The University of Queensland (UQ) has developed a technology to help control corrosion in sewers, as well as manage sewer odour.
Researchers from the UQ Advanced Water Management Centre (AWMC) developed the technology which uses free nitrous acid to remove biofilms that coat to the inner surfaces of sewer mains.
Lead researcher and AWMC Director, Professor Zhiguo Yuan, said the technology was developed with municipal wastewater collection systems in mind.
“Corrosion and odour problems in sewers are most often caused by sulphate-reducing bacteria in sewer biofilms that produce hydrogen sulphide,” Professor Yuan said.
“Hydrogen sulphide is released into the atmosphere above the wastewater, causing odour problems, and is converted by sulphide-oxidising bacteria into sulphuric acid, which is corrosive to concrete sewer pipes.
“Sewer networks can include many kilometres of sewer pipe and various topographical elements, such as rising mains.
“These can create ‘hot spots’ where sulphate becomes sulphide, accelerating corrosion and causing odours, leading to community complaints.”
Professor Yuan said most existing treatments for managing sulphide-related problems in sewers involve sewer pipe lining, sewer air ventilation with follow-on air treatment and round-the-clock chemical dosing, resulting in high operating costs.
USP general manager, Tom Walkosak, said the technology could help solve an ongoing multi-billion-dollar problem for water utilities.
“This technology is different from existing treatments because it is delivered intermittently, provides longer duration control and effectively stops the production of hydrogen sulphide at its source,” Mr Walkosak said.
“It is highly effective, can be used in sensitive environmental areas or to treat smaller lines, and offers water utilities the opportunity to make significant reductions to their maintenance costs.
“According to the Water Infrastructure Network, the total annual cost of hydrogen sulphide corrosion in the US sewer network in 2000 was $US13.75 billion.”
UQ commercialisation company UniQuest has negotiated an exclusive licence agreement for the technology with USP Technologies, an Atlanta-based provider of chemical treatment programs for water and wastewater applications.
UniQuest Chief Executive, Dr Dean Moss, said the first Australian field trial of the technology was undertaken by UQ in 2012 in collaboration with USP and the Gold Coast City Council, followed by a second field trial in partnership with USP and Unitywater at Scarborough in Moreton Bay in 2014.
“These trials led to further refinement of the technology and ongoing field tests in the US,” Dr Moss said.
“It’s always exciting to see tangible results from industry engagement, but this is a fantastic example of universities and companies working together to produce a solution to a costly problem and then to refine that solution.”
