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'''Sedimentation or Thickening Ponds are simple settling ponds that allow the sludge to thicken and dewater. The effluent is removed and treated, while the thickened sludge can be treated in a subsequent technology.'''
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Faecal sludge is not a uniform product and therefore, its treatment must be specific to the characteristics of the specific sludge. In general, there are two types of faecal sludges: high strength (originating from latrines and unsewered public toilets) and low strength (originating from [[Septic Tank|Septic Tanks]]. High strength sludge is still rich in organics and has not undergone significant degradation, which makes it difficult to dewater. Low strength sludge has undergone significant anaerobic degradation and is more easily dewatered.
As the sludge settles and digests, the supernatant must be decanted and treated separately. The thickened sludge can then go on to be dried or composted further.
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===Adequacy===
Settling/Thickening Ponds are appropriate where there is inexpensive, available space that is far from homes and businesses; it should be on the edge of the community.
This is a low-cost option that can be installed in most hot and temperate climates. Excessive rain may prevent the sludge from properly settling and thickening.
===Health Aspects/Acceptance===
The incoming sludge is pathogenic, so workers should be equipped with proper protection (boots, gloves, and clothing). The thickened sludge is also infectious, although it is easier to handle and less prone to splashing and spraying. The pond may cause a nuisance for nearby residents due to bad odours and the presence of flies. Therefore, the pond should be located sufficiently away from urban centres.
===Maintenance===
Maintenance is an important aspect of a well-functioning pond, although it is not intensive. The discharging area must be maintained and kept clean to reduce the potential for disease transmission and nuisance (flies and odours). Grit, sand, and solid waste that are discharged along with the sludge must be removed.
The thickened sludge must be removed mechanically (front end loader or specialized equipment) when the sludge has thickened sufficiently.
===References===
* Heinss, U., Larmie, SA. and Strauss, M. (1999). [http://www.sswm.info/sites/default/files/reference_attachments/HEINSS%20et%20al%201994%20Characteristics%20of%20Faecal%20Sludges%20and%20their%20Solids-Liquid%20Seperation.pdf Characteristics of Faecal Sludges and their Solids-Liquid Separation]. Eawag/[http://www.sandec.ch Sandec] Report, Dübendorf, Switzerland.
* Montangero, A. and Strauss, M. (2002). Faecal Sludge Treatment. Lecture Notes, IHE Delft. [http://www.sswm.info/sites/default/files/reference_attachments/EAWAG%20SANDEC%202008%20Module%205%20FSM%20Lecture.pdf Faecal Sludge Management].
===Acknowledgements===
{{:Acknowledgements Sanitation}}
