Wastewater plant improvements clean up Oraka
At the NZ River Awards held late last year, the Oraka Stream was awarded the most improved stream in the Waikato region and was the second most improved stream in the North Island!
The awards identified rivers in nine regions across New Zealand that had shown meaningful and significant improvement over the past decade as a result of deliberate action to bring about water quality improvement.
The awards were based on a review of regional councils' monitoring of long term trends of E.coli data at over 300 water quality monitoring sites throughout New Zealand. E.coli is an indicator of pathogens associated with faecal contamination of rivers and therefore an important indicator of water quality. The main sources of faecal contamination in New Zealand are wastes from humans and farm animals such as sheep and cows.
"Improvements to Council's wastewater treatment plants in Putāruru and Tīrau which are located upstream of the water quality monitoring site on the Oraka Stream were a significant contributor to the 7.3% improvement in the quality of the Oraka Stream," said Andrew Pascoe, Council's Services Manager.
"Our Council has made substantial upgrades to the Putāruru wastewater treatment plant, particularly targeted at the final disinfection of the wastewater," continued Mr Pascoe.
"The 2001 upgrade at Putāruru consisted of refurbishing and reconfiguring the existing plant, adding additional tertiary treatment in terms of a final clarifier, UV disinfection and a diffuse stream discharge filter," explained Colin Cranfield of Harrison Grierson, the engineering firm that was contracted for the project. "In 2007 a further upgrade was undertaken to the plant to install a drum filter before the UV disinfection system to improve the removal of suspended solids and hence the performance of the disinfection process."
"The Tirau Sewage Treatment Plant was commissioned in 2006 and was New Zealand's first ever municipal membrane bioreactor (MBR) sewage treatment plant," continued Mr Cranfield. "MBR is the combination of an intensive biological treatment process and the use of advanced membrane technology for filtration. This process produces a disinfected effluent that removes viruses and practically all bacteria."
It is likely that other mitigation measures from improved farming practices, increased riparian protection and advances made by other industries to their discharge into the stream have also contributed to the improved water quality of the Oraka Stream. Ends: words: 380
