May 24, 2018
Stainless steel – easier to digest
When the Millennium drought and Melbourne Australia’s growing population put a greater strain on finite resources like water and energy, Weltec Biopower, a bioenergy producer, and engineers, Aquatec Maxcon, brought their expertise to Yarra Valley Water to build a waste-to-energy facility. The Aurora waste-to-energy plant processes commercial food waste into clean, renewable energy. This in turn generates enough biogas to run the existing Aurora sewage treatment plant and the new recycled water facility, with the surplus energy being sold or exported to the electrical grid.
Rubbish to renewable energy
Operating since May 2017, nearby markets and food manufacturers deliver the equivalent of 33,000 tonnes of commercial food waste to the facility annually. The first stand-alone food waste processing facility constructed by a water utility in Australia, the ReWaste plant is based on the process of anaerobic digestion.
Eight stainless steel tanks including five pre-storage tanks, two digesters and a large storage tank were put together on site. Stainless steel was an ideal material to withstand the corrosive environments created by decaying organic matter which contains hydrogen sulphide, chlorides and organic acids.
Austenitic stainless steel grade Type 304 (UNS S30400) was used for the tanks. The upper part of the digesters, which are partly in the splash zone and partly in the gas phase, were made from the more highly alloyed grade of austenitic stainless steel Type 316Ti (S31635).
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