Waste Stabilization Ponds (WSP)

Waste Stabilization Ponds (WSPs) are large, man-made water bodies. The ponds can be used individually, or linked in a series for improved treatment. There are three types of ponds, (1) anaerobic, (2) facultative and (3) aerobic (maturation), each with different treatment and design characteristics.

For the most effective treatment, WSPs should be linked in a series of three or more with effluent being transferred from the anaerobic pond to the facultative pond and, finally, to the aerobic pond. The anaerobic pond is the primary treatment stage and reduces the organic load in the wastewater. The entire depth of this fairly deep man-made lake is anaerobic. Solids and BOD removal occurs by sedimentation and through subsequent anaerobic digestion inside the accumulated sludge (see also anaerobic digestion general). Anaerobic bacteria convert organic carbon into methane and through this process, remove up to 60% of the BOD.

In a series of WSPs, the effluent from the anaerobic pond is transferred to the facultative pond, where further BOD is removed. The top layer of the pond receives oxygen from natural diffusion, wind mixing and algae-driven photosynthesis. The lower layer is deprived of oxygen and becomes anoxic or anaerobic. Settleable solids accumulate and are digested on the bottom of the pond. The aerobic and anaerobic organisms work together to achieve BOD reductions of up to 75%.

Anaerobic and facultative ponds are designed for BOD removal, while aerobic ponds are designed for pathogen removal (see also pathogens and contaminants). An aerobic pond is commonly referred to as a maturation, polishing, or finishing pond because it is usually the last step in a series of ponds and provides the final level of treatment. It is the shallowest of the ponds, ensuring that sunlight penetrates the full depth for photosynthesis to occur. Photosynthetic algae release oxygen into the water and at the same time consume carbon dioxide produced by the respiration of bacteria. Because photosynthesis is driven by sunlight, the dissolved oxygen levels are highest during the day and drop off at night. Dissolved oxygen is also provided by natural wind mixing.

Design Considerations

Anaerobic ponds are built to a depth of 2 to 5 m and have a relatively short detention time of 1 to 7 days. Facultative ponds should be constructed to a depth of 1 to 2.5 m and have a detention time between 5 to 30 days. Aerobic ponds are usually between 0.5 to 1.5 m deep. If used in combination with algae and/or fish harvesting (see Fish Pond), this type of pond is effective at removing the majority of nitrogen and phosphorus from the effluent. Ideally, several aerobic ponds can be built in series to provide a high level of pathogen removal.

Pre-treatment (see Pre Treatment Technologies) is essential to prevent scum formation and to hinder excess solids and garbage from entering the ponds. To prevent leaching into the groundwater, the ponds should have a liner. The liner can be made from clay, asphalt, compacted earth, or any other impervious material. To protect the pond from runoff and erosion, a protective berm should be constructed around the pond using the excavated material. A fence should be installed to ensure that people and animals stay out of the area and that garbage does not enter the ponds.

Appropriateness

WSPs are among the most common and efficient methods of wastewater treatment around the world. They are especially appropriate for rural communities that have large, open and unused lands, away from homes and public spaces and where it is feasible to develop a local collection system. They are not appropriate for very dense or urban areas.

Health Aspects/Acceptance

Although effluent from aerobic ponds is generally low in pathogens, the ponds should in no way be used for recreation or as a direct source of water for consumption or domestic use.

Operation and Maintenance

Scum that builds up on the pond surface should be regularly removed. Aquatic plants that are present in the pond should also be removed as they may provide a breeding habitat for mosquitoes and prevent light from penetrating the water column.

The anaerobic pond must be de-sludged approximately once every 2 to 5 years, when the accumulated solids reach one third of the pond volume. For facultative ponds sludge removal is even rarer and maturation ponds hardly ever need desludging. Sludge can be removed by using a raft-mounted sludge pump, a mechanical scraper at the bottom of the pond or by draining and dewatering the pond and removing the sludge with a front-end loader.

References

Further Readings

  • Cover image of a reference book or miscellany.

    EPA (Editor) (2002): Facultative Lagoons. United States Environment Protection Agency. URL [Accessed: 12.04.2010]. PDF

    Short factsheet on the design, operation, maintenance and costs of facultative ponds in the United States.

  • Cover image of a reference book or miscellany.

    KONE, D. (2002): Epuration des eaux usées par Lagunage a Microphytes et a Macrophytes en Afrique de l'Ouest et du Centre- Etat des lieux, performances épuratoires et critères de dimensionnement. Lausanne: Swiss Federal Institute of Technology (EPFL).. PDF

    Stabilization ponds are a very promising sustainable centralized wastewater treatment option for West Africa due to the favourable climate. Pilot studies could demonstrate their performance in the local context; however none of the full-scale applications works. Besides the poor economic situation and little political support, it is also the lack of training and research that contributes to this situation. This work presents the establishment of an international research collaboration network and main technical recommendations based on an exhaustive assessment on the state-of-the-art of stabilization ponds in the West-African context.

    Language: French

  • Cover image of a reference book or miscellany.

    MARA, D.D. (1997): Design Manual for Waste Stabilization Ponds in India. Leeds: Lagoon Technology International. URL [Accessed: 11.06.2014].

  • Cover image of a reference book or miscellany.

    MONVOIS, J.; GABERT, J.; FRENOUX, C.; GUILLAUME, M. (2010): How to Select Appropriate Technical Solutions for Sanitation. 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.

  • Cover image of a reference book or miscellany.

    ROSE, D.G. (1999): Community-Based Technologies for Domestic Wastewater Treatment and Reuse- options for urban agriculture. Ottawa: International Development Research Center Canada (IDRC). PDF

    The report suggests that emerging trends in low-cost, decentralised naturally-based infrastructure and urban wastewater management which promote the recovery and reuse of wastewater resources are increasingly relevant. Technologies for these sanitation options are presented. The concept of managing urban wastewater flows at a decentralised or "intermediate" level, based on micro watersheds, is explored. Effluent treatment standards that are currently accepted in order to protect public health and safety are reviewed.

  • Cover image of a reference chapter of a book/miscellany.

    SPERLING, M. von (2005): Part Three: Stabilization Ponds. In: SPERLING, M. von; LEMOS CHERNICHARO, C.A. de (2005): Biological Wastewater Treatment in Warm Climate Regions Volume 1. London, 495. URL [Accessed: 16.02.2011].

    Almost 200 pages on the treatment process and design parameters of waste stabilisation ponds. Very exhaustive.

  • Cover image of a reference book or miscellany.

    SPERLING, M. von (2007): Basic Principles of Wastewater Treatment. London: International Water Association (IWA) Publishing. URL [Accessed: 01.11.2013]. PDF

    Basic Principles of Wastewater Treatment is the second volume in the series Biological Wastewater Treatment, and focusses on the unit operations and processes associated with biological wastewater treatment. The major topics covered are: microbiology and ecology of wastewater treatment, reaction kinetics and reactor hydraulics, conversion of organic and inorganic matter, sedimentation, aeration.

  • Cover image of a reference book or miscellany.

    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.

  • Cover image of a reference book or miscellany.

    UNEP (Editor); MURDOCH UNIVERSITY (Editor) (2004): Environmentally sound technologies in wastewater treatment for the implementation of the UNEP/GPA "Guidelines on Municipal Wastewater Management". The Hague: United Nations Environment Programme Global Programme of Action (UNEP/GPA), Coordination Office. PDF

    Technical information on environmentally sound technologies in wastewater treatment.

Case Studies

  • Cover image of a reference book or miscellany.

    INGALLINELLA, A.M.; FERNANDEZ, R.; SANGUINETTI, G.; HERGERT, L.; QUEVDO, H.; STRAUSS, M.; MONTANGERO, A. (2001): Lagunas de Estabilizacion para Descarga de Liquidos de Camiones Atmosfericos. Duebendorf and Acra: Swiss Federal Institute of Aquatic Science (EAWAG) and Water Research Institute (CSIR) Ghana. URL [Accessed: 19.04.2010]. PDF

    This publication deals with the feasibility of waste stabilisation ponds for the simultaneous treatment of collected sludge (by vacuum trucks) and wastewater from the domestic sewer system. The principal objective of the study was to asses if existing treatment ponds could be used in the future as thickening ponds for the sludge.

    Language: Spanish

  • Cover image of a reference book or miscellany.

    JENSSEN, P.D.; HEEB, J.; HUBA-MANG, E.; GNANAKAN, K.; WARNER, W.; REFSGAARD, K.; STENSTROEM, T.A.; GUTERSTRAM, B.; ALSEN, K.W. (2004): Ecological Sanitation and Reuse of Wastewater. Ecosan. A Thinkpiece on ecological sanitation. Norway: The Agricultural University of Norway. URL [Accessed: 19.04.2010]. PDF

    This paper shows that there are comprehensive experiences and available technologies that meet new and sustainable sanitation requirements. Ecological sanitation constitutes a diversity of options for both rich and poor countries, from household level up to wastewater systems for mega-cities and needs to become recognised by decision-makers at all levels.

  • Cover image of a reference journal article.

    NANDEESHA, M.C. (2002): Sewage Fed Aquaculture Systems of Kolkata. A Century-old Innovation of Farmers. In: Aquaculture Asia 7, 28.URL [Accessed: 19.04.2010]. PDF

    Case Study on the fishponds in sewage-fed lagoons in Kolkata.

  • Cover image of a reference book or miscellany.

    SPUHLER, D.; KENFACK, S.; TOGOLA, L.; KLUTSE, A.; TANDIA C.T. (2006): Evaluation des performances épuratoires de trois systèmes d’épuration biologique des eaux usées domestique à Ouagadougou- Burkina Faso . Ouagadougou: Réseau CREPA (Centre Régional Pour l'Eau Potable et l'Assainissement à faible coût). URL [Accessed: 19.04.2010]. PDF

    Comparative assessment of three waste stabilization ponds (from very small to very large scale) in Ouagadougou.

    Language: French

  • Cover image of a reference book or miscellany.

    STRAUSS, M.; LARMIE, S.A.; HEINSS, U.; MONTANGERO, A. (1999): Treating Faecal Sludge in Ponds. Duebendorf and Accra: Swiss Federal Institute of Aquatic Science (EAWAG) and Water Research Institute (CSIR) Ghana. URL [Accessed: 19.04.2010]. PDF

    Field research conducted by SANDEC and its partners at the Water Research Institute in Ghana, and information gathered from the scarce literature on faecal sludge treatment is presented in this publication. Issues dealt with in this document are the differences in design principles for the treatment of faecal sludge in waste stabilization in opposition to the treatment of wastewater; handling of faecal sludge solids; the role of anaerobic ponds in faecal sludge treatment; and ammonia (NH3-N) toxicity.

Awareness Material

  • Cover image of a reference book or miscellany.

    STRAUSS, M.; MONTANGERO, A. (2002): FS Management – Review of Practices, Problems and Initiatives. London and Duebendorf: DFID Project R8056, Capacity Building for Effective Decentralised Wastewater Management, Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 24.05.2012]. PDF

    A study on management and institutional aspects regarding the challenges and possible improvements in managing faecal sludge.

Training Material

  • Cover image of a reference book or miscellany.

    ARTHUR, J.P. (1983): Notes in the Design and Operation of Waste Stabilization Ponds in Warm Climates of Developing Countries . Washington: The World Bank. PDF

    Anaerobic, facultative and maturation ponds as wells as aerated lagoon systems are presented as an appropriate solution in developing countries where sewerage systems are present. The technical content was reviewed by Prof. Duncan Mara (University of Leeds, England). Detailed design, operation and maintenance guidance is given. Hence, this paper can be useful as a technical manual.

  • Cover image of a reference book or miscellany.

    EAWAG/SANDEC (Editor) (2008): Faecal Sludge Management. Lecture Notes. Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 23.05.2012]. PDF

    This module pays special attention to the haulage, treatment and reuse or disposal of faecal sludge. It covers both technical and non-technical (socio-cultural, economic, political etc.) aspects and provides practical information on design, financing and planning of faecal sludge treatment plants.

  • Cover image of a reference book or miscellany.

    KAYOMBO, S.; MBWETTE, T. S. A.; KATIMA, J. H. Y.; LADEGAARD, N. ; JORGENSEN, S. E. (2004): Waste Stabilization Ponds and Constructed Wetlands Design Manual. Dar es Salaam/Copenhagen: United Nations Environmental Program - International Environmental Technology Centre (UNEP-IETC) and Danish International Development Agency (Danida). URL [Accessed: 11.06.2014]. PDF

  • Cover image of a reference book or miscellany.

    MARA, D.D. (1997): Design Manual for Waste Stabilization Ponds in India. Leeds: Lagoon Technology International. URL [Accessed: 11.06.2014].

  • Cover image of a reference book or miscellany.

    ROBBINS, D.M.; LIGON, G.C. (2014): How to Design Wastewater Systems for Local Conditions in Developing Countries. London: International Water Association (IWA). URL [Accessed: 20.01.2015].

    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.

  • Cover image of a reference book or miscellany.

    UNEP (Editor) (n.y.): Waste Stabilization Ponds and Constructed Wetlands Manual. . United Nations Environmental Programme International Environmental Technology Center (UNEP-IETC) and the Danish International Development Agency (Danida). URL [Accessed: 19.04.2010]. PDF

    Design manual for designers, builders and operators on the design and operation of artificially constructed wetlands and waste stabilization ponds. The supporting information includes a standard systems approach which can be adopted universally; the theoretical background on the biological, chemical and physical processes of each method, the current state of the technology and technical knowledge on how to design, operate and maintain them; and theoretical knowledge on how best the models may be used to describe the systems.