基于不同基质人工湿地的“一级A”尾水提标

“Grade A”tail water standard improvement based on constructed wetlands with different substrates

针对人工湿地用于污水厂尾水提标改造中脱氮效率低、关键参数水力负荷不明确等问题,构建了砾石(湿地A)、沸石(湿地B)、沸石+黄铁矿(湿地C)为基质的3组人工湿地,通过改变水力负荷,研究不同基质人工湿地将市政污水厂“一级A”尾水提标至“准Ⅳ类水水质”的限制因素及最优运行水力负荷。结果表明,总氮(total nitrogen,TN)是限制尾水提标的最关键因素,湿地A、湿地B的最佳运行水力负荷为0.30 m/d。只有湿地C能在水力负荷≤1.80 m/d条件下稳定达到“Ⅳ类水水质”湖库TN≤1.50 mg/L的要求。综合考虑氮磷去除效果和经济用地,得出0.90 m/d是湿地C将尾水提标至“准Ⅳ类水水质”的最佳运行水力负荷,为尾水人工湿地实际工程设计、运行、管理及黄铁矿的应用提供重要参考价值。

In response to issues such as low denitrification efficiency and unclear hydraulic load of key parameters in the upgrading and reconstruction of tail water in wastewater treatment plants by constructed wetlands,three groups of constructed wetlands with gravel(wetland A),zeolite(wetland B)and zeolite+pyrite(wetland C)as substrates were constructed.By changing the hydraulic retention time(HRT),the restriction factors and optimum operation hydraulic load of upgrading the“Grade A tail water”of municipal sewage treatment plants to“Quasi-Class Ⅳ water quality”were studied in constructed wetlands with different substrates.The results indicate that total nitrogen(TN)is the most critical factor limiting tailwater elevation,and the optimal operating hydraulic load for wetlands A and B is 0.30 m/d.Only wetland C can stably meet the requirement of TN≤1.50 mg/L for Class IV water quality lakes and reservoirs under hydraulic load≤1.80 m/d.Taking into account the nitrogen and phosphorus removal efficiency and economic land use,it is concluded that 0.90 m/d is the optimal operating hydraulic load for wetland C to elevate the tail water to Class IV water quality.This provides important reference value for the actual engineering design,operation,management,and application of pyrite in the tail water artificial wetland.