SA treatment plant harnesses the power of biosolids

Posted 2 February 2017
Biogas
South Australia's largest wastewater treatment plant is now 87% energy self-sufficient, thanks entirely to biogas production from biosolids. 

Self-sufficiency at the 150ML/day Bolivar WWTP has risen from 63% in the 2014-15 financial year following major investment, said SA Water’s Chief Executive Roch Cheroux

“We achieved this by investing around $26 million to install and connect new infrastructure to vastly improve biogas power generation,” he said. 

“By installing three new gas engines, each capable of producing an instantaneous load of around 2400kW, we’re able to make the best use of biogas to produce renewable electricity and heat

“The engines are also regularly tuned to ensure optimal power generation.”

Cheroux said the self-sufficiency gains were not only driven by technology investment, but also by on-site refinements.

“A credit to the constant efforts of operational staff at the Bolivar WWTP, improved engine reliability and more efficient use of biogas means the site is close to being energy self-sufficient,” he said.

Bolivar WWTP has six 7800m3 digesters, which are designed to process more than 120 tonnes of biosolids per day. 

The renewable electricity they help to generate is enough to power 4000 houses.

“The renewable energy generated at the Bolivar Wastewater Treatment Plant (WWTP) is sourced entirely from biogas production,” Cheroux said.

“Most of the substrates entering the digesters are in the form of primary sludge and waste-activated sludge.”