VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE NAKHONEKHAM XAYBOUANGEUN SEAFOOD PROCESSING WASTEWATER TREATMENT BY USING ACTIVATED SLUDGE REACTOR FOLLOWED BY CYPERUSMALACENSIS LAM CONSTRUCTED WETLAND MASTER THESIS HANOI, 2011 VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE NAKHONEKHAM XAYBOUANGEUN SEAFOOD PROCESSING WASTEWATER TREATMENT BY USING ACTIVATED SLUDGE REACTOR FOLLOWED BY CYPERUSMALACENSIS LAM CONSTRUCTED WETLAND MASTER THESIS Supervisor: Dr HOANG VAN HA HANOI, 2011 Table of Contents Abstract Acknowledgement Abbreviations List of tables List of figures .9 Introduction 10 Objectives of Study .10 Chapter 1: Review of the literature 11 1.1 Wastewater from food processing factory 11 1.2 Constructed wetlands 12 1.2.1 General information 12 1.2.2 Classify and design 13 1.2.3 Microorganisms 17 1.2.4 Plants 18 1.3 Pretreatment system 20 1.4 Wastewater treatment by constructed wetlands .21 1.4.1 Microorganisms role 21 1.4.2 Plant role 22 1.4.3 Removing of organic materials 23 1.4.4 Nitrogen removal .25 1.4.5 Phosphorus removal 26 1.4.5 Pathogen removal 27 1.4.6 Acidity - Alkalinity 27 Chapter 2: Materials and method .28 2.1 Chemicals and equipment 28 2.2 Equipment design .28 2.2.1 Aeration tank design 28 2.2.2 CW design 29 2.3 Experiment design 30 2.3.1 Batch experiments .30 2.3.2 Flow rate optimization of the pretreatment system 30 2.3.3 Plant selection 31 2.4 Procedures and analysis method .32 2.4.1 Determination of COD 32 2.4.2 Determination of ammonium by colorimetric method with Nessler indicator 33 2.4.3 Determination of NO2- concentration in water by colorimetric method with Griss reagent .36 2.4.4 Determination of NO3- concentration 37 2.4.5 Determination of phosphorus by mean of optical measurement with reagents Amonimolipdat-vanadate 39 Chapter Results and discussions 42 3.1 Batch treatment 42 3.1.1 Anaerobic process 42 3.1.2 Aerobic process 43 3.2 Continuous treatment – retention time optimization 45 3.3 Plant selection 47 3.4 Constructed wetland 49 Conclusion 53 Referents 55 Abstract Wastewater from squid processing has high content of organic pollutants, but low fat oil and grease content (FOG) Wastewater of the company was found to have a COD of 800-2500mg/L depending on the time of the day Ammonium, phosphate content were much higher the limit of TCVN 5945-2005 (type B) Anaerobic treatment in a batch reactor required long retention time After days, COD value reduced from 2546 to 1973 mg/L that didn’t meet requirement of constructed wetland (CW) input Aerobic treatment in batch reactor quickly reduced COD value to 200-400mg/L in less than a day In an activated sludge continuous reactor, COD value reduced more than 80% in 12.7 hours, longer retention time didn’t help to lower COD content Ammonium, nitrate, nitrite contents in all set retention times were acceptable for CW Two species of Limnophila and Cyperus genera have potential of using in constructed wetland (CW) Results showed that they met the conditions of high organic matter and salt content of wastewater Both systems using these plants were equivalent in reducing COD value and phosphorous, achieved percentage 60%, 68%, respectively The species of Limnophila genus advantaged in treating ammonium, nitrite, nitrate ions, achieved 66.3%, 76.4%, 65.0%, respectively Biomass of the selected plants could take into account as food for animal and materials of handicraft Constructed wetland (CW) was cultivated Cyperus Malaccensis Lam Hydraulic loading rate was controlled approximately 135mm/day Percentage of nutrition conversion of ammonium, nitrite, nitrate, total phosphorous was stable according to the time The system had high effect in removing ammonium, nitrite, nitrate, phosphorous, 80.3±15.8%, 93.2±7.2%, 72.8±25.0%, 73.1±26.6%, respectively Output concentrations met requirements of the Vietnamese standard QCVN 11:2008 COD value was reduced from 300-400mg/L to 91.6±9.9 mg/L The presence of anammox strain could cause reducing concentration of nitrite remarkably Acknowledgement I would like to thank the government of German, German Acadeic Exchange Service (Deutscher Akademischer Austausch Dienst, DAAD), the University of Technology Dresden, Germany and Hanoi University of Science, Vietnam National University (HUS, VNU) for scholarship of the Master’s program My sincere thanks also due to the Prime Minister’s Office, Ministry of Science and Technology (MOST) of Lao P.D.R for the kind permission offered me to study I would like to express the profound gratitude and the great appreciation to my advisor Dr Hoang Van Ha for his excellent guidance, excellent encouragement and valuable suggestions throughout this study Special appreciation is extended to Prof Bui Duy Cam, Prof Bernd Bilitewski, Prof Nguyen Thi Diem Trang and committee members for their valuable recommendation and dedicated the valuable time to evaluate my work and my study here during I was being a HUS, VNU student The experiments have been conducted at the Laboratory of Biotechnology and Food Chemistry, Faculty of Chemistry, HUS I gratefully thanks are extended to the staff members for offering lots of the good laboratory instruments, especially Prof Trinh Le Hung and Ms Vu Thi Bich Ngoc Gratefully acknowledgement is extended to Hanoi University of Science, VNU for providing the scholarship and giving me opportunity to pursue the study in here Thanks are due to all friends, the Waste Management and Contaminated Site Treatment program staff members and colleagues in HUS for their full cooperation during the experiment and for encouragement During studying in HUS, I felt very lucky, it gives me the opportunity to have lots of good friends, good memory, so I would like to say thanks and pleasure to meet all of you, even though we came from different country, but we can make friend together I hope and wish that we would be working together and meet each other again in future Finally, I would like to express deep appreciation to my lovely family, my beloved family and relatives for their love, kind support, and encouragement for the success of this study This thesis is dedicated for you Abbreviations ABS: Absorptance ADP: Adenosine Di phosphate AMP: Adenosine Mono Phosphate ATP: Adenosine Tri Phosphate CW: Constructed Wetland DAAD: Deutscher Akademischer Austausch Dienst (German Academic Exchange Service) COD: Chemical Oxygen Demand FWS: Free Water Surface HLR: Hydraulic loading rate HUS: Hanoi University of Science SF: Subsurface Flow TSS: Total Suspended Solids TCVN: Vietnamese standard QCVN: Vietnamese guide VNU: Vietnam National University, Hanoi List of tables Table 1-1 Pollution Remove Mechanisms in constructed wetlands (Cooper et al…1997) ……… ………………………………………………….……………… 24 Table 2-1 Flow rate and corresponding retention time and continuous operation conditions ……….……………………….…………………….……………………31 Table 2-2 Data of standard curve NH4+ …………………………………………35 Table 2-3 Data of NO2- standard curve 37 Table 2-4 Results of standard NO3- ……….…………… ………………………38 Table 2-5 Results of standard PO43- ……….…………… …………………… 40 Table 3-1 Anaerobic treatment from May 13th, 2011 to May 17th, 2011 and May 19th, 2011 to May 28th 2011……… ……………………………………………… 42 3.2 Continuous treatment – retention time optimization The pretreatment system was operated at retention times of 3, 6, 9, 12, 15 hours In an activated sludge continuous reactor, COD value reduced more than 80% in 12.7 hours (figure 3-3), longer retention time didn’t help to lower COD content The COD value lies in the range of 70-80% (Figure 3-2), and no significant differences, which indicates that approximate 20% is more difficult to disintegrate They could be needed very long retention time in CW Activated sludge concentration standing for 30 minutes was in the range of 100-150ml/L, during the operation, equipment does not meet quality requirements because of small size tank From these two reasons, the retention time in the reactor and the system could be shorten in full size system Figure 3-3 Effect of retention time on the COD value of effluent 45 (a) (b) (c) (d) Figure 3-4 Effect of retention time on ammonium (a), nitrate (b), nitrite (c), phosphate (d) removal Ammonia concentration significantly reduced when the retention time was increased (Figure 3-4a), when the retention time was longer 15 hours, ammonium concentration dropped below the limit of TCVN 5945-2005 on industrial waste water- type B (10 mg/L) At the retention time in the reactor of 63.3h, ammonium concentration decreased to 99.8%, and there was no significant change after waste water went out of the settling tank (5) The trend of changing of nitrite and nitrate concentration showed in figure 3-4bc, the wide desperation of markers means that the concentration increased but wasn’t linear to retention time Nitrite concentration increased when the retention time was less than 20 hours and decreased with longer 46 retention time, whereas nitrate concentration increased when the retention time increased (Figure 3-4b) and had high value when retention time set at 20 hours to 40 hours Phosphate content in the artificial samples was lower than mg/L, so, the equivalent concentration of phosphorus was below the TCVN 5945-2005 standard (5mg/L) Figure 3-4d showed that after the different retention times, phosphate concentrations fell below mg/L (equivalent to 1.6 mg P/L) While at these concentrations of ammonia, nitrate, nitrite, phosphorous don’t affect to the proper working of CWs, COD value need to be considered When the retention time was 12.7 hours the COD value of effluence was acceptable for CW 3.3 Plant selection Two plants were grown in the same conditions Figure 3-5 showed that in a cycle of days the COD value reduced about 80% after days At beginning days (1, 2, 3), organic compounds were only mineralized apart, that limits using of plants, micro-organism and leading to COD value lowered insignificantly Figure 3-5 Percentage of COD reduction in Limnophila basin and Cyperus basin After days, when organics were hydrolized and inorganized, micro-organism and plants easily used for development The COD value lowered significant, reached to 85% The ability in COD treatment of two genera were similar However, percentages of ammonia, nitrite nitrate removal of sedge were higher 47 those of Limnophila genus about 10%, and error bar showed that sedge basin was more stable than Limnophila basin (Figure 3-6) Figure 3-6 Amoni, nitrit, nitrat treatment of Cyperus (sedge) and Limnophila genera Figure 3-7 Phosphorous treatment of Cyperus (sedge) and Limnophila genera Phosphats treatment of two basins were similar in every day Average concentration of influence were 14.2 mg/L of the Limnophila basin and 17,7 mg/L of sedge basin and average percentage of phosphate removal was 68% 48 Sedge had the advantage of Limnophila in ammonium, nitrite, nitrate treatment and was suitable for growing in CW of local area 3.4 Constructed wetland Sedge was chosen to grow in the CW pilot Wastewater from the pretreatment system was fed to the CW with the hydrolytic retention time 135L.m-2.day-1 The initial COD value was under 400mg/L, this was the harder digestion part of organics Reduction of 70% COD was obtained, and the concentration decreased gradually from level to lever That was the same way as ammonium concentration (figure 3-8abcd) It means that plants and bacterial were good cooperation in the CW (figure 3-8abcd) COD removal effect of the SVF-CW in the experiments was close to the report of Vymazal, 2005; Kadlec et al., 2000 In this study, for the HLR of cm.day-1, the maximum removal efficiency in terms of COD was 67% for an average inflow of 1966mgO2 L-1 (590 kgha-1 d-1) Concerning the HLR of 6cmd-1, the maximum removal efficiency in terms of COD was 73% for an average inflow of 2093mgO2 L-1 (1256 kgha-1 d-1) In another study, carried out with effluent of the manufacture of finished shoe upper leather from multisource wet blue with a typical COD inflow of 1160mg L-1, reductions of 85%, 82% and 70% COD were obtained, for CWs planted with two subspecies of Glyceria maxima and Phragmites, respectively, in a five day root–zone system Both species proved to be extremely robust and survived shock dosing, long periods of drying out, total immersion and cold (Daniels, 1998) 49 (a) (b) (c) (d) (e) (f) 50 (g) (h) (i) Figure 3-8: Percentages of COD (a), ammonium (c), nitrite (e), nitrate (g), phosphate equivalent reduction; Column graphs b, d, f, h, i show average contents of these parameters according to levels; the straight line scatter showed removal effect according to levels NO2- is the product of aerobic treatment process when oxygen is provided insufficiently for the demand This easily happens because aerobic processing requires much energy for aeration NO2- is not useful even harmful for the development of plants but NO2- in the experiment declined dramatically, reaching 90% at effluent of CW (Figure 3-8f, level 4) This maybe have two reasons: the first was the oxygen carried by roots oxidized nitrite to nitrate then NO3- was absorbed by the plants, the second was anammox bacteria which had ability to transform 50% NH4+ and 50% NO2- into nitrogen releasing from the filtering area with other gases was the product of nutritious metabolism process in general 51 The more permanent removal of N in constructed wetlands is dependent on the N cycle As part of the cycle, the various forms of N are converted into gaseous components that are expelled into the atmosphere as nitrogen gas (N2) or nitrous oxide (N2O) Key processes in the N cycle include ammonification, nitrification, and denitrification Nitrification denitrification reactions are the dominant removal mechanisms in constructed wetlands (Benham and Mote 1999) Nitrification is the biological formation of nitrite-N (NO2 N) or NO3 N (Alexander 1977) from NH4+ Nitrification occurs in aerobic regions of the water column, soil-water interface, and root zone (Reddy and D’Angelo 1997) Dissolved oxygen levels < 1-2 mg/L in water substantially reduces nitrification (Hammer and Knight 1994; Lee et al 1999) Denitrification is the biological process of reducing NO3 N or NO2 N, into N2, N2O, or nitric oxide (NO) (Kadlec and Knight 1996) Denitrification is significant mechanism inequality degradation, reducing NH3 concentrations drives the design process for many wetland treatment systems (Kadlec and Knight 1996) Thus, unsuitable conditions for nitrification can seriously limit the treatment potential of these systems The use of supplemental aeration may enhance nitrification activity, due to the addition of dissolved oxygen into the wastewater which would induce a more aerobic environment for this reaction Cottingham et al (1999) found that aerating laboratory scale subsurface flow constructed wetlands promoted increased rates of nitrification Surface flows, or free water surface constructed wetlands, however, are used for treating livestock wastewater in Nova Scotia due to their ability to handle relatively high solids content Subsurface flow wetlands are generally not recommended for agricultural wastewater treatment with substantial solids content (NRCS 1991) Percentage of treatment varies in a wide range from 30% to close 100% Nitrate concentration seems to be instable that because of much changing the initial nitrate content and affected by many factors In constructed wetlands, after NO3- is formed under aerobic conditions; it diffuses down into the anaerobic portion of the soil, where it is denitrified (Patrick and Reddy 1976; Nichols 1983) Since ammonium 52 was being nitrified to NO3- within the system, NO3- increased at level as a result The accumulation of NO3- at level indicates that after NH3 was nitrified, subsequent denitrification was limited (figure 3-8gh) At level 4, nitrate and nitrite contents were low, possible factors that could promote denitrification include enough residence time for denitrification to remove NO3 N, lack of DO, available carbon (C) within the system Denitrification activity is reduced if available C supplies are low (Gersberg et al 1983; Hammer and Knight 1994; Wood et al 1999) and proceeds only when the oxygen supply is inadequate for microbial demand (Hammer and Knight 1994) However, limited denitrification activity has been observed in the presence of DO (Phipps and Crumpton 1994) Phosphor at the top layer was absorbed strongly by the roots and microorganism, thus they declined significantly, reaching over 45% At subsequent layer, due to not ingrained roots, only microorganism use them, PO43- declines much less, just reaching over 20% Beside that PO43- could be participated with other cations Conclusion Seafood processing wastewater treatment using the anaerobic method required long retention time, which didn’t meet the requirement of reducing COD down to 200-300mg/L even after days The results of aerobic treatment in the continuous aeration tank using activated sludge indicated the possibility of applying for pre-treatment of wastewater containing high COD When the retention time was 12.7 hours the COD value of effluence was acceptable for CW Sedge had the advantage of Limnophila in ammonium, nitrite, nitrate treatment and was suitable for growing in CW of local area Sedge should be grown in CWs because of the reduction of ammonium, nitrite, nitrate, total phosphorous was stable The system had high effect in removing 53 ammonium, nitrite, nitrate, phosphorous, 80.3±15.8%, 93.2±7.2%, 72.8±25.0%, 73.1±26.6%, respectively which meet Vietnamese Guide QCVN 11:2008 COD value was reduced from 300-400mg/L to 91.6±9.9 mg/L 54 Referents Ahn, C., Gillevet, P.M., Sikaroodi, M., 2007 Molecular characterization of microbial communities in treatment microcosm wetlands as influenced by macrophytes and phosphorus loading Ecol Indicat 7, 852–863 Baptista, J.D.C., Davenport, R.J., Donnelly, T., Curtis, T.P., 2008 The microbial diversity of laboratory-scale wetlands appears to be randomly assembled Water Res 42, 3182–3190 Bernard, J.M., Lauve, T.E., 1995 A comparison of growth and nutrient uptake in Phalaris arundinaceae L growing in a wetland and a constructed bed receiving landfill leachate Wetlands 15, 176–182 Calheiros, C.S.C., Duque, A.F., Moura, A., Henriques, I.S., Correia, A., Rangel, A.O.S.S., Castro, P.M.L., 2009 Changes in the bacterial community structure in two-stage constructed wetlands with different plants for industrial wastewater treatment Bioresour Technol 100, 3228–3235 Caravaca, F., Alguacil, M.M., Torres, P., Roldan, A., 2005 Plant type mediates rhizospheric microbial activities and soil aggregation in a semiarid Mediterranean salt marsh Geoderma 124, 375–382 Chong-Bang Zhang, Wen-Li Liu, Jiang Wang, Tong Chen, Qing-Qing Yuan, Cheng-Cai Huang,Ying Ge, Scott X Chang, Jie Chang,2011 Plant functional group richness-affected microbial community structure and function in a full-scale constructed wetland Collins, B., McArthur, J.V., Sharitz, R.R., 2004 Plant effects on microbial assemblages and remediation of acidic coal pile runoff in mesocosm treatment wetlands Ecol Eng 23, 107–115 Cooper, P.E and Boon, A.G (1987) The use of Phragmites for wastewater treatment by the root zone method Aquatic plants for wastewater treatment and resource recovery Orlando, Florida: Magnolia 55 Cronk, J.K and Fennessy, M.S (2001) “Wetland Plants : Biology and Ecology” Lewis Publishers, United States of America DeJournett, T.D., Arnold, W.A., LaPara, T.M., 2007 The characterization and quantification of methanotrophic bacterial populations in constructed wetland sediments using PCR targeting 16S rRNA gene fragments Appl Soil Ecol 35, 648–659 Don Eckert Efficient Fertilizer Use –Nitrogen Faulwetter, J.L., Gagnon, V., Sundberg, C., Chazarenc, F., Burr, M.D., Brisson, J., Camper, A.K., Stein, O.R., 2009 Microbial processes influencing performance of treatment wetlands: a review Ecol Eng 35, 987–1004 Green, M.B., Martin, J.R., 1996 Constructed reed beds clean up storm overflows on small wastewater treatment works Water Environ Res 68, 1054– 1060 Hammer, D.A., 1992 Designing constructed wetlands systems to treat agricultural nonpoint source pollution Ecol Eng 1, 49–82 Hammer, D.A., Pullin, B.P., McCaskey, T.A., Eason, J., Payne, V.E.W., 1993 Treating livestock wastewaters with constructed wetlands In: Moshiri, G.A (Ed.), Constructed Wetlands for Water Quality Management Lewis Publishers, Ann Arbor, MI Hill, V.R., Sobesy, M.D., 1998 Microbial indicator reductions in alternative treatment systems for swine wastewater Water Sci.Technol 38 (12), 119–122 Hilton, B L 1993 Performance evaluation of a closed ecological life support system (CELSS) employing constructed wetlands pp 117-125 in Constructed Wetlands for Water Quality Improvement, G A Moshiri (ed.) CRC Press, Boca Raton, FL 56 Hofmann, K., 1996 The role of plants in subsurface flow constructed wetlands In: Etnier, C., Gusterstam, B (Eds.), Ecological Engineering for Wastewater Treatment Lewis Publishers, Boca Raton, FL, pp 83–196 Humenik, F.J., Szogy, A.A., Hunt, P.G., Broome, S., Rice, M., 1999 Wastewater utilization: a place for manage wetlands – review Asian–Australian J Anim Sci 12 (14), 629–632 Johnson, D., Booth, R.E., Whiteley, A.S., Bailey, M.J., Read, D.J., Grime, J.P., Leake, J.R., 2003 Plant community composition affects the biomass, activity and diversity of microorganisms in limestone grassland soil Eur J Soil Sci 54, 671– 677 Kadlec, R.H., Knight, R.L., 1996 Treatment Wetland CRC Press, FL, USA Kantawanichkul, S., Kladpraserta, S., Brix, H., 2009 Treatment of high-strength wastewater in tropical vertical flow constructed wetlands planted with Typha angustifolia and Cyperus involucratus Ecol Eng 35, 238–247 Karathanasis, A.D., Thompson, Y.L., 1995 Mineralogy of iron precipitates in constructed acid mine drainage wetland Soil Sci Soc Am J 59, 1773–1779 Krasnits, E., Friedler, E., Sabbah, I., Beliavski, M., Tarre, S., Green, M., 2009 Spatial distribution of major microbial groups in a well established constructed wetland treating municipal wastewater Ecol Eng 35, 1085–1089 Lim, W.H., Tay, T.H and Kho, B.L (2002) “Plants Used in the Putrajaya Wetland System and Problems Associated with Their Establishment and Maintenance” In : Editors : Mansor, M., Eng, L.P and Shutes, R.B.E “Constructed Wetlands : Design, Management and Education” Universiti Sains Malaysia Publisher, Malaysia Marsh, B Spink, D (2007) Technical Specifications: Seair 40-foot Wastewater Treatment Plant Revision 57 Mavrogianopoulos, G., Volgi, V., Kyritsis, S., 2002 Use of wastewater as a nutrient solution in a closed gravel hydroponic culture of giant reed (Arundo donax) Bioresour Technol 82, 103–107 Milcu, A., Partsch, S., Langel, R., Scheu, S., 2006 The response of decomposers (earthworms, springtails and microorganisms) to variations in species and functional group diversity of plants Oikos 112, 513–524 Neralla, S., Wever, R.W., Lesikar, B.J., Persyn, R., 2000 Improvement of domestic wastewater quality by cubsurface flow constructed wetlands Bioresour Technol 75, 19–25 Osem, Y., Chen, Y., Levinsonc, D., Hadar, Y., 2007 The effects of plant roots on microbial community structure in aerated wastewater-treatment reactors Ecol Eng 29, 133–142 Prapa Sohsalam, Andrew Joseph Englande, Suntud Sirianuntapiboon 2007 Seafood wastewater treatment in constructed wetland Reed, S.C., Middlebrooks, E.J., Crite, R.W., 1988 Natural Systems for Waste Management and Treatment McGraw-Hill,New York Sirianuntapiboon, S., Nimnu, N., 1999 Management of water consumption and wastewater of seafood processing industries in Thailand Suranaree J Sci Technol (3), 158–167 Spehn, E.M., Joshi, J., Schmid, B., Alphei, J., Korner, C., 2000 Plant diversity effects on soil heterotrophic activity in experimental grassland ecosystems Plant Soil 224, 217–230 Suwasa Kantawanichkula, Supreeya Kladprasert, Hans Brix, Treatment of highstrength wastewater in tropical vertical flow constructed wetlands planted with Typha angustifolia and Cyperus involucratus, ecological engineering 35 (2009) 238–247 58 Szogy, A.A., Hunt, P.G., Humenik, F.J., 2000 Treatment of swine wastewater using saturated-soil-culture soybean and flooded rice system Trans ASAE 43 (2), 327–335 T.S Jamieson, G.W Stratton, R Gordon and A Madani The use of aeration to enhance ammonia nitrogen removal in constructed wetlands Tietz, A., Kirschner, A., Langergraber, G., Slrytr, K., Haber, R., 2007 Characterisation of microbial biocoenosis in vertical subsurface flow constructed wetlands Sci Total Environ 380, 163–172 Tietz, A., Langergraber, G., Watzinger, A., Haberl, R., Kirschner, A.K.T., 2008 Bacterial carbon utilization in vertical constructed wetlands Water Res 42, 1622– 1634 UN-HABITAT, 2008 Constructed Wetlands Manual UN-HABITAT Water for Asian, Cities Programme Nepal, Kathmandu Vietnam economic time 2007 Vrhovsek, D., Kukanja, V., Bulc, T., 1996 Constructed wetland (CW) for industrial wastewater Water Res 30, 2287–2292 Vymazal, J., Brix, H., Cooper, P.F., Green, M.B., Haberl, R., 1998 Constructed Wetland for Wastewater Treatment in Europe Backhuys Publishers, Leiden, The Netherlands, pp 17–66 Wang, L., Gan, H., Wang, F., Sun, X.M., Zhu, Q.L., 2010 Characteristic analysis of plants for the removal of nutrients from a constructed wetland using reclaimed water Clean - Soil Air Water 38, 35–43 59 ...VIETNAM NATIONAL UNIVERSITY, HANOI VNU UNIVERSITY OF SCIENCE NAKHONEKHAM XAYBOUANGEUN SEAFOOD PROCESSING WASTEWATER TREATMENT BY USING ACTIVATED SLUDGE REACTOR FOLLOWED BY CYPERUSMALACENSIS LAM CONSTRUCTED. .. (Sirianuntapiboon and Nimnu, 1999) To avoid this impact, treatment of seafood processing wastewater before discharge has been proposed A candidate method of treatment is constructed wetland Wetlands have... et al., 1996; Higgins et al., 1993; Karathanasis and Thompson, 1995; Bernard and Lauve, 1995) Natural treatment systems have been shown to have a significant capacity for both wastewater treatment