Project targets Oxley Creek nitrogen wastewater loads
The State Government is providing substantial funding for a pilot project to lower effluent nitrogen levels from the 30-year-old Oxley Creek Wastewater Treatment Plant.
The one-year $260,000 pilot project involves a partnership between the University of Queensland, Brisbane Water and Swedish company ANOX.
The State Government's Advanced Wastewater Treatment Technologies scheme has provided half the project funding, with project partners providing the balance.
Director of the University's Advanced Wastewater Management Centre Dr Jurg Keller said the $5.2 million Brisbane River and Moreton Bay Wastewater Management Study - the most comprehensive undertaken of the area - this year had identified nitrogen as the principal algal stimulant in Moreton Bay.
An excess of nutrients in water (such as nitrogen and phosphorus) can lead to severe environmental impacts, such as cyanobacteria (blue-green algae) outbreaks.
"The Oxley Creek Wastewater Treatment Plant discharges into Brisbane River, accounting for 15 percent of its nitrogen loading," he said.
"Lord Mayor Soorley has pledged to improve effluent quality, and this project is among a number of innovative approaches to address nitrogen concentrations."
Dr Keller said the plant itself, built to an English design, was a major bottleneck in solids separation, with the clarifiers working at capacity. There were also economic and space constraints making further plant expansion very difficult.
The pilot project for nitrogen removal uses patented plastic carriers originally developed by the Swedish company for industrial wastewater treatment. The Advanced Wastewater Management Centre approached ANOX suggesting a novel application of the carriers for domestic wastewater.
The 50mm diameter injection-moulded carriers are suspended in the wastewater and retained in the plant reactor by coarse screens. They remove nitrogen by trapping slow-growing bacteria that in turn convert the ammonium in the wastewater to harmless nitrogen gas. Since these bacteria are fixed in the biofilm on the carriers, the load on the clarifiers can be substantially reduced.
The process, which is still being commissioned, has shown very good biofilm growth on the carriers during the past two months.
Dr Keller said nitrification was developing well on the suspended carriers, and ongoing plant monitoring and optimisation would occur in the next few months.
Planning for the project's next stage is under way, with the potential to replace one of the plant's full-scale treatment stages with the new technology.
"This approach should be able to reduce capital costs for a plant upgrade by 20 to 50 percent, and this will save millions of dollars," Dr Keller said.
Other researchers involved in the project are research assistant Shane Morgan of the Advanced Waterwater Management Centre; and Dr Elisabeth v. Munch (a recent UQ graduate) and Keith Barr of Brisbane Water.
For further information, contact Dr Keller, telephone 07 3365 4727.
