基于污水处理厂尾水深度净化的漂浮植物生态治理工程模式比较研究

Comparative Study on the Ecological Treatment Mode of Floating Macrophytes Based on Deeply Purifying Tail Water of Sewage Treatment Plants

为了减少城镇污水处理厂尾水直接排放后对受纳水体造成的污染负荷和生态毒害,应该进一步的深度处理尾水。利用漂浮植物水葫芦(Eichhornia crassipes)和水浮莲(Pistia stratiotes),构建两种三级串联净化塘生态治理工程模式深度净化城镇污水处理厂尾水,即单一种养水葫芦模式和水葫芦、水浮莲组合种养模式。通过监测净化塘内漂浮植物生物量及水体氮、磷等指标变化,研究两种不同治理模式对尾水的净化效果,以期为漂浮植物深度净化污水处理厂尾水提供合适的生态工程模式与理论依据。结果表明:两种治理模式下,漂浮植物生长迅速,一级净化塘漂浮植物单位面积平均生物量最高,三级净化塘最低;尾水pH和DO浓度小幅度下降;尾水氮、磷浓度沿着水流流程方向逐渐降低,尤其是一级和二级净化塘对尾水中氮、磷的削减效果明显;2015年单一种养水葫芦模式下,尾水TN和TP平均质量浓度分别由10.62 mg·L^-1和0.38 mg·L^-1降至3.07 mg·L^-1和0.12 mg·L^-1,去除率为71.06%和68.42%;2016年缩小工程规模,采用水葫芦、水浮莲组合种养模式时,尾水TN和TP平均质量浓度分别由13.13 mg·L^-1和0.42 mg·L^-1降至1.26 mg·L^-1和0.12 mg·L^-1,去除率为90.37%和70.53%。综合分析,水浮莲、水葫芦组合种养模式,不仅节约工程用地面积,同时对尾水的净化效能更佳,每组合种养5-6 m2即可处理1吨一级A尾水至地表Ⅴ类水标准,适合用于深度净化污水处理厂尾水。

The tail water of sewage treatment plants need to be further purified for reducing the pollution load and the eco-toxicity.Making full use of the Eichhornia crassipes and Pistia stratiotes,two kinds of three-level series purification pond ecological treatment engineering modes were constructed to deeply purify the tail water of urban sewage treatment plant,namely,single cultivation mode of Eichhornia crassipes and combination cultivation mode of Eichhornia crassipes and P.stratiotes.Aims to provide the suitable mode for ecological treatment engineering and to afford a theoretical guidance on deeply purifying tail water by the floating macrophytes,the treatment effect on tail water by these two modes were researched by monitoring,the parameters of plants like biomass,N and P content in tail water.The results revealed that the floating plants grew rapidly in both modes,and the average biomass in per unit area of floating plants in the first purification pond was the highest,while that in the third purification pond was the lowest.The pH and DO concentration of tail water showed a small decline.The concentration of N and P in tail water decreased gradually along the flow direction,and decreased obviously especially in the first and second purification ponds.In 2015,the average concentration of TN and TP in tail water decreased from 10.62 mg·L^-1 and 0.43 mg·L^-1 to 3.07 mg·L^-1 and 0.12 mg·L^-1 respectively by the mode of single planting Eichhornia crassipes,with removal rate of 71.06%and 68.42%respectively.When the scale of the project was reduced in 2016,the average concentration of TN and TP in tail water decreased from 13.13 mg·L^-1 and 0.42 mg·L^-1 to 1.26 mg·L^-1 and 0.12 mg·L^-1 respectively under the combination planting mode of Eichhornia crassipes and P.stratiotes,and the removal rate was 90.37%and 70.53%.To summarize,the combination planting mode of Eichhornia crassipes and Pistia stratiotes,not only save land area,but also has better purification effectiveness of tail water.It changed the water quality of 1 ton tail water from A level toⅤstandard of surface water through combination planting these two plants about 5 to 6 square meters,which is suitable for deep purification of tail water of sewage treatment plants.