Water Purification Capacity of the Constructed Wetland to Micro-Pollution Water Source —— a Case Study in Jiaxing

Abstract

Constructed wetlands are commonly applied to improve and maintain water quality of micro-polluted water sources as a feasible and cost-effective technique. However, the purification capacity of the constructed wetland for micro-polluted water was lacking of understanding. This study collected the turbidity, ammonia nitrogen (NH3-N), nitrite nitrogen (NO2-N), total nitrogen (TN), Fe, Mn, total phosphorus (TP), permanganate index (CODMn), dissolved oxygen (DO), and chemical oxygen demand (COD) at the water inlet and outlet of Guanjinggang Wetland in Jiaxing City from 2019 to 2021. The comparisons among the pollution indicators showed that the wetland reduced the pollutions and slowed down the fluctuations of pollution indicators, except for Do, TN and COD. The removal rates are different due to the causes of pollution indicators. The partial regression analysis to different influencing factors showed the water temperature were the main influencing factor to the turbidity, NH3-N, Fe with the partial correlation of 0.447, -0.631, 0.510, respectively. Precipitation showed the highest influence on Mn with the partial correlation of 0.323. Flow showed highest influence on COD with the partial correlation of -0.339. Both flow and water temperature were the highest influence factors on No2-N, CODMn, Do and TN. However, water purification agent was not the main influence factor on any pollution indicators. The research results are conducive to improving the understanding of water security in the Yangtze River Delta region.