Biosolids are treated sewage sludges. Sewage sludge is the solids that are collected from the wastewater treatment process but which have not undergone further treatment. Sludge normally contains up to around 3% solids. Biosolids are a product of the sewage sludge once it has undergone further treatment to reduce disease causing pathogens and volatile organic matter significantly, producing a stabilised product suitable for beneficial use. Biosolids, normally contain between 15% to 90% solids. Biosolids are carefully treated and monitored and they must be used in accordance with regulatory requirements.
Bisolids are commonly used as a fertiliser and soil conditioner for agricultural land.
Most Australian utilities make biosolids available as a fertiliser and soil conditioner for agricultural land.
A number of projects are being conducted that us biosolids to produce energy.
Key Challenges and opportunities:
Biosolids are a potential source of carbon for energy production. nutrients and trace metals.
Biosolids may contain traces of synthetic organic compounds and metals, including arsenic, cadmium, chromium, lead, mercury, nickel and selenium. High levels of trace chemicals may restrict biosolid use for agriculture.
Emerging knowledge about other trace chemicals may mean that historical use of biosolids may have health or environmental concerns.