Biosolids
Biosolids are a valuable by-product of modern sewage treatment. Dried biosolids have a range of uses, notably as nutrient rich fertilizer.
Dried biosolids can be used as fertilizer or an alternative fuel.
What are biosolids?
Modern sewage treatment utilises billions of microscopic bacteria and other organisms to break down and digest sewage to produce recycled water.
In these nutrient rich conditions, the microbes eat, multiply and die. Their dead bodies accumulate at the bottom of sewage treatment tanks and are regularly drained and dried. The resultant product is known as biosolids.
Because biosolids are organic and nutrient rich themselves, they can be recycled as fertilizer. Dried biosolids can also be used as a sustainable, greenhouse friendly alternative fuel.
Producing of biosolids
Black Rock Water Reclamation Plant, the region's largest sewage treatment and water recycling facility, produces almost 140 tonnes of biosolids every day. Our other water reclamation plants produce biosolids in smaller quantities.
Currently, biosolids are transported in closed trucks to large drying bays in Werribee, where they slowly dry in the sun and wind, before being transported again for use as fertiliser.
This process is not economically or ecologically sustainable.
Biosolids drying facility
A new facility is being constructed adjacent to the Black Rock plant to dry the biosolids, producing small biosolids pellets suitable for immediate use as fertilizer.
The biosolids drying facility will:
- significantly reduce greenhouse gas emissions associated with transporting biosolids
- significantly reduce the land needed to dry biosolids
- have no visible emissions or odours outside the property boundary
- produce a renewable product for beneficial reuse.
The facility is being constructed and operated by Plenary Environment as a public-private partnership under the state government's Partnerships Victoria program.
The drying facility is due to begin operation late 2011.
More information
Plenary Environment's dedicated project microsite