Wastewater treatment plants well placed for renewable energy biogas production from food scrap rubbish

Mar 25, 2022

For years, wastewater treatment plants have mainly been the destination for what is flushed down the toilet.

But the methods used for processing human organic waste could also extend to treating organic food waste destined for landfill. Within 10 years, the country's wastewater treatment plants could provide growing communities a means to reduce their carbon footprint by processing kitchen scraps and creating biogas.

At Wollongong Water Recycling Plant the infrastructure is already in place. Sydney Water strategic planning manager Phil Woods said the vision was for a resource recovery hub or circle economy hub.

"Historically, these have been termed as 'wastewater treatment plants', but there's so much resource potential and we're seeing that already with the production of recycled water, renewable energy from biogas and the addition of solar panels," he said.

Central to the process are the company's anaerobic digesters. They are large mechanical stomachs that take in organic waste and process it, creating biogas and compost material in the process, all the while diverting it from landfill. Phil Woods stands in front of an anaerobic digester at the Sydney Water Wollongong treatment plant.

Working alongside FOGO

Many local government areas in Australia already operate FOGO (food organics and garden organics) kerbside garbage collection services that turn an enormous amount of organic waste into nutrient-rich compost. In doing so, it stops organic matter going to landfill where it decomposes and creates greenhouse gases.

Soon, wastewater treatment plants could be complementing that service by producing biogas in the process, which can be used to generate electricity. Mr Woods said the state's waste and resource recovery strategy had a target to remove commercial food waste out of landfill by 2025 and households by 2030.

"We see a real opportunity to provide the service for cities in maximising the resource recovery from that waste," he said.

"How we get from where we are now with that waste going into household red bins and getting it to a place like this is the challenge we're working through at the moment, and it'll require a lot of collaboration.

"We can't provide all the solutions, but we have a fantastic facility that will be used to provide even greater value for the city." He said the anaerobic digesters also provide a fertiliser by-product, similar to FOGO composting.

A carbon-zero operation

Sydney Water currently uses its anaerobic digesters to lower its own carbon emissions. "The long-term future here is we can be an energy self-sufficient, carbon-zero facility producing high-quality recycled water," Mr Woods said.

"It's a significant target here because water recycling ramps up our energy demand."

Beyond that, commercial businesses may be the starting point for bringing in additional food waste. "It's a matter of what works best for the city. We have 29 wastewater treatment plants and Wollongong is one of the more significant," he said.

"We're looking at all of those to see how we can turn them into resource recovery hubs where we can maximise the potential that comes with a plant like this."

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