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UNSW engineers have identified a number of chemicals that may merit closer scrutiny to ensure water utility companies and regulators can make informed decisions about the management of biosolids.

Biosolids are treated sewage sludge—that is, wastewater from household kitchens, laundry rooms and bathrooms that has been processed to create a product suitable for beneficial use.

About 80% of biosolids produced in Australia are reused on farmland because they provide valuable nutrients and organic matter that can improve soil quality and support plant growth.

However, biosolids can also contain traces of chemicals entering the system from everyday household activities such as washing, cleaning and taking medicines.

A new study, led by UNSW researchers, has examined what happens to some of those chemicals when biosolids are applied to farmland, including how long they can remain in the environment and whether their concentrations could affect plants and animals.

Their…