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'''Digested or stabilized Faecal Sludge is refered to as ‘Biosolids’. Depending on the quality of the biosolids, they can be applied to public or private lands, for landscaping or for agriculture.'''
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'''Digested or stabilized Faecal Sludge is referred to as ‘Biosolids’. Depending on the quality of the biosolids, they can be applied to public or private lands, for landscaping or for agriculture.'''
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The USEPA defines different levels of biosolids depending on the treatment and quality, and therefore the health risk. Class A biosolids (i.e. biosolids that can be sold for public use) can be used with nearly no restrictions.
Biosolids are spread on the ground surface using conventional manure spreaders, tank trucks or specially designed vehicles. More liquid biosolids (e.g. from anaerobic reactors) can be sprayed onto, or injected into, the ground. Dewatered biosolids may be ‘flung’, which is most common in forests.
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{{procontable | pro=
- Can accelerate reforestation. <br> - Can reduce use of chemical fertilizers and improve water retention of soils. <br> - Can reduce erosion. <br> - Low cost. | con=
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===Adequacy===
Although biosolids are sometimes criticized for containing potentially high levels of metals or contaminants, commercial fertilizers are also contaminated to varying degrees, most likely with cadmium or other heavy metals. Faecal sludge from pit latrines has no, if any, chemical inputs and is therefore not a high risk source of contamination. Faecal sludge that originates at large-scale wastewater treatment plants is more likely to be contaminated since it receives industrial and domestic chemicals, as well as surface water run-off which may contain hydrocarbons and metals. Depending on the sludge source, biosolids can serve as a valuable and often much-needed source of nutrients. Land application of biosolids may be less expensive than disposal.
Application rates and usages for biosolids should take into account not only the presence of pathogens and contaminants, but also the quantity of nutrients such that they are spread at a sustainable and ‘agronomic’ rate. Appropriate safety and application regulations should be followed.
===Health Aspects/Acceptance===
The greatest barrier to biosolid use is generally acceptance. However, even when biosolids are not accepted in agriculture or by local industries, they can still be useful for municipal projects and can actually provide significant savings to public projects (e.g. mine reclamation). Depending on the source of the faecal sludge and on the treatment method, biosolids can be treated to a level where they are generally safe and without significant odour or vector problems.
===Maintenance===
Spreading equipment must be maintained to ensure continued use. The amount and rate of biosolid application should be monitored to prevent overloading and thus, the potential for nutrient pollution.
==Acknowledgements=={{:Acknowledgements Sanitation}} ==References and external links===
* U.S. EPA (1999). Biosolids Generation, Use, and Disposal in the United States, EPA-530/R-99-009. U.S. Environmental Protection Agency: Washington, D.C. Available: http://www.epa.gov
* U.S. EPA (1994). A Plain English Guide to the EPA Part 503 Biosolids Rule, EPA832-R-93-003. U.S. Environmental Protection Agency: Washington, D.C. Available: http://www.epa.gov
===Acknowledgements===
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