Difference between revisions of "Waste Stabilization Pond"

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'''Waste Stabilization Ponds (WSPs) are large, manmade water bodies. The ponds are filled with wastewater that is then treated by naturally occurring processes. 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.'''
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'''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 of more with effluent being transferred from the anaerobic pond to the facultative pond and finally the aerobic pond. The anaerobic pond reduces solids and BOD as a pre-treatment stage. The pond is a fairly deep man-made lake where the entire depth of the pond is anaerobic. Anaerobic ponds are built to a depth of 2 to 5m and have a relatively short detention time of 1 to 7 days. The actual design will depend on the wastewater characteristics and the loading; a comprehensive design manual should be consulted for all types of WSPs. Anaerobic bacteria convert organic carbon into methane and in the process, remove up to 60% of the BOD. Anaerobic ponds are capable of treating strong wastewaters.
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<br>
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For the most effective treatment, WSPs should be linked in a series of three or more with effluent flowing 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 pond is anaerobic. Solids and BOD removal occurs by sedimentation and through subsequent anaerobic digestion inside the sludge. 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. A facultative pond is shallower than an anaerobic pond and both aerobic and anaerobic processes occur within the pond. The top layer of the pond receives oxygen from natural diffusion, wind mixing and algaedriven 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%. The pond should be constructed to a depth of 1 to 2.5m and have a detention time between 5 to 30 days.
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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. 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.
  
Following the anaerobic and the facultative ponds can be any number of aerobic (maturation) ponds to achieve a highly polished effluent. 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, usually constructed to a depth between 0.5 to 1.5m deep to ensure that the sunlight penetrates the full depth for photosynthesis. Because photosynthesis is driven by sunlight, the dissolved oxygen levels are highest during the day and drop off at night. Whereas anaerobic and facultative ponds are designed for BOD removal, maturation ponds are designed for pathogen removal. Dissolved oxygen in the lake is provided by natural wind mixing and by photosynthetic algae that release oxygen into the water. If used in combination with algae and/or fish harvesting, this type of pond is effective at removing the majority of nitrogen and phosphorus from the effluent.
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===Design Considerations===
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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 [[Aquaculture Ponds | algae and/or fish harvesting]] (see D.9), 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.
  
To prevent leaching, the ponds should have a liner. The liner can be clay, asphalt, compacted earth, or another impervious material. To protect the pond from runoff and erosion, a protective berm should be constructed around the pond using the excavated material.
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[[Pre-Treatment Technologies|Pre-Treatment]] (see PRE, p. 100) 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.
  
 +
<br>
 
{{procontable | pro=
 
{{procontable | pro=
- High reduction in pathogens. <br> - Can be built and repaired with locally available materials. <br> - Construction can provide short-term employment to local labourers. <br> - Low operating cost. <br> - No electrical energy required. <br> - No real problems with flies or odours if designed correctly. | con=
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- Resistant to organic and hydraulic shock loads <br>
- Requires expert design and supervision. <br> - Variable capital cost depending on the price of land. <br> - Requires large land area. <br> - Effluent/sludge require secondary treatment and/or appropriate discharge. 
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- High reduction of solids, BOD and pathogens <br>
 +
- High nutrient removal if combined with aquaculture <br>
 +
- Low operating costs <br>
 +
- No electrical energy is required <br>
 +
- No real problems with insects or odours if designed and maintained correctly
 +
| con=
 +
- Requires a large land area <br>
 +
- High capital costs depending on the price of land <br>
 +
- Requires expert design and construction <br>
 +
- Sludge requires proper removal and treatment
 
}}
 
}}
  
==Adequacy==
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===Appropriateness===  
 
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WSPs are among the most common and efficient methods of wastewater treatment around the world. They are especially appropriate for rural and peri-urban communities that have large, unused land, at
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 unused lands, away from homes and public spaces. They are not appropriate for very dense or urban areas. WSPs work in most climates, but are most efficient in warm, sunny climates. In the case of cold climates, the retention times and loading rates can be adjusted so that efficient treatment can be achieved.
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a distance from homes and public spaces. They are not appropriate for very dense or urban areas.
 
 
==Health Aspects/Acceptance==
 
  
 +
===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.
 
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.
  
==Upgrading==
+
===Operation & Maintenance===
 +
Scum that builds up on the pond surface should be regularly removed. Aquatic plants (macrophytes) 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 desludged 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.
  
 +
===Upgrading===
 
Ideally, several aerobic ponds can be built in series to provide a high level of pathogen removal. A final aquaculture pond can be used to generate income and supply a locally grown food source.
 
Ideally, several aerobic ponds can be built in series to provide a high level of pathogen removal. A final aquaculture pond can be used to generate income and supply a locally grown food source.
  
==Maintenance==
+
===References===
 
 
To prevent scum formation, excess solids and garbage from entering the ponds, pre-treatment (with grease traps) is essential to maintain the ponds. The pond must be desludged once every 10 to 20 years. A fence should be installed to ensure that people and animals stay out of the area and excess garbage does not enter the ponds. Rodents may invade the berm and cause damage to the liner. Raising the water level should prompt rodents to evacuate the berm. Care should be taken to ensure that plant material does not fall into the ponds. Vegetation or macrophytes that are present in the pond should be removed as it may provide a breeding habitat for mosquitoes and prevent light from penetrating the water column.
 
 
 
==References==
 
  
* Arthur, JP. (1983). Notes on the Design and Operation of Waste Stabilization Ponds in Warm Climates of Developing Countries. The World Bank+ UNDP, Washington.
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* Kayombo, S., Mbwette, T. S. A., Katima, J. H. Y., Ladegaard, N. and Jorgensen, S. E. (2004). [https://sswm.info/sites/default/files/reference_attachments/KAYOMBO%20et%20al%202004%20Waste%20Stabilization%20Ponds%20and%20Constructed%20Wetlands%20Design%20Manual_0.pdf Waste Stabilization Ponds and Constructed Wetlands Design Manual]. UNEP-IETC/Danida, Dar es Salaam, TZ/Copenhagen, DK.
  
* Crites, R. and Tchobanoglous, G. (1998). Small and Decentralized Wastewater Management Systems. WCB and McGraw-Hill, New York, USA.
+
* Peña Varón, M. and Mara, D. D. (2004). [https://sswm.info/sites/default/files/reference_attachments/VARON%202004%20%20Waste%20Stabilistion%20Ponds.pdf Waste Stabilisation Ponds]. Thematic Overview Paper. IRC International Water and Sanitation Centre, Delft, NL.
  
* Mara, DD. and Pearson, H. (1998). Design Manual for Waste Stabilization Ponds in Mediterranean Countries. Lagoon Technology International Ltd., Leeds, England.
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* Shilton, A. (Ed.) (2005). Pond Treatment Technology. Integrated Environmental Technology Series, IWA Publishing, London, UK. (Book)
  
* Mara, DD. (1997). Design Manual for Waste Stabilization Ponds in India. Lagoon Technology International Ltd., Leeds, England.
+
* von Sperling, M. (2007). [https://www.iwapublishing.com/sites/default/files/ebooks/9781780402109.pdf Waste Stabilisation Ponds. Biological Wastewater Treatment Series, Volume Three]. IWA Publishing, London, UK.
  
* Sasse, L. (1998). DEWATS: Decentralised Wastewater Treatment in Developing Countries. BORDA, Bremen Overseas Research and Development Association, Bremen, Germany. (Detailed description and Excel ® Spreadsheet codes for design.)
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* von Sperling, M. and de Lemos Chernicharo, C. A. (2005). [https://www.iwapublishing.com/sites/default/files/ebooks/9781780402734.pdf Biological Wastewater Treatment in Warm Climate Regions, Volume One]. IWA Publishing, London, UK. pp. 495-656.
  
* von Sperlin, M. and de Lemos Chernicharo, CA. (2005). Biological Wastewater Treatment in Warm Climate Regions. Volume One. IWA, London. pp 495–656.
+
* Ulrich, A. (Ed.), Reuter, S. (Ed.), Gutterer, B. (Ed.), Sasse, L., Panzerbieter, T. and Reckerzügel, T. (2009). [https://wedc-knowledge.lboro.ac.uk/resources/books/DEWATS_-_Chapter_01.pdf Decentralised Wastewater Treatment Systems (DEWATS) and Sanitation in Developing Countries. A Practical Guide]. WEDC, Loughborough University, Leicestershire, UK. (Detailed description and Excel spreadsheets for design calculations)
  
==Acknowledgements==
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===Acknowledgements===
 
{{:Acknowledgements Sanitation}}
 
{{:Acknowledgements Sanitation}}

Latest revision as of 06:00, 20 October 2020

English Français Español भारत മലയാളം தமிழ் 한국어 中國 Japanese
Applicable in systems:
1, 6 , 7 , 8 , 9
Level of Application
Household
Neighbourhood X
City XX

 

Inputs
Blackwater, Greywater, Brownwater, Sludge


Level of management
Household
Shared X
Public XX

 

Outputs
Sludge, Effluent
Waste stabilization ponds.png




Icon waste stabilization ponds.png

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 flowing 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 pond is anaerobic. Solids and BOD removal occurs by sedimentation and through subsequent anaerobic digestion inside the sludge. 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. 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 D.9), 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, p. 100) 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.


Advantages Disadvantages/limitations
- Resistant to organic and hydraulic shock loads

- High reduction of solids, BOD and pathogens
- High nutrient removal if combined with aquaculture
- Low operating costs
- No electrical energy is required
- No real problems with insects or odours if designed and maintained correctly

- Requires a large land area

- High capital costs depending on the price of land
- Requires expert design and construction
- Sludge requires proper removal and treatment


Appropriateness

WSPs are among the most common and efficient methods of wastewater treatment around the world. They are especially appropriate for rural and peri-urban communities that have large, unused land, at a distance from homes and public spaces. 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 & Maintenance

Scum that builds up on the pond surface should be regularly removed. Aquatic plants (macrophytes) 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 desludged 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.

Upgrading

Ideally, several aerobic ponds can be built in series to provide a high level of pathogen removal. A final aquaculture pond can be used to generate income and supply a locally grown food source.

References

  • Peña Varón, M. and Mara, D. D. (2004). Waste Stabilisation Ponds. Thematic Overview Paper. IRC International Water and Sanitation Centre, Delft, NL.
  • Shilton, A. (Ed.) (2005). Pond Treatment Technology. Integrated Environmental Technology Series, IWA Publishing, London, UK. (Book)

Acknowledgements

Eawag compendium cover.png

The material on this page was adapted from:

Elizabeth Tilley, Lukas Ulrich, Christoph Lüthi, Philippe Reymond and Christian Zurbrügg (2014). Compendium of Sanitation Systems and Technologies, published by Sandec, the Department of Water and Sanitation in Developing Countries of Eawag, the Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.

The 2nd edition publication is available in English. French and Spanish are yet to come.