Long-term effects and performance of two-stage baffled surface flow constructed wetland treating polluted river

Abstract In order to provide a reference for the ecological restoration of polluted river and technical guidance for Jialu River floodplain constructed wetlands (CWs) renovation scheme, a demonstration project that two-stage baffled surface-flow constructed wetland (BSFCW) with a total area of 7400 m 2 , hydraulic loading of 14 cm/d and substrate of high viscosity silt loam was constructed along the Jialu River floodplain in Zhengzhou city of China. Its plants configuration was a combination of emerging plants + submerged plants + floating plants + emerging plants, and it had been operated for two years. Treatment effects indicated that the mean removal rates of total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH 4 + -N), chemical oxygen demand (COD cr ), suspended solid (SS) were about 75%, 78%, 85%, 40%, 80% respectively in summer and autumn. While it decreased in winter, the average removal rates were respectively about 30%, 73%, 45%, 25%, 78%. Analysis of the results showed that the BSFCW system was performed steadily and great potential to improve the water quality, in addition, it was easy in maintenance and simpler in operation, thus, it could be considered an effective treatment option for restoring polluted river and potentially be suitable for generalizing elsewhere. This paper could also hopefully help researchers to gain a broader perspective on processes evolving in the BSFCW in future polluted river ecological restoration.