Improvement of water quality by emergent vegetation restoration in Chaohe river

A field experiment for river restoration was carried out in Chaohe river, a second largest river in Beijing, China. The study site with an area of 2, 800 m² was set up in the downstream zone of Miyun reservior. Multiple water quality parameters, including pH, TN, TP and COD, were used to evaluate the removal efficiency of the river restoration project. The results showed that pH of water changed in a narrow rang from 6.98 to 7.11 during the investigation period. The pH value had no significant difference between the planted treatment and the non-planted control. From April to October, 2009, TN and TP of water were reduced regularly. At the beginning, the reduction tendency was sharp, then became flat. The mean removal efficiencies of TN and TP were 5.8% and 16%, respectively. No significant difference existed between the TN content of the planted treatment and that of the control. Contrarily, the TP content difference was significant between the two treatments. The maximum removal efficiencies were 30.2% on COD, 7.8% on TN and 25.5% on TP for the aquatic plant-based remediation system. This study suggested that the restoration of aquatic vegetation could potentially be used for mitigating the degradation of water quality and improve water carrying capacity.