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Composting of Biosolids

Composting is the biological degradation of organic materials under controlled aerobic conditions. The process is used to stabilize wastewater solids prior to their use as a soil amendment or mulch in landscaping, horticulture, and agriculture. Stabilization of wastewater solids prior to use destroys pathogens (disease causing organisms), minimizes odors, and reduces vector (e.g., flies) attraction potential.

The process is used to stabalize wastewater to create an end-product that is easy to handle, store, and use as a soil amendment. The product is often a Class A, humus-like consistency without detectable levels of pathogens that can be applied as a soil conditioner and fertilizer to gardens, food and feed crops, and rangelands. This compost provides large quantities of organic matter and nutrients (such as nitrogen and potassium) to the soil, improves soil texture, and elevates soil cation exchange capacity (an indication of the soil’s ability to hold nutrients), all characteristics of a good organic fertilizer. Biosolids compost generally has a high degree of acceptability by the public. 

The biosolids technology fact sheet for in-vessel composting in biosolids discusses composting in a contained vessel, enabling the operator to maintain closer control over the process in comparison with other composting methods.