Long-Term and Effective Removal of Nutrients in Stormwater Using a Field-Scale WoodChip Bioretention System

Abstract:

The nutrients are usually leaching from the bioretention system and reducing the reusable value of stormwater for landscape water supplement. In this paper, wood chips were used as the organic component of the bioretention system to reduce the medium nutrient content and to increase the nitrogen removal capacity of the system. The pollutant concentrations in the effluent, the factors affecting the effluent quality, and the nutrients reduction impact on plant growth were analyzed. The results show that the mass concentrations of nitrogen (N) and phosphorus (P) in the effluent are much lower than that of the wastewater reclamation, indicating that both N and P are effectively controlled. The amount of wood chips in the medium is decreased in the continuous operation for two years, while the average mass concentrations of chemical oxygen demand (COD) and total phosphorus (TP) in the effluent are decreased to 10.88 and 0.08 mg?L-1, respectively. The mass concentration of total nitrogen (TN) does not change significantly with the average value of 2.72 mg?L-1. Using wood chips as the medium organic component can stably provide the carbon source for the denitrification, while reducing the organic matter and nutrients concentration in the effluent. The effluent of the woodchip bioretention system can provide high quality supplementary water for urban rivers.