A University of Queensland Professor's work to reduce sewer corrosion has led him to be named a Fellow of the Australian Academy of Technological Sciences and Engineering (ATSE).
Professor Zhiguo Yuan is Director of the UQ Advanced Water Management Centre. He played a key role in developing an innovative and cost-effective way to reduce sewer corrosion.
Sewer systems are one of the most critical infrastructure assets for urban societies. But the costs of maintaining sewers cost billions of dollars a year worldwide.
Professor Yuan and his colleagues found that a major contributor to sewer corrosion comes from hydrogen sulfide. Microbes on the walls of sewers take up the hydrogen sulfide gas, oxidise it with air, and form sulfuric acid, which corrodes the concrete used to build sewer pipes. The rate of corrosion can be as rapid as 10mm/year, reducing sewer pipe life spans to as little as 10 years.
Sewer maintenance and rapid costs Australian utilities hundreds of millions of dollars per year. Efforts to treat corrosion, including chemical dosing and ventilation, cost a similar amount.
Because hydrogen sulfide is generated in the sewage from sulfate and organic waste, high levels of sulfate in sewage is ultimately responsible for the increased pipe corrosion.
The researchers performed a two-year sampling campaign in South East Queensland, an extensive industry survey across Australia, a global literature review, and a comprehensive model-based scenario analysis of the various sources of sulfate.
They found that a common coagulant added in the drinking water treatment, aluminium sulfate, can be a key contributor to the sulfate levels in sewage. Coagulants are added in the drinking water treatment process to remove turbidity from the water.
When aluminium sulfate (also known as alum) is added to the water, the aluminium binds to the particles in the water and is removed. But the sulfate is soluble and thus remains in the treated drinking water.
The researchers found that systems with low sulfate levels in the raw water, the sulfate added ion the drinking water treatment can cause significant additional sulfide formation in sewers.
By switching to sulfate-free coagulants, which do not cost a lot more than aluminium sulfate, water utilities can reduce sulfate levels in sewage and thus mitigate pipe corrosion.
UQ Vice-Chancellor and President Professor Peter Høj said Professor Yuan’s breakthrough was a good example of academia working with the industry to ensure research outcomes were implemented.
“By working with industry to deliver innovative, cost-effective solutions to a global problem, Professor Yuan has been able to create change on a massive scale, with the majority of water utilities in Australia adopting the outcomes of his research,” said Professor Høj.
According to Professor Yuan, the AWMC’s sewer research team had received more than $10 million in funding over the past decade from industry and research grants. In return, the research outcomes have delivered more than $400 million in documented savings to the Australian water industry.
“We’re persistently working to find practical solutions to improve wastewater process engineering, overall systems optimisation and infrastructure operation and maintenance,” he said.
ATSE fellowships recognise Australia's leading minds in technology and engineering, and are awarded to people who apply technology in smart, strategic ways for social, environmental and economic benefit. Fellows are drawn from academia, research, government and industry.