Modeling the Effect of Plants and Peat on Evapotranspiration in Constructed Wetlands

[摘要] Evapotranspiration (ET) in constructed wetlands (CWs) represents a major factor affecting hydrodynamics and treatment performances. The presence of high ET was shown to improve global treatment performances, however ET is affected by a wide range of parameters including plant development and CWs age. Our study aimed at modelling the effect of plants and peat on ET in CWs; since we hypothesized peat could behave like the presence of accumulated organic matter in old CWs. Treatment performances, hydraulic behaviour, and ET rates were measured in eight 1 m2CWs mesocosm (1 unplanted, 1 unplanted with peat, 2 planted withPhragmites australis, 2 planted withTypha latifoliaand 2 planted withPhragmites australiswith peat). Two models were built using first order kinetics to simulate COD and TKN removal with ET as an input. The effect of peat was positive on ET and was related to the better growth conditions it offered to macrophytes. Removal efficiency in pilot units with larger ET was higher for TKN. On average, results show for COD ak20value of 0.88d-1and 0.36d-1for TKN. We hypothesized that the main effect of ET was to concentrate effluent, thus enhancing degradation rates.

[学科分类] 工业化学