东北屯人工湿地污水处理系统的设计与应用

Design and Application of Waste Water Treatment System of Constructed Wetlands of Dongbeitun Village

从人工湿地规划设计的角度出发,依据地表水环境质量标准,以现有废弃渠道、坑塘为基础,通过开挖回填、调坡整治、基础压实等措施,建立了衡水市故城县郑口镇东北屯人工湿地污水处理系统。该系统包括前池、沉淀池、垂直流湿地、生态塘湿地、表面流湿地和蓄水池。探讨了人工湿地渗滤处理系统的主要设计参数;采用Freundlich公式、Kikuth公式和有关经验公式,分析了渗滤系统对污水生化需氧量、总氮、总磷的处理效果;研究了处理系统中垂直流、生态塘渗流和表面流的污染物去除率;针对水质、水量和环境温度3个主要因素进行了敏感性分析,给出了渗滤系统敏感性分析结果,并与湿地去污实验结果进行了比较,变化趋势基本一致。研究结果表明:①人工湿地规划设计应进行敏感性分析,以便更好地制定系统的控制运行预案;②湿地出水口高度应能够调节,以便控制湿地床体的"饱和"状态,充分发挥湿地渗滤、微生物的作用;③北方人工湿地的去污效果,受季节性影响较大,应采取塑料大棚或秸秆覆盖进行保温,在冬季,塑料大棚能够使湿地温度维持在13.3℃以上,日照时间基本不减少,湿地植物可正常生长;④当进水的生化需氧量浓度超过75mg/L时,应减小进水负荷,控制污染物总量在湿地高效处理范围内;⑤当日污水处理量超过3000m3/d时,应提高集污渠、前池、沉淀池的临时蓄存水位。

Design and construction of waste water treatment system of constructed wetlands is an important re- search topic in giving full play to the natural ecological recovery ability. The technology of using constructed wetlands to treat waste water is an effective way to realize waste water reuse, to control non-point source pol- lution and to protect ecological environment. As the living standards of urban and rural residents steadily im- proved, many rural small and medium-sized enterprises and aquaculture industry develop rapidly, so the raised the question is how to protect and manage the environment. To solve this problem, we should take full advantage of the rural discarded channels and ponds to waste water treatment system of construct wetlands. The waste water treatment technology of constructed wetlands has the features of high efficiency, easy opera- tion, low investment, low consumption, extensive applicability and sustainable development. From the point of view of constructed wetlands planning and design, a waste water treatment system of constructed wetlands was established according to the surface water environment quality standards. The system was based on the existing discarded channels and ponds. Many technical measures, including excavation and backfill, side slope treatment and foundation compaction, the waste water treatment system is constructed. This system in- cludes forebay, sedimentation basin, vertical flow wetland, ecological pond wetland, surface flow wetland and impounding reservoir. The main design parameters of the waste water treatment system of constructed wet- lands were discussed. The Freundlich equation, Kikuth equation and many other empirical equations were ad- opted to analyze the treatment effects of biochemical oxygen demand, total nitrogen and total phosphorus in the infiltration system. The pollutant removal rates of the vertical flow wetland, ecological pond wetland and surface flow wetland were also analyzed in this paper. Three main factors including water quality, water quan- tity and ambient temperature were considered in sensitivity analysis. The sensitivity analysis results of the ill- tration system were given in this paper, and these results were in good agreement with the measured results of the wetland decontamination test. The results showed that sensitivity analysis is necessary in planning and de- signing a constructed wetland in order to make a proper control operation plan for the system; the outlet height of the wetland should be adjustable so as to control the saturation status of the wetland bed, and in that case, wetland filtration and microbial role can be fully displayed; decontamination efficiency of the construct- ed wetlands in the north changes greatly as the season changes, so in winter, the wetland should be covered with vinyl houses or straw; the temperature of the wetlands will be more than 13.3 ~C if it is covered with vi- nyl houses, and the duration of sunshine will not be reduced, so the wetland plants are able to grow normally; the inflow load should be decreased when its concentration of biochemical oxygen demand is more than 75 mg/L to make sure the wetlands could treat the waste water with high efficiency; when the daily total treated waste water is more than 3 000 m3/d, temporary accumulation of the waste water sump, forebay and sedimen- tation basin should be increased. These above research results have important significance for the design and operation of the constructed wetland, and they also establish the theoretical foundation for future operation plan and safety management of the constructed wetland system.