Turning food waste into energy

Sydney Water and the University of Wollongong are collaborating on an innovative research project in which food waste is added to sewage as part of a process called anaerobic co-digestion. The project was officially opened recently by NSW Minister for Energy and Utilities Don Harwin.

The project will see food waste blended with sewage at Sydney Water’s Shellharbour Wastewater Treatment Plant. The mixture is then converted into methane gas, a renewable energy source. The obtained methane is used as fuel to heat an anaerobic digester and to produce electricity to power the plant. The entire process occurs in a contained system to eliminate any odours.

“The first stage of the research is using waste from beverage production and turning into additional energy, so the project is basically turning beer, wine and soft drink waste into power,” said Harwin.

Benefits of the process include:

• More power is able to be generated by the co-digestion process through additional biogas production. 
• Food waste is diverted away from landfill and greenhouse emissions are reduced.
• Producing green energy at the plant keeps operation costs lower, which in turn puts downward pressure on water bills for customers.

Sydney Water Principal Scientist Treatment Dr Heri Bustamante noted that the project will develop a tool which will predict the biogas production of a range of food wastes — an initiative that is believed to be a world first.

“The research will enable Sydney Water to determine exactly the correct amounts of different types of food waste to be added in a variety of mixtures, to maximise energy production and to ensure that there are no downsides to the process,” Dr Bustamante added.

“Once products and methodologies are tested and proven, Sydney Water will be able to roll out the processes at its wastewater treatment plants, accepting a range of additional food waste products.”

A pilot plant with two 1000-litre digesters has now been installed at the Shellharbour Wastewater Treatment Plant.

Image caption: University of Wollongong Professor Long Nghiem, NSW Water Minister Don Harwin and Sydney Water Energy Manager Phil Woods inspecting the Shellharbour co-digestion unit.