Field-Scale Constructed Floating Wetland Applied for Revitalization of a Subtropical Urban Stream in Brazil

Abstract

Constructed floating wetland (CFW) is an ecotechnology used to improve water quality using emergent macrophytes on a floating mat structure. The goals of this research were to design and evaluate a low-cost field-scale CFW for revitalization of a polluted lentic section of an urban stream, located in the subtropical coastal region of South Brazil. To attain these goals (i), the design parameters were selected from field-scale applications in the literature, and (ii) the influence of the meteorologic and hydraulic data over the CFW performance to improve water quality were analyzed during five months. Macrophyte leaves grew 1 cm·day−1. Biochemical oxygen demand (BOD) (72%), total phosphorus (TP) (52%), turbidity (53%), total solids (TS) (60%), dissolved oxygen (DO) (39%) and water temperature (WT) (0.4 °C) showed statistically significant reductions. The HRT was sufficient to reduce dissolved carbonaceous organic matter. HRT and solid particles-related parameters showed reductions both on high and low HRT. The resulting loading rates can be used for the design purposes of similar CFW field applications. The CFW promoted water quality improvement, attractiveness of fauna, temperature regulation, carbon sequestration, and is a potential ecotechnology towards the depollution of river basins in urban areas.