Sydney Water is conducting a research project aimed to generate additional green energy by adding food waste to sewage through a co-digestion process.

The first stage of the project, which is in collaboration with the University of Wollongong, is using waste from beverage production and turning it into additional energy. The project is basically turning beer, wine and soft drink waste into potential power for homes and businesses.

The food waste will be blended with sewage and the mixture is then converted into methane gas through a process called anaerobic co-digestion. The obtained methane is then 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.

A typical Sydney Water customer is now saving nearly $100 a year on their water bill, and projects like this could make even more savings possible in the future.

Adding food waste like beverage waste to the wastewater treatment process provides a number of benefits:

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

Dr Heri Bustamante, Principal Scientist Treatment at  Sydney Water said, “One aspect of the Shellharbour research, which is believed to be a world first, is that the project will develop a tool which will predict the biogas production of a range of food wastes.

“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.

“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,” Dr Bustamante said.

Sydney Water is already producing additional energy onsite, across a number of its wastewater treatment facilities.

Sydney Water currently generates more than 20 per cent of its total energy needs across its network from wastewater treatment, along with hydro and solar power. That’s the equivalent energy to power over 11,000 homes each year, reducing greenhouse gas emissions by over 70,000 tonnes a year and which is the equivalent of keeping 17,500 cars off the road for a year.

In addition to producing 20 per cent of its power needs, Sydney Water also exports eight gigawatt hours to the electricity grid a year, enough energy to power about 1000 average NSW homes.

Sydney Water’s Bondi Wastewater Treatment Plant produces 13 per cent more electricity than it consumes each year, allowing the return of electricity to the grid.

Sydney Water is also currently trialling the use of fruit and vegetable waste at its Cronulla Wastewater Treatment Plant to allow the production of additional energy and to keep fruit and vegetable waste out of landfill.

“The ability to recover energy from wastewater will see treatment plants become bio-generators of the future,” Dr Bustamante said.

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