SA sludge research impacts UN climate guidelines

Greenhouse gas (GHG) research conducted by SA Water and the University of Queensland (UQ) has been incorporated into the United Nations’ (UN) climate change policies, forming a benchmark for the global reporting of nitrous oxide emissions at wastewater treatment plants.

The study applied a novel research method at South Australia’s Bolivar Wastewater Treatment Plant, using floating hoods anchored on sludge pools to capture, monitor and better understand GHG emissions in real time.

As part of the trial, optimised aeration at one of Bolivar’s activated sludge plants led to a 30% reduction in nitrous oxide emissions.

SA Water’s Lead Scientist Environment and Wastewater Dr Ben van den Akker said acknowledgement from the UN is a feather in the cap for science and water research in South Australia.

“Nitrous oxide is a by-product of biologically removing nitrogen from wastewater, which represents up to 50% of total emissions from wastewater treatment plants, and we’ve put a substantial focus over the years on investigating how to reduce this output and positively impact our emissions footprint,” Dr van den Akker said.

“This allows us to accurately predict emissions at any of our locations at any time and helps to map emissions hot spots to better target optimisation and control measures.”

The Intergovernmental Panel on Climate Change (IPCC) — the UN body for assessing climate change science — has included the research findings in refinements to guidelines on GHGs published in May.

“The end result of this project has provided the most comprehensive data set on nitrous oxide emissions for step-fed activated sludge plants like we have at Bolivar, and there is no greater recognition of the importance of this work on climate change than from the IPCC,” Dr van den Akker said.

“We can now say that we’ve positively impacted international climate change policy, which is a pretty cool thing for SA Water and South Australia.”

Nitrous oxide emissions at treatment plants are far greater than methane emissions or those from electricity consumption, with an estimated global warming potential 310 times greater than carbon dioxide.

UQ Advanced Water Management Centre Director Professor Zhiguo Yuan AM said nitrous oxide levels are a worldwide issue.

“Combatting nitrous oxide remains a real problem facing water utilities globally, and this goes to show how improving a plant’s design and operation can make a real impact on reducing the emissions footprint,” Professor Yuan said.

“Our work together with SA Water on this project demonstrates the importance of researchers and industry partners collaborating to deliver real benefits to society.”

Image caption: A floating gas-capture hood in action at SA Water’s Bolivar Wastewater Treatment Plant. Image credit: SA Water.