Study on Water Purification Efficiency and Influencing Factors of a Constructed Wetland in Jiaxing

Abstract

Constructed wetland plays an important role in the removal of micro-polluted water pollutants in urban water sources. However, the water purification capacity and influencing factors of the constructed wetlands still need to be explored. This study monitored the turbidity, ammonia nitrogen (NH3-N), dissolved oxygen (DO), and chemical oxygen demand (COD) at the water inlet and outlet of Shijiuyang Wetland in Jiaxing City from 2019 to 2021. The results showed that the turbidity and the wetland turbidity removal rate stayed high. The DO couldn’t meet national standard III for surface water during the high temperature time in summer, and NH3-N and COD are stable within national standard III. The partial regression analysis shows that the addition of chemicals is the most important factor affecting the turbidity. Temperature had the most important affect to NH3-N and DO, the higher the temperature, the lower the NH3-N value and the DO. The flow rate is the most important factor affecting the COD, the higher the flow rate, the lower the COD. Moreover, this paper proposes operation and maintenance improvement measures for the problem of excessive turbidity and DO in Shijiuyang Wetland. The research results are conducive to improving the understanding of water security in the Yangtze River Delta region.