Membrane Fouling Studies in Suspended and Attached Growth Membrane - - PowerPoint PPT Presentation

Asian Institute of Technology School of Environment, Resources & Development Environmental Engineering & Management

Membrane Fouling Studies in Suspended and Attached Growth Membrane Bioreactor Systems

Examination Committee:

• Prof. C. Visvanathan (Chairman)
• Prof. Sudip K Rakshit
• Prof. Ajit P. Annachhatre
• Dr. Oleg V. Shipin
• Prof. Jy S. Wu

Kwannate (Manoonpong) Sombatsompop

• K. Sombatsompop-May 2007

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Sludge storage Clarifier Aeration tank Sludge return Treated water Excess sludge Influent

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Membrane Membrane Bioreactor Bioreactor System System

Limitation of MBR : Limitation of MBR : Fouling

Fouling

• A reduction of the membrane performance
• A decrease of flux
• An increase in filtration resistance
• Membrane cleaning requirement

High effluent quality Small size Flexible in the operation Low sludge production Removal of infectious pathogens

immerged MBR Membrane module

Permeate Air Wastewater Wastewater Biological Biological reactor reactor 3 3/47 /47

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Advantages and disadvantages of Advantages and disadvantages of membrane bioreactor membrane bioreactor

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Advantage for attached growth bioreactor

Better oxygen transfer High organic removal ability Relatively short HRT Being more compact

(Tavares et al, 1994; Ødegaard et al,1994; Ødegaard 2000 ) Effluent Screen Air Carrier Influent

Attached growth reactor

Biomass growth on small carrier materials that move along with the water in the reactor

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Attached growth bioreactor Attached growth bioreactor

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Objectives of the study Objectives of the study

To examine suitable test conditions and to select suitable media for attached growth reactor To investigate effects of operating conditions, such as HRT and MLSS on membrane performance, fouling characteristics, EPS production and sludge properties To compare membrane fouling behavior of attached and suspended growth MBRs

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Scope of the study Scope of the study

• Synthetic wastewater with a constant COD value of 500 mg/L
• Five different types of media

polyethylene bead (PB), polyethylene granule (PG), polyethylene sheet (PS), cylindrical polypropylene (CP) and polyethylene sponge (S)

• Effect of operating conditions;
• 1. HRT was varied at 2, 4, 6 and 8 h.
• 2. MLSS was altered at 6, 10 and 15 g/L.
• Sludge characteristics, EPS production, fouling rate, cake

resistance and microscope observation

• Removal efficiency of COD, and nitrogen compounds

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Preliminary study Preliminary study

To examine suitable test conditions and to select suitable media for attached growth reactor

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Research methodology Research methodology

Batch reactor Batch reactor EPS Extraction analysis EPS Extraction analysis

Preliminary Study Preliminary Study

Variation of media Variation of media Removal efficiency Removal efficiency EPS production EPS production Variation of re-suspended solution Variation of re-suspended solution Variation of centrifugation speed Variation of centrifugation speed Variation of centrifugation time Variation of centrifugation time Attached growth reactor Attached growth reactor Suspended growth reactor Suspended growth reactor

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Media types Media types

Cylindrical Cylindrical polypropylene (CP) polypropylene (CP)

Sponge(S) Sponge(S) Polyethylene Polyethylene beads (PB) beads (PB) Polyethylene Polyethylene sheet (PS) sheet (PS) Polyethylene Polyethylene granule (PG) granule (PG)

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Experimental set Experimental set-

• up

up and operation and operation

Timer

Air Air diffuser Motor PB PG CP S PS Control (no media) Suspended growth reactor Attached growth reactors

Conditions: Conditions: pH 7 pH 7-

• 8

8 DO 2 DO 2-

• 4 mg/L

4 mg/L COD 500 mg/L COD 500 mg/L HRT 6 h. HRT 6 h. SRT 10 d. SRT 10 d. MLSS 4000 mg/L MLSS 4000 mg/L F/M 0.1 F/M 0.1 kgCOD/kgMLSS.d kgCOD/kgMLSS.d

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Question and Recommendation Question and Recommendation

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Table 4.1 Removal efficiency of COD and TKN in batch reactors

S CP PS PG PB Control (no media) Batch reactor 83 5 94 25 Effluent Attached growth 86 4 95 22 Effluent Attached growth 86 4 95 21 Effluent Attached growth 90 3 95 22 Effluent Attached growth 88 4 95 23 Effluent Attached growth 79 6 95 23 Effluent Suspended growth

• 30
• 460

Influent

• % removal

mg/L % removal mg/L TKN COD Sampling point System

A.

• A. Selection of Media Type for Attached Growth Reactor

Selection of Media Type for Attached Growth Reactor

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Question and Recommendation Question and Recommendation

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Figure 4.2 EPS compositions in different media types

5 10 15 20 25 C

• n

t r

• l

P B P G P S C P S Media types EPS compositions (mg/gVSS)

Protein Carbohydrate Ratio of Protein/Carbohydrate

A.

• A. Selection of Media Type for Attached Growth Reactor

Selection of Media Type for Attached Growth Reactor

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Question and Recommendation Question and Recommendation

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1 10 100 1000 10000 PS PG PB CP S Media types EPS (mg/m

2 of media surface)

A.

• A. Selection of Media Type for an Attached Growth Reactor

Selection of Media Type for an Attached Growth Reactor

Figure 4.4 EPS content in terms of media surface at different media types

Cylindrical polypropylene was selected due to; floating, well mixing, high surface media and non biodegradable nature.

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Conclusions for Preliminary study Conclusions for Preliminary study

• No significant difference in COD removal efficiency

was found between the suspended and the attached growth systems.

• The average TKN removal efficiency in the attached

growth system was in the range of 83 to 90%.

• There was no significant difference in EPS production

in the suspended and the attached growth systems.

• The productions of EPS and biofilm formation were

affected by shape and size characteristics of media

• used. Cylindrical polypropylene (CP) was most suitable.

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Laboratory Laboratory-

• scale MBR study

scale MBR study

To investigate effects of operating conditions, such as HRT and MLSS

• n

membrane performance, fouling characteristics, EPS production and sludge properties To compare membrane fouling behavior of attached and suspended growth MBRs

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Laboratory Laboratory-

• scale MBR study

scale MBR study

Operational conditions Operational systems Operational analysis Suspended growth MBR Suspended growth MBR Attached growth MBR Attached growth MBR

Laboratory-scale MBR study Laboratory-scale MBR study

Removal efficiency Removal efficiency Fixed media Fixed media Moving media Moving media Variation of MLSS Variation of MLSS Variation of HRT Variation of HRT Fouling characteristics Fouling characteristics Sludge characteristics Sludge characteristics Microscope

• bservation

Microscope

• bservation

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Question and Recommendation Question and Recommendation

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Experimental set Experimental set-

• up

up of MBR

• f MBR

Storage tank Timer Air line SG-MBR Air flow meter Control tank Pressure gauge 3 1 2 Level control Air diffuser AG-MBR Moving media AG-MBR Fixed media Manometer Effluent Pump Solenoid valve Baffle Hollow fiber membrane Note: SG: Suspended growth AG: Attached growth Mitsubishi Rayon Pore size - 0.1 µm Surface area- 0.42 m2

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Question and Recommendation Question and Recommendation

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Table 4.6 COD removal in the MBRs with varying HRT 25 (94) 23 (96) 15 (97) 19 (96) Effluent of attached growth MBR with fixed media 10 (98) 16 (97) 10 (98) 13 (97) Effluent of attached growth MBR with moving media 15 (97) 19 (96) 12 (98) 16 (97) Effluent of suspended growth MBR 435 522 507 504 Influent HRT 2 h HRT 4 h HRT 6 h HRT 8 h COD (mg/L) (%Removal efficiency) Item

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Results and Discussions Results and Discussions Effect of Hydraulic Retention Time (HRT) Effect of Hydraulic Retention Time (HRT)

Question and Recommendation Question and Recommendation

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Effect of HRT Effect of HRT

Table 4.7 TKN removal in the MBRs with varying HRT

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3.4 (92) 2.1 (95) 1.9 (97) 3.3 (94) Effluent of attached growth MBR with fixed media 2.5 (94) 1.7 (96) 1.3 (98) 2.9 (95) Effluent of attached growth MBR with moving media 2.8 (94) 1.7 (96) 1.3 (98) 2.8 (95) Effluent of suspended growth MBR 44.8 45.4 56.8 57.5 Influent HRT 2 h HRT 4 h HRT 6 h HRT 8 h TKN (mg/L) (%Removal efficiency) Item

Question and Recommendation Question and Recommendation

• K. Sombatsompop-May 2007
• B. EPS Compositions

Effect of HRT Effect of HRT

20 20/36 /36 30 60 90 120 150 8 6 4 2 HRT (hours) Bound EPS (mg/gVSS)

Suspended growth MBR Attached growth MBR with moving media Attached growth MBR with fixed media

Figure 4.16 Bound EPS concentration in the MBR with varying HRT 30 60 90 120 150 8 6 4 2 HRT (hours) Soluble EPS (mg/L)

Suspended growth MBR Attached growth MBR with moving media Attached growth MBR with fixed media

Figure 4.17 Soluble EPS concentration in the MBR with varying HRT

Question and Recommendation Question and Recommendation

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Table 4.10 Dewatering properties of sludge (CST-sec.) in the MBR for different HRTs

30.2 20.6 17.9 10.0 Attached growth MBR with fixed media 101.3 86.0 78.3 50.0 Attached growth MBR with moving media 52.8 32.7 18.1 9.6 Suspended growth MBR 2 4 6 8 HRT (hours) Reactor

Sludge in the moving media reactor was more difficult to dewatering than that in the other reactors. Sludge dewatering property was found to increase with decreasing HRT.

Effect of HRT Effect of HRT

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Question and Recommendation Question and Recommendation

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Table 4.11 Floc morphologies in MBR system Compact, large and round floc with some filamentous embedded within floc and some protozoa 2 Attached growth MBR with fixed media Dense and matrix floc, irregular shape floc and small floc size 1 Attached growth MBR with moving media Compact, round floc with some filamentous and some type of protozoa 2 Suspended growth MBR Description of floc morphology FI Sample

(a) Suspended growth MBR (b) Attached growth MBR with moving media (c) Attached growth MBR with fixed media

Figure 4.26 Sludge particle observed under optical microscope

Effect of HRT Effect of HRT

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Question and Recommendation Question and Recommendation

• K. Sombatsompop-May 2007

Conclusions: Effect of HRT

1. COD removal efficiency was greater than 90% with a short HRT. 2. The removal efficiencies of TKN and ammonia were greater than 90% and 94%, respectively at HRT of 2 h. 3. There was no significant difference in bound EPS for all HRT while the soluble EPS was high at short HRT (2 and 4 h). 4. CST value in the attached growth MBR with moving media was higher than that in the suspended growth MBR, and attached growth MBR with fixed media. 5. Sludge morphologies of the three reactors were different in terms

• f floc shape, floc size and type of microorganism.

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Question and Recommendation Question and Recommendation

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Effect of Mixed Liquor Suspended Solid (MLSS) Effect of Mixed Liquor Suspended Solid (MLSS) Results and Discussions Results and Discussions

MLSS was varied at 6, 10 and 15 g/L

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Question and Recommendation Question and Recommendation

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20 40 60 80 100 120 5 10 15 20 25 30 Time (Days) Transmembrane pressure (kPa)

Suspended growth MBR Attached growth MBR with moving media

Chemical cleaning

20 40 60 80 100 120 10 20 30 40 50 60 70 80 Time (Days) Transmembrane pressure (kPa)

Suspended growth MBR Attached growth MBR with moving media

Chemical cleaning

20 40 60 80 100 120 5 10 15 20 25 Time (Days) Transmembrane pressure (kPa)

Suspended growth reactor Attached growth reactor

Chemical cleaning

Figure 4.27 TMP changes with time at MLSS of 6 g/L Figure 4.28 TMP changes with time at MLSS of 10 g/L Figure 4.29 TMP changes with time at MLSS of 15 g/L

• B. Membrane Fouling Behavior

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Question and Recommendation Question and Recommendation

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8.86 16.76 15 2.67 10.38 10 1.73 5.83 6 Attached growth MBR Suspended growth MBR Total cake formation (g/m2)* MLSS (g/L)

Table 4.13 Total cake formation on membrane surface for varying MLSS concentration

*(weight of the cake / membrane surface area)

• B. Membrane Fouling Behavior

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Table 4.14 Resistance values for suspended and attached growth reactors at 6, 10 and 15 g/L MLSS 0.32 0.33 0.84 0.62 0.65 0.58 0.82 1.06 2.09 0.66 0.84 14.0 2.09 2.55 16.7 6 10 15 Attached growth MBR 0.95 0.97 0.97 0.63 0.63 0.54 0.98 0.46 1.18 33.1 42.4 49.7 34.7 43.5 51.4 6 10 15 Suspended growth MBR Rc/Rt Rm (*1012 m-1) Rf (*1012 m-1) Rc (*1012 m-1) Rt (*1012 m-1) MLSS (g/L) Reactor

4 8 12 16 20 0.01 0.1 1 10 100 1000 Particle diameter (mm) % Intensity

6 gMLSS/L of Suspended growth MBR 10 gMLSS/L of Suspended growth MBR 15 gMLSS/L of Suspended growth MBR 6 gMLSS/L of Attached growth MBR with moving media 10 gMLSS/L of Attached growth MBR with moving media 15 gMLSS/L of Attached growth MBR with moving media

0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.01 0.1 1 10 Particle diameter (mm) % Intensity

6 gMLSS/L of Suspended growth MBR 10 gMLSS/L of Suspended growth MBR 15 gMLSS/L of Suspended growth MBR 6 gMLSS/L of Attached growth MBR with moving media 10 gMLSS/L of Attached growth MBR with moving media 15 gMLSS/L of Attached growth MBR with moving media

Question and Recommendation Question and Recommendation

• K. Sombatsompop-May 2007

Figure 4.32 Relationship between particle size and MLSS concentration

Particle size Particle size distribution distribution

Enlarge scale Normal scale Attached growth reactor

• B. Membrane Fouling Behavior

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(µ (µm) m)

(µ (µm) m)

Question and Recommendation Question and Recommendation

• K. Sombatsompop-May 2007

Sludge viscosity Sludge viscosity Suspended growth reactor: (242, 970 and 1387mPa.s.) Attached growth reactor: (277 and 705 and 900 mPa.s) Sludge viscosity increased with increasing MLSS concentration.

Figure 4.33 Relationship between sludge viscosity and MLSS concentration

300 600 900 1200 1500 1800 6 10 15 MLSS (g/L) Sludge Viscosity (mPa.s)

Suspended growth MBR Attached growth MBR with moving media

• C. Sludge Characteristics

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Question and Recommendation Question and Recommendation

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CST CST Small floc in attached growth led to a decrease in dewatering property.

1 100 10000 6 10 15 MLSS (g/L) CST (sec)

Suspended growth MBR Attached growth MBR with moving media

Figure 4.34 Relationship between CST and MLSS concentration

• C. Sludge Characteristics

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Question and Recommendation Question and Recommendation

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Bound EPS compositions Bound EPS compositions

30 60 90 120 150 180 6 10 15 MLSS (g/L) EPS component (mg/gVSS)

Bound Protein Bound Carbohydrate Total Bound EPS

Figure 4.35 Bound EPS components in Figure 4.35 Bound EPS components in suspended growth suspended growth MBR at varying MLSS concentration MBR at varying MLSS concentration

30 60 90 120 150 180 6 10 15 MLSS (g/L) EPS component (mg/L)

Bound Protein Bound Carbohydrate Total Bound EPS

Figure 4.36 Bound EPS components in Figure 4.36 Bound EPS components in attached growth attached growth MBR at varying MLSS concentration MBR at varying MLSS concentration

• D. Bound and Soluble EPS Compositions

30 60 90 120 150 180 6 10 15 MLSS (g/L) EPS component (mg/L)

Soluble Protein Soluble Carbohydrate Total Soluble EPS

Figure 4.37 Soluble EPS components in Figure 4.37 Soluble EPS components in suspended suspended growth MBR at varying MLSS concentration growth MBR at varying MLSS concentration

30 60 90 120 150 180 6 10 15 MLSS (g/L) EPS component (mg/L)

Soluble Protein Soluble Carbohydrate Total Soluble EPS

Figure 4.38 Soluble EPS components in Figure 4.38 Soluble EPS components in attached attached growth growth MBR at varying MLSS concentration MBR at varying MLSS concentration

Soluble EPS compositions Soluble EPS compositions

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Question and Recommendation Question and Recommendation

• K. Sombatsompop-May 2007

1. As the MLSS was increased from 6, 10 and 15 g/L, the TMP values were found to increase due to clogging of the membrane. More membrane fouling in the suspended growth MBR was greater than that in the attached growth MBR. 2. More cake formation was observed on membrane surface in the suspended growth as compared with the attached growth reactors for all MLSS concentrations. 3. The total resistance (Rt) in the suspended growth reactor was higher than that in the attached growth reactor. The majority of the membrane fouling in suspended growth reactor was caused by the cake resistance (Rc). 4. Membrane fouling increased with increasing MLSS concentration. The cake resistance (Rc) increased with the MLSS concentration. The fouling on the membrane was found to be affected by the design of operating system.

Conclusions: Effect of MLSS

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Question and Recommendation Question and Recommendation

• K. Sombatsompop-May 2007

5. The attached growth reactor with moving media was found to have lower fouling and prolong filtration as compared to the suspended growth reactor. 6. The bound EPS contents in the suspended growth and attached growth reactors was similar. The amount of soluble EPS at 15 g/L MLSS was higher than that at 6 and 10 g/L MLSS. The EPS was not the main factor to cause fouling. 7. The particle size of the biomass influenced by the movement of the media had a significant effect on the formation of cake layers

• n the membrane.

Conclusions: Effect of MLSS

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Question and Recommendation Question and Recommendation

• K. Sombatsompop-May 2007

1. Conduct pilot scale to verify the laboratory-scale results. 2. Comparing removal efficiency and fouling performance between moving bed MBR and anaerobic MBR in the condition of high

• rganic loading.

3. Considering bio-mechanisms of microbial activity and bio- kinetics in the moving bed MBR in more detail and identifying microbial species and their quantification through microbial techniques (FISH, PCR and DGGE).

Recommendations for Further Study

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Originality and novelty of this work Originality and novelty of this work

Experimental technique: The operating system and design of MBR are novel and quite different from the other researches. That is, the media is moving during the operation. The moving media was coupled with the membrane bioreactor into a single unit. Experimental explanation: The proposed explanation is based on the movement

• f media which produced small particles in the attached growth system

leading to high cake porosity, small cake thickness and low cake resistance in the attached growth MBR. Outcome and contribution: The performance and lifetime of the membrane used in MBR could be improved by the use of attached growth system with the presence of moving media. Attached growth system can withstand high

• rganic loading and consequently require small footprint making it feasible

for domestic and industrial wastewater treatment. Conclusion: The attached growth MBR exhibited less fouling than the suspended growth MBR.

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Publication for this study Publication for this study

Sombatsompop, K., Visvanathan, C. and Ben, Aim, R. 2006. Evaluation of biofouling phenomenon in suspended and attached growth membrane bioreactor

• systems. Desalination, 201, 138-149.

Sombatsompop, K. M. and Visvanathan, C. 2005. Evaluation of biofouling phenomenon in suspended and attached growth membrane bioreactor

• systems. Proceedings of 3rd Regional Symposium on Membrane Science

& Technology: Membrane Technology for Industry and Environmental Protection Institute Teknologi Bandung, Indonesia, 26-27 April. Manoonpong, K. and Visvanathan, C. 2004. Fouling behavior in attached and suspended growth membrane bioreactor. AIT-KIST International Joint Symposium, Asian Institute of Technology, Pathumthani, Thailand, 20-21 May.

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Thank you very much for Thank you very much for your attention your attention

Acknowledgements

• Prof. C. Visvanathan
• Prof. Ajit P. Annachhatre
• Prof. Sudip K Rakshit
• Prof. Jy S. Wu
• Dr. Oleg V. Shipin
• Prof. R. Ben Aim
• Prof. R. Ben Aim
• Prof. Chris A. Buckley
• Prof. Chris A. Buckley
• Dr. Nguyen
• Dr. Nguyen Phuoc

Phuoc Dan Dan Dr.

• Dr. Boonchai

Boonchai Wichitsathian Wichitsathian, ,

• Mr.
• Mr. Sher

Sher Jamal Khan Jamal Khan Ms.

• Ms. Nimaradee

Nimaradee Boonapatcharoen Boonapatcharoen

• My lab colleagues and all Environmental Engineering Laboratory s

My lab colleagues and all Environmental Engineering Laboratory staff taff

• King

King Mongkut Mongkut’ ’s s Institute of Technology North Bangkok (KMITNB) Institute of Technology North Bangkok (KMITNB)

• Prof. Dr.
• Prof. Dr. Narongrit

Narongrit Sombatsompop Sombatsompop, daughters , daughters ( (Achiraya Achiraya and and Pawitchaya Pawitchaya Sombatsompop Sombatsompop) and my ) and my parents parents

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