Biosolids – what are they?

Sewage sludge produced at our sewage treatment plants is called biosolids. Biosolids contain significant quantities of organic matter, moisture, plant nutrients, trace elements, chemical contaminants and potentially harmful microorganisms.

EPA Victoria regulates biosolids production, quality and usage to maximise reuse while protecting the environment and public health

For more information on biosolids.


Biosolids drying pan at Cowes Waste Water Treatment Plant


Biosolids stockpiles at Cowes Waste Water Treatment Plant

How we manage biosolids?

We produce about 500 dry tonnes of biosolids every year. Our aim is to use all biosolids produced for beneficial land applications. We have developed a Regional Environment Improvement Plan approved by the EPA Victoria to manage biosolids reuse. Click here to view the plan in PDF format.

Based on the EPA classification, biosolids produced at our sewage plant can be used for the following purposes:

  • Human food crops consumed raw in direct contact with biosolids; includes lettuces, strawberries and carrots
  • Dairy and cattle grazing/fodder (also poultry)
  • Processed food crops
  • Sheep grazing and fodder (also horses and goats), on non‐human food crops such as turf, woodlots, flowers and ornamental plants (not for human consumption)
  • Landscaping with unrestricted public access, forestry and land rehabilitation

Biosolids stockpile on farm


Spreading Biosolids on farm

Biosolids for farming

We have a strong partnership with the local farmers and provide technical support and financial assistance to promote farm application of biosolids in Philip Island. Biosolids are being successfully used for fodder production.


Incorporating biosolids


Biosolids applied land

Biosolids for remediating saline soil

We are conducting a research project in collaboration with RMIT and a local farm to assess the suitability of biosolids to improve quality of salt affected soil on the Island. The outcome of this ongoing project can potentially expand the reuse of biosolids across Australia.

For more information on the project.