Abstract
In this study, the effect of hybrid constructed floating treatment wetlands (FTWs) in a low-flow urban river was evaluated, and the influence radius on dissolved oxygen (DO), ammonia nitrogen (NH4+-N), and total phosphorus (TP) under different flow conditions was quantified. It was found that DO considerably increased and NH4+-N and TP decreased at the outlet after treatment with hybrid constructed FTW. The NH4+-N removal rate continued to increase to 72.03%, whereas that for TP decreased to 63.16% with fluctuation. The cloud picture of the influence radius showed that when DO ≤ 3 mg/L, Rflow ≈ 5 m, Rstill ≈ 3 m, and when DO > 3 mg/L, Rflow = Rstill ≈ 8 m. For NH4+-N under flow conditions, Rflow ≈ 8 m, whereas under still conditions when NH4+-N ≤ 7 mg/L, Rstill ≈ 5 m, and when NH4+-N > 7 mg/L, the concentration changes were not considerable. When TP ≤ 0.4 mg/L, Rflow ≈ 5 m, and when TP > 0.4 mg/L, Rflow ≈ 8 m; while under still conditions, when TP ≤ 0.8 mg/L, Rstill ≈ 5 m, and when TP > 0.8 mg/L, the concentration changes were not remarkable. Various water quality parameters and water flow affected the radius of influence of FTW on DO, NH4+-N, and TP at the spatial level. For the same water quality parameter, the influence radius in the flow state was larger than that in the still state (Rflow ≥ RStill). This study evaluated treatment efficiency of the hybrid constructed FTW in urban rivers and provided guidance and support for FTW deployment in future.
Published Version
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