Well-placed sewage treatment plants for the production of renewable energy biogas from food waste

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

But the methods used for the treatment of human organic waste could also extend to the treatment of organic food waste destined for landfill.

Within 10 years, the country’s wastewater treatment plants could provide growing communities with a way to reduce their carbon footprint by treating kitchen waste and creating biogas.

At the Wollongong water recycling plant, the infrastructure is already in place.

Sydney Water’s head of strategic planning, Phil Woods, said the vision was for a resource recovery hub or circular economy hub.

“Historically these have been referred to as ‘wastewater treatment plants’, but there is so much resource potential and we are already seeing this with the production of recycled water, renewable energy from biogas and the adding solar panels,” he said.

At the heart of the process are the company’s anaerobic digesters.

These are large mechanical stomachs that collect organic waste and process it, creating biogas and compost, while diverting it from landfill.

Sydney Water’s head of strategic planning, Phil Woods, says his organization has 29 sewage treatment plants that could step up waste treatment.(ABC Illawarra: Justin Huntsdale)

Alongside FOGO

Many local government areas in Australia already operate FOGO (Food Organics and Garden Organics) refuse collection services that turn huge amounts of organic waste into nutrient-rich compost.

In doing so, it prevents organic matter from going to landfill where it decomposes and creates greenhouse gases.

Soon, wastewater treatment plants could supplement this service by producing biogas in the process, which can be used to generate electricity.

Woods said the state’s waste and resource recovery strategy aims to remove commercial food waste from landfills by 2025 and households by 2030.

“We see a real opportunity to deliver the service to cities by maximizing resource recovery from this waste,” he said.

A person in a suit is holding a green bin.
Organic waste collected through FOGO curbside waste collection services helps compost the material into reusable products.(ABC News: Harry Frost)

“How are we going to get from where we are now with this waste that goes into household red bins and get it to a place like this is the challenge we are facing right now, and it will take a lot of collaboration.

“We can’t provide all the solutions, but we have a fantastic facility that will be used to bring even more value to the city.”

He said anaerobic digesters also provide a fertilizer byproduct, similar to FOGO composting.

A giant tank with a mechanical arm pushed into the side to mix food waste inside.
Anaerobic diggers have the added benefit of not only breaking down waste, but also trapping methane to produce biogas.(ABC News: Stephanie Anderson)

A zero carbon operation

Sydney Water currently uses its anaerobic digesters to reduce its own carbon emissions.

“It’s an important goal here because recycling water increases our energy demand.”

Beyond that, commercial businesses can be the starting point for bringing in additional food waste.

“It’s a question of what works best for the city. We have 29 sewage treatment plants and Wollongong is one of the biggest,” he said.

“We are looking at all of these to see how we can turn them into resource recovery centers where we can maximize the potential of a plant like this.”

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