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Beer to biogas: creating renewable energy during COVID-19

In South Australia, millions of litres of expired beer is being converted to renewable energy to fully power the Glenelg wastewater treatment plant.

Beer consumption significantly reduced in March amid the coronavirus pandemic, as public venues such as pubs, clubs, and restaurants were forced to limit patronage.

As a result, various South Australian breweries have been sending 150,000 litres per week of expired beer to the Glenelg plant, where it is mixed with sewerage sludge to produce renewable biogas used to power the plant.

Millions of litres of expired beer is being sent to Glenelg Wastewater Treatment Plant. Source: Wikimedia Commons

SA Water has an impressive track record incorporating new and innovative technologies at the Glenelg wastewater treatment plant.

The first activated sludge plant in Australia was commissioned at Glenelg in 1933, only 20 years after the technology was invented in the UK.

Activated sludge is a common sewerage treatment process that typically uses aerobic micro-organisms to digest the wastewater’s organic matter, producing treated water relatively free of solids and organics.

The digestion process also produces waste called ‘Activated Sludge’, which is recycled and thickened in digestion and settling tanks, as shown in the diagram below.

Activated sludge process

Waste sludge from the Glenelg plant is sent 30 kilometres via a sludge pipeline to the Bolivar wastewater treatment facility, where it is dried and supplied to local farmers as a highly fertile soil conditioner.

The major operational cost associated with the activated sludge process is power consumption, due to the high loads drawn by aerating, heating, and pumping. However, the digestion process also produces biogas – a potential renewable energy source that is wasted at most sewerage treatment sites.

Activated sludge at the top of a digestion tank. Source: SA Water

In 2017, SA Water partnered with listed company 1414 Degrees to install a cutting edge system at the Glenelg plant that captures the biogas and converts it to renewable energy.

The biogas system usually covers 80 per cent of Glenelg’s power requirements, however the recent influx of beer has increased biogas production, allowing the site to become completely self-reliant.

SA Water’s senior manager of production and treatment Lisa Hannant is encouraging other trade waste customers to contact SA Water, to see if their waste is compatible with the Glenelg wastewater treatment plant.

"It's a win for SA Water because we can reduce our costs by generating our own power, and it's a win for industry because it reduces their disposal and treatment costs," Ms Hannant said.

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