Experimental designs of field-based constructed floating wetland studies: A review

A Constructed Floating Wetland (CFW) is a relatively recent innovation in stormwater treatment and is a hydroponic device that is designed to move up and down with changing water levels as urban runoff enters a stormwater retention pond. This floating capability is designed to improve the pollutant removal efficiency of the CFW. The CFW studies undertaken so far have produced encouraging results under a range of conditions such as system size, inflow pollutant concentrations, climatic conditions, and coverage ratio. However, these results have not yet been drawn together to better understand how the various design features of a CFW influence its performance. This paper reviews the available field investigations with the aim of helping guide and improve the experimental designs and installations of future CFW installations. This in turn will improve the knowledge and acceptance of these recently developed stormwater treatment systems. One of the findings of this review was that using a percentage coverage design approach may not be as effective as improving the design efficiency. Understanding the hydraulics of the entire pond and CFW system is also critical to effective design. The review also found that the performance evaluation of future CFW installations would be improved if consideration is given to including both baseline monitoring and experimental controls.