Anaerobic Baffled Reactor (ABR)

Compiled by:
Eawag (Swiss Federal Institute of Aquatic Science and Technology), Dorothee Spuhler (seecon international gmbh)
Adapted from:
TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2014)

Executive Summary

An anaerobic baffled reactor (ABR) is an improved Septic Tank with a series of baffles under which the grey-, black- or the industrial wastewater is forced to flow under and offer the baffles from the inlet to the outlet. The increased contact time with the active biomass (sludge) results in improved treatment. ABRs are robust and can treat a wide range of wastewater, but both remaining sludge and effluents still need further treatment in order to be reused or discharged properly.
In Out

Blackwater, Faecal Sludge, Greywater, Brownwater

Fertigation Water, Biogas, Compost/Biosolids

Introduction

Anaerobic baffled reactors (ABR) are septic tanks  that have been upgraded with a series of baffles along the treatment chamber. The upflow chambers provide enhanced removal and digestion of organic matter. As septic tanks, ABRs are based on a physical treatment (settling) and a biological treatment (anaerobic digestion).

 TILLEY et al. (2014).

Schematic of the Anaerobic Baffled Reactor. Source: TILLEY et al. (2014).

 An ABR consists of a tank and alternating hanging and standing baffles that compartmentalise the reactors and force liquid to flow up and down from one compartment to the next, enabling an enhanced contact between the fresh wastewater entering the reactor and the residual sludge, containing the microorganisms responsible for anaerobic digestion of the organic pollutants. The compartmentalised design separates the solids retention time from the hydraulic retention time, making it possible to anaerobically treat wastewater at short retention times of only some hours (EPA 2006). Solids high treatment rates are high, while the overall sludge production is characteristically low (FOXON et al. 2004). They are simple to build and simple to operate, as well as very robust to hydraulic and organic shock loading (SASSE 1998). Yet, both sludge and effluent still need further treatment.

 N. Zimmermann in SUSANA (2008)

Flow-chart of a DEWATS wastewater management plant. Source: N. Zimmermann in SUSANA (2010)

ABRs are suitable for a wide range of wastewater, including high-strength industrial wastewater, but its efficiency increases with higher organic load. Therefore, ABRs are particularly suited for influents with a high percentage of non-settleable suspended solids and a narrow COD/BOD ratio (SASSE 1998). ABRs are typically applied in DEWATS, usually in combination with several other treatment steps. A typical DEWATS could be a five component system of first three anaerobic steps consisting of a biogas settler; an ABR and an anaerobic filter; followed by an aerobic treatment unit such as a constructed wetland (Free-Water Surface CV, Horizontal Subsurface Flow CV or Vertical Flow CV) and a maturation pond (WHO 2009). BOD may be reduced by up to 90%, which is far superior to its removal in a conventional Septic Tank.

Design Considerations

ABRs are a combination of the principles of septic tanks, moving bed reactors and up-flow anaerobic sludge blanket reactors. The difference to MBRs and UASBs lies in the fact that it is not necessary for the sludge blanket to float; and that effluent retention is not necessary since a part of the active sludge that is washed out from one chamber is trapped in the next (SASSE 1998). The majority of settleable solids are removed in a sedimentation chamber in front of the actual ABR. Small-scale stand-alone units typically have an integrated settling compartment, but primary sedimentation can also take place in a separate Settler or another preceding technology (e.g., existing Septic Tanks). Designs without a settling compartment are of particular interest for (Semi-) Centralized Treatment plants that combine the ABR with other technologies, or where prefabricated, modular units are used. 

Typical inflows range from 2 to 200 m3 per day. Critical design parameters include a hydraulic retention time (HRT) between 48 to 72 hours, upflow velocity of the wastewater below 0.6 m/h and the number of upflow chambers (3 to 6). The connection between the chambers can be designed either with vertical pipes or baffles. Accessibility to all chambers (through access ports) is necessary for maintenance. Usually, the biogas produced in an ABR through anaerobic digestion is not collected because of its insufficient amount. The tank should be vented to allow for controlled release of odorous and potentially harmful gases.

The reactor always starts with a settling chamber for larger solids and impurities (SASSE 1998) followed by a series of at least 2 (MOREL & DIENER 2006), sometimes up to 5 (SASSE 1998) up-flow chambers. The wastewater enters the chambers at the bottom and needs to pass through the sludge to move up and to the next compartment. Thereby particles settle against the up-stream (SASSE 1998). As the wastewater passes through the sludge, intensive contact between the active biomass in the resident sludge and newly incoming wastewater occurs. To equally distribute the entering liquid in the chambers, they should be designed as relatively short compartments (< 75 cm of length and < 50% to 60% of the height, SASSE 1998). To retain any possible scum formed in the up-flow chamber, the outlets of each tank as well as the final outlet should be placed slightly below the liquid surface (SASSE 1998).

The up-flow velocity is the most crucial parameter for dimensioning, especially with high hydraulic loading. It should not exceed 2.0 m/h (SASSE 1998; MOREL & DIENER 2006). Based on a given HRT, the up-flow velocity increases in direct relation to the reactor height. Therefore, the reactor height cannot serve as a variable parameter to design the reactor for the required HRT. The limited upstream velocity results in large but shallow tanks. It is for this reason that the baffled reactor is not economical for larger plants (SASSE 1998). The organic load should be below 3 kg COD/m3/day. Higher loading-rates are possible with higher temperature and for easily degradable substrates (SASSE 1998).

During the anaerobic digestion, biogas is produced, which can be recovered and reused in the kitchen or for driving pumps and other equipment when necessary. Methane concentration increases steadily from the first compartment to the last (WANG et al. 2004). The methane producing activity of anaerobic sludge in different compartments depends on the substrate, which suggests that the proper anaerobic consortium in each separate compartment develops in accordance to the substrate available and the specific environmental conditions (WANG et al. 2004). The use of the produced biogas in the kitchen might be the most realistic and easiest way to reuse the biogas in decentralised systems. If the gas is not recovered, the tanks need to be vented to prevent the release of the potentially harmful gases (TILLEY et al. 2008).

To increase the treatment efficiency (especially regarding pathogens), the last chamber may be an anaerobic filter (WSP 2008).

Treatment performance

 BORDA (2009)

Construction of different toilet blocks connected to two pre-fabricated fibreglass reactor comprising a settling chamber, an aerobic baffled reactor and a final anaerobic filter unit. Source: BORDA (2009)

Treatment performance of ABRs is in the range of 65% to 90% COD (Chemical Oxygen Demand) removal, corresponding to about 70% to 95% of BOD (Biological Oxygen Demand) (SASSE 1998; MOREL & DIENER 2006; BORDA 2008). This is far superior to that of a conventional septic tank (30 to 50 %, UNEP 2004). The majority of the settleable solids are removed in the sedimentation chamber at the beginning of the ABR, which typically represents 50 % of the total volume of TSS (TILLEY et al. 2008). The special design also allows for an enhanced treatment of non-settleable solids and a Total Suspended Solids (TSS) removal of up to 90% can be achieved (SINGH 2008). The tanks put in series also help to digest substances that are difficult to degrade, predominantly in the rear part, after easily degradable matters have been digested in the front part already (SASSE 1998). Consequently, recycling of effluent would have a slightly negative effect on treatment quality. ABRs can be designed for a daily inflow in a range of some m3/day up to several hundreds of m3/day (FOXON et al. 2004; TILLEY et al. 2008). The Hydraulic Retention Time (HRT) in ABRs is relatively short and varies from only a few hours up to two or three days (FOXON et al. 2004; MOREL & DIENER 2006; TILLEY et al. 2008).

Health Aspects/Acceptance 

Under normal operating conditions, users do not come in contact with the influent or effluent. Effluent, scum and sludge must be handled with care as they contain high levels of pathogenic organisms. The effluent contains odorous compounds that may have to be removed in a further polishing step. Care should be taken to design and locate the facility such that odours do not bother community members.

In general, the quality of ABR effluents has been shown to consistently meet guidelines for irrigation regarding the removal of organics (e.g. COD or BOD) for reuse in agriculture, but not for discharge to surface water (FOXON et al. 204). The effluents do also contain high amounts of nutrients, ammonia and phosphorus and these nutrients may be regarded as a resource from an agricultural point of view (FOXON et al. 2004). The problem is though, that pathogen removal is generally not satisfactory for the reuse in agriculture and when, only very restricted reuse is recommended.

Costs considerations

Septic tank are generally low cost. However, the costs vary depending on the availability of materials and economy of scale (EAWAG/SANDEC 2008). In any case, ABRs have a high potential to be used in DEWATS. As they do not require any electricity and are simple to construct and operate, they are generally cheaper than more mechanical, centralised technology options. ABRs can be constructed with locally available material. However, expert design is required.

Operation & Maintenance

An ABR requires a start-up period of several months to reach full treatment capacity since the slow growing anaerobic biomass first needs to be established in the reactor. To reduce start-up time, the ABR can be inoculated with anaerobic bacteria, e.g., by adding fresh cow dung or septic tank sludge. The added stock of active bacteria can then multiply and adapt to the incoming wastewater. In principle, it is advantageous to start with a quarter of the daily flow and then slightly increase loading rates over three months, allowing the bacteria enough time to multiply before suspended solids are washed out (SASSE 1998). As a long start up time is required for the anaerobic digestion of the sludge, the ABR technology should not be used when the need for a treatment system is immediate (TILLEY et al. 2008). Because of the delicate ecology, care should be taken not to discharge harsh chemicals into the ABR.

Scum and sludge levels need to be monitored to ensure that the tank is functioning well. Process operation in general is not required, and maintenance is limited to the removal of accumulated sludge and scum every 1 to 3 years (EAWAG/SANDEC 2008). This is best done using a Motorized Emptying and Transport technology or a Human-powered Emptying and Transport Technology to avoid that humans get in contact with the sludge and are exposed to health risks (TILLEY et al. 2008). The desludging frequency depends on the chosen pre-treatment steps, as well as on the design of the ABR. When emptying the tanks, it is vital that some active sludge is left in each of the compartments to maintain a stable treatment process (SASSE 1998).

ABR tanks should be checked from time to time to ensure that they are watertight.

 

At a Glance

Working Principle

Vertical baffles in the tank force the pre-settled wastewater to flow under and over the baffles guaranteeing contact between wastewater and resident sludge and allowing an enhanced anaerobic digestion of suspended and dissolved solids; at least 1 sedimentation chamber and 2–5 up-flow chambers.

Capacity/Adequacy

Community (and household) level; For pre-settled domestic or (high-strength) industrial wastewater of narrow COD/BOD ration. Typically integrated in DEWATS systems; Not adapted for areas with high ground-water table or prone to flooding.

Performance

70- 95% BOD; 80% - 90% TSS; Low pathogen reduction.
HRT: 1 to 3 days

Costs

Generally low-cost; depending on availability of materials and economy of scale.

Self-help Compatibility

Requires expert design, but can be constructed with locally available material.

O&M

Should be checked for water tightness, scum and sludge levels regularly; Sludge needs to be dug out and discharged properly (e.g. in composting or drying bed); needs to be vented.

Reliability

High resistance to shock loading and changing temperature, pH or chemical composition of the influent; requires no energy.

Main strengths

Strong resistance; built from local material; biogas can be recovered.

Main weakness

Long start-up phase.

Applicability

This technology is easily adaptable and can be applied at the household level, in small neighbourhoods as DEWATS or even in bigger catchment areas (preferably with a transport system such as a simplified sewer or a solids-free sewer system in place). It is most appropriate where a relatively constant amount of blackwater and greywater is generated. A (semi-) centralized ABR is appropriate when there is a pre-existing Conveyance technology, such as a Simplified Sewer. ABRs in DEWATS are also suited for industrial wastewaters.
Up to several hundreds of m3/day can be treated. However, a good community organisation is required to ensure that the ABR is used and maintained properly. The effluent is not fully treated and must be disposed of properly or sent to secondary treatment (EAWAG/SANDEC 2008).
This technology is suitable for areas where land may be limited since the tank is most commonly installed underground and requires a small area. However, a vacuum truck should be able to access the location because the sludge must be regularly removed (particularly from the settling compartment). Also, it should not be installed in areas with a high groundwater table or prone to flooding as infiltration will affect the treatment efficiency and contaminate the groundwater.
BORDA has developed pre-fabricated ABRs made out of fibreglass and including anaerobic filters as a final step for emergency sanitation (BORDA 2009). Even though start-up of the ABR takes several months, these pre-fabricated models are rapidly constructed and can consist in a long-term solution once the start-up phase is completed. Therefore, such pre-fabricated models might also find more and more application for other than emergency situations. 
Fibreglass is available and affordable in nearly all parts of the world and fibreglass constructions can be built quickly and well in advance of need (BORDA 2009). However, one should keep in mind, that the start-up of ABR generally requires at least three month.
ABRs can be installed in every type of climate, although the efficiency is lower in colder climates. They are not efficient at removing nutrients and pathogens. The effluent usually requires further treatment.

Advantages

  • Resistant to organic and hydraulic shock loads
  • No electrical energy is required
  • Low operating costs
  • Long service life
  • High reduction of BOD
  • Low sludge production; the sludge is stabilized
  • Moderate area requirement (can be built underground)
  • Simple to operate

Disadvantages

  • Long start-up phase
  • Requires expert design and construction
  • Low reduction of pathogens and nutrients
  • Effluent and sludge require further treatment and/or appropriate discharge
  • Needs strategy for faecal sludge management (effluent quality rapidly deteriorates if sludge is not removed regularly)
  • Needs water to flush
  • Clear design guidelines are not available yet

References Library

BACHMANN, A.; BEARD, V. L.; MCCARTY, P. L. (1985): Performance Characteristics of the Anaerobic Baffled Reactor. In: Water Research 19, 99-106. London: IWA Publishing.

BARBER, W.P.; STUCKEY D.C. (1999): The use of the anaerobic baffled reactor (ABR) for wastewater treatment- A review. In: Wat. Res 33, 7.

BORDA (Editor) (2009): EmSan - Emergency Sanitation. An innovative & rapidly installable solution to improve hygiene and health in emergency situations. (= Concept Note). Bremen: Bremen Overseas Research and Development Association . URL [Accessed: 26.03.2010]. PDF

EAWAG/SANDEC (Editor) (2008): Sanitation Systems and Technologies. Lecture Notes . (= Sandec Training Tool 1.0, Module 4). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). PDF

FOXON, K. M.; BUCKLEY, C. A.; BROUCKAERT, C. J.; DAMA, P.; MTEMBU, Z.; RODDA, N.; SMITH, M.; PILLAY, S.; ARJUNG, N.; LALBAHADUR, T.; BUX, F. (2006): Evaluation of the Anaerobic Baffled Reactor for Sanitation in Dense Peri-urban Settlements. (= WRC Report No 1248/01/06). Pretoria: Water Research Commission. URL [Accessed: 21.08.2014]. PDF

FOXON, K.M.; PILLAY, S.; LALBAHADUR, T.; RODDA, N.; HOLDER, F.; BUCKLEY, C.A. (2004): The anaerobic baffled reactor (ABR)- An appropriate technology for on-site sanitation. In: Water SA 30, 5. PDF

GUTTERER, B.; SASSE, L.; PANZERBIETER, T.; RECKERZÜGEL, T.; ULRICH, A. (Editor); REUTER, S. (Editor); GUTTERER, B. (Editor) (2009): Decentralised Wastewater Treatment Systems (DEWATS) and Sanitation in Developing Countries. Loughborough University (UK): Water Engineering and Deveopment Centre (WEDC). URL [Accessed: 20.03.2014]. PDF

MOREL, A.; DIENER, S. (2006): Greywater Management in Low and Middle-Income Countries, Review of different treatment systems for households or neighbourhoods. (= SANDEC Report No. 14/06). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 19.05.2010]. PDF

SANIMAS (Editor) (2005): Informed Choice Catalogue. pdf presentation. BORDA and USAID. PDF

SASSE, L. ; BORDA (Editor) (1998): DEWATS. Decentralised Wastewater Treatment in Developing Countries. Bremen: Bremen Overseas Research and Development Association (BORDA). PDF

SINGH, S.; HABERLA, R.; MOOG, O.; SHRESTA, R.R.; SHRESTA, P.; SHRESTA, R. (2009): Performance of an Anaerobic Baffled Reactor and Hybrid Constructed Wetland treating high-strength Wastewater in Nepal- A model for DEWATS . In: Ecological Engineering 35, 654-660.

STUCKEY, D. C.; H. H. P. Fang (Editor) (2010): Anaerobic Baffled Reactor (ABR) for Wastewater Treatment. In: H. H. P. Fang (Editor) (2010): Environmental Anaerobic Technology. London.

SUSANA (Editor) (2010): Decentralized Wastewater Management at Adarsh College Badalapur, Maharashtra, India. Factsheet. (= SuSanA - Factsheet). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 12.01.2011]. PDF

TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). URL [Accessed: 28.07.2014]. PDF

TILLEY, E.; LUETHI, C.; MOREL, A.; ZURBRUEGG, C.; SCHERTENLEIB, R. (2008): Compendium of Sanitation Systems and Technologies. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (EAWAG) and. URL [Accessed: 15.02.2010]. PDF

See document in FRENCH

U.S. EPA (Editor) (2006): Emerging Technologies for Biosolids Management. (= EPA 832-R, 5/6). United States Environmental Protection Agency, Office of Wastewater Management. PDF

WANG, J.; HUANG, Y.; ZHAO, X. (2004): Performance and Characteristics of an Anaerobic Baffled Reactor. In: Bioresource Technology 93, 205–208.

WHO (Editor) (2009): Ecosan Expert Training Course for the Introduction of Ecological Sanitation in Bhutan. (= Training Course Report). Geneva: World Health Organisation. URL [Accessed: 12.01.2011]. PDF

WSP (Editor) (2008): Technology Options for Urban Sanitation in India. A Guide to Decision-Making. pdf presentation. Washington: Water and Sanitation Program. URL [Accessed: 26.03.2010]. PDF

Further Readings Library

Reference icon

BORDA (Editor) (2009): EmSan - Emergency Sanitation. An innovative & rapidly installable solution to improve hygiene and health in emergency situations. (= Concept Note). Bremen: Bremen Overseas Research and Development Association . URL [Accessed: 26.03.2010]. PDF

This source presents the DEWATS emergency sanitation service package, including options for different types of prefabricated materials, developed by BORDA.


Reference icon

FOXON, K.M.; BUCKLEY, C.A. (2006): Guidelines For The Implementation of Anaerobic Baffled Reactors for On-Site Or Decentralised Saniation. Durban: University of KwaZulu-Natal. URL [Accessed: 03.01.2011]. PDF

This paper provides a framework within which a process engineer can design an anaerobic baffled reactor for the treatment of a specific domestic wastewater.


Reference icon

FOXON, K.M.; PILLAY, S.; LALBAHADUR, T.; RODDA, N.; HOLDER, F.; BUCKLEY, C.A. (2004): The anaerobic baffled reactor (ABR)- An appropriate technology for on-site sanitation. In: Water SA 30, 5. PDF

The publication analyses the appropriateness of anaerobic baffled reactors (ABRs) for on-site primary sanitation in low-income communities. COD removal in domestic wastewater by a pilot ABR (3000L) was assessed. Results indicate that COD was sufficiently reduced for the reuse of the water in agriculture, but not for directly discharging it into natural surface or groundwater bodies.


Reference icon

KOOTTATEP, T.; SRI-ANANT, W.; ANTOINE, M.; SCHERTENLEIB, R. (2004): Potential of the Anaerobic Baffled Reactor as decentralized Wastewater Treatment System in the Tropics. Klong Luang and Duebendorf: School of Environment, Resources and Development (SERD)/Asian Institute of Technology (AIT) and Water and Sanitation in Developing Countries (SANDEC) at the Swiss Federal Institute for Environmental Science (EAWAG). URL [Accessed: 03.01.2011]. PDF

The anaerobic baffled reactor (ABR) could be a valuable alternative to conventional septic tanks. In this study, 3 lab-scale experimental ABR (2 baffles with and without anaerobic filter, respectively, and 3 baffles) were studied and compared to a conventional 2 chambers septic tank. The experimental units were fed with a mixture of septage and sewage in order to imitate the characteristics of toilet wastewater from households.


Reference icon

LEMOS CHERNICHARO, C.A. de (2007): Anaerobic Reactors. (= Biological Wastewater Treatment Series, 4). London: International Water Association (IWA) Publishing. URL [Accessed: 01.11.2013]. PDF

Anaerobic Reactors is the forth volume in the series Biological Wastewater Treatment. The fundamentals of anaerobic treatment are presented in detail, including its applicability, microbiology, biochemistry and main reactor configurations. Two reactor types are analysed in more detail, namely anaerobic filters and especially UASB (upflow anaerobic sludge blanket) reactors. Particular attention is also devoted to the post-treatment of the effluents from the anaerobic reactors. The book presents in a clear and informative way the main concepts, working principles, expected removal efficiencies, design criteria, design examples, construction aspects and operational guidelines for anaerobic reactors.


Reference icon

MONVOIS, J.; GABERT, J.; FRENOUX, C.; GUILLAUME, M. (2010): How to Select Appropriate Technical Solutions for Sanitation. (= Six Methodological Guides for a Water and Sanitation Services' Development Strategy, 4). Cotonou and Paris: Partenariat pour le Développement Municipal (PDM) and Programme Solidarité Eau (pS-Eau). URL [Accessed: 19.10.2011]. PDF

The purpose of this guide is to assist local contracting authorities and their partners in identifying those sanitation technologies best suited to the different contexts that exist within their town. The first part of the guide contains a planning process and a set of criteria to be completed; these assist you in characterizing each area of intervention so that you are then in a position to identify the most appropriate technical solutions. The second part of the guide consists of technical factsheets which give a practical overview of the technical and economic characteristics, the operating principle and the pros and cons of the 29 sanitation technology options most commonly used in sub-Saharan Africa.

See document in FRENCH


Reference icon

MOREL, A.; DIENER, S. (2006): Greywater Management in Low and Middle-Income Countries, Review of different treatment systems for households or neighbourhoods. (= SANDEC Report No. 14/06). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 19.05.2010]. PDF

This report compiles international experience in greywater management on household and neighbourhood level in low and middle-income countries. The documented systems, which vary significantly in terms of complexity, performance and costs, range from simple systems for single-house applications (e.g. local infiltration or garden irrigation) to rather complex treatment trains for neighbourhoods (e.g. series of vertical and horizontal-flow planted soil filters).


Reference icon

ROBBINS, D.M.; LIGON, G.C. (2013): How to Design Wastewater Systems for Local Conditions in Developing Countries. London: International Water Association (IWA). URL [Accessed: 25.08.2014].

This manual provides guidance in the design of wastewater systems in developing country settings. It promotes a context-specific approach to technology selection by guiding the user to select the most suitable technologies for their area. It provides tools and field guides for source characterization and site evaluation, as well as technology identification and selection. This manual is primarily addressed to private and public sector service providers, regulators and engineers/development specialists in charge of implementing wastewater systems.


Reference icon

SASSE, L. ; BORDA (Editor) (1998): DEWATS. Decentralised Wastewater Treatment in Developing Countries. Bremen: Bremen Overseas Research and Development Association (BORDA). PDF

Exhaustive report on technological, operational and economic aspects of decentralised waste water treatment systems. Spreadsheet examples support the reader in designing and planning waste water treatment systems components.


Reference icon

SPERLING, M. von; LEMOS CHERNICHARO, C.A. de (2005): Biological Wastewater Treatment in Warm Climate Regions Volume 1. London: International Water Association (IWA) Publishing. URL [Accessed: 01.11.2013]. PDF

Biological Wastewater Treatment in Warm Climate Regions gives a state-of-the-art presentation of the science and technology of biological wastewater treatment, particularly domestic sewage. The book covers the main treatment processes used worldwide with wastewater treatment in warm climate regions given a particular emphasis where simple, affordable and sustainable solutions are required. The 55 chapters are divided into 7 parts over two volumes: Volume One: (1) Introduction to wastewater characteristics, treatment and disposal; (2) Basic principles of wastewater treatment; (3) Stabilisation ponds; (4) Anaerobic reactors; Volume Two (also available in the SSWM library): (5) Activated sludge; (6) Aerobic biofilm reactors; (7) Sludge treatment and disposal.


Reference icon

SRI-ANANT, W. (2003): Upgrading conventional Septic Tanks by integrating in tank Baffles. Klong Luang: School of Environment, Resources and Development (SERD)/Asian Institute of Technology (AIT) . URL [Accessed: 03.01.2011]. PDF

The objective of this research study was to compare the treatment performance of the conventional septic tank system with upgraded septic tank systems, and to try to define the optimal operation conditions.


Reference icon

WSP (Editor) (2007): Philippines Sanitation Source Book and Decision Aid. pdf presentation. Washington: Water and Sanitation Program. PDF

This Sanitation Sourcebook distils some of the core concepts of sanitation in a user-friendly format so that the book can serve as a practical reference to sanitation professionals and investment decision-makers, particularly the local governments. The annexe contains a practical collection of factsheets on selected sanitation system options.


Reference icon

WSP (Editor) (2008): Technology Options for Urban Sanitation in India. A Guide to Decision-Making. pdf presentation. Washington: Water and Sanitation Program. URL [Accessed: 26.03.2010]. PDF

These guidance notes are designed to provide state governments and urban local bodies with additional information on available technologies on sanitation. The notes also aid in making an informed choice and explain the suitability of approaches.


Case Studies Library

Reference icon

BORDA (Editor) (2007): Community Based Sanitation — SANIMAS. Islamic Centre An Nawawi, Purworejo, Central. (= Technical Data Sheet, No.: ID-JTa-L– 75). DEWATS Indonesia and Bremen Overseas Research and Development Association (BORDA). PDF

Case study of the construction a DEWATS system for 190 of students and teachers comprising a sedimentation step, an anaerobic baffle reactor (ABR) and an expansion chamber, which consisting of 7 compartments. The effluent is discharged into river/waterbody.


Reference icon

BORDA (Editor) (2008): Decentralized Wastewater Treatment System - DEWATS. Animal Products Development Centre, Bureau of Animal Industry (APDC-BAI). (= Sustainable Sanitation – Project Data Sheet). Bremen: Bremen Overseas Research and Development Association (BORDA). PDF

The Animal Products Development Centre, Bureau of Animal Industry (APDC-BAI) together with Bremen Overseas Research and Development Association (BORDA) developed together this DEWATS system in the view of a resources-saving and environmental friendly management of slaughterhouses and meat processing wastes in the Philippines. The system comprises a closed small-scale sewer system, an anaerobic digester, an anaerobic baffled reactor (ABR), an anaerobic filter (AF) and an aerobic planted filter as a final step to reduce odours.


Reference icon

BORDA (Editor) (2008): Decentralized Wastewater Treatment System - DEWATS. Manjuyod Public Market. (= Sustainable Sanitation – Project Data Sheet). Bremen: Bremen Overseas Research and Development Association (BORDA) . URL [Accessed: 26.03.2010]. PDF

The wastewater from Manjuyod’s public market is treated in a decentralized system (DEWATS) composed of four different components: a settling tank; a anaerobic baffled reactor which reduces the BOD/COD content from 20% to 85%; a planted gravel filter; and finally a polishing pond.


Reference icon

MOREL A.; DIENER S. (2006): Ecosan Greywater Demonstration Project. Case study from Kuching, Malaysia. In: MOREL, A.; DIENER, S. (2006): Greywater Management in Low and Middle-Income Countries, Review of different treatment systems for households or neighbourhoods. Duebendorf, 76-79.

The city of Kuching is currently lacking a wastewater treatment plant, and the local subsurface conditions make a conventional centralised wastewater system expensive to implement. Most buildings are equipped with two separate wastewater outlets, one outlet for blackwater and one for greywater. The proposed system treats greywater from nine households, and consists of a baffled septic tank, followed by a dosing chamber from where the greywater flows into four vertical down-flow, single-pass aerobic biofilters before reaching a subsurface horizontal-flow planted filter. Finally, the treated greywater is discharged into a stormwater drain.


Reference icon

NASR, F.A.; DOMA, H.S.; NASSAR, H.F. (2008): Treatment of domestic wastewater using an anaerobic baffled reactor followed by a duckweed pond for agricultural purposes . pdf presentation. (= Environmentalist, 270/29). Egypt: Water Pollution Control Department. URL [Accessed: 26.03.2010]. PDF

In this study, an anaerobic baffled reactor (ABR) was fed continuously with domestic wastewater at four HRTs ranging from 8 to 24 h and corresponds to organic loading rates ranging from 0.67 to 2.1 kg COD/m3/day. The ABR effluent was fed to a DWP operating at 10 and 15 days. The performance of the ABR at the four HRTs gave satisfactory results.


Reference icon

ROBBINS, D.; STRANDE, L.; DOCZI, J. (2012): Opportunities in Fecal Sludge Management for Cities in Developing Countries: Experiences from the Philippines. North Carolina: RTI International . URL [Accessed: 15.01.2013]. PDF

In July 2012, a team from RTI International deployed to the Philippines to evaluate four FSM programs with the goal of reporting on best practices and lessons learned. The four cases—Dumaguete City, San Fernando City, Maynilad Water for the west zone of metro Manila, and Manila Water from the east zone of metro Manila—were chosen to highlight their different approaches to implementing FSM.


Reference icon

SINGH, S.; HABERLA, R.; MOOG, O.; SHRESTA, R.R.; SHRESTA, P.; SHRESTA, R. (2009): Performance of an Anaerobic Baffled Reactor and Hybrid Constructed Wetland treating high-strength Wastewater in Nepal- A model for DEWATS . In: Ecological Engineering 35, 654-660.


Reference icon

SUSANA (Editor) (2010): Decentralized Wastewater Management at Adarsh College Badalapur, Maharashtra, India. Factsheet. (= SuSanA - Factsheet). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 12.01.2011]. PDF


Training Material Library

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EAWAG/SANDEC (Editor) (2008): Sanitation Systems and Technologies. Lecture Notes . (= Sandec Training Tool 1.0, Module 4). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). PDF

Lecture notes on technical and non-technical aspects of sanitation systems in developing countries.


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EAWAG/SANDEC (Editor) (2008): Sanitation Systems and Technologies. Exercise: Anaerobic Baffled Reactor (ABR). (= Sandec Training Tool 1.0, Exercises). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). PDF

Exercise on the dimensioning of am anaerobic baffled reactor.


Reference icon

EAWAG/SANDEC (Editor) (2008): Sanitation Systems and Technologies. Exercise: Anaerobic Baffled Reactor (ABR). (= Sandec Training Tool 1.0, Exercises). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). PDF

Exercise on the dimensioning of am anaerobic baffled reactor.


Reference icon

MANG, H.-P.; LI, Z. (2010): Technology Review of Biogas Sanitation. (= Technology Review ). Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH. URL [Accessed: 17.06.2013]. PDF

This document provides an overview and introduction on biogas sanitation (anaerobic digestion) for blackwater or for brown water, or excreta treatment for reuse in developing countries. The main technologies discussed are biogas settlers (BSs), biogas septic tanks, anaerobic baffled reactor (ABRs), anaerobic filter (AFs) and upflow anaerobic sludge blanket reactors (UASBs).


Important Weblinks

http://watsanexp.ning.com [Accessed: 21.08.2014]

This site is dedicated to individuals, groups, or institutions interested in improving the quality of life and health of their communities through wastewater treatment. The tools and information contained here are provided to help with planning, building and operating low cost wastewater systems.

http://youtu.be/n9EzBNuR0cM [Accessed: 21.08.2014]

This film is on sanitation post tsunami. It's a case study about East Devdhanam in Trichy (Tamil Nadu), where Community Based Sanitation-DEWATS has been quite successful.

http://youtu.be/Ow2scqvsoLo [Accessed: 21.08.2014]

The video shows DEWATS-engineers and community facilitators during a whole process of implementation of a DEWATS approach at Khoualuang Primary School in Vientiane Capital, Lao P.D.R.

http://youtu.be/zTqE-8j9Unw [Accessed: 21.08.2014]

This video shows how the Decentralised Wastewater Treatment System (DEWATS) works in Aravind Eye Hospital in Tamil Nadu.

http://www.gpa.unep.org [Accessed: 23.02.2010]

The Train-Sea-Coast GPA is an active inter-agency collaboration between the UNESCO-IHE Institute for Water Education, the EU ACP Water Facility, the UN DOALOS, UNDP, GEF and UNEP/GPA. It aims to train experts and local, regional and international instructors in coastal populations. The compendium of technologies offers a description of several technologies for wastewater treatment suitable for typical physical conditions in Small Islands Developing States (SIDS) and low income coastal countries.