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SA Water reduces nitrous oxide emissions by 30%

SA Water has set a new benchmark for wastewater treatment plants around the world, demonstrating its ability to reduce nitrous oxide emissions by almost one third.

Nitrous oxide is a by-product of biologically removing nitrogen from wastewater and is about 300 times more powerful in warming the climate than carbon dioxide.

The gas represents up to 50% of total emissions released from wastewater treatment plants, which SA Water Lead Scientist Environment and Wastewater Ben van den Akker said is far greater than methane or emissions from electricity consumption.

In a trial conducted in partnership with the University of Queensland, SA Water used floating hoods anchored at various points in its activated sludge plant to collect and monitor nitrous oxide. This was then analysed in short intervals by a computer system.

“Using this method, we are able to record and quantify nitrous oxide emissions at our Bolivar Wastewater Treatment Plant for the very first time and will eventually [be able] to predict emissions at any of our locations at any time,” van den Akker said.

“This is the first detailed data set ever reported for a step-feed activated sludge plant – one of the most common wastewater treatment technologies in the world – and enables us to map emissions ‘hot spots’ to better target necessary optimisation and control measures.”

He said data from the trial might be included in the revised Guidelines for National Greenhouse Gas Inventories, which will be put out by the United Nations’ Intergovernmental Panel on Climate Change later this year.

“[It] shows the global significance and interest this research has had on revising industry policy,” van den Akker said.

“Tackling climate change is everyone’s responsibility, and with nitrous oxide having a global warming potential 310 times greater than carbon dioxide, it is vitally important that all utilities work to reduce emissions in their operations without compromising on plant performance.”

The technology was developed by SA Water’s commercial business unit, Water Engineering Technologies.