Australians are some of the highest water consumers per capita in the world. Australia’s natural water resources are continuing to dry out and exceed sustainable extraction limits. As the population of Western Australia continues to grow so too does the pressure on current water resources and water demand. Seeking alternate water sources as a solution for fit-for-purpose end uses will help to reduce WA’s reliance on mains water, reduce discharge of wastewater into sewers and obtain sustainability in the water industry.
This project focuses on the pre-commissioning stages for the Timbers Edge Greywater Treatment System which was built in 2004, but never commissioned due to bankruptcy of the land developer. The system treats and recycles the residential greywater to irrigate the 1.8ha of public open spaces at Timbers Edge via subsurface dripline irrigation. The treatment system has the design capacity to treat 48kL/day of greywater (excluding kitchen) from all residential homes in the Timbers Edge Residential Village. There are currently around 210 homes built, with a maximum of 260 lots. The collected water passes through a lint filter, four constructed wetlands (totalling a treatment area of 1,105m2), two 10kL Envirophos tanks (which acts to absorb excess phosphorous), and a chlorine dosing system before being used for irrigation at a design application rate of 17ML per annum.
Ground-truthing was completed to verify the design documentation with the in-situ installation and a number of needed repairs and rectifications were identified. Subsequently, all repair and maintenance issues concerning the Timbers Edge Greywater Treatment System have been rectified and resolved in line with the WA Department of Health and AS1547 requirements. A chlorine dosing system has been installed to the irrigation tank’s pump. The constructed wetlands will require planting of native species in autumn of 2017 to give the seedlings the best chance of survival after rehoming. The species selected to be replanted are Schoenoplectus validus and Baumea articulata. In order for this system to pass its commissioning stage, a Recycled Water Quality Management Plan is required to be submitted to and approved by the Department of Health and the preliminary documentation has been drafted.
There is still more research required into the field of greywater treatment through constructed wetlands and also the treatment role which native plants provide; future research recommendations are listed in this paper
