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.
{{procontable | pro=
- Requires large land area <br> - Odours and flies are normally noticeable. <br> - Long storage times. <br> - Requires front-end loader for monthly desludging. <br> - Requires expert design and operation.
}}
==Adequacy==
The thickened sludge must be removed mechanically (front end loader or specialized equipment) when the sludge has thickened sufficiently.
==Acknowledgements==
{{:Acknowledgements Sanitation}}
==Referencesand external links== * Elizabeth Tilley et.al (2008). [http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_sesp/downloads_sesp/compendium_high.pdf Compendium of Sanitation Systems and Technologies] ([http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_sesp/downloads_sesp/compendium_low.pdf low res version]). Department of Water and Sanitation in Development Countries ([http://www.sandec.ch/ Sandec]) at the Swiss Federal Institute of Aquatic Science and Technology (Eawag). (Provides a full overview of sanitation systems.)
* Heinss, U., Larmie, SA. and Strauss, M. (1999). Characteristics of Faecal Sludges and their Solids-Liquid Separation. Eawag/Sandec Report, Dübendorf, Switzerland. Available: http://www.sandec.ch