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Floating Treatment Wetland (FTW) systems are purpose-built devices designed to replicate the water treatment processes that occur in and around naturally occurring floating vegetated islands. FTWs can be used to improve the water quality of water storage ponds by contributing to water treatment processes through adhesion, filtration, nutrient uptake (direct use by plants), and sequestration. This paper presents the results of a twelve-month investigation into the pollution removal performance of a FTW receiving stormwater runoff from a 7.46 ha urban residential catchment. As anticipated, there was a high degree of variation in FTW treatment performance between individual rainfall events. Overall pollution removal performance was calculated to be 80% for Total Suspended Solids (TSS), 53% for Total Phosphorous (TP), and 17% for Total Nitrogen (TN) for a FTW footprint of 0.14% of the contributing catchment. TSS and TP concentrations were found to be significantly reduced after FTW treatment. The minimum FTW footprint to catchment size ratio required to achieve regulated nutrient removal rates was calculated to be 0.37%. Sum of loads calculations based on flow resulted in pollution load reductions of TSS 76%, TP 55%, and TN 17%. Pollution treatment performance (particularly for TN) was found to be affected by low influent concentrations, and highly-variable inflow concentrations. The study demonstrated that FTWs are an effective treatment solution for the removal of pollution from urban stormwater runoff.

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Field monitoring of a stormwater treatment train has been underway between November 2013 and May 2015 at a townhouse development located at Ormiston, southeast Queensland. The research was undertaken to evaluate the effectiveness of a 200 micron mesh pit basket in a 900 square format and an 850 mm high media filtration cartridge system for removing total suspended solids and nutrients from stormwater runoff. The monitoring protocol was developed with Queensland University of Technology (QUT), reflecting the Auckland Regional Council Proprietary Device Evaluation Protocol (PDEP) and United States Urban Stormwater BMP Performance Monitoring Manual with some minor improvements reflecting local conditions. During the 18 month period, more than 30 rain events have occurred, of which nine comply with the protocol. The Efficiency Ratio (ER) observed for the treatment devices are 32% total suspended solids (TSS), 37% for total phosphorus (TP) and 38% total nitrogen (TN) for the pit basket, and an Efficiency Ratio of 87% TSS, 55% TP and 42% TN for the cartridge filter. The performance results on nine events have been observed to be significantly different statistically (p < 0.05) for the filters but not the pit baskets. The research has also identified the significant influence of analytical variability on performance results, specifically when influent concentrations are near the limits of detection. OPEN ACCESSWater 2015, 7 4497

Field testing of a proprietary stormwater treatment device was undertaken over 14 months at a site located in Nambour, South East Queensland. Testing was undertaken to evaluate the pollution removal performance of a Stormceptor treatment train for removing total suspended solids (TSS), total nitrogen (TN) and total phosphorous (TP) from stormwater runoff. Water quality sampling was undertaken using natural rainfall events complying with an a priori sampling protocol. More than 59 rain events were monitored, of which 18 were found to comply with the accepted sampling protocol. The efficiency ratios (ER) observed for the treatment device were found to be 83% for TSS, 11% for TP and 23% for TN. Although adequately removing TSS, additional system components, such as engineered filters, would be required to satisfy minimum local pollution removal regulations. The results of dry weather sampling tests did not conclusively demonstrate that pollutants were exported between storm events or that pollution concentrations increased significantly over time.

Stormwater has been identified as a pathway for microplastics (MPs), including tire wear particles (TWPs), into aquatic habitats. Our knowledge of the abundance of MPs in urban stormwater and potential strategies to control MPs in stormwater is still limited. In this study, stormwater samples were collected from microlitter capture devices (inlet and outlet) during rain events. Sediment samples were collected from the material captured in the device and from the inlet and outlet of a constructed stormwater wetland. MP (>25 μm) concentration in stormwater varied across different locations ranging from 3.8 to 59 MPs/L in raw and 1.8 to 32 MPs/L in treated stormwater, demonstrating a decrease after passage through the device (35–88% removal). TWPs comprised ∼95% of all particles, followed by polypropylene (PP) and poly(ethylene terephthalate) (PET). The concentration of TWPs ranged from 2.5 to 58 TWPs/L and 1450 to 4740 TWPs/kg in stormwater and sediment, respectively. A higher abundance of MPs was found in the sediment at the inlet of the constructed wetland compared to the outlet, indicating a potential role of wetlands in removing MPs from stormwater. These findings suggest that both constructed wetlands and microlitter capture devices can mitigate the transport of MPs from stormwater to the receiving waterways.

Abstract:Hydrocarbon spills and management in the marine environment are of significant environmental and public health concern and the subject of many research projects. In freshwater environments the treatment and management of hydrocarbons from point and diffuse sources appears less well investigated. For hydrocarbon treatment technologies introduced into the European market, they must be tested and comply with the requirements of the European Standard EN BS858-1-2002. This Standard requires laboratory testing of full-scale models. Testing of several models of a hydrocarbon capture technology was performed in accordance with EN BS858-1:2002 at the HR Wallingford, United Kingdom (UK) and repeated at the University of South Australia (UniSA) laboratories. The results of the laboratory testing demonstrated compliance with the Standard's Class 1 criteria of less than 5 mg/L of hydrocarbons in the effluent. Field testing of several installations of the hydrocarbon capture device in Australia has also confirmed outlet concentrations conforming to the Class 1 requirement of <5 mg/L hydrocarbons.