Researchers are developing technology to convert biogas from sewage into electricity, offsetting the massive amounts of energy traditionally used to treat waste.
Sewage treatment can account for up to 20% of total electricity consumption in some cities. To counter this, University of Queensland has partnered with Queensland Urban Utilities to conduct research at Luggage Point, Queensland’s largest wastewater treatment facility.
Wastewater contains concentrated amounts of nitrogen that can lead toxic algae blooms and oxygen depletion or dead zones if it enters natural waterways.
Most wastewater treatment facilities use ethanol for nitrogen removal, costing millions of dollars each year.
UQ Advanced Water Management Centre’s Dr Shihu Hu says this expensive process uses up almost half the organic matter in the waste, meaning less is available for conversion to methane.
“The new technology we are developing can recover more methane without requiring ethanol to be used to remove nitrogen,” he says.
“This also means we can recover almost all of the organic matter in the wastewater to produce even more biogas.”
His research indicates that a mix of waste-munching anaerobic ammonium oxidation (anammox) bacteria and dentrifying anaerobic methane oxidation (DAMO) microorganisms, fed with the nitrogen-rich wastewater containing ammonium and nitrate/nitrite, could remove nitrogen without requiring ethanol or additional oxygen feed.
Dr Hu has plans to upscale his work, with potential for it to be implemented in many more wastewater facilities.
“We expect this technology will be rapidly adopted,” he explains.
“It means the energy-intensive water treatment industry can go from big energy consumers to being energy neutral.
“It would save hundreds of thousands of dollars for large facilities and it is more sustainable for the planet.”
Dr Hu said his research with Queensland Urban Utilities since 2011 had enabled him to get insight from operators and to work translate laboratory research to 1.2km of piping at Luggage Point.
“The site gives me unlimited access to free samples, with about 60 Olympic swimming pools of waste arriving every day,” he says.