The Challenge
The Etiwanda Wetlands in Mildura form part of an established storm water catchment and treatment system. The wetlands provide a natural treatment of water using a sedimentation pond and wetland area. A portion of this treated water could be used for local irrigation purposes. This project tested the efficiency of floating reed beds in improving water quality for this purpose.
The Project
Floating Islands Australasia partnered with The Mildura Shire Council to install 159 square metres of floating reed beds in the sedimentation pond of the Etiwanda Wetlands system. Floating reed bed islands have proven efficacy in treating wastewater from sewerage effluent and a key aim in this project was to establish this system as a viable treatment of stormwater effluent. The Etiwanda Wetlands system provided an
excellent test location as it handles local stormwater runoff before its discharge into the Murray River. A suite of water quality parameters were selected to establish benchmarks and to monitor improvements in water quality following installation of the reed beds.
The Outcome
Prevailing drought conditions during the project led to sporadic rainfall. Consequently, establishing the efficacy of the reed bed system via comparison of water quality measures did not return statistically significant improvements. While improvements in water quality were not conclusive, there were some encouraging observations. Measurements showed a drop in nutrient levels across the sedimentation pond after the floating islands were established.
The reed bed system proved effective in treating algal blooms around the floating islands. Reed bed growth advanced to the stage that the biomass was sufficiently developed to gain some initial positive results from water testing. Some water recycling and cartage was carried out. However, the next step of pipelining the water to the Mildura Recreation Reserve was not feasible as too little of the wetland water could be retrieved under prevailing drought conditions.
This method of treating stormwater may be more effective than more traditional macrophyte plantings but at the close of the project, this was not yet proven.
This system continues as an ongoing experiment in treating stormwater. Prior experience shows floating island reed beds are efficient in treating waste water from sewerage effluent and Floating Island Australasia decided to continue to adapt this system for stormwater effluent applications.
