The effectiveness of floating wetlands in treating stormwater pollutants from urban runoff was investigated in this study. The monitoring site for the Floating Treatment Wetland (FTW) is located within an ongoing residential development off Crystal Avenue, Bongaree, on Bribie Island, Queensland. The FTW system covers approximately 1.7% of its accommodating lake and receives runoff from an external developed catchment of 10 hectares. The system was assessed through event based sampling and a simulated flow event at two different flow rates (100L/s and 200L/s). Registry problems with the flow meter resulted in six out of nine event based samples and all twenty-three simulated flow samples being time weighted rather than flow weighted. The event based samples produced average percent removal efficiencies of 3.9%, 0% and -1.7% for Total Suspended Solids (TSS), Total Phosphorus (TP) and Total Nitrogen (TN) respectively, as a result of low influent pollutant concentrations and flow rates. The simulated event produced average percent removal efficiencies of 95.6%, 89.5% and 41.1% for TSS, TP and TN for the 100L/s samples and 68.1%, 57.5% and 12.9% for the 200L/s samples. Greater percentage removal efficiencies are likely due to higher influent pollutant concentrations and substantial flow rates.
Submitted in the fulfilment of the requirements of the degree of Bachelor of Engineering (Civil Engineering), University of the Sunshine Coast, 2014.