|
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
Ahn, K. H. & Song K. G. (1999). Treatment of domestic wastewater using microfiltration
for reuse of wastewater. Desalination, 126, 7-14.
Aim, R.B. (2007). Industrial waste abatement and management: Reuse and recycling of
water in industry, what membranes can do (Lecture notes, Course No. ED78.20, School of
Environment, Resources and Development). Bangkok : Asian Institute of Technology.
Alaton, I. A., Tanik A., Ovez, S., Iskender, G., Gurel, M., & Orhon D. (2007). Reuse
potential of urban wastewater treatment plant effluents in Turkey: a case study on selected
plants. Desalination, 215, 159–165.
American Water Works Association (1987). American water works association statement
of policy: Recreation use of domestic water supply reservoirs. Journal AWWA, 79(12), 10.
American Water Works Association (1999). Water quality and treatment: A handbook of
community water supplies. (5th ed.). New York: McGraw-Hill, Inc.
American Water Works Association, & American Society of Civil Engineers (1998).
Water treatment plant design. (3rd ed.). New York: McGraw-Hill, Inc.
Amirtharajah, A., & O'Melia, C. R. (1990). Coagulation processes: Destabilization,
mixing, and flocculation. New York: McGraw-Hill,
Amirtharajah, A., & Mills, K. M. (1982). Rapid-mix design for mechanisms of alum
coagulation Journal of AWWA, 74(4), 210–216.
APHA, AWWA, WPCE (1998). Standard methods for examination of the water and
wastewater. (20th ed.). Washington DC: APHA.
Atherholt, LeChevallier, T. B., M. W., and Rosen, J. S. (1998). Variation of giardia cyst
and cryptosporidium oocyst concentrations in a river used for potable water. New Jersey
Department of Environmental Protection Division of Science and Research.
Argaman, Y., and W. F. Kaufman. (1970). Turbulence and flocculation. Journal of
Sanitary Engineering Division, ASCE, 96, 223.
Carroll, T., King S., Gray, S. R., Bolto, B. A., & Booker, N. A. (2000). The fouling of
microfiltration membranes by NOM after coagulation treatment. Water Research, 34 (11),
2861-2868.
Christian, V., Kimberly, B., Eva, I., Debbie, V., Gary, A., & Mark, L. (2000). Impact of
enhanced and optimized coagulation on removal of organic matter and its biodegradable
fraction in drinking water. Research, 34 (12), 3247-3257,
Christensen, L. A. (1983). Water quality: A multidisciplinary perspective. Soil
Conservation Society of America.
Cirelli, G. L., Consoli, S., & Grande, V. D. (2008). Long-term storage of reclaimed water: the case studies in Sicily (Italy). Desalination, 218 (62–73). Clair, N.S., Perry, L.M., & Gene, F.P. (2003). Chemistry for environmental engineering and science. (5th ed.). New York: McGraw-Hill, Inc. Chen, H. H., Yeh, H. H., & Shiau S. (2005). The membrane application on the wastewater reclamation and reuse from the effluent of industrial WWTP in northern Taiwan. Desalination, 185, 227–239. Cho, M. H., Lee, C. H., Lee, S. (2006). Effect of flocculation conditions on membrane permeability in coagulation–microfiltration. Desalination, 191, 386–396. Davis, R. H. (1992). Definition of microfiltration, membrane handbook. New York: Chapman & Hall. Driscoll,C.T., Yan, C., Schofield, C. L., Munson, R., & Holsapple, J. (1994). The mercury cycle and fish in the Adirondack Lakes. Environmental Science and Technoogy, 28(3), 136–143. Doek, S., Simon, B., Dik, B., & Bas, H. (2007). Particle removal from surface water with ceramic microfiltration. Netherlands: Leeuwarden. Environmental Protection Agency (2004). Guidelines for water reuse: EPA/625/R-04/108 Washington, DC: U. S. Agency for International Development Ernst, M., Sperlich, A., Zheng, X., Gan, Y., Hu, J., Zhao, X., Wang, J., & Jekel, M. (2007). An integrated wastewater treatment and reuse concept for the Olympic Park 2008, Beijing Desalination 202, 293–301. Fan, L. F., Harris, J. L., Roddick, F.A., & Booker, N.A. (2001). Influence of the characteristics of natural organic matter on the fouling of microfiltration membranes. Water Research, 35 (18), 4455–4463. Fang L.J. (1996). Evaluation of the factors affecting membrane flux. (Master research study No. EV-96-18). Bangkok : Asian Institute of Technology. Fiksdal, L., & Leiknes, T. (2006). The effect of coagulation with MF/UF membrane filtration for the removal of virus in drinking water. Journal of Membrane Science, 279, 364–371. Gleick, P. H (1996). Water resouce. Encyclopaedic dictionary on climate and weather. New york: Oxford, 2, 817 - 823. Jarusuthirak, C., & Amy, G. (2007). Understanding soluble microbial products (SMP) as a component of effluent organic matter (EfOM). Water Research, 41, 2787–2793. James, C. V., Mark, A. Th., & Uday, G. K. (1995). The use of membrane filtration in conjunction with coagulation processes for improved NOM removal. Desalination, 102, 57-61.
Janya, J. (1997). Coagulation with iron (III) salts: An alternative in water treatment. (Master research study No. EV-97-19). Bangkok : Asian Institute of Technology. Judd, S. J., & Hillis, P. (2001). Optimization of combined coagulation and microfiltration for water treatment. Water Research, 35 (12), 2895-2904. Kanto, Y., Yonekawa, H., Aoki, N., Tomita, & Y., Matsui, Y. (2004). Novel hybrid ceramic membrane systems. Japan: NGK Insulators. Kennedy, M. D., Bichii, A.K., Gaulinger, S.I., Heijman, B.G.J., Amy, G. (2007). NOM fouling of ceramic membranes in surface wayet treatment applications. Netherlands: Institute for Water Education. Kim, H. C., Hong, J.H., Lee, S. (2006). Fouling of microfiltration membranes by natural organic matter after coagulation treatment: A comparison of different initial mixing conditions. Journal of Membrane Science, 283, 266–272. Kim, H. S., Katayama, H., Takizawa, S., & Ohgaki, S. (2006). Development of a microfilter separation system coupled with a high dose of powdered activated carbon for advanced treatment. Desalination, 186 (3), 215-226. Khan M. M. T., Kim H., Katayama H., Takizawa S., & Ohgaki S. (2002). The effect of particulate material and the loading of bacteria on a high dose PAC-MF system. Water Science and Technology: Water Supply, 2, 359-365. Konieczny, K., Bodzek, M., Rajca M. (2006). A coagulation–MF system for water treatment using ceramic membranes. Desalination, 198, 92–101. Konieczny, K., & Klomfas, G. (2002). Using activated carbon to improve natural water treatment by porous membranes. Desalination, 147, 109-l 16 Koning, J., Bixio, D., Karabelas, A., Salgot, M., & Schäfer, A. (2008). Characterisation and assessment of water treatment technologies for reuse. Desalination, 218, 92–104. Krasner, S. W. (1996). The regulatory role of TOC measurements in the ICR and DBP rules. In Proceedings of the AWWA Water Quality Technology Conference, November 17–21, Boston, MA. Lens, P., Hulshoff Pol, L., Wilderer, P., & Asano, T. (2002). Water recycling and resource recovery in industry: Analysis, technologies and implementation. New York: McGraw-Hill. Lerch, A., Panglisch, S., Buchta, P., T Tomita, Y., Yonekewa, H., Hattori, K., & Gimbel, R. (2005). Direct river water treatment using coagulation/ceramic membrane microfiltration. Desalination 179, 41-50. Lin, S.H., & Cheng, K.W. (2001). A new sequencing batch reactor for treatment of municipal sewage wastewater for agricultural reuse. Desalination 133, 41-51.
Mallevialle.J, Odendaal.P.E, & Wiesner.M.R. (1996). Water treatment membrane processes. American Water Works Association Research Foundation., New York: McGraw- Hill. Matsushita, T., Matsui, Y., Shirasaki, N., Kato Y. (2005). Effect of membrane pore size, coagulation time, and coagulant dose on virus removal by a coagulation-ceramic microfiltration hybrid system. Desalination, 178, 21-26. Metcalf & Eddy (2004). Wastewater engineering: Treatment and reuse. (4th edition). New York: McGraw-Hill. Meyn, T., Leiknes, T., & Odegaard, H. (2007). Coagulation/flocculation – ceramic membrane filtration for removal of natural organic mater under Norwegian conditions. Norway: Norwegian University of Science and Technology. Milton, G.W., Erilsson U., Abrahamsson, J., Rogalla, F., & Hattori, K. (2007). Comparing coagulation conditions on ceramic membrane for TOC removal from surface waters. UK: Birmingham. Qin, J.J., Oo, M. H., Kekre, K. A., Knops, F., & Miller, P. (2006). Impact of coagulation pH on enhanced removal of natural organic matter in treatment of reservoir water. Separation and Purification Technology, 49 (3), 295-298. Oh, H.K., Takizawa, S., Ohgaki, S., Katayama, H., Oguma, K., & Yu, M.J. (2007). Removal of organic matter by coagulation enhanced with adsorption on PAC. Desalination, 202,191-198 Pienta R., Boller M., Janex M., Chappaz A., Birou B., Ponce, & Walther J. (1998). Micro- and ultrafiltration of karstic spring water. Dasalination, 117, 61-71. Pikkarainen, A.T., Judd, S.J., Jokela, J., & Gillberg, L. (2004). Pre-coagulation for microfiltration of an upland surface water. Water Research, 38, 455–465. Scott, K. (1990). Membrane separation technology. Oxford: Scientific and Technical Information. Scott, K. (1996). Industrial membrane separation technology. New York: Blackie Academic & Professional, an imprint of Chapman & Hall. Siddiqui, M., Amy G., Ryan, J., & Odem, W. (2000). Membranes for the control of natural organic matter from surface waters. Water Research. 34 (13), 3355-3370. Sproul, O.J. (1980). Critical review of virus removal by coagulation processes and pH modifications. Ohio: Office of R&D of U.S. EPA. Stein, O., Kamal, A., Torove, L., & Hallvard, O. (2007). Membrane filtration for particales removal after ozonation-biofiltration. Norway: University of Science and Technology.
Suwanan, K. (2001). Pilot scale experimental investigation of membrane filtration for water and wastewater reuse. (Master research study No. EV-01-19). Bangkok : Asian Institute of Technology. Syed, R.Q., & Edward, M.M.G.Z. (2000). Water works engineering: Planning, design and operation. U.S.: Prentice Hall, Inc. Taku, M., Yoshihiko, M., Daisuke, S., Koichi, O. (2007). Simulatious removal of cyanobacteria and a musty odor compound by a combination of activated carbon adsorption, coagulation, and ceramic microfiltration. Japan: Hokkaido University. Takizawa, S., Zhao, P., Ohgaki, S., & Katayama, H. (2007). Kinetic analysis of PAC cake-layer formation in hybrid PAC-MF systems. Japan: The University of Tokyo. Tomaszewska, M., Mozia, S., Morawski, A.W. (2004). Removal of organic matter by coagulation enhanced with adsorption on PAC. Desalination, 161, 79-87. Thurman, E. M. (1985).Developments in biochemistry: Organic geochemistry of natural waters. Germany: Nijhoff & Junk Publ. Vernet A., Bellon-Fontaire M., Brillouet J., Roesink E., & Moutounet M. (1997). Wetting properties of microfiltration membrane: determination by means of the capillary rise technique and incidence on the adsorption of wine polysacchrides and tannins. Journal of Membrane Science, 128,163-174. Wang, Z., Liu, D., Wu, W., Liu, M. (2006). Study of dead-end microfiltration flux variety law. Desalination, 201, 175–184. Watanabe, Y., & Yonekawa, H. (2007). Floccolation and its inclusion into membrane filtration. Japan: Hokkaido University. Water Environment Federation (2006). Membrane systems for wastewater treatment. WEF and McGraw-Hill. World Health Organization (WHO) (2008). Guidelines for drinking-water quality: incorporating first addendum. Vol. 1, Recommendations. (3rd edition). Switzerland: Geneva. Yan, M., Dongsheng, Wang, D., You, S., Qu, J., & Tang, H. (2006). Enhanced coagulation in a typical North-China water treatment plant. Water Research, 40 (19), 3621-3627. Yiantsios S. G. and Karabelas A. J. (2001). An experimental study of humic acid and PAC deposition on UF membranes and their removal by backwashing. Desalination, 140, 195-209. Yuan W. and Zydney A. L. (1999). Effects of solution of environment on humic acid fouling during microfiltration. Desalination. 122, 63-76.
Yonekawa, H., Kanaya, sh., Tomita, Y., & Watanabe, Y. (2006). Filtration properties of ceramic MF membranes and their influence on backwash strength during higher flux operation. Japan: NGK Insulators. Yusa, A., Yim, M., Katayama, H., & Nambu, T. (2006). Removal efficiency of microparticales by ceramic pot filters for drinking water purification in Cambodia. Japan: Gifu University. Yuasa, A., Nambu, T., Wirojanagud, W., & Va, D. (2006). Microparticles removal efficiency in drinking water treatment processes – survey in Thailand, Laos, and Cambodia. Gifu, Japan. Yuasa, A., Yonekawa, H., Okumura, S., & Watanabe, Y. (2006). Application of ceramic membrane microfiltration for the reuse of sand-filter backwash wastewater in a drinking water treatment plant. Japan: Gifu, NGK Insulators, & Hokkaido University. Yoshihiko, M., Kenji, M., Hiroshi, S., Koichi, O., Taku, M. (2007). Submicron-sized astivated carbon particles for the rapid removal of chlorinous and earthy-musty compounds. Japan: Hokkaido University. Yonekawa, H., Tomita, Y., & Watanabe, Y. (2004). Behavior of micro-particles in monolith ceramic membrane filtration with pre-coagulation. Water Science and Technology, 50 (12), 317-325. Zhu, H. T., Wen, X.H., & Huang, X. (2007). Pre-ozonation for dead-end microfiltration of secondary effluent: suspended particles and membrane fouling. China: Tsinghua University. Zhao, P., Takizawa, S., Katayama, H. & Ohgaki, S. (2005). Factors causing PAC cake fouling in PAC-MF (Powdered activated carbon – microfiltration) water treatment system. Water Science and Technology, 51 (6-7).
APPENDIX A
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
Last Updated: September 20, 2016 Costa Rica Quest - CRQ 9 days: San José to San José • G Adventures-supported coffee plantation tour with local lunch (Sarapiquí) • Hot springs visit (La Fortuna) • Santa Elena Cloud Forest Reserve guided tour (Monteverde) • Beach time in Quepos/Manuel Antonio • All transport between destinations and to/from included activities
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