A high-flux constructed wetland for tertiary treatment of brackish wastewater treatment plant effluent: Process performance and influence factors

With the scarcity of water resources and environmental degradation of water bodies, tertiary treatment of wastewater and brackish water have become necessary in countries like China. Operational data from a constructed wetland (CW), treating an average flow of 27 thousand m3/d of secondarily-treated brackish wastewater, is analyzed in this study. At a salinity level of 2-8g/L (as Cl−), and an average hydraulic loading rate (HLR) of 1.08 m/d, the high-flux CW system had an average removal rate of 20.43% and 65.16% for NH4+-N and COD respectively, while tertiary treatment of total phosphorus (TP) and total nitrogen (TN) was less successful, indicating a background concentration in the system. Correlation analysis was done to investigate the influences of HLR, rainfall, temperature and chloride concentration on the treatment performance. Kinetic model fitting was done to determine reaction coefficients.