Floating Vegetated Island Retrofit to Treat Stormwater Runoff

A novel approach to improve retention basin water quality performance is retrofit with a floating vegetated island (FVI) to introduce wetland-like vegetation. Limited studies have identified the capability of pollutant removal of FVI but none have dealt with treatment efficiency at a full scale specifically for stormwater.

This paper presents the expected different pollutant removal pathways induced by a FVI as well as the monitoring methodology used to assess the overall efficiency of a retention pond with a FVI compared to an unvegetated one. Sampling and analysis methodologies to quantify the magnitude of each pollutant removal pathway are explained and a preliminary analysis of plant roots from a well established FVI is presented. The results show that the roots hanging in the water below the FVI can host microorganisms. Furthermore they become covered by deposits (clay and iron plaques) which have sorption capacity for elements like sulphur and zinc. Preliminary analysis confirms that roots surfaces below the FVI can act as a sink for pollutants.