2. A nutrient-rich organic material, or byproduct, resulting from the treatment of municipal wastewater.
Biosolids can be safely recycled; for example, for fertilizers.
Biosolids contain nitrogen and phosphorus along with other supplementary nutrients in smaller doses; such as, potassium, sulfur, magnesium, calcium, copper, and zinc.
Soil that is lacking in these substances can be reclaimed with biosolids use. The application of biosolids to land improves soil properties and plant productivity, and reduces dependence on inorganic fertilizers.
There are some obstacles to sewage sludge reuse because in modern societies; especially, with sewage biosolids reuse in agriculture. Even if problems of pollutant contamination (heavy metals, organic contaminants, pharmaceuticals) and public opinion were resolved, considerable obstacles would still remain.
Cities and intensive livestock production units both lead to localized surpluses of nutrients. Biosolids have relatively low nutrient content compared to high water content.