The Wannon Water program has moved on from its extensive research phase in an attempt to improve the treatment of Hamilton’s sewage.

Culminating a concerted research effort over recent years, Wannon Water’s aquaculture team released the goldfish into a series of floating cages — a first for the Australian water industry.

The novel approach has the potential to significantly reduce operating costs and carbon emissions associated with sewage treatment by reducing the need for costly de-sludging and lowering the amount of energy used.

Wannon Water managing director Grant Green said previous research undertaken with Deakin University showed goldfish consumed and removed nutrients and sludge from sewage while maintaining the quality of recycled water.

“Wannon Water has monitored more than 20,000 fish in the last few years, fine-tuning the research program to determine the most efficient and cost-effective approach to improving sewage treatment through aquaculture,” Mr Green said.

“The experiments have been highly successful, with the goldfish thriving in our experimental tanks and substantially reducing the amount of sludge accumulated in the sewage treatment process.

“We are confident that the fish released into the sewage treatment lagoons will reduce our reliance on costly mechanical de-sludging, providing a more cost-efficient sewage treatment option for south-west Victoria.

“Wannon Water will monitor the success of the project at Hamilton to assess the potential of goldfish to aid sewage treatment at other water reclamation plants.” 

Wannon Water has established a dedicated fish hatchery in Warrnambool to produce larvae and fry for delivery to its own juvenile fish production facility in Hamilton, which has been converted from obsolete biosolids drying beds. 

The fry are then grown to a suitable size to be introduced into the sewage treatment lagoons.