农田排灌水湖滨带湿地处理系统的设计与运行

Design and Operation of Lakeside Wetland for Treatment of Irrigation and Drainage

依据背景调查资料对滇池东岸王家庄湿地处理系统进行了设计并对工程的经济性进行了分析。本工程自2002年8月开始投入运行,运行效果表明,湿地对于总氮、氨氮、总磷和COD的负荷削减量分别为5.6、1.9、0.5、114.7t·hm-2·a-1。本工程的总投资和运行费均低于传统活性污泥法。

Wangjiazhuang lakeside wetland was located to the east of the Dian chi Lake, with an area of 12 000 m2, length of 300 m, and averaged width of 80 m . It was designed to treat wastewater from five ditches from the upstream. Irrig ation and drainage were an important component of the Dianchi Lake's non-point pollution source. Various natural plants were selected to be used as indicators in the wetland, including Zizania caduciflora, Phragites austrails, Acrous cala mus, Willow tree, Lotus root and Magic taro. The design and the economic analysi s of the wetland were made according to site investigation. The contaminant load mainly came during rainy season, from May to September, due to a large inflow d uring the period. The flow and the influent pollutant exhibited significantly da ily and seasonal variance. Though acreage per ton wastewater of this wetland was larger than that of conventional activated sludge process, gross investment and operation cost of this wetland were lower than those of conventional activated sludge process. The high cost of this wetland construction was for the borderlin e construction, due to the loose ground resulted from the long-term flooded so ils near Dianchi Lake. The aim of this research was to investigate the effects o f lakeside wetland in the treatment of irrigation and drainage water used for ec ological restoration. And then it can act as a demonstration model for others to design similar lakeside wetland. Comprehensive monitoring had been in operation since August 2002. The operation result, from March 2003 to September 2003, ind icated that the averaged inflow was 674.5 m3·d-1, the total nitrogen (TN), a mmonia,total phosphorus (TP) and chemical oxygen demand (COD) of the wetland i nfluent were 5.06,1.60,0.37 and 106 mg·L-1, respectively. The monthly averag e hydraulic retention times in the wetland ranged from 0.3 to 3.7 days and the m onthly average hydraulic load from 2.7 to 36.7 cm·d-1, the average organic l oad 8.6 g COD·m-2·d-1. The TN, ammonia,TP and COD removal rate in the wetland were 53.8%, 58.4%, 68.8%and 52.4%, respectively. The TN, ammoni a,TP and COD load reduction amounts were 5.6, 1.9, 0.5 and 114.7 t·hm-2· a-1, respectively.