| At present China faces the problem of the shortage of water resources, water environmental pollution and the degeneration of aquatic ecosystem. Constructed wetland, a kind of ecological engineering, is an effective and suitable means for controlling water body pollution, improving water quality and recovering water useful function for our country national condition, and has been widely applied in sewage treatment. Although constructed wetland has been used to purify polluted water, little research has been done on microbial food chain of wetland system. While most of constructed wetland systems have imperfect microbial food chain, which contributes to limit processing power. Based on constructed wetland project of Wujiadui along the Dianchi Lake in Kunming city in this paper, the sewage treatment project summarized and analyzed in this system:the complete microbial food chain was cultivated in the park water body, which compensated the slow water improvement using aquatic plants in the wetland and resolved the defect of imperfect animal food chain in sewage treatment, and improved sewage treatment effect of wetland. The paper chose the complete microbial food chain in the park water body of Wujiadui constructed wetland as a research object. The purification efficiency of sewage treatment project in this wetland system, the influencing factors, operation conditions and maintenance and management were analyzed through successive monitoring of operation conditions in a long-term in our research. The results are important significance for the design of constructed wetland, operation, management and development, innovation and perfection constructed wetland. The project provides a successful example on improving and protecting water environment along the Dianchi Lake.The following results were proved through the experimental study:(1) The effect of sewage treatment was very satisfactory in constructed wetland and the effluent quality met the fifth level criteria specified in Environmental Quality Standards for Surface Water (GB 3838-2002)(2) The complete microbe food chain was cultivated in the park water body:sewage—contaminant (organisms)—fungi, alga(e)—protozoa—metazoan—fish and prawn—clear water. The first microscope appeared in the wetland were bacteria of microorganisms, such as Cyanoobacteria,actinomycetes and so on, the number of algae in the constructed wetland was the largest, including Chlorella,Naicula Microcystis aeruginosa, Scenedesmus, Peridiniaceae, Tribonema and so on, the main algae were Cyanobacteria and Chlorella. As the process moved forward, Protozoa and metazoan gradually appearance after algae appeared. Protozoa were mainly Nematodes, Vorticella and Rotifer; metazoan were mainly Daphnia pulex, Cyclops, fish and prawn were crayfish, Shrimp, small carp and so on.(3) The removal efficiency of various pollutants in different seasons was:summer> spring>autumn> winter. The removal rate of CODcr, BOD5, TP, NH3—N, SS were 44.78%, 74.77%,43.41%,33.49%,76.76% respectively.(4) The paper monitored pH, DO, temperature in the influent and effluent of wetland system, and the result indicates:the pH of influent water was higher than that in effluent water; the DO concentration of influent water was higher than that in effluent water; the temperature of effluent water was higher than it in the influent water. The influencing factors of temperature, hydrological load, Pollution load, detention time on wetland system were also analyzed.(5) The paper analyzed the ecological and environmental, economical and social benefits of wetland system. The project obtains great ecological and environmental, economical and social benefits, and provides a successful example on improving and protecting water environment along the Dianchi Lake.(6) The paper researched the operation and management of wetland system, and the result indicated that the perfect operation and management were important conditions for stable running of Wujiadui Constructed Wetland... |
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