Treatment of polluted creek water by multifunctional constructed wetland in China's subtropical region

West Lake is one of the most famous lakes for sightseeing in China. It has been polluted by discharges such as domestic wastewater and agricultural runoff along the upland regions. A medium-scale pilot (MSP) of vertical/reverse-vertical flow-constructed wetland was established to treat the polluted creek water draining into this lake and to collect data for the construction and operation of a full-scale system in the future. The influent and effluent concentrations of pollutants were monitored for one year and the average removal rates of chemical oxygen demand, biochemical oxygen demand, total nitrogen, ammonia nitrogen and nitrate nitrogen were found to be 40.86%, 47.7%, 48.7%, 93% and -33.05%. Although removal rate of nitrate nitrogen was negative, its concentration in the influent remained at a low level. From the monitoring results it was seen that this constructed wetland could be appropriate for improving the quality of the polluted creek water. In addition, the constructed wetland planted with Lolium perenne and Coix lacryma-jobi reached a high biomass production bringing great economic benefits.