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INVESTIGATION OF ANAEROBIC BAFFLED SEPTIC TANK (ABR) FOR DOMESTIC WASTEWATER by Tran Thi Mai Hoa A research study submitted in partial fulfillment of the requirements for the degree of Master of Science Examination Committee: Dr Thammarat Koottatep (Chairman) Dr Nguyen Thi Kim Oanh Dr Toshiya Aramaki Nationality: Vietnamese Previous Degree: Bachelor of Science, Hanoi Teacher University Hanoi Vietnam Scholarship Donor: AIT Fellowship Asian Institute of Technology School of Environment, Resources and Management Thailand May 2005 Acknowledgement The author wishes to express her sincere gratitude to Prof Thammarat Kottatep for his valuable suggestions, strong support, encouragement and readiness to help through out the study period His availability at every steps of the research work has made it possible to accomplish this work It was a valuable experience to work under his supervision The author expresses the heartfelt gratitude towards Dr Nguyen Thi Kim Oanh and Dr Toshiya Aramaki for their serving as members of the thesis committee Their critical suggestions, encouragements and moral support are highly appreciated The author is equally indebted her lecturers for their valuable instruction throughout her Master program Special thanks are also given to Ms Suchitra Piempinsest, Ms Salaya Phunsiri, Mr Somchai Aremsum-Ang and Mr Zaw Win Aung for their ever-willing help in academic and laboratory work as well as their invaluable suggestions, ideas and interest through out the study Gratitude is extended to the Asian Institute of Technology providing fellowship to this author for master program in Environmental Engineering and Technology The author also thanks to her parents, sister, brother, nephew and relatives for their strong moral supports to complete this work Abstract Sanitation projects in developing countries mainly focus on toilets, neglecting other aspects of liquid waste management, such as greywater Greywater represents volumewise by far the biggest wastewater source and needs therefore to be treated and disposed or reused correctly Main problem is the lack of appropriate systems for the treatment and management of greywater on household level The decentralized approach is a new means of addressing wastewater management needs of sewered and unsewered areas in a comprehensive fashion The basic idea of that is to treat the wastewater (possibly together with refuses) on-site by means of lowcost treatment systems, and make direct use the treatment products (water, compost and biogas) This alternative can meet a sustainable wastewater management requirement and has a promising future, especially for developing country of Vietnam, where the water and sanitation issues are becoming a more and more important issue and are under new period of infrastructure development This study was conducted to determine the ability of baffled septic tank system treating greywater For determination of the four laboratory-scale baffled septic tank units, made of acrylic plastic with dimensions of 0.25 x 0.64 x 0.64 m3 (width x length x depth) The greywater supply for the systems from AIT campus It was found that the removal efficiencies of baffled septic tank systems in terms of COD, TS, TSS of greater than conventional septic tank Due to Wanasen (2002) study report that performance of baffled septic tank systems at HRT 48 hours is higher tan at HRT 24 hours then, the experiments were conducted at the HRT 48 hours Characteristics of influent wastewater, baffled septic tank performance, relationships between removal efficiency and organic loads,up -flow velocity, hydraulic retention time, ambient temperature, presence of anaerobic filter and number of baffled chambers were discussed Further, the authors describe results from experiment on real greyewater treatment by baffled septic tank that could be most feasible option for on-site wastewater treatment in residential areas of Vietnam The investigations of treatment performance indicated that a septic tank with three baffles was the best as compared to conventional, two –baffles, two-baffles with filter media septic tank.The data show that septic tank with baffled could effectively treat greywater in Vietnamese conditions, with average COD, TS and TSS removal of 65%, 57% and 90%.The decentralized schemes of wastewater management are also proposed for medium and small cities of Vietnam iii Abstract Sanitation projects in developing countries mainly focus on toilets, neglecting other aspects of liquid waste management, such as greywater Greywater represents volumewise by far the biggest wastewater source and needs therefore to be treated and disposed or reused correctly Main problem is the lack of appropriate systems for the treatment and management of greywater on household level The decentralized approach is a new means of addressing wastewater management needs of sewered and unsewered areas in a comprehensive fashion The basic idea of that is to treat the wastewater (possibly together with refuses) on-site by means of lowcost treatment systems, and make direct use the treatment products (water, compost and biogas) This alternative can meet a sustainable wastewater management requirement and has a promising future, especially for developing country of Vietnam, where the water and sanitation issues are becoming a more and more important issue and are under new period of infrastructure development This study was conducted to determine the ability of baffled septic tank system treating greywater For determination of the four laboratory-scale baffled septic tank units, made of acrylic plastic with dimensions of 0.25 x 0.64 x 0.64 m3 (width x length x depth) The greywater supply for the systems from AIT campus It was found that the removal efficiencies of baffled septic tank systems in terms of COD, TS, TSS of greater than conventional septic tank Due to Wanasen (2002) study report that performance of baffled septic tank systems at HRT 48 hours is higher tan at HRT 24 hours then, the experiments were conducted at the HRT 48 hours Characteristics of influent wastewater, baffled septic tank performance, relationships between removal efficiency and organic loads,up -flow velocity, hydraulic retention time, ambient temperature, presence of anaerobic filter and number of baffled chambers were discussed Further, the authors describe results from experiment on real greyewater treatment by baffled septic tank that could be most feasible option for on-site wastewater treatment in residential areas of Vietnam The investigations of treatment performance indicated that a septic tank with three baffles was the best as compared to conventional, two –baffles, two-baffles with filter media septic tank.The data show that septic tank with baffled could effectively treat greywater in Vietnamese conditions, with average COD, TS and TSS removal of 65%, 57% and 90%.The decentralized schemes of wastewater management are also proposed for medium and small cities of Vietnam iv Acknowledge Nowadays there are 571 cities and towns in Vietnam The country is under rapid urbanization and industrialization process, with positive indicators in socio-economic development However, there is an increasing problem of water pollution The water supply capacity has increased from 1.95 million m3/day in 1990 to nearly million m3 /day in late 2001 In the same period, the urban population has raised from 12 million in late 1980 to nearly 18 million in late 1999, accounting for 23.5% of the population of the whole country There is very low ratio of population served by adequate sanitation, especially in rural, peri-urban and poor urban areas Urban sewerage and drainage systems are still poor and under degradation In most of cities and towns, flood and inundation often occur in rainy season Existing sewer networks (if any) in cities have been built for surface water drainage only Mainly domestic wastewater from houses is directly discharged to the common sewerage network and then flows to the canals, lakes and ponds without any treatment In consequence, self-purification capacity of receiving water bodies is overloaded and it causes surface and ground water pollution, impacting directly to the health of community, reducing the value of environment More than ever, development of urban sewerage and drainage systems in Vietnam has become an urgent need In Vietnam, the septic tank is the most common on-site treatment facility in urban and peri-urban areas In Hanoi, there are about 10,000 septic tanks in operation for treatment of the domestic wastewater In urban centers the ratio of households equipped with septic tanks is nearly 0-80% In the rest of the city the ratio is 20-30% (Hanoi PC, 1998) Dislodging of septic tanks is not often followed There is still subsidizing form of management of public utilities including wastewater management, without or with very poor public involvement Thus, looking for the appropriate solutions for wastewater management is becoming very hot issue and is to be paid adequate attention, especially in this period of increasing urbanization, industrialization, improvement and development of water supply and sanitation facilities v Table of Contents Chapter Title Acknowledgement Abstract Table of Contents List of Tables List of Figures Page i ii iii iv v 1.1 Background 1.2 Objectives of study 1.3 Scope of study 1 Literature review 2.1 Decentralized wastewater treatment systems (DEWATS) 2.2 Septic Tank 2.3 Anaerobic baffled reactor (ABR) 2.3.1 Introduction of ABR 2.3.2 Treatment wastewater by ABR systems 2.4 Vietnam sanitation situation 3 6 Methodology 3.1 Preparation of wastewater 3.2 Experimental set up 3.2.1 Apparatus 3.2.2 Unit Installation 3.3 Start-up of the experiments 3.3.1 Operating conditions 3.3.2 Experimental investigations 13 13 14 14 16 17 17 Result and Discussion 4.1 Influent characteristics 4.2 Result of experimental units 4.2.1 COD removal 4.2.2 TS removal 4.2.3 TSS removal 4.2.4.Gas production 4.3 Discussions 19 19 19 21 22 23 24 Conclusions and Recommendations 5.1 Conclusion 5.2 Recommendation 25 25 References Appendices 26 28 iii List of Tables Table 2.1 2.2 2.3 3.1 3.2 3.3 3.4 3.5 4.1 4.2 4.3 4.4 4.5 4.6 Title Wastewater management options for unsewered areas Urban and rural sanitation in Vietnam 2000 Vietnam sanitation and clean water for Ho Chi Minh City, Haiphong and Hanoi Characteristics of AIT wastewater Characteristics of AIT greywater and blackwater Operating conditions of experiment Parameter and analytical methods Sampling frequency Influent characteristics COD removal efficiencies of experimental units TS removal efficiencies of experimental units TSS removal efficiencies of experimental units Gas volume of experimental units Gas compositon of experimental units iv Page 10 13 13 17 17 18 19 20 21 22 23 23 List of Figures Figure 2.1 2.2 2.3 3.1 3.2 3.3 3.4 3.5 4.1 4.2 4.3 Title Tank dimensions Conventional septic tank Anaerobic baffled reactor Conventional septic tank Septic tank with baffles Septic tank with baffles Septic tank with baffles and an aerobic filter media Schematic diagram of laboratory–scale units Result of COD removal efficiency Result of TS removal efficiency Result of TSS removal efficiency v Page 14 15 15 16 16 20 21 22 Chapter Title Table of Contents List of Tables List of Figures Background 1.1 Objectives of study 1.2 Scope of study Literature review 2.1 Decentralized wastewater treatment systems (DEWATS) 2.2 Septic Tank 2.3 Anaerobic baffled reactor (ABR) 2.3.1 Introduction of ABR 2.3.2 Treatment wastewater by ABR systems 2.4 Vietnam sanitation situation Methodology 3.1 Preparation of wastewater 3.2 Experimental set up 3.2.1 Apparatus 3.2.2 Unit Installation 3.3 Start-up of the experiments 3.3.1 Operating conditions 3.3.2 Experimental investigations Result and Discussion 4.1 Influent characteristics 4.2 Result of experimental units 4.2.1 COD removal 4.2.2 TS removal 4.2.3 TSS removal 4.2.4 Gas production Conclusion and Recommendation 5.1 Conclusion 5.2 Recommendation Reference vi Page i ii iii Chapter Results and Discussions 4.1 Influent characteristics The experimental units were operated at HRT of 48 Characteristics of influent greywater are shown in table 4.1 Table 4.1: Influent characteristics No Parameter COD Unit mg/L BOD mg/L 45 TS mg/L 233 TSS mg/L 44 TKN mg/L 35 Alkalinity mg/L 300 Temperature pH o C Average value 124 29 7.5 As followed to Metcalf and Eddy 2003 the temperatures of influent are in the mesophilic range of 25-40oC which should provide the optimal operation of the system In addition, the alkalinity concentration of 3,000 to 5,000 mg/L as CaCO is needed for anaerobic process, it can be known that alkalinity concentration of influence were relatively low Anaerobic biodegradation in baffled septic tank systems could not work perfectly when it operate with this influent 4.2 Result of experimental units 4.2.1 COD removal Base on COD experimental results (see Appendix 1), it can be noticed that the highest effluent COD concentration of 74 mg/L could obtained from Septic tank with two-baffles and anaerobic media and the lowest effluent COD concentration of 38 mg/L could be obtained from Septic tank with three baffles Both these results could satisfy with the Vietnamese Standard for Domestic supply water ( see Appendix 5) 19 Table 4.2: COD removal efficiencies of experimental units Experimental unit Influent Conventional septic tank Three baffles septic tank Two -baffles septic tank Two- baffles septic tank with anaerobic media COD (mg/L) 130 65 46 52 65 57% 65% 60% 50% %COD removal Table 4.2 shows the COD removals efficiencies of experimental units A conventional septic tank (Reactor 1), it can be observed that the COD removal is 57% And the COD removals efficiencies of septic tank with three baffles (Reactor 2), septic tank with two baffles (Reactor 3) and septic tank with two baffles and aerobic media (Reactor 4) are 65%, 60% and 50%, respectively The highest COD removals efficiency could be obtained from Reactor (65%) Base on experimental, results of COD removal are lower in comparison with Withauer and Stuckey research (1982) with the efficiency of COD removal could be reached at 63-84% (inlet COD is 480mg/L) %COD removal 100% 80% 60% 40% 20% 0% Reactor Reactor Reactor Reactor Figure 4.1: Result of COD removal efficiency 20 4.2.2 TS removal The experimental results (see Appendix 2) shown that the lowest effluent of TS concentration of 72 mg/L could be obtained from Reactor and the highest effluent of TS concentration of 141 mg/L could be obtained from Reactor Table 4.3: TS removal efficiencies of experimental units Experimental unit Influent Conventional septic tank Three -baffles septic tank Two -baffles septic tank Two- baffles septic tank with anaerobic media TS (mg/l) 234 119 100 106 118 49% 57% 55% 50% %TS removal Table 4.3 shows the TS removals efficiencies of experimental units A conventional septic tank, it can be observed that the TS removal is 49% And the TS removals efficiencies of septic tank with three baffles, septic tank with two baffles and septic tank with two baffles + anaerobic media are 57 %, 55%, 50%, respectively The highest TS removal efficiency could be obtained from Reactor %TS removal 100% 80% 60% 40% 20% 0% Reactor Reactor Reactor Reactor Figure 4.2 : Result of TS removal efficiency Base on experimental results in term of TS removal can be noticed that treating greywater by baffled septic tanks could be satisfy with Discharge to main Drainage systems but still not meet The Standard for Domestic water supply (see Appendix 5) 21 4.2.3 TSS removal Table 4.4: TSS removal efficiencies of experimental units Experimental unit Influent Conventiona l septic tank Three -baffles septic tank Two -baffles septic tank Two -baffles septic tank with anaerobic media TSS (mg/L) 44 16 82% 90% 86% 64% %TSS removal Table 4.4 shows the TSS removals efficiencies of experimental units A conventional septic tank (Reactor 1), it can be observed that the TSS removal is 82% And the COD removals efficiencies of septic tank with three baffles, septic tank with two baffles and septic tank with two baffles + anaerobic media are 90 %, 86%, 64 %, respectively %TSS removal 100% 80% 60% 40% 20% 0% Reactor Reactor Reactor Reactor Figure 4.3: Result of TSS removal efficiency Base on experimental results, it can be noticed that the lowest effluent TSS concentration of mg/L could obtained from septic tank with three baffles and the highest effluent TSS concentration of 16 mg/L could be obtained from two baffles + anaerobic media 22 4.2.4 Result of gas production Table 4.5: Gas volume of experimental units Experimental unit Average volume of gas (mL/week) Conventional septic tank Three - baffles septic tank 15 Two- baffles septic tank 30 28 Two- baffles septic tank with anaerobic media 32 The table 4.5 shows the biogas production of experimental units operating at the same condition Volume of gas from experimental units were measured weekly A conventional septic tank (Reactor 1) can be observed 15 mL biogas production per week A septic tank with three baffled (Reactor 2), a septic tank with baffles and a septic tank with baffles and anaerobic media can be observed that the biogas productions are 30, 28 and 32 mL for one week, respectively Table 4.6: Gas composition of experimental units Experimental unit CO (%) O (%) N (%) CH (%) CO (%) Conventional septic tank 41.93 1.17 3.03 52.27 1.55 Three - baffles septic tank 21.62 1.14 2.27 73.54 1.43 Two - baffles septic tank 22.15 1.03 3.49 72.48 0.86 Two - baffles septic tank with anaerobic media 22.40 0.92 3.17 71.47 2.01 Table 4.6 shown the gas composition of experimental units Based on the experimental results, a conventional septic tank had percentages of methane production about 52.27%, whereas three baffles, baffles and two baffles + anaerobic media were about 73.54%, 72.48% and 71.47%, respectively It is means that the baffles could obtain the best biodegradation organic matter in compare with conventional septic tank As followed by Metcalf and Eddy (2003) the COD loss in the anaerobic reactor was accounted for by the methane production and only some portion of COD removed were trapped at the sludge blanket It was obtained from Polpprasert (1996) that the methane in the composition of biogas could be range of 55-65% So the methane productions of baffled septic tank could satisfy the theoretical value 23 4.3 Discussions - The treatment efficiency for the models reached 50% and more after months of operation, after sludge layer has formed in bottom of up-flow chambers The sludge was grown naturally The growth has been accelerated from second and third month.15cm depth layer of the sludge from 40 cm-total depths of the chambers has been reached after months of operation - COD removal efficiency is 50-65% and could obtained highest efficiency from septic tank with three baffles (65%) - TS removal efficiency is 49-57% and could obtained highest efficiency from septic tank with three baffles (57%) - TSS removal efficiency is 64-90% and could obtained highest efficiency from septic tank with three baffles (90%) - With appropriate hydraulic regime (i.e proper design) septic tank with baffles chamber could increase treatment efficiency of the model, especially for COD (8%) and for TS (8%) in compare with conventional septic tank For the case of experiment, high flow rate during continuous operational regime led in washing out of suspended solids from chamber to the outlet SS removal could be improved by reducing flow rate (i.e increasing dimension of the septic tank for the same user) Batch regime (hence, with less flow rate and longer HRT) of experimental units gave much better SS removal - The anaerobic baffled reactors have more significant removal efficiency with dissolved organic matters rather than the solids - Baffled septic tank has shown positive results for greywater treatment in Vietnamese condition It could be developed further for practical implementation Results from this study could be adapted for revision of existing septic tank design standards in the country 24 25 26 Chapter Conclusions and Recommendations 5.1 Conclusions According to the experimental unit results obtain from four reactors at the same operating condition, it was found that a septic tank with three baffled (Reactor 2) should be the most promising system, because of its highest COD, TS, TSS removal efficiencies This reactor also achieved the highest biogas productions Implementation of baffled septic tank has positive results for real greywater treatment in Vietnamese condition It could be developed for practical use and included for design standard instead of under-designed and improperly operated existing septic tanks in residential areas in over the country 5.2 Recommendations It was noticed that due to the fluctuation of influent greywater coming to the system the removal under shock load should be investigated The removal efficiency of baffled septic tank systems in terms of nitrogen, total organic carbon, BOD should be further investigated According to the research, it was obtained that the scum could overflow the systems so in the future studies should be solving this problem The proper design of baffled septic tank should be further study 25 References Bachmann A., Beard V and McCarty P (1985) Performance characteristics of the anaerobic baffled reactor Water Research, Vol 19, No 1, pp 99 - 106, 1985 Bachmann A., Beard V.L and McCarty P.L (1983) Comparison of Fixed Film Reactor with a Modified Sludge Blanket Reactor, Fix film Biological Processes for Wastewater treatment , ed Y.C Wu and E.D Smith Noyes Data, NJ Barber W and Stuckey D (1999) The use of the anaerobic baffled reactor (ABR) for wastewater treatment: A review Water Research, Vol 33, No 7, pp 1559 – 1578 Barber W.P and Stuckey D.C (1997) Start-up strategies for anaerobic baffled reactors treating a synthetic sucrose feed Proceedings of the 8th International Conference on Anaerobic Digestion, Vol 2, Dendai, Japan, pp 32-39 Bouns, T.R., Dedinger, M.S., Jonhson, A.I , and Felming, J.S (1997) Design and Performance of Septic Tank American Society for Testing Material, Philadenphia Canter, L.W and Knox, R.X (1985) Septic Tank System Effect on Ground Water Quality Lewis Publishers, Inc., Michigan Crites, R and Tchobanoglous, G (1998) Small and Decentralized Wastewater Management Systems Mcgraw-Hill, Inc., New York Henze M and Harremoe P (1983) Anaerobic treatment of wastewater in fixed film reactors ; a literature review Wat.Sci.Technol.15,1-101 Koottatep T., (2004) Environmental Health and Sanitation Lecture note Laak R., (1980) Multichamber septic tank Journal of the environmental engineering division, Proceeding of the American Society of Civil Engineers, 12:348-352 Metcalf and Eddy (2003) Wastewater Engineering: Treatment and Reuse, th edition Mcgraw-Hill, Inc., New York Larsen, T and M.Boller (2001) Perspectives of nutrient recovery in DESAR concepts In: Decentralised Sanitation and Reuse: Concepts, Systems and Implementation Edited by P Lens, G Zeeman and G Lettinga IWA Publishing Polprasert C (1996) Organic Waste Recycling Thechnology and management Second Edition John Wiley and Sons Sasse, l (1998) (DEWATS) Decentralized Wastewater Treatment in Developing countries BORDA publication 26 Slever D.M (1988) Particle trapping in an anaerobic treatment of slaughterhouse waste using a flocculants sludge UASB reactor Biol.Wastes 21,11-28 Stronach S.M Rudd t.and Lester J.N (1986) Start-up of anaerobic bioreactors In Anaerobic Digestion Processes in Industrial Wastewater Treatment , Springer Berlin Wanasen, D (2003) Upgrading conventional septic tank by integrating in-tank baffles, Asian Institute of Technology, Thailand Watt, S.B (1984) Septic Tank and Aqua-Privies from Ferrocement Intermediate technology publications Ltd., London Withauer D and Stuckey D.C (1982) Laboratory studies on anaerobic processes to treat dilute organic wastewater in developing countries Study by IRCWD, EAWAG Dubendorf, Switzerland 27 Appendix 1: COD result of experimental units (mg/L) Sample 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 I Influent 120 134 119 148 126 135 143 124 132 118 143 120 129 125 132 141 130 123 125 133 110 154 133 135 123 98 134 118 128 Reactor 47 62 51 63 54 59 69 50 61 45 65 48 50 54 59 65 52 63 49 59 43 69 62 66 59 35 63 65 63 Reactor 39 55 46 53 45 42 57 38 52 37 57 40 44 45 42 47 38 49 38 54 38 57 51 48 45 38 57 50 52 28 Reactor 41 61 58 57 53 48 61 44 57 41 64 42 58 53 48 59 46 57 50 49 41 61 58 57 48 43 51 54 57 Reactor 59 72 68 65 61 63 71 58 69 59 75 67 65 61 63 69 57 69 60 70 59 72 68 61 61 51 71 62 74 Appendix 2: TS result of experimental units (mg/L) Sample 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Influent 269 270 264 242 238 226 212 197 215 267 259 263 253 237 231 219 195 206 198 215 272 264 268 234 242 220 186 198 210 Reactor 132 125 128 130 135 132 98 101 110 136 131 125 133 129 128 101 97 112 99 106 128 123 131 127 129 124 82 87 107 Reactor 112 105 119 113 118 94 77 79 85 107 101 115 121 120 95 81 79 84 92 102 110 107 120 112 106 94 75 72 88 29 Reactor 116 125 112 106 115 108 86 82 96 118 127 115 108 125 104 90 85 98 97 114 113 122 105 103 113 104 73 78 93 Reactor 132 143 131 124 121 115 97 89 101 136 141 129 127 126 118 99 90 101 110 121 135 141 128 124 115 107 86 84 97 Appendix 3: TSS result of experimental units (mg/L) Sample 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Influent 44 40 48 44 40 40 44 48 44 48 44 44 40 40 44 48 44 48 44 40 44 40 48 44 40 40 44 48 44 Reactor 12 8 12 12 4 8 12 12 8 12 8 12 Reactor 4 4 4 4 4 4 4 4 4 4 4 4 4 4 30 Reactor 4 4 8 8 4 4 8 8 4 4 8 Reactor 16 16 24 16 12 16 20 16 20 16 16 12 16 20 16 20 16 16 16 16 20 16 12 16 20 16 Appendix 4: Gas volume production (mL/week) Gas volume (ml/week) Week 1st Week 2nd Week 3th Week 4th Week 5th Week 6th Week 7th Reactor Reactor Reactor Reactor 13 14 16 14 17 15 14 27 29 28 29 32 29 35 23 25 28 24 27 31 30 29 31 34 33 32 32 34 Appendix 5: Vietnamese Standard for Discharge of Wastewater 31 ... made it possible to accomplish this work It was a valuable experience to work under his supervision The author expresses the heartfelt gratitude towards Dr Nguyen Thi Kim Oanh and Dr Toshiya Aramaki... services Table 2.3: Vietnam sanitation and clean water for Ho Chi Minh City, Haiphong and Hanoi Indicator HCMC Haiphong Hanoi Total Untreated Waste Discharge (million cu/m/yr) 240-300 70 120 Population... lakes and ponds within the city Wastewater is conveyed through a joint drainage and sewage system, most of which was constructed before 1954, to the water bodies throughout the city This waste is