What are biosolids?
Biosolids are nutrient-rich organic materials that look, smell and feel like dark, rich organic soil. They’re produced as a by-product of the sewage treatment process.
How are biosolids produced?
During the treatment process, naturally occurring bacteria and micro-organisms consume the sewage. They completely break down the original organic solids and remove contaminants.
Treated water is then decanted and discharged to the ocean or dams. We remove the remaining material, known as sludge, from the bottom of the tank and siphon any excess water.
The sludge comprises dead micro-organisms and a small number of active micro-organisms. It also contains inert solids, such as sand, which have come down the sewer.
We transport the sludge to our specialised facilities where it’s dried and composted. This take a few years and satisfies Environment Protection Authority guidelines. It’s then known as biosolids, a product ready for beneficial reuse as soil conditioner. The material is mainly spread on broad-acre agriculture, pasture and cropping properties.
Does it smell?
The sludge drying process sometimes creates odours. This isn’t harmful to health but may impact people in the nearby area. We undertake monitoring and adjust our operations to suit wind conditions.
On-site misters can spray natural deodoriser, reducing odours when we process the sludge. The mist is a natural blend of essential oils, food grade surfactants and purified water.
Where are the biosolid facilities located?
We operate two major sites to process sludge into biosolids – one at Camperdown and the other in Hamilton. We also have a smaller site at Portland.
