Sludge is a mixture of solids and liquids, containing mostly Excreta and water, in combination with sand, grit, metals, trash and/or various chemical compounds. A distinction can be made between faecal Sludge and wastewater Sludge. Faecal Sludge comes from onsite sanitation technologies, i.e., it has not been transported through a sewer. It can be raw or partially digested, a slurry or semisolid, and results from the Collection and Storage/Treatment of Excreta or Blackwater, with or without Greywater. For a more detailed characterization of faecal Sludge refer to Strande et al., 2014 (see Sector Development Tools, p. 9). Wastewater Sludge (also referred to as sewage Sludge) is Sludge that originates
from sewer-based wastewater collection and (Semi-) Centralized Treatment processes. The Sludge composition will determine the type of treatment that is required and the end-use possibilities.
====Treated Sludge====
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Treated Sludge is the general term for partially digested or fully stabilized faecal sludge. The US Environmental Protection Agency has strict criteria to differentiate between degrees of treatment and consequently, how those different types of sludges can be used. ‘Treated Sludge’ is used in the System Templates and in the Technology Information Sheets as a general term to indicate that the sludge has undergone some level of treatment, although it should not be assumed that ‘treated sludge’ is fully treated or that it is automatically safe. It is meant to indicate that the sludge has undergone some degree of treatment and is no longer raw. It is the responsibility of the user to inquire about the composition, quality and therefore safety of the local sludge.
====Stored urineEffluent====
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Stored urine Effluent is urine the general term for liquid that has been hydrolyzed naturally over time, iundergone some level of treatment and/or separation from solids.e. the urea has been converted by enzymes into carbon dioxide It originates at either a Collection and ammonia. Stored urine has Storage/Treatment or a pH of approximately 9(Semi-) Centralized Treatment Technology. After 6 months Depending on the type of storagetreatment, the risk effluent may be completely sanitized or may require further treatment before it can be used or disposed of pathogen transmission is reduced considerably.
====EffluentBiomass====
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Effluent is Biomass refers to plants or animals cultivated using the general term for liquid that has undergone some level of treatment water and/or separation from solids. It originates at either nutrients flowing through a Collection and Storage/Treatment or a (Semi-) Centralized Treatment Technologysanitation system. Depending on the type of treatmentThe term Biomass may include fish, insects, vegetables, fruit, the effluent may be completely sanitized forage or may require further treatment before it other beneficial crops that can be used or disposed ofutilized for food, feed, fibre and fuel production.