INVESTIGATION OF ANAEROBIC BAFFLED SEPTIC TANK (ABR) FOR DOMESTIC WASTEWATER 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, sương support, encouragement and readiness to help through out the study period, His availability at every steps of the research work has made i possible to accomplish this work, I was a valuable experience to work under his supervision, ‘The author expresses the heattfelt 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 Phunsii, Mr. Somchai Aremsum-Ang and Mr. Zaw Win Aung for their ever-willin 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 or their st ‘moral supports to complete this work Abstraet Sanitation projects in developing countries mainly focus on toilets, neglecting other aspects of liquid waste management, such as greywater, Greywater represents volume- wise by far the biggest wastewater source and needs therefore to be treated and disposed ‘of 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 isto treat the wastewater (possibly together with refuses) on-site by means of low= cost treatment systems, and make direct use the treatment products (water, compost and biogas). This altemative 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 ‘ofacrylic plastic with dimensions of 0. The ‘greywater supply for the systems from AIT campus. It was found that the removal efficiencies of balled 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 ‘ime, 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 fo conventional, two -baffles, ‘wo-baffles with filter media septic tank The data show that septic tank with 3 batfled 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, Abstraet Sanitation projects in developing countries mainly focus on toilets, neglecting other aspects of liquid waste management, such as greywater, Greywater represents volume- wise by far the biggest wastewater source and needs therefore to be treated and disposed ‘of 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 isto treat the wastewater (possibly together with refuses) on-site by means of low= cost treatment systems, and make direct use the treatment products (water, compost and biogas). This altemative can meet a sustainable wastewater management requirement and has apromising 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 ofthe four laboratory-scale baffled septic tank units, made ‘ofacrylic plastic with dimensions of 0. The ‘greywater supply for the systems from AIT campus. It was found that the removal efficiencies of balled 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 ‘ime, ambient temperature, presence of anaerobic filter and number of baffled chambers 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 oftreatment performance indicated that a septic tank with three baffles was the best as compared to conventional, two -baffles, ‘wo-baffles with filter media septic tank The data show that septic tank with 3 batfled 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 cites of Vietnam, 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 m/day in 1990 to nearly 3 million m` ‘ay in late 2001, Inthe 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 teatment. In consequence, self-purification capacity of receiving water bodies is overfoaded 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. Table of Contents Chapter Title Acknowledgement Abstract ‘Table of Contents List of Tables List of Figures 1.2 Objectives of study 13 Scope of study Literature review 2.1 Decentralized was water treatment systems (DEWATS) 2.3 Anaerobic baffled reactor (ABR) 2.1 Introduction of ABR 2.
Treatment wastewater by ABR systems 2.4, Vietnam sanitation situation Methodology 3.1 Preparation of wastewater 3.2 Experimental set up B 32. Start-up ofthe experiments 16 3.2 Experimental investigations 0 Result and Discussion 4.2 Result of experimental units 19 42.2 TS removal 2I 423 TSS removal 4.3 Discussions » Conclusions and Recommendations 5. Recommendation References Appendices List of Tables Table Title Page 24 Wastewater management options for unsewered areas 22 Urban and rural sanitation in Vietnam 2000 23 ‘Vietnam sanitation and clean water for Ho Chi Minh City, Haiphong and Hanoi 31 Characteristics of AIT wastewater 32 Characteristics of AIT greywater and blackwater 33 Operating conditions of experiment 34 Parameter and analytical methods 35 ‘Sampling frequency 41 Influent characteristics 42 COD removal eficiencies of experimental units 43 TTS removal efficiencies of experimental units 44 TSS removal elficiencies of experimental units 45 Gas volume ofexperimental units Gas compositon of experimental units List of Figures Title Page ‘Tank dimensions Conventional septic tank Anaerobic baffled reactor ‘Conventional septic tank 14 Septic tank with 3 baffles 15 Septic tank with 2 baffles 15 Septic tank with 2 baffles and an l6 16 2L Chapter Title [Page “Table of Contenis i List of Tables ii List of Figures m7 Background 11 Objectives oF stud) 1.2 Scope of study 2 Literature review 2.1 Decentralized wastewater treatment systems (DEWATS) 2.3 Anaerobic baffled reactor (ABR) 2.1 Introduction of ABR.2, Treatment wastewater by ABR systems *2. Vietnam sanitation situation 3__ Methodology 3.1, Preparation of wastewater 3.
Experimental set up 3. Star-up of the experiments 3.2 Experimental investigations 4 Result and Discussion 4. Result of experimental units 42.1 COD removal 422 TS removal 4.4, Gas production 5_— Ï Conclusion and Recommendation 5. Recommendation Reference Chapter 1 Introduction 1.1 Background Environmental Sanitation Planning nowadays plays an important role in our life.
As population has increased in urban area of developing countries, so has the number of people lacking access to sanitation. Since 1990, an additional 300 million individuals are making do ‘without decent sanitation, an ominous indication that the world community if failing in its efforts to provide services where they are most needed. Many large cities are still no have central sewage systems for the millions of residents and an inadequate exereta disposal system are rarely considered a problem by the people). In the absence of sanitation systems, some ‘communities rely on natural processes; defecation takes place in the open fields or on surface ‘waters.
In te latter option, human waste is directly disposed of into the river, canal and sea For transport and eventual dilution In developing countries, the primary constraints to successful provision of sunitation facilities are the lack of investment, trained personnel and lack of knowledge about acceptable alternative technologies. So the selection of appropriate sanitation system for a given ‘community is very necessary for environmental sanitation planning Decentralized wastewater treatment systems scem to be a suitable alternative, whieh has been proposed in both developing and developed countries. Nowadays, more than 60 millions people in the United States live in homes that are served by decentralized collection and ‘reatment systems (Crites and Tchobanoglous, 1998). Decentralized wastewater treatment systems comprise of many type treatment facilities such as Imhoff tank, constructed wetlands, privy, septic tank, ete Septic tank systems are widely applied in households in developing countries for treating ‘wastewater because of its low costs in construction and maintenance systems.
However, the conventional septic tank cannot provide effluent that able to meet the standards.