What are the different kinds of biosolids?
The federal Clean Water Act Part 503 regulations identify two classes of pathogen reduction for biosolids: Class B biosolids undergo a “Process to Significantly Reduce Pathogens” (PSRP). Digesters and other forms of treatment kill from 90 to 99.5 percent of the pathogens originally found in wastewater solids. This means that pathogens are reduced to levels that are well below those found in animal manures. As an added layer of public protection, additional best management practices (BMPs) are required at the site where biosolids are applied, such as buffers and restrictions on access immediately after application. The natural environment of sunlight and existing organisms in the soil break down remaining pathogens. In Virginia, Class B biosolids are used in bulk as fertilizers in agriculture and forestry and to reclaim barren lands. Site permits from the Virginia Department of Environmental Quality (DEQ) are required for Class B biosolids use. Class A biosolids undergo a “Process to Fu
