Cr(III) and Cr(VI) removal in floating treatment wetlands (FTWs) using Typha domingensis

Floating treatment wetlands (FTWs) are a cost-effective ecological engineering tool for the restoration of polluted water bodies. The aims of this work were to evaluate the removal of Cr(III) and Cr(VI) by FTWs using Typha domingensis, and to assess Cr accumulation and distribution in plant tissues and sediment. Treatments were 5 and 10 mg L^-1 of Cr(III), and 5 and 10 mg L^-1 of Cr(VI), with and without FTWs, and biological control (BC) with FTW without Cr addition. Both Cr species were efficiently removed from water in all treatments (Cr removal > 80%). Cr concentration in sediments of treatment without FTWs was significantly higher than in sediments of treatments with FTWs, indicating that T. domingensis was directly involved in Cr removal. In sediment, Cr was mainly bound to the organic matter in all treatments with a low risk of future release under FTW conditions. T. domingensis demonstrated tolerance to both Cr species at 5 and 10 mg L^-1 with Cr accumulated mainly in the roots in all treatments. The use of FTWs planted with T. domingensis is a suitable tool to remediate water bodies contaminated with Cr.