4种水生植物深度净化村镇生活污水厂尾水效果研究

通过设置动态模拟试验,持续进水、出水条件下分析比较了漂浮植物凤眼莲和水浮莲、沉水植物轮叶黑藻和挺水植物黄菖蒲对村镇生活污水厂(一级A标准)尾水深度净化效果,筛选出具有去污效果优势的水生植物,为优化水生植物生态修复工程技术在尾水深度净化中的应用提供依据。结果表明:经水生植物深度净化后,尾水水质得到明显改善,漂浮植物凤眼莲和水浮莲对尾水氮、磷的净化效果优于挺水植物黄菖蒲和沉水植物轮叶黑藻。试验周期内,污水厂尾水总氮、总磷和高锰酸盐指数(CODMn)平均浓度为12.22 mg?L-1、0.38mg?L-1和3.88 mg?L-1,凤眼莲、水浮莲、轮叶黑藻、黄菖蒲和对照各系统的总氮平均去除率分别为46.25%、45.74%、43.41%、38.39%和29.22%,总磷去除率分别为36.84%、34.21%、31.58%、28.95%和26.32%,CODMn去除率分别为42.27%、30.93%、32.47%、32.47%和37.89%。凤眼莲、水浮莲、黄菖蒲和轮叶黑藻生物量净增长率分别为550.5%、418.8%、210.6%和80.3%,凤眼莲生物量净增率最大。各处理系统内凤眼莲、水浮莲、黄菖蒲和轮叶黑藻对尾水氮富集量分别为7.36 g、2.33 g、5.12 g和4.46 g,对磷的富集量分别为0.60 g、0.19 g、0.33 g和0.78 g,凤眼莲富集氮能力优于另外3种水生植物,轮叶黑藻磷富集量高于另外3种水生植物。凤眼莲、水浮莲、黄菖蒲和轮叶黑藻植株吸收作用对尾水总氮去除的表观贡献率分别为15.29%、4.90%、11.17%和11.34%,对尾水总磷去除的表观贡献率分别为50.34%、17.17%、35.24%和76.34%。因此,可利用漂浮植物凤眼莲和沉水植物轮叶黑藻立体复合种养的方式深度净化生活污水厂尾水。

The deep purification of four aquatic macrophytes for tailrace of rural sewage treatment plants

To provide theoretical basis for optimized application of restoration engineering of aquatic macrophytes in deep purification of tail water of rural sewage treatment plant, a dynamic simulation experiment with running water was conducted, in which the purifying effects of Eichhornia crassipes, Pistia stratiotes, Hydrilla verticillata, and Iris pseudacorus on effluent from sewage treatment works (STW) were compared. Based on the results, plant systems significantly improved water quality of effluent from STW. The purifying effects of E. crassipes and P. stratiotes on nitrogen (N) and phosphorus (P) in STW effluent were better than those of I. pseudacorus and H. verticillata. The average concentration of total nitrogen (TN) in STW effluent was 12.22 mg·L^-1. The average removal efficiency of TN by E. crassipes, P. stratiotes, I. pseudacorus, H. verticillata and control group were 46.25%, 45.74%, 43.41%, 38.39% and 29.22%, respectively. The average concentration of total phosphorus (TP) in STW effluent was 0.38 mg·L^-1. The average removal efficiency of TP by the five experimental treatments were 36.84%, 34.21%, 31.58%, 28.95% and 26.32%, respectively. The average concentration of permanganate index (COD_Mn) in STW effluent was 3.88 mg·L^-1. The average removal rates of COD_Mn in the five experimental treatments were 42.27%, 30.93%, 32.47%, 32.47% and 37.89%, respectively. The net growth rates of E. crassipes, P. stratiotes, H. verticillata, and I. pseudacorus biomass were 550.5%, 418.8%, 210.6% and 80.3%, respectively. The amount of TN absorbed by E. crassipes, P. stratiotes, H. verticillata, I. pseudacorus were 7.36 g, 2.33 g, 5.12 g and 4.46 g, respectively. The amounts of absorption of TP by the four aquatic plants were 0.60 g, 0.19 g, 0.33 g and 0.78 g, respectively. The ability of E. crassipes to assimilate nitrogen was stronger than the other three aquatic plants. Meanwhile, the ability of H. verticillata to assimilate phosphorus was stronger than the other three aquatic macrophytes. The apparent contribution rates of absorption by E. crassipes, P. stratiotes, H. verticillata, I. pseudacorus to nitrogen removal were 15.29%, 4.90% 11.17% and 11.34%, respectively. Meanwhile, the apparent contribution rates of absorption by the four plants to phosphorus removal were 50.34%, 17.17%, 35.24% and 76.34%, respectively. It was feasible and effective to cultivate the floating plant of E. crassipes and submerged plant of H. verticillata in different water layers and combinations in space for deep purification of STW effluent.