variation of Fe with period of treatment
Total Fe concentrations of the permeate were very low (0.02 – 0.04 mg/L) compared with
those of feed water (1.02 – 2.05 mg/L). The efficiency of the direct CMF system for the
synthetic water treatment in terms of Fe removal was reached highly of 98 %. Fe of the
synthetic water came from tap water and the kaolin clay. Through observation, it was seen
that light yellow-brown color of Fe3+ form in the tap water which was used for preparing
the synthetic water. In addition, the kaolin clay had the size range of 100- 235 µm, so
almost all of removed Fe was un-dissolved Fe (Fe3+). The supposition also was ensured
when the color of membrane after running was yellow brown color.
g. Performance in terms of Mn removal
Both Mn concentrations of the feed water and the permeate were very low. The permeate
had lower Mn concentration (0 – 10 µg/L) compared with those of the feed water (10 – 185
µg/L). The efficiency of the direct CMF system for the synthetic water treatment in terms
of Mn removal was from 70 to 100 %. The mechanism of Mn removal can be explained as
Fe removal as well. That means removed Mn from feed water was in un-dissolved form
existing in kaolin clay and a part of tap water.

Figure B.7, appendix B, shows the changes of Mn in the feed water and the permeate.
After 26 days of operation, Mn content of the permeate was none detected although the Mn
still existed in the feed water. This could be caused by the accumulation of foulant inside
pores of the ceramic membrane that helped to remove Mn more effectively.

h. Performance on micro-particle removal

The number of micro-particles was measured twice a week. Figure 4.13 presents the
graphical results on removing micro-particle with size range from 5 to 15 µm. Table B.13,
appendix B, gives detailed measurement on micro-particles.
Period of treatment (days) Figure 4.13 Micro-particles of the feed and the permeate water

The results pointed out micro-particles (5 – 15 µm) or Giadia and Crypto removal
efficiency of the direct CMF system was very high, 99.95 - 99.99%. The log micro-particle
removal (5 – 15 µm) was from 3.28 – 4.21. Compared with a research conducted by Arika
et al. (2006), researched in Cambodia with a ceramic membrane having pore size of 0.1
µm, the micro-particles of permeate was 130 count/mL, the direct CMF system running at
AIT was much more effective.

The measurement of the micro-particles could not tell exactly the number of
microbiological particles with synthetic water, but it relatively could tell performance of
the CMF system for Giadia and Cryptosporidium removals in experiments with real water
sources.
i. Performance on TSS and TS removal
Quality of the feed water and the permeate, and the removal efficincy in terms of TSS and
TST is established in table B.12, appendix B.
The direct microfiltration system had a very high TSS removal efficiency, 99 - 100%, with
the TSS of permeate was from 0 to 0.5 mg/L. TSS almost existed in the kaolin clay
(particle form), so it was effectively removed by the ceramic membrane with pore size of
0.1 µm.

On the other hand, TS removal efficiency was achieved from 44-70%. This pointed out the
direct CMF could not remove completely dissolved solid matter of tap water (a component
constituting the synthetic water). Beside, injecting NaClO with dosage of 10 mg/l to filtrate
tank for enhancement of backwashing is another reason that made the high remained total
solid in the permeate.

4.2.2 Conclusion

After 50 day of the operation with the synthetic water, the ceramic membrane filter was not
fouled even the turbidity of synthetic water was very high (120 NTU). In addition, the
quality of the permeate was very good. Therefore, the experimental run with synthetic
water was stopped and no further experiment with pre-treatments conducted. For next
experimental runs with real water sources, the membrane was taken out from the casing
and chemically cleaned by citric acid solution 1%, and then NaClO 0.3%.
In this experimental run, the feed water used was the synthetic water prepared from tap
water and kaolin clay. The feed water had the inorganic characteristics, so the pollutants
were also inorganic matters. The inorganic pollutants made inorganic foulants to the
membrane. These inorganic foulants were easily removed by backwashing using air
scouring and filtrate flushing. However, when the feed water used is surface water or
wastewater, foulants would be both inorganic and organic matters. Therefore, experimental
runs with surface water (AIT pond water) and municipal wastewater (AIT wastewater)
would have to include backwashing enhanced by NaClO.
4.3 Experimental runs with surface water
4.3.1 Scenario 1: Direct ceramic microfiltration

With this scenario, two experimental runs were conducted and the results are summarized
in the following section.

a. Transmembrane pressure (TMP)

Figure 4.14 presents graphical results on TMP and turbidity changing tendencies of two
different runs with AIT pond water using direct microfiltration scenario. Table B.15 and
B.20, appendix B, show detailed results.
Period of treatment (days) Figure 4.14 Changes of TMP and turbidity of feed water with period of treatment
In the first experimental run, the fouling with TMP of 120 kPa was achieved on the 7th day of operation. Meanwhile, in the second run, the starting TMP was the same as this of the first run (15kPa), but it got 11 days for getting fouling at TMP of 120 kPa. The difference of time duration for occurring fouling between the two experimental runs is explained by the difference between the qualities of the feed waters. The turbidity of the feed water 1 (7.38 – 7.94 NTU) was slightly higher than that of the feed water 2 (7.07 – 7.62) since the third day of the operation, this prolonged time filtration of the run 2 compared with that of the run 1. Further more, through observation during backwashing process, TPM recovery by backwashing in both runs was from 20 – 50 kPa. TMP recoveries by chemical cleaning using acid citric 1% solution and NaClO 0.3% solution respectively were 60 kPa (TMP was reduced from 120 kPa down to 60 Kpa after 24 hours of soaking) and 45 kPa (TMP was reduced from 60 Kpa to 15 Kpa after 24hours of soaking). b. Performance of the system in terms of turbidity removal
Figure 4.15 gives graphical changing tendency and relationship among turbidity, time
duration of the operation, and efficiency of the system on turbidity removal for the two
runs with the same scenario direct CMF with surface water. (Refer to tables B.15 and B.20,
appendix B).
In both the experimental runs, the turbidity of permeate was the highest value on the first
day of operation. This phenomenon is explained by the proportional increase of foulant
accumulation with period of treatment. On the starting day of each run, membrane was
pure after chemical cleaning of the last run, so its pore size was large and the turbidity of
permeate therefore was high. Day by day, foulants were accumulated inside pores and on
surface of feed channels and they helped to remove more effectively turbidity of feed water.
Period of treatment (days) Figure 4.15 Changes of turbidity with period of treatment


From the 3rd day of operation, the operation of the system was stable. This made turbidity
of permeate was kept constantly and steadily from 0.064 to 0.071 NTU in both two
experimental runs. The turbidity removal efficiency was 99.02 – 99. 16%.

c. Performance in terms of TOC and DOC removals

Figures 4.16 and 4.17 show the removals and concentrations of TOC and DOC. The
numerical concentrations are given in tables B.16 and B.21, appendix B.
In the first run, with time duration for getting fouling of 7 days, TOC of feed water was
10.05 – 12.1 mg/L, and permeate had lower TOC concentrations, 7.46 – 8.30 mg/L. The
TOC removal efficiency of the direct CMF system for the surface water treatment was 18.8
– 26.1 %. DOC of feed water was from 9.15 – 10.51 mg/L and higher than this of permeate,
7.01 – 7.81 mg/L. DOC removal rate of this run was 15 – 31%.
Period of treatment (days) Figure 4.16 Changes of TOC and TOC removal efficiency with period of treatment
Period of treatment (days) Figure 4.17 Changes of DOC and DOC removal efficiency with period of treatment

In the second run, with period of treatment for getting fouling of 11 days, TOC of feed
water was 10.88 to 12.34 mg/L, and permeate had lower TOC concentrations, 7.836 to
9.42 mg/L. TOC removal efficiency of the direct CMF system for the surface water
treatment was 19.3 to 28.3 %. DOC of the feed water was from 8.42 – 10.37 mg/L and
higher than that of the permeate, 7.05 – 7.68 mg/L. DOC removal efficiency of this run
was 16.3 – 25.9%.
In conclusion, the TOC and DOC efficiencies of the two different runs were relatively low.
It was found out from this experiment that the direct ceramic microfiltration was not
effectively for treatment of highly organic contaminated surface water. Without pre-
treatments such as coagulation-flocculation, adsorption, and etc., the organic pollutants
removal efficiencies were very low. High remained TOC and DOC are really issues for a
water treatment plant to choose disinfection methods. If such organic contaminated
permeate is disinfected by chlorine, THMs will exist as by-disinfection products leading to
harmful effects to human health (potentials of cancer diseases). Therefore, it is really
necessary to include pre-treatment processes such as coagulation-flocculation and powder
activated carbon adsorption to enhance TOC and DOC removals of the ceramic membrane.
d. Performance on micro-particle removal

Figures 4.18 and 4.19 give the graphical results on removing micro-particle with size range
from 5 to 15 µm. Tables B.18 and B.23, appendix B, shows detailed measurement on the
micro-particles.
Period of treatment (days) Figure 4.18 Change of number of micro-particle with period of treatment of run 1
In the experimental run 1, removal efficiency on micro-particles with the same size range of Giadia and Crypto was 99.48 - 99.59%, and log micro-particle removal was 2.28 – 2.39. The feed water had 4592 – 6872 particles/mL, and permeate had 23-28 particles/mL with size of 5 – 15 µm. The number of the micro-particles of permeate was decreased with the increase of period of treatment. This can be explained by increasing thickness of fouling inside membrane with time, and it enhanced the particle removal through cake filtration mechanisms. In the experimental run 2, removal efficiency on micro-particles with same size range of Giadia and Crypto was 99.59 - 99.78 %, and log micro-particle removal was 2.39 – 2.66. The feed water had 4680 – 11488 particles/mL, and permeate had 19-30 particles/mL. The number of the micro-particles of permeate was also decreased with the increase of period of treatment. This is caused by foulant accumulation inside membrane that enhanced the particle removal through cake filtration mechanisms. In summary, the results pointed out removal efficiency of the direct CMF system in terms of micro-particles (5 – 15 µm) or Giadia and Crypto was 99.48 - 99.78 %. The log micro-particle removal (5 – 15 µm) was from 2.28 – 2.66. The measurement of the micro-particle number indirectly and relatively told number of parasite pathogens, Crypto and Giadia that exist in the feed and permeate, and performance of the direct CMF system for removing the microbiological pollutants. Period of treatment (days) Figure 4.19 Change of number of micro-particle with period of treatment of run 2

e. Performance on TSS and TS removal
Tables B.16 and B.21, appendix B, present the quality of the feed water and the permeate
and the removal efficiencies in terms of TSS and TS of the two different runs.
On the first day of operation, TSS of permeate was 0.5 mg/L and the removal efficiency
was 95.5-97.7 % for the run 1 and run 2 respectively. After three days of operation, the
system worked steadily and TSS of permeate was zero with the TSS removal efficiency of
100 %.
TS of the permeate was slightly lower than that of the feed water. Although when TSS
removal was 100 %, TS of the permeate was still very high and TS removal efficiency was
very low, less than 10 %. This can be explained by the adding NaClO into filtrate tank, and
the NaClO contribute to TS increase of the permeate. TS of the permeate was 188 - 204
mg/L and 308 – 312 mg/L in run 1 and run 2, respectively.

f. Performance on removal of other pollutants: Fe, Mn, total coliform, fecal coliform,
free Cl

2 residual and total alkalinity.
Tables B.17 and B.22, appendix B, show results on measurement of total Fe, dissolved Fe, total Mn, and dissolved Mn on two experiments. Total Fe of the feed water was 0.39 – 0.75 mg/L, and total Fe of the permeate was 0.03 – 0.06 mg/L. Dissolved Fe of the feed water was 0.15 – 0.3 mg/L, and that of the permeate was 0 – 0.07 mg/L. Total Mn of feed water was 30 – 114 µg/L and that of permeate was 5 – 107 µg/L. Dissolved Mn of the feed and permeate was 0- 5 µg/L and 0 µg/L respectively. The results show that Fe and Mn of both the feed water and the permeate were very low, almost zero. Total coliform and fecal coliform of the feed water were 190 – 438 MPN/100mL and 4 – 14 MPN/100mL respectively. Both total colifrom and fecal coliform of the permeate were none-detected. This means the direct CMF removed 100% total coliform and fecal coliform. The feed water had no free chlorine, but the permeate had free Cl2 residual of 3.65 – 4.1
mg/L due to adding continuously NaClO to filtrate tank for enhancement of the backwash.
Alkalinity of the feed water was 59 – 62 mg/L as CaCO3 and this of the permeate was 66 –
70 mg/L as CaCO3. The difference between alkalinities of the feed water and the permeate
also was caused by the used NaClO. NaClO made pH of water increases leading to higher
total alkalinity of treated water compared with total alkalinity of the feed water.
4.3.2 Scenario 2: Coagulation-flocculation and CMF
Based on the results of the pre-experiment on jar test that was mentioned in the section
4.1.2.a, coagulant dosage of 20 mg PACl /L was selected for coagulation process. Two
experimental runs were conducted with AIT pond water using hybrid ceramic
microfiltration system in which a pre-treatment by coagulation-flocculation was used.
Results of these two runs are summarized in the following section.

a. Transmembrane pressure (TMP)
Figure 4.20 presents changes of TMP and turbidity of the feed water, and tables B.25 and
B.30, appendix B, give numerical results.
Period of treatment (days) Figure 4.20 Changes of TMP, turbidity of feed water and period of treatment

In the first experimental run, the fouling with TMP of 105 kPa was achieved on the 13th
day of the operation. In the second run, fouling at TMP of 120 kPa was achieved after 20
days of the treatment. The difference between time durations of occurring fouling can be
reasoned by the different qualities of the feed waters. The quality of AIT pond water
which was used as surface water source could be changed by time. The run 1 was
conducted in the different time with the run 2. The turbidity of the feed water 1 (14.2 –
18.1 NTU) was much higher than that of the feed water 2 (5.76 – 9.02). This made the run
2 had the longer filtration time compared with run 1.
Through observation, TMP of this scenario did not increased rapidly as that of the scenario
without coagulation-flocculation. But TMP from 5 – 7 kPa recovered by each time of
backwashing process of this hybrid scenario was lower. It was found out that, after
coagulated and flocculated, the particle and colloidal contents of the feed water were
reduced highly. A small amount remained colloidal of the feed water made the low TMP
increase due to colloidal fouling. Then this fouling was removed by the EBW. This finding
is the reason for the lower TMP increase and TMP recovery by EBW as well. TMP
recoveries by chemical cleaning using acid citric 1% solution and NaClO 0.3% solution
were 80 - 85 kPa (TMP was reduced from 105-110 kPa down to 25 Kpa after 24 hours of
soaking) and 10 - 12 kPa (TMP was reduced from 25 Kpa to 13 - 15 Kpa after 24hours of
soaking), respectively.

b. Performance of the system in terms of turbidity removal
Figure 4.21 presents graphical changes of turbidities of the system in the two experi,ental
runs. Tables B.25 and B.30, appendix B, give detailed data
On the first day of operation, when foulants were not accumulated notably inside pores of
the membrane, the turbidity of permeate was the highest value. However, the difference
between turbidities on the first day and second days was very small, 0.003 – 0.01 NTU.
This difference was lower than that of the scenario without coagulation-flocculation, 0.17-
0.26 NTU. This pointed out that the formation of big flocs due to coagulation-flocculation
helped to remove more effectively turbidity even on the first day of operation when the
ceramic membrane had very clean pores.
Period of treatment (days) Figure 4.21 Change of turbidity with period of treatment

In the first run, after 1 days of operation, a steady state on removing turbidity was achieved.
From this time, turbidity of the permeate was kept stably from 0.061 to 0.069 NTU with
turbidity removal efficiency of 99.55 – 99.65%. Meanwhile, in the second run, after 2 days
of operation, the performance of the system was stable. In this steady state turbidity of the
permeate also was 0.053 to 0.068 NTU. The turbidity removal efficiency was 99.02 – 99.
23%. This points out that lower turbidity of feed water prolonged time duration of the
hybrid system, but it took longer period of treatment for getting steady performance and
fouling.

c. Performance in terms of TOC and DOC removals

Figures 4.22 and 4.23 present TOC, DOC removal efficiencies and concentrations in the
feed water and the permeate of the two experimental runs. The numerical concentrations
are given in tables B.26 and B.31, appendix B.
In the first run, with the fouling cycle of 13 days, TOC of the feed water was 10.97 to
11.45 mg/L, and that of the permeate was 2.69 – 2.97 mg/L. TOC removal efficiency of
the PACl + CMF hybrid system for the surface water treatment was 72.59 to 75.63 %.
Compared with the scenario without pretreatment by coagulation-flocculation, this
scenario with pre-treatment by coagulation-flocculation is very highly effective on TOC
removal. The coagulation-flocculation enhanced strongly both period of treatment and
TOC removal. In addition, DOC of feed water was from 6.86 – 7.87 mg/L and higher than
this of permeate, 2.28 – 2.52 mg/L. DOC removal rate of this run was 63.4 – 69.5%, very
high compared with this of the scenario without coagulation-flocculation (15 – 31%).
Period of treatment (days) Figure 4.22 TOC and TOC removal rate with period of treatment


In the second run, period of treatment for getting fouling of 19 days, TOC of the feed water
and the permeate was 10.18 to 12.5 mg/L and 3.41 – 3.98 mg/L, respectively. The TOC
removal efficiency of the hybrid CMF system for the surface water treatment in terms of
was 63.6 – 69.7 %. In addition, DOC of feed water was from 8.11 – 9.74 mg/L and higher
than this of permeate, 3.28 – 3.80 mg/L. DOC removal efficiency of this run was 57.66 –
63.23 %. The TOC and DOC removal efficiencies of the run were much higher compared
with the scenario without coagulation-flocculation process.
Period of treatment (days) Figure 4.23 DOC and DOC removal rate with period of treatment

In conclusion, the efficiencies on removing both TOC and DOC of the two different runs
with the same scenario were relatively high compared with the last experiment without
coagulation-flocculation. In addition, this experiment pointed out clearly that when
combined with pre-treatment by coagulation-flocculation process to have the hybrid
ceramic microfiltration system, for treatment of surface water with high organic, the time
duration for getting fouling was prolonged from 7-11 days up to 13-20 days removal rates
for removing organic pollutants were very low. Enhanced by PACl coagulation-
flocculation, TOC and DOC removal efficiency could be improved up to 63.6 – 75.63 %
and 57.66 – 69.5 %, respectively.
However, remained TOC and DOC are still higher than 2 and 3 mg/L in run 1 and run 2,
respectively, and it is really necessary to conduct study on powder activated carbon
adsorption that is used as one more pre-treatment process to enhance TOC and DOC
removals of the ceramic membrane.

d. Performance on micro-particle removal


Figures 4.24 and 4.25 present the graphical results on removing micro-particle with size
range from 5 to 15 µm, and tables B.28 and B.33, appendix B, give detailed measurement
on the micro-particles.
In the experimental run 1, on micro-particles removal efficiency with size range of Giadia
and Crypto was 99.69 - 99.80 %. Log micro-particles removal was 2.51 – 2.70. The feed
water had 5918 – 7266 particles/mL, and permeate had 13-21 particles/mL with size of 5 –
15 µm.
The number of the micro-particles of permeate was decreased with the increase of filtration
time. This can be explained by increasing thickness of fouling inside membrane with time.
The foulants accumulation enhanced the particle removal through cake filtration
mechanisms.
Period of treatment (days) Figure 4.24 Number of micro-particle and period of treatment of run 1
In the experimental run 2, Giadia and Crypto were removed at 99.68 - 99.84 %, and log removal of 2.52 – 2.70. The feed water had 5890 – 7511 particles/mL, and the permeate had 12-20 particles/mL. The number of the micro-particles of the permeate was also decreased with the increase of the period of treatment. This again shows role of foulant accumulation inside membrane that enhanced the particle removal through cake filtration. Period of treatment (days) Figure 4.25 Number of micro-particle and period of treatment of run 2
In summary, the measurement indirectly and relatively told the number of parasite pathogens, Crypto and Giadia existing in the feed and the permeate, and the performance of the PACl + CMF hybrid system. The results pointed out that the hybrid CMF system enhanced by coagulation-flocculation remove much more effectively Giadia and Crypto (5 – 15 µm), 99.69 – 99.84% compared with 99.48 - 99.78 % of direct CMF. The log micro-particles removal was 2.51 to 2.70. 4.3.3 Scenario 3: Adsorption, coagulation-flocculation, and CMF
a. Transmembrane pressure (TMP)
Figure 4.26 presents changes of turbidity of feed water and TMP, and table B.35 gives
detailed results.
Period of treatment (days) Figure 4.26 Changes of TMP and turbidity of feed water with period of treatment


The fouling with TMP of 105 kPa was achieved on the 21th day of operation. Compared
with the last runs without adsorption, this run had a longer filtration time. The feed water
had turbidity of 7.35 - 11.6 NTU.
The TMP did not increased rapidly as the situation of scenarios without the PAC
adsorption. TMP recovered by each time of backwashing was around 5 kPa and less than
other scenarios. TMP recoveries by chemical cleaning using acid citric 1% solution and
NaClO 0.3% solution were 85 kPa (TMP was reduced from 105 kPa down to 20 Kpa after
24 hours of soaking) and 5 kPa (TMP was reduced from 20 Kpa to 15 Kpa after 24hours
of soaking), respectively.

b. Performance of the system in terms of turbidity removal

Figure 4.27 gives graphical changes of turbidity and turbidity removal efficiency of the
experimental run. (Refer to table B.35, appendix B, for numerical data).

On the first day of operation, when foulants were not accumulated notably inside pores of
the membrane, the turbidity of the permeate was the highest value of 0.18 NTU. From the
3rd day, a steady state on removing turbidity was achieved. In this state, turbidity of the
permeate was kept stably of 0.053 – 0.066 NTU, with turbidity removal efficiency of 99.44
– 99.53 %. Compared with last runs without PAC adsorption, the permeate of this run is
clearer than the others.
Period of treatment (days) Figure 4.27 Relationship between turbidity and period of treatment

c. Performance in terms of TOC and DOC removals

Figures 4.28 and 4.29 give removal efficiencies and concentrations of TOC and DOC in
the feed water and the permeate. The numerical values are given in table B.36, appendix B.
Period of treatment (days) Figure 4.28 TOC and TOC removal rate with period of treatment

TOC of the feed water was 8.54 – 10.54 mg/L, and that of the permeate was 1.29 – 2.2
mg/L. TOC removal efficiency of the PAC + PACl + CMF hybrid system was 75.14 –
86.30 %. Compared with this of scenarios without coagulation-flocculation, 18.8 – 26.1 %,
and without PAC adsorption, 72.59 – 75.63 %, the scenario with pre-treatment by both
PAC and PACl was much more effective on TOC removal. In addition, the PAC
adsorption and coagulation-flocculation also prolonged the filtration time of the membrane.
DOC of the feed water was 6.26 to 7.31 mg/L and higher than this of the permeate, 1.11 –
1.83 mg/L. Meanwhile, the last experiment without PAC adsorption had the remaining
DOC in permeate of 2.28 – 2.52 mg/L. This comparison clarifies important role of PAC on
removing DOC composition in the feed water. DOC removal efficiency of the PAC + PACl + CMF hybrid system was 76.56 – 82.26 %. This value was very high the DOC removal efficiencies of the other scenarios (without PAC: 63.4 – 69.5%, and without both PAC and PACl: 15 – 31%). Period of treatment (days) Figure 4.29 DOC and DOC removal rate with period of treatment

d. Performance on micro-particle removal
Figures 4.30 gives the graphical results on removing micro-particle with range size from 5-
15 µm. Table B.38, appendix B, presents detailed measurement on the micro-particles.
Period of treatment (days) Figure 4.30 Number of micro-particle and period of treatment of the PAC + PACl + CMF

Removal efficiency on micro-particles with same range size of Giadia and Crypto was
99.86 - 99.94 %, and log micro-particles removal was 2.87 – 3.26. The feed water had
6607 – 8726 particles/mL, and the permeate had 4 - 9 particles/mL with size of 5 – 15 µm.
The number of the micro-particles of the permeate was decreased with the increase of
treatment duration due to accumulation of foulants.

4.3.4 Comparison of results
a. Filtration time, TMP, and TMP recovery
Figure 4.31 presents changes of TMP with filtration time in the different scenarios.
Through the graph, the experiment runs with direct ceramic microfiltration had the shortest
filtration durations, 7 and 11 days. When combined with pre-treatment by PACl
coagulation-flocculation, the hybrid CMF system had longer filtration times, 13 and 19
days. Moreover, pre-treatment by adsorption using PAC helped to increase period of
treatment up to 21 days. The results pointed out the advantages of hybrid CMF systems
compared with direct CMF system. With the hybrid systems, increase of filtration time and
lower TMP increase were found out.
The pre-treatment processes including coagulation-flocculation, and adsorption reduced
effectively colloidal-organic matters. Therefore, they helped the hybrid systems to reduce
irreversible fouling caused by the colloidal materials inside the membrane pores. These
results indicate lower increase of TMP with time of the hybrid scenarios compared with
that of other runs of the direct CMF scenario.
Period of treatment (days) Figure 4.31 Changes of TMP with filtration time
In the direct CMF system, the TMP increased quickly, and the average TMP recovery by each time of backwashing also was the highest. This was caused by high particle content in the feed water and no pretreatment for reducing them prior to the membrane. In contrast, TMP of the hybrid systems increased slowly with time and the average TMP recovery by backwashing was also smaller. The figure 4.31 and 4.32 point out that more hybridized system, lower TMP increase with time and smaller TMP recovery by backwashing also. Figure 4.32 Recovery of TMP by each time of backwashing

Table 4.1 presents TMP recovery by steps of chemical cleaning procedure. Based on the
results, more enhanced by pre-treatment, the ceramic membrane was cleaned better by the
first step using citric acid solution. Citric acid has the function for dissolving inorganic
matters existed in both inorganic and inorganic-organic complexes such as ion-organic
compound. Pretreated by coagulation-flocculation and adsorption, a notable amount of ions
and colloid was constituted into the flocs or adsorbed in the PAC particles. This flocs then
were removed effectively by backwashing. These processes reduced ions and colloidal
fouling, so the effectiveness of citric acid on cleaning was enhanced with the increase of
the pretreatment levels.
Table 4.1 TMP recovery by chemical cleaning
TMP with tap water (kPa) at flux of 50 L/m2.h After washed by NaClO 0.3 % PAC + PACl + CMF
b. Pollutant removal and quality of treated water

Figure 4.33 is the summarized comparison on removing main pollutants of the different
scenarios, and table B.39, appendix B, presents detailed comparative results. In both direct
CMF and hybrid systems, total coliform, fecal coliform, and TSS were removed
completely in the steady states of the operations. With the pore size of 0.1 µm, the ceramic
membrane was very attractive to remove the bacteria and TSS. Moreover, adding NaClO
into the filtrate tank for enhancing backwashing also contributed to the disinfection of the
bacteria in the filtrate if any.
Figure 4.33 also clarified important roles of the pre-treatment processes. Without pre-
treatment, the direct CMF system had lower pollutants removal efficiencies. Both TOC and
DOC were not removed well by the direct filtration, less than 25%. But in the hybrid
systems, they were removed more than 60% by coagulation-floccualtion combined with
the CMF. In the other hand, PAC adsorption also played an important role through
increasing significantly pollutants removal efficiencies including DOC, more than 80 %.
Figure 4.33 Comparison among scenarios on removals of major pollutants

Two currently available standard systems were used for evaluation of the treated water.
They are given in table 4.2. From the table, compliances were achieved at all scenarios if
the permeate is used for domestic supply water in Vietnam, a developing country located
on Mekong river delta. For drinking purposes in the USA, only the permeate of the hybrid
system that all PAC, PACl, and CMF were constituted complied fully the standard. With
other systems including direct CMF and hybrid CMF enhanced by PACl, permeate also
met the USA standard for almost all of parameters except percentage requirement on
Giardia and Cryptosporidium removals.
Table 4.2 Quality of treated water and standards
Permeate of scenario Cryptosporidium % removed TDS mg/L 312 214 204 a Vietnamese national standards TCVN 5502:2003 - Domestic supply water
b National secondary drinking water standards, EPA, USA- The maximum permissible level of a contaminant
in water which is delivered to any user of a public water system

4.4 Experimental runs with municipal wastewater

In these experiments, AIT wastewater was used as a municipal wastewater source, which
had the seriously polluted characteristics presented in the table 3.3. Therefore, pre-
sedimentation tank were added to reduce TSS of the feed water that made rapid clogging to
the membrane. In addition, operational conditions for experiments also were adjusted in
comparison with the last experiments with surface water. Backwashing interval of the
CFM system used for wastewater treatment was 40 minutes instead of 2 hours as used for
surface water treatment. NaClO solution with dosage of 15 mg/L also was used for
enhancement backwashing process. The experimental results are summarized as the
followings.

4.4.1 Scenario 1: Direct ceramic microfiltration
a. Transmembrane pressure (TMP)

Figure 4.34 presents graphical results on TMP and turbidity changing tendencies of the
scenario, and table B.41, appendix B, shows detailed results.
Period of treatment (days) Figure 4.34 Changes of TMP and turbidity of feed water with period of treatment
The fouling with TMP of 120 kPa was achieved on the 4th day of the treatmento. Although turbidity of feed water was kept stably from 56.9 to 61.5 NTU, the TMP of the system was increased rapidly day by day. Compared with the same scenario used for treatment of surface water (turbidity of 7.06-7.62 NTU, BW interval of 2 hours and filtration time of 11 days), the experiment had much shorter filtration time although BW interval was shortened down to 40 mintues. This pointed out clearly that in wastewater treatment, the filtration cycle for getting fouling is much smaller than that in surface water treatment. TPM recovery by each time of backwashing was 10 to 15 kPa. TMP recoveries by chemical cleaning using acid citric 1% solution and NaClO 0.3% solution respectively were 45 kPa (TMP was reduced from 110 kPa down to 65 Kpa after 24 hours of soaking) and 50 kPa (TMP was reduced from 65 Kpa to 15 Kpa after 24hours of soaking), respectively. b. Performance of the system in terms of turbidity removal

Figure 4.35 presents graphical changes of turbidities with filtration time. For more detailed
data, refer to table B.41, appendix B.
Period of treatment (days) Figure 4.35 Changes of turbidity of feed water and permeate with time

Due to the accumulation of foulants, a steady state was achieved on the 3rd day of the
operation. In this case, turbidity of permeate was kept constantly around 15 NTU with the
turbidity removal efficiency of 75 %. This efficiency was lower than that of the surface
water treatment. The phenomenon can be explained by the higher colloidal fraction in
wastewater (refer to the DOC concentrations on the tables 3.2 and 3.3). In addition, a part
of DOC fraction passed to pores of ceramic membrane without pre-treatment such as
coagulation or adsorption.

d. Performance on micro-particle removal

Figures 4.36 gives graphical results on removing micro-particles within the size range of 5
to 15 µm (refer to table B.42, appendix B).
Period of treatment (days) Figure 4.36 Number of micro-particle and period of treatment of the direct CMF system
Micro-particles removal efficiency (Giadia and Crypto removal efficicncy) was 99.17 -
99.61 %, and log micro-particles removal was 2.08 – 2.41. The feed water had 36780 –
37080 particles/mL, and the permeate had 144-303 particles/mL with size of 5 – 15 µm.
When the operation was steady, the micro-particles removal was stable with the removal
efficiency of 99.61 % and the permeate had 144 particles/mL.

c. Performance in removing other pollutants: TOC, BOD, COD, total coliform, and
fecal colifrom.

Figure 4.37 summarizes performance of the direct CMF system on removing major
pollutants when the system was operated at the steady state. Table B.43, appendix B,
presents detailed analytical results.
Figure 4.37 Removals of pollutants by the direct CMF system
TOC of the permeate was 11.4 mg/L, and smaller than the value of the feed water, 16.9 mg/L. TOC removal efficiency was 32.5 %. Compared with the direct CMF for surface water treatment, TOC removal of 28.3 %, the higher TOC removal efficiency was achieved in the treatment of municipal wastewater. This result can be explained through the difference between TSS of wastewater and surface water. After pre-treated by mesh screen and pre-sedimentation tank, the wastewater had TSS of 25 mg/L (figure 4.38). This value was higher than TSS of the surface (table 3.2). Once organic TSS was removed, TOC also was removed. Therefore, the TOC removal efficiency of wastewater reclamation was higher that of surface water treatment. COD of the feed water was 106 mg/L. The treated wastewater had 44 mg COD/L with the removal efficiency of the system of 58.5 %. BOD5 removal efficiency was 21.9 %, with BOD5 of the feed water and the permeate was 32 mg/L and 25 mg/L respectively. Total coliform and fecal coliform in feed water was 4.4*106 MPN/100mL and 3.1*106 MPN/100mL respectively. Both total colifrom and fecal coliform of permeate were none-detected. This means the direct CMF removed completely total coliform and fecal coliform. 4.4.2 Scenario 2: Coagulation-flocculation and CMF
a. Transmembrane pressure (TMP)

Figure 4.38 presents graphical results on TMP and turbidity changing tendencies of the
scenario. Table B.45, appendix B, shows detailed results.
Period of treatment (days) Figure 4.38 Changes of TMP and turbidity of feed water with period of treatment

In the experiment, a fouling with TMP of 110 kPa was achieved on the 15th day of the
operation. Compared with the last experimental run without coagulation that had only 4
days of a filtration cycle, the run with enhancement by coagulation-flocculation using
PACl had a much longer filtration time. Considering the feed water, after pre-
sedimentation tank, it had the almost same characteristics including turbidity compared
with that used for the last run without coagulation. Therefore, the important role of primary
coagulation-flocculation on prolonging filtration time was also confirmed strongly again.
TMP did not increase rapidly as it did in the scenario without coagulation-flocculation.
Each time of backwashing TMP recovery was from 5 to 10 kPa. Total TMP recovery rate
by chemical cleaning was 100 %, with 75 kPa and 25 kPa recovered by acid citric solution
1% and by NaClO solution 0.3%, respectively.

b. Performance of the system in terms of turbidity removal
Figure 4.39 gives graphical changes of turbidities with filtration time. Table B.45,
appendix B, points out analytical results and performance of the hybrid system in removing
turbidity.

Turbidity of the feed water was fluctuated slightly from 60 to 65 NTU. On the 1st day of
the treatment, turbidity of permeate was 3.68 NTU. This value was decreased with time to
1.12 and 0.43 NTU on the 2nd and 3rd day due to foulants accumulation. A steady state in
term of turbidity removal was started on the 4th day. In this state, turbidity of permeate was
0.18 - 0.23 NTU. Compared with the run without coagulation-flocculation, permeate had
turbidity of 15 NTU, the PACl + PAC run had much higher quality of permeate in terms of
turbidity. The turbidity removal efficiency of the hybrid scenario was 99.65%.
Period of treatment (days) Figure 4.39 Changes of turbidity of feed water and permeate with time

d. Performance on micro-particle removal
Figures 4.40 presents results on removing micro-particle (Giardia and Cryptoporidium) of
the hybrid CMF system. Table B.46, appendix B, gives detailed micro-particles
measurement of the experiment.
Period of treatment (days) Figure 4.40 Number of micro-particle and period of treatment of the PACl + CMF hybrid
Compared with the last experiment on direct CMF, this scenario had a higher performance in removing micro-particles. Removal efficiency on micro-particles with same range size of Giadia and Crypto was 99.86 - 99.95 %. Log micro-particle removal was 2.86 – 3.32. The feed water had 37380 – 37480 particles/mL, and permeate had 18 - 51 particles/mL with size of 5 – 15 µm (18 particles/mL in the steady state). The number of the micro-particles of permeate was decreased with the increase of period of treatment due to accumulation of foulants. In the steady state, the average removal efficiency and log removal was 99.95% and 3.2 respectively. c. Performance in removing other pollutants: TOC, BOD, COD, total coliform, and
fecal colifrom.

Figures 4.41 gives summarized results on performance of the hybrid PACl + CMF system
on removing major pollutants when it was operated in steady state. Table B.48, appendix B,
presents detailed analytical results.
Removal rat e (%) Figure 4.41 Removals of pollutants by the PACl + CMF hybrid system

Average TOC of the feed water was 17.3 mg/L, and this of the permeate was 5.22 mg/L.
TOC removal efficiency was 68.83 % and very high when compared with the direct CMF
(TOC removal efficiency of 32.5 % only). This result presents the important role of
coagulation-flocculation for enhancing the ceramic membrane on TOC removal.
COD of feed water was 108 mg/L and this of permeate was 44 mg COD/L present COD
removal rate of the hybrid system of 66.67%, slightly higher than the removal of the direct
CMF system, 58.5 %. BOD removal rate of 62.5 % also was higher than BOD removal rate
of the last scenario without coagulation-flocculation, 21.9 %. BOD of feed water and
permeate was 32 mg/L and 12 mg/L, respectively.
Total coliform and fecal coliform of feed water was 4.4*106 MPN/100mL and 3.1*106
MPN/100mL respectively. Both total coliform and fecal coliform of permeate were none-
detected, so the removal rate of the hybrid system on these microbial pathogens was 100% .
4.4.3 Comparison of results
a. Filtration time, TMP, and TMP recovery
Figure 4.42 presents changes of TMP in different scenarios. Through the graph, the
experiments with direct ceramic microfiltration had the shortest filtration filtration, only 4
days of a cycle. When combined with pre-treatment by PACl coagulation-flocculation, the
hybrid CMF system had a longer filtration time, 18 days. The results pointed out the
advantage of hybrid CMF systems in terms of prolonging filtration time compared with
direct CMF system. The longer filtration cycle also increased treated water production and
saved chemical utilization for the chemical cleaning.
Period of treatment (days) Figure 4.42 Changes of TMP with filtration time

The pre-treatment processes using coagulation-flocculation reduced effectively colloidal-
organic matters. Therfore it helped the hybrid systems to reduce irreversible fouling caused
by the colloidal materials inside the membrane pores. These results indicate lower TMP
increase with time of the hybrid scenario compared with the direct CMF scenario.
In the direct CMF system, the TMP increased quickly. The average recovered TMP by
each time of backwashing also was high. In contrast, TMP of hybrid system increased
more slowly with time, and the average TMP recovery of backwashing was also smaller.
The figures 4.42 and 4.43 tell that more hybridized system, lower TMP increase with time
and smaller TMP recovery by backwashing as well.

TMP recovered by steps of chemical cleaning procedure is given in table 4.3. Based on the
data, when enhanced by pre-treatment, the ceramic membrane was cleaned better by the
first cleaning step using citric acid solution.
Figure 4.43 Recovery of TMP by each time of backwashing

Table 4.3 TMP recovery by chemical cleaning
TMP with tap water (kPa) at flux of 50 L/m2.h After washed by NaClO 0.3 % Hybrid PACl + CMF
b. Pollutant removal and quality of treated water

Figure 4.44 is summarized comparison on removing main pollutants of the two different
scenarios. Table B.49, appendix B, presents detailed comparative results.
CM
C
+
Figure 4.44 Comparison among scenarios on removals of major pollutants
In both the direct CMF and hybrid systems, total coliform, fecal coliform were removed completely. With the pore size of 0.1 µm, the ceramic membrane was very attractive to remove the bacteria. In addition, adding NaClO into the filtrate tank for enhancing backwashing also served as a disinfection factor for killing the bacteria. The comparison also clarified important roles of the pre-treatment by the coagulation-flocculation. Without the pre-treatment, the direct CMF system had lower efficiency on removing pollutants. TOC, COD, and BOD5 were removed better by the hybrid CMF system compared with the direct filtration. However, removals of both the two scenarios on these parameters were not high. This can be understood that the soluble form of organic carbon could not be treated by only the physico-chemical processes combined with the membrane. Some currently available standards used for investigation of potentials of the treated wastewater for reuse activities are given in table 4.4. With direct microfiltration, turbidity, BOD5, and COD could not meet any the reuse standards except Vietnammese standards for irrigation. Other remaining parameters including pH, TSS, TDS, free Cl2 residual, Fe, Mn , total coliform, and fecal coliform complied fully or partly requirements for reuse activities in the all given countries. These reuse activities are irrigation, toilet flushing, sprinkling, and landscape. With the hybrid CMF system in which PACl coagulation-flocculation was combined with the CMF, the improved quality of treated wastewater become more suitable and compliable the reuse standards. The permeate completely met all Vietnamese, Taipei and Chinese national standards for irrigation, and reclaimed water standard in Florida, USA. Further more, this permeate also complied other standards for reuse activities of other countries including Japan, Italy, Korea, and etc. In conclusion, there were great potentials for reusing treated municipal wastewater including irrigation, sprinkling, and etc. The hybrid ceramic microfiltration system presented attractive and important roles in treatment of the wastewater for reuse activities. Based on the achieved results in terms of standard compliance, technical and economical aspects, the research with municipal wastewater was stopped after the experiment on PACl + CMF hybrid systems. Table 4.4 Quality of treated wastewater and standards for reusing activities
Permeate of scenario Parameters Unit Direct Chlorine residual a Vietnamese national standards TCVN 6773:2000 - Irrigation water − Quality requirements (Vietnam Environmental Protection Agency, 2008) b Italian standards (D.M 185/03, 2003) for reclaimed wastewater (Cirelli et al, 2008) c National irrigation water quality standards of Turkey, class: satisfactory (Alaton et al, 2007). d Chinese national water quality standards for reclamation (GB/T18920,T18921-2002): d1) Toilet flushing, d2) Irrigation of green, d3) Washing purpose. (Ernst et al, 2007). e Korean national standard for water reuse: e1) For toilet flushing, e2) For sprinkling, e3) For landscape. (Ahn & Song, 1999). f Water quality requirements for agricultural irrigation in Taiwan, Long-term usage: continuously used for all types of soil. (Lin & Cheng, 2001). g Japanese standard for toilet flushing purpose (Asian Science and Technology Seminar by Japan Science and Technology Agency. 10th March,2008, Bangkok, Thailand) h Guidelines for Water Reuse-EPA/625/R-04/108 September 2004. Unrestricted urban reuse in Florida including use of reclaimed water for irrigation of residential lawns, golf courses, cemeteries, parks, playgrounds, schoolyards, highway medians, and other public access areas (EPA, 2004). 4.5 Operational problems generated from the dead-end CMF system and solutions
Operational problems during treatment of the surface water and municipal wastewater were investigated in the study with the dead-end filtration.
The problems were generated in direct CMF or hybrid ceramic microfiltration systems in the tropical condition. Preventative solutions for
avoiding the operational problems were found out based on experience during the study. However, in some urgent cases that problems still were
occurred, successful solutions were investigated and adopted to overcome them. Table 4.5 presents briefly operational problems, preventative
solutions, and usefully applied solutions for the dead-end CMF system.
Table 4.5 Operational problems and solutions of the dead-end CMF system
During power failure The system was stopped Need to frequently check the system Re-start system manually on PLC automatically re-started Too low level of water in the The system was stopped Need to frequently check the system Feed raw water to the storage tank, increase capacity of the and "low level" lamp on first raw water pump before storage tank until appearing overflow in drainage pipe. Clogging of feed pump (piston The system was stopped Considering quality of feed water and Stopping operation, plugging out electricity, and cleaning the and "overload" lamp on checking frequently the system piston pump using tap water and washing liquid. Piston pump has sound Big sound generated Checking carefully the pump whether it Taking out and filling machine oil into the suitable part of the form the piston pump Damage of PG due to TMP was PG was damaged or not Considering quality of feed water and Cleaning and setting up pre-treatment system to reduce TSS increased too rapidly more than indicating exactly TMP status of pre-treatment such as mesh of feed water as high as possible. Changing PG. screen and pre-sedimentation tank Membrane was fouled too TMP was increased Considering quality of feed water and Shortening BW interval and increase NaClO dosage for EBW quickly before BW status of pre-treatment such as mesh screen and pre-sedimentation tank Chapter 5
Conclusions and Recommendations
5.1 Conclusions

In this study, the influences of pre-treatment processes on treatment of SW and MWW of
ceramic membrane filtration were investigated on a series of scenarios in pilot scale. The
membrane was operated at constant flux of 50 L/m2.h in all the experimental runs. It was
found out that pollutants removal efficiency and performance of a hybrid CMF system
would differ depending on the pre-treatment process and operational conditions.
The research on treatment of surface water was conducted with the highly organic surface
water source. Coagulation-flocculation with poly aluminum chloride (PACl) was
optimized for the hybrid system at a coagulant dose of 2.0 mg Al/L. With the coagulation-
flocculation, the hybrid CMF system removed completely TSS, total coliform, and fecal
coliform. In addition, 99.8% of Crytoporidium and Giadia, 99 % of turbidity, 70.8 % of
TOC and 63.5 % of influent DOC were also pollutants removal efficiencies of the hybrid
CMF system.
Furthermore, optimum conditions in combination between adsorption and coagulation-
flocculation were found out to enhance the ceramic microfiltration. With optimized doses
of 20 mg/L powder activated carbon (PAC) and 2 mg Al/L PACl, the hybrid PAC + PACl
+ CMF system removed completely TSS, total coliform, and fecal coliform. On the other
hand, the highest efficiencies on removing other pollutants also were achieved in this
scenario. More than 99 %, 83 %, and 81 % are the removal efficiencies of Crytoporidium
and Giadia, TOC, and DOC of the influent, respectively.
Reduction of fouling, higher filtration time and more effectively chemical cleaning are also
investigated in the hybrid CMF systems. With direct CMF system, the time duration of a
filtration cycle that was needed to conduct chemical cleaning was only 7 - 11 days. The
filtration time was prolonged in hybrid CMF systems, 13 – 19 days for PAC + CMF and
21 days for PAC + PACl + CMF. The highest quality of permeate was found out in the
PAC + PACl + CMF hybrid system and it complies all requirements of the EPA's drinking
water standard, especially on Giardia and Cryptoporidium removal.
In reclamation of wastewater aspect, the research focused on investigation of reuse
potentials of municipal wastewater. Pre-treatments also influenced strongly to the
operation of ceramic filtration and quality of treated wastewater. Performance of the
ceramic membrane was improved notably when the CMF was combined with PACl
coagulation-flocculation. In the hybrid system, all total coliform, fecal coliform and TSS of
the influent were removed completely, 100 %. COD and BOD5 removal efficiencies were
70 % and 63 %, respectively.
In comparisons with national reclaimed wastewater standards, reuse applications were
investigated for the treated MWW in the direct and hybrid CMF systems. The treated
MWW could be reused for toilet flushing, sprinkling, and irrigation purposes. Irrigations
activities are the most suitable applications due to the rich nutrient budget of the permeates.
The direct CMF for the MWWT had a filtration cycle of 4 days only. But in the hybrid
CMF system, the time duration of a filtration cycle would be increased up to 18 days. The
prolonged filtration cycle helped to increase amount of treated WW production, reduce
chemical utilization for chemical cleaning and increase life time of the membrane.
In the both SWT and MWWT, lower TMP recovery by each time of backwashing and
lower TMP increase were found out in the hybrid systems. Chemical cleaning by citric
acid solution also was more effective with the hybrid CMF systems.
In conclusion, ceramic membrane has been investigated many its unique advantages in
water and wastewater treatment in this research. Moreover, the study evaluated and
investigated performances of different CMF systems. Technical advantages such as highly
automatic operation and higher period of treatment are also observed during the
experiments. It was investigated that the more enhanced hybrid systems, the higher
qualities and more satisfied use activities of the permeates.

5.2 Recommendations for future works
Due to limitations of time budget and currently analytical equipment, some interesting
works could not be conducted in the thesis study. Therefore, the followings are proposed
on-going researches for the CMF system:
1. Researches on hybrid Ozonation + PACl coagulation + CMF system in which the CMF
will be enhanced by pre-ozonation process prior to the coagulation process:
Ozonation will serve as both pre-disinfection and physical processes for enhancement of
coagulation. As a pre-disinfection, the ozonation helps to reduce bio-fouling by killing
bacteria. In addition, the process also helps to disinfect protozoan parasites,
Cryptoporidium and Giadia, especially their oocyst and cyst, that are very resistant to other conventional disinfectants. In the other hand, the pre-ozonation process should also be considered in terms of enhancement for the PACl coagulation process. Ozonation will reduce Zeta potential of raw water leading to a reduction of optimum coagulant dosage needed for the coagulation. However, DOC concentration will be increased with the increase of ozone dosage due to the breaking down of organic materials caused by ozone. Once DOC concentration is too high, it will not be removed completely by coagulation and flocculation. The remained DOC then will go though membrane pores and cause high DOC content in permeate. Therefore, an optimum ozone dosage has to be considered carefully to enhance coagulation and also limit DOC produced. In short, an optimum ozone dosage should be found by doing ozonation test and jar-test. Analytical parameters for the tests should be pH, zeta potential, and DOC. 2. A practical research with a real river water source in Thailand. In the thesis, AIT pond water was used as a surface water source. Actually, this water was created by the combination of rain water and secondary effluent (effluent of oxidation ponds) of AIT WWT plant. Therefore, compositions of the AIT pond water can be different from those of real river water. A case study in Thailand is a very interesting research direction. Certainly a case study will contribute attractively to transferring the
CMF technology for SWT in Thailand and other adjacent countries in the Mekong river
delta.
To conduct the research, the CMF pilot should be moved to a SWT plant nearly from an
obtain river. Moreover, it should sure that the laboratory conditions where placing the pilot
are good enough for sampling, preservation, and quick measurements of some parameters.
3. Researches on potentials of reusing the secondary effluent of the AIT WWT plant.
The effluent of AIT oxidation pond has a better quality compared with this of AIT sewer.
Therefore, treatment of the effluent promises many other reusing activities even
portabilities of treated water.
The research can be conducted in the same scenarios which were implemented with the
AIT Pond water: direct microfiltration and hybrid CMF systems including PAC adsorption
and PACl coagulation-flocculation.
4. Researches on functions of the PAC or ozonation in removing organic toxic substances
in surface water.
Although the PAC adsorption was used in the thesis study, toxic organic pollutants such as
herbicides and fertilizers were not subjected and researched. Actually, the PAC can remove
effectively the toxic substances existing in many surface water sources affected by
agricultural activities. Therefore, researches on effects of the PAC can be clarified in terms
of toxic chemicals affecting to health safety aspects of drinking water.

Furthermore, ozonation also is an attractive solution for removing the toxic substances,
especially aromatic organics. Ozone is a strong oxidant, it breaks well persistent organics.
When combing the pre-ozonation with the CMF system, it is very interesting to point out
important roles of the hybrid system for treatment of surface water sources contaminated
by POPs from agricultural activities.
Based on results of the PAC or ozonation combined with CMF, a most suitable solution
will be selected for a case study with specific characteristics of raw water (in the Mekong
delta, for example).
5. A comparative study between the hybrid CMF and conventional treatment systems in
pilot scale.
Although the CMF is an advanced technology, it almost has been being researched in pilot
scales. In the world, only some developed countries such as Japan and Turkey transferred it
to practical cases. In the Southeast region, there is no water treatment plant built by the
technology. Therefore, a comparative study in terms of technical and economic aspects
should be conducted.
A pilot modeling a conventional surface water treatment plant can be set-up including bar
screen, coagulation, flocculation, sedimentation, sand filtration, and post disinfection by
chlorine. The treatment of same raw water will be conducted in parallel with that of the
hybrid CMF system.
Comparisons among the conventional pilot and differently operational scenarios of the hybrid CMF system will be pointed out in terms of economy (capital and operational cost) and technique aspects (complication, problems and solutions for design and operation of the systems, and etc.). In conclusion, on-going researches can be conducted with the fives proposed directions, but the followings should be considered for the operation and analysis of the hybrid CMF systems: - Depending on specific feed water and scenario, backwashing interval should be checked and adjusted if necessary. The adjustments are to get good TMP recovery, low energy consumption, and high treated water production a day. - NaClO dosage for enhancement of backwashing should be adjusted depending on the characteristics and levels of pollutants in raw water. The used NaClO should be selected carefully to get both high reduction of fouling and compliance of standards (on free chlorine residual for detailed using/reusing activities of treated water). - Cryptosporidium and Giaidia should be measured exactly by a microbial-analysis such as polymerase chain reaction (PCR) method to get more exact results on the micro pathogens removal. - In the treatment of such highly organic surface water for drinking purposes, once the chloride solution (NaClO) is injected continuously to the filtrate, THMs should be measured. This is to ensure health safety aspects of the treated water. References
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Operation procedure of the pilot system
Photos of the experiments
Operation procedure for the CMF pilot

a. Manual operation

- Turn the switches located on the middle to lower control panel on to operate the
equipment manually.
- Turn the switch OFF to stop the operation
- Turn the switch to open the valve. Turn the switch SHUT to close the valve. Either
operation is full open or full close.
- The membrane feed after valve (AV1) needs to be opened when the feed pump is
operated
- Compressed air (0.2 – 0.5 MPa) will flow into the equipment when backwash air valve
and blow valve

b. Automatic operation
The system can be operated automatically by a program that was set in the controller PLC.
The equipment will repeat the automatic operation process following the software program.
The cycle including feeding water, filtration and backwashing is repeated. This automatic
operation is shown on the upper side of the control panel.
"Raw water feed" means filling up the raw water side of the ceramic membrane with the
coagulated water. "Filtration" means filtrating the coagulated water through the ceramic
membrane. "Backwash" means the ceramic membrane with the filtrate pushed by the
compressed air through the raw water side of the ceramic membrane. Automatic operation
procedure is as expressed as the following step:
- Turn all the switches located on the middle to lower part of the control panel to - Press the "operation START button" - The equipment operating" and the "feed water" sign that are located on the upper part of the control panel are on and connecting, this indicates that the equipment began operating. In cases that need to stop automatic operation such as for taking membrane out to clean by chemical, the following steps should be implemented: - Press the "equipment STOP button" - "Run" pilot lamp located on the upper part of the control panel will be off after the - For emergency situation, press the "Emergency stop: (red color) located on the bottom part of the control panel. Also, turn the emergency switch to the right to clear all. Backwash is automatically operated after 2-3 hours of filtration (depending on setting up interval). However, we can use manual backwash during automatic operation. While the "Filtration" pilot lamp is light, press "manual backwash button". Backwash process is operated automatically, after completed the process enters into the "feed water" process automatically and continues automatic operation. Figure A.1 The hybrid ceramic micro-filtration systems
Figure A.2 Chemical cleaning after the experiment with synthetic water: a) & b): After the
experimental run; c) Cleaning by citric acid solution 1%; d) Cleaning by NaClO solution 0.3 %; e) & f): Cleaned ceramic membrane Figure A.3 a) Fouled ceramic membrane after the PAC + PCl + CMF hybrid system used
for the SWT, b) Cleaning by citric acid solution 1%; c) PAC cake foulant; d) Cleaning by NaClO solution 0.3%; e) & f) Cleaned membrane Figure A.4 a) Fouled ceramic membrane after the MWWT by the PCl + CMF hybrid
system; b) During chemical cleaning; c) Cleaned membrane APPENDIX B
Standard curves used for the analysis
Monitoring and analyzing results
Figure B.1 TC and IC standard curves which were used for TOC measurement
Figure B.2 Fe standard curve which was used for iron measurement by AAS machine
Figure B.3 Mn standard curve used for manganese measurement by AAS machine
Table B.1 Characteristics of tap water in the AIT's ambient lab

Micro particles count/mL

Table B.2 Relationship between Kaolin clay dosage and turbidity of synthetic water
Kaolin clay dosage (mg/L) Turbidity 20 14.5 40 28.2 60 42 80 58.5 100 73.2 120 115 140 131 160 145 180 171 200 199 250 238
Table B.3 Jar test with coagulation-flocculation for AIT pond water

PACl Dosage (mg/L) Table B.4 Jar test with adsorption for AIT pond water

10 7.15 4 9.55 15 7.16 4 9.49 20 7.18 4 9.31 25 7.2 4 9.23 30 7.24 4 9.04 35 7.26 4 8.95 40 7.29 4 8.25 45 7.3 4 7.97 50 7.33 3 7.49 100 7.4 2 6.59 150 7.5 2 6.2 200 7.75 2 6.1 250

Table B.5 Jar test with the combination of adsorption and coagulation-flocculation
for AIT pond water (with PAC dosage of 20 mg/L)



Table B.6 Jar test with coagulation-flocculation for AIT wastewater

PACl Dosage (mg/L) Table B.7 Jar test with adsorption for AIT wastewater

10 6.99 18 10.77 20 7.01 18 9.2 30 7.04 18 8.7 40 7.05 18 8.22 50 7.14 17 8.13 60 7.21 17 6.2 80 7.32 14 5.75 100 7.58 13 5.34 150 7.72 10 3.15

Table B.8 Jar test with the combination of adsorption and coagulation-flocculation
for AIT wastewater (with PAC dosage of 30 mg/L)

Table B.9 Conductivity, pH and temperature of the experiment with synthetic water

Conductivity (µs/cm) 49.7 7.2 7.3 27.3 26.9 48.3 7.1 7 27.6 27.2 50.2 6.8 6.7 30.6 29.1 47.9 7.1 7.1 27.5 27.1 10-Sep 4 49.8 47.9 6.9 11-Sep 5 47.5 47.6 7.1 12-Sep 6 48.9 48.2 7.3 18 48.8 52.7 7.4 Table B.10 Turbidity and TMP of the experimental run with synthetic water

Turbidity removal 9/13/2007 7 35.9 0.098 9/14/2007 8 38.2 0.082 9/15/2007 9 41.7 0.077 9/16/2007 10 38.9 0.069 9/17/2007 11 39.5 0.072 9/18/2007 12 40.1 0.057 9/19/2007 13 39.5 0.061 9/20/2007 14 38.7 0.076 9/21/2007 15 39.2 0.068 9/22/2007 16 39.8 0.077 9/23/2007 17 39.5 0.063 9/24/2007 18 41.7 0.085 9/25/2007 19 80.6 0.092 9/26/2007 20 77.3 0.079 9/27/2007 21 79.8 0.082 9/28/2007 22 80.5 0.065 9/29/2007 23 81.5 0.073 9/30/2007 24 82.5 0.085 10/1/2007 25 85.7 0.094 10/2/2007 26 81.6 0.078 10/3/2007 27 82.6 0.08 10/4/2007 28 81.7 0.086 10/5/2007 29 84.5 0.084 10/6/2007 30 80.7 0.069 10/7/2007 31 80.2 0.077 10/8/2007 32 79.5 0.067 10/9/2007 33 84.5 0.087 10/11/2007 35 122.5 0.115 Table B.11 Total Fe and Mn of the experimental run with synthetic water

Total Mn (µg/L) water Permeate Feed 0 1.25 0.03 10 ND 5 1.22 0.04 20 10 12 1.53 0.03 30 10 19 1.02 0.03 20 10 26 1.52 0.07 185 ND 36 2.05 0.07 40 ND 42 1.47 0.05 50 ND 48 1.57 0.03 40 ND
Table B.12 DOC, TOC, TSS, and TS of the experimental run with synthetic water

water Permeate Feed 1.062 2.89 1.23 150 0.5 226 0.998 2.91 1.79 148 0.5 221 1.011 2.87 1.63 153 0.5 219 1.005 2.57 1.12 304 0.5 454 26 1.58 1.08 3.79 1.73 302.5 0.5 460 36 1.48 1.18 2.59 2.08 149 0.5 442 42 1.13 0.86 1.93 1.13 153 0.5 304 48 1.07 0.78 2.14 1.22 178 ND 314

Table B.13 Micro-particles measurement of the experiment with synthetic water

Micro-particles , Micro-particles, Micro-particles, Micro-particles, 102,200 8 1900 1 77,800 17 1500 2 82,760 11 1800 1 Table B.14 pH, conductivity, and temperature of the experimental run 1 on direct
CMF with surface water

Conductivity µs/cm
Table B.15 Turbidity and TMP of the experimental run 1 on direct CMF with surface
water


Table B.16 DOC, TOC, TSS, and TS of the experimental run 1 on direct CMF with
surface water

water Permeate Feed water Permeate Feed water Permeate water Permeate 7.23 11.23 8.30 11 0.5 210
Table B.17 Fe and Mn of the experimental run 1 on direct CMF with surface water
Dissolved Fe (mg/L) Total Mn (µg/L) Dissolved
Table B.18 Micro-particles measurement of the experimental run 1 on direct CMF
with surface water

Micro-particles , Micro-particles, Micro-particles, Micro-particles, Table B.19 pH, conductivity, and temperature of the experimental run 2 on direct
CMF with surface water

Conductivity µs/cm

Table B.20 Turbidity and TMP of the experimental run 2 on direct CMF with surface
water



Table B.21 DOC, TOC, TSS, and TS of the experimental run 2 on direct CMF with
surface water

water Permeate Feed 7.68 12.34 8.85 21 0.5 315

Table B.22 Fe and Mn of the experimental run 2 on direct CMF with surface water

Dissolved Fe (mg/L) Total Mn (µg/L) Dissolved Table B.23 Micro-particles measurement of the experimental run 2 on direct CMF
with surface water

Micro-particles , Micro-particles, Micro-particles, Micro-particles, 111,712 335 99,472
Table B.24 Conductivity, pH and temperature of the experiment 1 with surface water
on CMF combined with pretreatment by coagulation-flocculation

Conductivity µs/cm
Table B.25 Turbidity and TMP of the experiment 1 with surface water on CMF
combined with pretreatment by coagulation-flocculation

Turbidity removal
Table B.26 DOC, TOC, TSS, and TS of the experiment 1 with surface water on CMF
combined with pretreatment by coagulation-flocculation

water Permeate Feed 6.86 2.52 11.45 2.97 15 7.87 2.84 11.02 3.02 10 6.93 2.36 10.97 2.74 16 7.47 2.28 11.04 2.69 12 7.31 2.29 11.22 2.86 18 Table B.27 Fe and Mn of the experiment 1 with surface water on CMF combined with
pretreatment by coagulation-flocculation

Dissolved Fe (mg/L) Total Mn (µg/L) Dissolved 1.623 0.105 1.068 ND 1.531 0.101 0.985 ND 1.498 0.098 0.866 ND 1.377 0.092 0.981 ND 1.333 0.097 1.014 ND

Table B.28 Micro-particles measurement of the experiment 1 with surface water on
CMF combined with pretreatment by coagulation-flocculation

Micro-particles , Micro-particles, Micro-particles, Micro-particles,
Table B.29 Conductivity, pH and temperature of the experiment 2 with surface water
on CMF combined with pretreatment by coagulation-flocculation

Conductivity µs/cm
Table B.30 Turbidity and TMP of the experiment 2 with surface water on CMF
combined with pretreatment by coagulation-flocculation

Turbidity removal efficiency (%) 9-Dec 0 9.02 0.075 10-Dec 1 8.56 0.072 11-Dec 2 8.17 0.068 12-Dec 3 8.03 0.062 13-Dec 4 6.97 0.057 14-Dec 5 5.76 0.054 15-Dec 6 6.13 0.053
Table B.31 DOC, TOC, TSS, and TS of the experiment 2 with surface water on CMF
combined with pretreatment by coagulation-flocculation

water Permeate Feed 8.11 3.38 10.88 3.62 20 9.74 3.8 10.93 3.98 18 9.6 3.6 11.92 3.65 18 ND 237 8.55 3.62 12.5 3.78 15 ND 249 9.12 3.55 11.88 3.69 16 8.87 3.37 10.39 3.54 18 8.92 3.28 10.18 3.41 18
Table B.32 Fe and Mn of the experiment 2 with surface water on CMF combined with
pretreatment by coagulation-flocculation

Dissolved Fe (mg/L) Total Mn (µg/L) Dissolved 0.49 0.02 0.19 ND 0.69 0.01 0.32 ND 1.02 0.03 0.45 ND 0.67 0.02 0.33 ND 0.87 0.02 0.37 ND 0.89 0.02 0.36 ND 0.92 0.03 0.41 ND
Table B.33 Micro-particles measurement of the experiment 2 with surface water on
CMF combined with pretreatment by coagulation-flocculation

Micro-particles , Micro-particles, Micro-particles, Micro-particles, water Permeate Feed 65,812 270 59,316 3 68,964 230 61,276 211 6 65,836 222 59,426 205 9 67,648 214 60,179 198 12 63,476 215 56,969 202 15 60,966 217 54,824 204 18 69,260 223 61,475 210 Table B.34 Conductivity, pH and temperature of the experiment with surface water
on CMF combined with pretreatments by adsorption and coagulation-flocculation

Conductivity µs/cm

Table B.35 Turbidity and TMP of the experiment with surface water on CMF
combined with pretreatments by adsorption and coagulation-flocculation

Turbidity removal
Table B.36 DOC, TOC, TSS, and TS of the experiment with surface water on CMF
combined with pretreatments by adsorption and coagulation-flocculation

water Permeate Feed 7.31 1.47 8.85 2.2 7.8 1.83 10.54 1.99 18 6.68 1.23 8.54 1.35 12 ND 252 6.26 1.11 8.72 1.32 21 ND 247 7.01 1.2 8.92 1.29 10 6.37 1.27 7.47 1.37 16 ND 261 7.21 1.28 9.56 1.31 18 ND 219 Table B.37 Fe and Mn of the experiment with surface water on CMF combined with
pretreatments by adsorption and coagulation-flocculation

Dissolved Fe (mg/L) Total Mn (µg/L) Dissolved 0.55 0.09 0.25 ND 0.34 0.07 0.19 ND 0.71 0.08 0.1 ND 0.63 0.02 0.08 ND 0.67 0.03 0.17 ND 0.59 0.02 0.21 ND 0.87 0.05 0.18 ND
Table B.38 Micro-particles measurement of the experiment with surface water on
CMF combined with pretreatments by adsorption and coagulation-flocculation

Micro-particles , Micro-particles, Micro-particles, Micro-particles, 49,088 97 42,216 87 5672 9 200 1 Table B.39 Comparison among different scenarios for surface water treatment
Average removal rate, % PAC + PACl + CMF Giardia and Cryptosporidium
Table B.40 Conductivity, pH and temperature of the experiment with municipal
wastewater on direct CMF

Conductivity µs/cm Table B.41 Turbidity and TMP of the experiment with municipal wastewater on
direct CMF

Turbidity removal
Table B.42 Micro-particles measurement of the experiment with municipal
wastewater on direct CMF

Micro-particles , Micro-particles, Micro-particles, Micro-particles, 421,200 5121 383,160 4807 36780 303 1260 11

Table B.43 Performance of direct CMF on removing pollutants of municipal
wastewater

Parameters Unit Feed water Removal rate (%) Free Cl2 residual
Table B.44 Conductivity, pH and temperature of the experiment with municipal
wastewater on CMF combined with pre-treatment by coagulation-flocculation

Conductivity µs/cm Table B.45 Turbidity and TMP of the experiment with municipal wastewater by the
PACl + CMF hybrid system

Turbidity removal Table B.46 Micro-particles measurement of the experiment with municipal
wastewater by the PACl + CMF hybrid system

Micro-particles , Micro-particles, Micro-particles, Micro-particles, 430,100 602 391,324 546 37380 51 1396 5 Table B.47 Performance of removals of pollutants by the PACl + CMF hybrid system
Parameters Unit Feed water Removal rate (%) Free Cl2 residual Table B.48 Comparison between different scenarios for municipal wastewater
treatment

Average removal rate, % Giardia and Cryptosporidium Period of treatment (day) Figure B.1 pH of feed water and permeate of the experiment with synthetic water
Period of treatment (day) Figure B.2 Variations of temperature of the experiment with synthetic water
Period of treatment (day) Figure B.3 Changes of conductivity of the experiment with synthetic water
Period of treatment (day) Figure B.4 Variation of Mn with filtration time of the experiment with synthetic water


ASIAN INSTITUTE OF TECHNOLOGY
Treatment of Surface Water and
Municipal Wastewater by
Hybrid Ceramic Microfiltration Systems
Le Anh Tuan
Examination Committee: Prof. C.Visvanathan (Chairperson)
Dr. Preeda Parkian
Dr. Thammarat Koottatep


Results and discussions
Conclusions and recommendations


Need of the surface water treatment and
reclamation of wastewater
Conventional treatment systems: disadvantages
ceramic microfiltration (CMF)


1.Evaluate the efficiency of the CMF on surface
and evaluate the
efficiency of the CMF on municipal wastewater
treatment for reuse activities
3.Investigate operational problems related to
dead-end filtration for the treatment of
surface water and municipal wastewater


Scope of The Study
 First Stage: Experiment on synthetic water
40 80 120 NTU
) Second Stage: Research on
surface water and municipal wastewater



Mesh screen
RAW WATER TANK
COAGULANT TANK
FILTRATE
TANK (FOR WWT)
CHLORINE
COAGULATION UNIT
Technical diagram for the operational scenarios
Raw water source
Mesh screen
Raw Water Tank
PACl (2, 3)
(for WWT)
Simplified flow diagram of the hybrid CMF systems
07/5/2008 Page 42
Concentration of Kaolin clay (mg/L)
) Synthetic water was prepared at three different types:
1. Synthetic water 1: 40 NTU, Kaolin clay of 55 mg/L
2. Synthetic water 2: 80 NTU, Kaolin clay of 95 mg/L
3. Synthetic water 3: 120 NTU, Kaolin clay of 137 mg/L
07/5/2008 Page 50
Optimum dosage, mg/L
PAC& PACl
Experiments with Synthetic Water
Adding NaClO for backwashing
) Effectively
cleaned by
Period of treatment (days)
’Turbidity of permeate was
very low and stable
Feed water
’ TSS was removed completely
Period of treatment (day)
Experiments with Synthetic Water
Feed w ater
Perm eate
TOC rem oval
Period of treatment (days)
TOC removal: 38 - 57 %
Experiments with Synthetic Water
Feed water
/m 260,000
Log particle removal
5 110,000
Period of treatment (days)
) Micro-particles (5 – 15 µm) removal: 99.95 - 99.99%.
Log removal: 3.28 – 4.21
After experimental run
After chemical cleaning
The characteristics of synthetic water
Foulants are inorganic and particular matters
Easily removed by backwash (BW)
Surface water and municipal wastewater: NaClO enhanced BW
Experiments with Surface Water
Scenario1: Direct CMF
Tubidity 1
Turbidity 2
)The higher turbidity, the
lower filtration time
Fouled after 7 & 11 days of
) Role of foulants accumulation
Period of treatment (days)
No foulants
Feed water 2
Feed water 1
Permeate 2
Permeate 1
z Role of foulants
on the 3rd day
Period of treatment (days)
07/5/2008 Page 61, 62
Experiments with Surface Water
Scenario1: Direct CMF
Feed water 1
Permeate 1
Feed water 2
Permeate 2
DOC removal 1
DOC removal 2
Period of treatment (days)
TOC and DOC
removals were low
) Need to have pre-treatments:
07/5/2008 Page 63
Experiments with Surface Water
Scenario1: Direct CMF
Feed water
15 mm ( 5000
Period of treatment (days)
)Removal efficiency in terms of micro-particles (5 –
15 µm) or Giadia and Crypto was 99.48 - 99.78 %.
07/5/2008 Page 64
Experiments with Surface Water
Scenario2: Direct PACl + CMF
Increased turbidity
due to EBW ?
Feed water 1
Feed water 2
zTurbidity < 0.08
Permeate 1
Permeate 2
NTU on the 1st day
Period of treatment (days)
07/5/2008 Page 67
Comparisons of Results
PAC + PACl + CMF
PACl + CMF
Direct CMF
Comparisons of Results
PAC + PACl + CMF
PACl + CMF 1
PACl + CMF 2
Period of treatment (days)
The more hybridized systems, the slower TMP
increase and longer filtration time
07/5/2008 Page 74
Comparisons of Results
reduced?
PACl + CMF
PACl + PAC + CMF
) Very interesting, attractive and important roles of
the pre-treatment processes
07/5/2008 Page 75
Experiments with Surface Water
1. TSS, Total coliform and fecal coliform were removed
2. Others were removed more effectively by hybrid systems
3. Permeate meets domestic supply/drinking water standards
(Vietnam & US.).
4. Fouling of the experimental runs could be overcome well by
enhanced backwashing (EBW) and chemical cleaning.
5. Considerations of clogging of feed pump: should have a
spare one in practical situation.
Experiments with Municipal Wastewater (MW)
Scenario1: Direct CMF
Removal (%)
Feed (mg/L)
) 4 days for 1 cycle
Permeate turbidity of 15 NTU
Experiments with MW
Scenario2: PACl + CMF
Removal rate (%)
Feed (mg/L)
) 18 days for 1 cycle
Permeate turbidity of 0.21 NTU
Comparisons of Results
) Once again… confirming
the very interesting, k 60
attractive and important P ( 40
roles of the pre-treatment
PACl + CMF
Period of treatment (days)
reduced? of
olloidal
PACl + CMF
07/5/2008 Page 83, 84
Comparisons of Results
CM
+
t CM
07/5/2008 Page 85
1. Performance of a hybrid CMF system would differ depending
on pre-treatment process and operational conditions.
2. Better permeate, reduction of fouling, higher filtration time
and more effectively chemical cleaning in the hybrid CMF systems.
3. The highest performance for SWT was in the PAC + PACl +
CMF hybrid system.
4. The treated MWW by direct CMF and hybrid CMF systems
can be reused for irrigation and other agricultural activities.
5. The highest performance for MWWT was in the PACl + CMF
1. The hybrid CMF system can be enhanced by pre-ozonation
process prior to coagulation process.
2. Practical researches with real river water sources in
3. Research on potentials of reusing the secondary effluent of
AIT wastewater treatment plant.
4. Research on function of PAC or ozonation in removing
organic toxic substances in surface water.
5. Comparative study between the hybrid CMF system and
conventional treatment in pilot scale.
Chemical Cleaning after SWT
Chemical cleaning by citric acid-
A view from bottom!!!!!
Chemical Cleaning after MWWT
During chemical cleaning Cleaned membrane
Cleaned feed pump
Feed pump problems
Clogged feed pump
Effects on Human Health
& Giardiasis, an intestinal illness.
& Chronic diarrhea, weight loss.
& Watery diarrhea/Stomach cramps
& Fever/General malaise
& Vomiting/Weight loss
Why Dead-end Selected?
Why not cross-flow ?
High flux
High pressure applied
Low fouling
High energy consumption
High operation cost
Closed valve
High fouling
Low pressure applied
Low energy consumption
Low operation cost
Low fouling due to BW
High filtration time
Opened valve
TMP Recovery by Chemical Cleaning
Surface water treatment
TMP with tap water (kPa) at flux of 50
After washed
Before After washed by
citric acid
Direct CMF
PACl + CMF
PAC + PACl +
TMP Recovery by Chemical Cleaning
Municipal wastewater treatment
TMP with tap water (kPa) at flux of 50 L/m2.h
After washed After washed
Before After by citric acid by NaClO
Direct CMF
Hybrid PACl
Experiments with Surface Water
Quality of treated water and standards
Permeate of scenario
PAC + PACl
Direct CMF
PACl + CMF
7.5 – 8.1
6.8 – 7.2
6.5 – 8.5
6.5 – 8.5
Turbidity
and % removed
a Vietnamese national standards TCVN 5502:2003 - Domestic supply water
b National secondary drinking water standards, EPA, USA- The maximum permissible level of a
contaminant in water which is delivered to any user of a public water system

07/5/2008 Page 76
Experiments with MWW
Quality of treated wastewater and standards for reusing activities
Permeate of scenario 6.8 – 7.8
5.5 – 8.5
Turbidity
Chlorine
07/5/2008 Page 87

Source: http://faculty.ait.ac.th/visu/public/uploads/Data/AIT-Thesis/Master%20Thesis%20final/Tuan.pdf

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Jc001909 1.10

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, C09S14, doi:10.1029/2003JC001909, 2004 Dissolved and particulate organic carbon in the Sea of Okhotsk: Transport from continental shelf to ocean interior Takeshi NakatsukaInstitute of Low Temperature Science, Hokkaido University, Sapporo, Japan Mari TodaGraduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan