木屑强化生物滞留池对径流中营养物质的长期有效去除

生物滞留设施出水通常含有较多淋出的营养物质,降低了其用作景观水体补充水的价值.采用硬木屑作为生物滞留设施基质的有机成分,以降低基质中的营养物质含量,同时强化设施除氮能力.通过连续2年的现场实验,考察设施出水中污染物的含量及其变化,分析影响设施出水水质的因素,并考察营养物质减少可能造成的对植物生长的影响.结果表明,设施出水中氮(N)和磷(P)均得到有效控制,质量浓度远低于污水再生利用能够达到的出水平均质量浓度.在连续2年的运行过程中,基质中木屑降解淋出量减少,设施出水化学需氧量(COD)和总磷(TP)平均质量浓度下降至10.88和0.08 mg·L~(-1),出水总氮(TN)质量浓度没有明显变化,平均质量浓度为2.72 mg·L~(-1).使用发酵木屑作为基质有机组分可在减少生物滞留设施出水中有机物与营养物质淋出的同时,稳定提供设施脱氮需要的碳源,设施出水可为城市河道提供优质的补充水源.

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

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.