How are biosolids classified?
Biosolids are classified in specific State, Territory or national Guidelines. Development of these Guidelines is usually the responsibility of regulatory agencies responsible for the environment. Primarily there are usually two parameters examined when determining the classification of biosolids: the treatment (microbiological) grading and the contamination grading. Most Australian State guidelines have three or four treatment grades and two or three contaminant grades. The overall combined grade (treatment and contaminant) is usually linked to the different ways in which Biosolids may be used or applied. Grade specifications can be checked with the relevant Guidelines.
Biosolids must be ‘classified’ to be suitable for use. Primarily there are two parameters examined when determining the classification of biosolids: the pathogen grading (P) and the contamination grading (C). State and national guidelines require biosolids to be adequately treated to significantly reduce pathogens. Biosolids must also contain very low concentrations of heavy metals, organo-chlorides and pesticides to permit use. Three classes of biosolids (P1C1, P2C2 & P3C2) are safe for use in direct land application such as agriculture and forestry where routine public contact does not occur. Other biosolids classes and uses are: • Class P1C1 – these biosolids can be safely used in home gardens and on lawns, parkland and golf courses. • Class P2C1 & P2C2 – These two levels of biosolids are suitable for use in horticulture and low public contact areas such as landscaping. Perth metropolitan wastewater treatment plants produce P3C2 biosolids and easily meet the requirements for restric
