Contaminant removal efficiency of floating treatment wetlands

Abstract Floating treatment wetlands are new ecological infrastructures for stormwater treatment. Despite a recent proliferation in their usage, their contaminant removal efficiency e continues to draw research attention. Here, the e from idealized FTWs is numerically computed across a wide range of flow and geometric conditions while accommodating joint contributions of advection, turbulent dispersion, and vegetation removal. The emerging mathematical structure describing e bears resemblance to a simplified plug flow model and supports an empirical shallow-basin model from long-term field measurements. The present model indicates that e remains significantly influenced by a Dämkohler number that quantifies the effects of both vegetation and flow properties. The impacts on e of the underflow region and contaminant blockage on the removal mechanisms are also investigated.