ABSTRACT An urban lake downstream of an acidic-wallum wetland has floating wetlands installed to help maintain water quality. Samples have been collected over a period of seven years. Physico-chemical testing has shown that the water quality improves as it passes through the overall system. Floating treatment wetlands (FTWs) have the advantage of providing water quality improvement with a smaller areal requirement than that of traditional constructed wetlands, resulting from the suspension of aquatic macrophyte roots in the water column, instead of emergent stems. FTWs have been monitored at Bribie Lakes, in Southeast Queensland, since 2015, in a unique hydrologic system comprising a large upstream wallum (acidic freshwater) catchment, with urban residential immediately adjacent to the lakes. Event monitoring and controlled, pump testing observed average pollutant reductions of 70%–95% for total suspended solids, 59%–93% for total phosphorus, and 14%–45% for total nitrogen. Over the longer term, the recirculating lake and FTW system has maintained pollutant levels and ecosystem health, satisfying Queensland regulatory water quality objectives for urban lakes. Condition assessment of the original FTW after ten years has observed a healthy, heterogeneous plant community distinct from the original monoculture.
Drapper et al. (Thu,) studied this question.