Cheese finds a whey to fuel Glenelg poo power

Already boasting a questionable diet, hungry digesters at SA Water’s Glenelg Wastewater Treatment Plant are now feasting on excess cheese whey from 3 major producers and converting it into electricity to power the plant.

Since April 2024, Glenelg has received regular weekly loads of more than 200,000 litres of cheese whey and milk waste, with SA-based La Casa Del Formaggio contributing around 150,000 litres per week. Another multinational company has added 30,000 litres since December 2024, and a third contributing 50,000 litres a week since April 2025.

The whey is delivered by the dairy manufacturers to the plant where, alongside other sources of organic waste and wastewater, it’s fed into the site’s digesters – which are used in the final stages of wastewater treatment – where it’s broken down to produce a source of sustainable energy known as biogas.

The boost to biogas production means the plant now generates about 589 megawatt hours of electricity every month, which is enough to power about 1,000 homes.

SA Water’s Senior Manager of Production and Treatment Paul Bendotti said the dairy by-product has driven a significant boost in energy production, with the plant’s average daily biogas output increasing by more than 16 per cent – up to 9,400 cubic metres – between April 2024 and August 2025.

“Through the advancement of technology, our wastewater treatment plants have transformed into sources of renewable energy, and our Glenelg facility has always been a strong performer,” Paul said.

“Glenelg’s co-digestion program adds high strength organic waste from various industries to sludge from the wastewater treatment process, which is heated in an oxygen-free environment within our digesters.

“Digesters are large, sealed concrete tanks with a floating dome roof and they facilitate a natural biological process that breaks down the combined waste to release biogas – a fuel mostly consisting of methane.

“The biogas is captured and piped to the plant’s 3 gas engines that convert it into a source of electricity to power the treatment plant and heat to keep the digesters warm and productive, making use of industrial waste that’s otherwise difficult to dispose of and treat.

“Cheese whey is a clear, yellowish liquid left over from the process of separating curds to make cheese, and is rich in nutrients and sugars like lactose, which gives it a high methane potential perfect for co-digestion.

“Since adding the daily deliveries of cheese whey into the digesters from mid-April last year, we’ve seen a noticeable increase in biogas production.

“This sustained emphasis on generating renewable energy across our metropolitan wastewater treatment plants is helping to reduce our carbon footprint and keep our operating costs down.”

At the height of COVID-19 restriction measures on the local hospitality industry in mid-2020, millions of litres of expired beer was used within Glenelg’s digesters to fuel record power generation – making the wastewater treatment plant 95 per cent energy self-sufficient during July of that year.

Since July 2024, Glenelg’s energy self-sufficiency has fluctuated between 77 and 90 per cent, with biogas production influenced by the availability of industrial waste for co-digestion.

Paul said co-digestion gives industrial waste a new lease of life, while protecting Adelaide’s sewers.

“Certain waste produced by industry, such as cheese whey and expired beer, is challenging and costly for manufacturers to manage and unlike domestic waste, isn’t suitable for discharge into our sewers as it has a detrimental impact on our infrastructure by damaging pipes and pump stations,” Paul said.

“Pleasingly, we work closely with members of the industry – including La Casa Del Formaggio – to help them segregate their waste to ensure it doesn’t enter our network, with a range of other substrates including milk, soft drinks and trapped grease accepted by our digesters.

“La Casa Del Formaggio recently moved into a new facility and installed equipment that can separate the cheese whey before it’s repurposed at our Glenelg plant on an ongoing basis at no cost.

“Rather than allowing it to go to waste, and seeing local manufacturers pay to safely dispose of their waste elsewhere, these substrates provide the complete ingredients to power a green energy source.”