An Australian-developed closed-loop technology could increase energy recovery from sludge while reducing the cost of sludge disposal.
Treating wastewater in Australia produces three million tons of sludge, which all needs to be treated and disposed of. The process is responsible for 50 per cent of the total operating costs of wastewater treatment plants.
A researcher from the University of Technology Sydney (UTS) has developed a new treatment technology that would reduce the amount of waste by a third. It would also increase the recovered energy (methane) by thirty per cent from the sludge itself.
The end product would also be safer biosolids for fertiliser than currently being produced.
This technology, only relying on a waste by-product of wastewater treatment itself, was invented by Huan Liu. Liu is completing her PhD at the university. Her research work has been published in a Nature-Index Journal. It has been commended by the Australian Water Industry.
“It is a closed-loop technology. The only chemical needed is a waste by-product of wastewater treatment,” Liu said.
“Instead of being a contaminant for wastewater treatment plants, the waste by-product becomes a useful part of the process,” she said.
Increased efficiency at generating energy and reducing sludge disposal costs
The process is also much more efficient at removing pathogens from the end product. Liu showed an 82 per cent reduction in pathogens. They also showed a 20~70 per cent reduction in antibiotic-resistant genes from traditional procedures. According to the New South Wales Environmental Protection Agency, the residue waste could achieve Grade A biosolids, reducing the health risks of using the sludge as fertiliser.
Liu estimates that if the technology were applied to wastewater treatment plants in NSW alone, it would save taxpayers an estimated $5 million a year.
The technique works in all wastewater treatment plants with anaerobic digestion and only requires the installation of a small and simple mixing tank. The technology is being commercialised.
The estimated payback time would be less than one year, while the benefits for plants and society will be lasting.
The project was part of a collaborative research program sponsored by Water Research Australia Limited, South East Water and the Australia Research Council (ARC). The project leader is Professor Qilin Wang, who is an ARC Future Fellow.
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