Research on the water quality evaluation and nutrients removal efficiency of ecological ditch

Ecological ditches have a good effect on improving polluted runoff, and their removal efficiency and construction length play a decisive role in the implementation of ditches. Based on the field monitored data of Wulihu River, the water quality was evaluated by the comprehensive index method. Then, the removal efficiency of nutrients in the ecological ditch was studied, and the optimum lengths of ecological ditch for main pollutant removal were obtained. The results showed that the water quality gradually became better along the Wulihu River and the removal efficiency of chemical oxygen demand was the largest (60.52%). The optimum ecological ditch length for total nitrogen removal was 6.05 km and that of nitrate nitrogen, nitrite nitrogen, chemical oxygen demand were 29.45 km, 5.61 km and 6.92 km, respectively.