Harvesting human waste for green energy

Associate Professor Qilin Wang is an ARC Future Fellow and winner of the 2020 Eureka Prize for Outstanding Early Career Researcher for his work on a technology that could turn wastewater treatment plants into carbon-neutral energy generators.

An environmental engineer with the Centre for Technology in Water and Wastewater at the University of Technology Sydney (UTS), Associate Professor Wang is working with partners to develop the energy recovery process for industry.

'My goal is to transform the energy-consuming and high emission sewage treatment process into a zero energy – or, even better, energy producing – low-emission process,' Associate Professor Wang says.

Treating human waste using current methods consumes a large amount of energy and also produces greenhouse gas emissions, while being a major expense for councils and water utilities. While some treatment plants already produce what’s known as biogas, existing processes recover just 5-10%of the energy stored in sewage sludge.

Associate Professor Wang’s breakthrough is to recruit an unwanted by-product of the wastewater treatment process – ammonia – by mixing it in with the sewage sludge to help transform some of its non-biodegradable components, and free up organics for biogas production.

	Named among Australia’s most innovative engineers in utilities in 2020 for his work, the Eureka Prizes judging panel noted that Associate Professor Wang’s ‘closed system nature of this innovation is particularly powerful. This is a breakthrough technology that has direct application for community and environmental benefit.’

Laboratory experiments suggest the process could improve energy recovery from sewage sludge by four to six times. It’s also easy to implement, with no need for special equipment or inputs such as chemicals or external energy.

‘It’s a simple process. Sewage sludge is added into a simple mixing tank, to be joined by free ammonia. Then we just mix them for around for a day or so,’ Associate Professor Wang says.

In an added bonus, recent experiments suggest this free-ammonia technology could also reduce the presence of antibiotic resistant genes in the sludge, and therefore in the environment, where they can negatively impact on human health.