Lakeside Rural Sewage Treatment And Demonstration Research By Combining Artificial Wetland And Natural Wetland

Nonpoint source pollution is dominated by the rural sewage in Lake area, a large number of the sewage discharges into the lakes without treated has produced heavy effect on the eutrophication of lake. Wucheng Town has became a main research filed of Poyang Lake due to its special geographical and environment position(Gan and Xiu river’s Lake inlet).The domestic sewage of high concentration in Wucheng Town(higher salinity during the fishing period) was directly discharged into the lake by the open channel without any treatment preprocessing, which has seriously influenced the water environment near the lake.Based on the vegetable plot of lakeside area in Wu Cheng as a research field, an artificial wetland was constructed combining natural wetland in the district of lake to treat domestic sewage(the sewage with high salt in this period). The purification effect of domestic sewage pollutants of high concentration and the effect degrees from the salt were investigated by the artificial wetland add natural wetland. The change situation of pollutants concentration along the way and the microbial number changes in constructed wetlands were researched. A demonstration field of artificial wetland combining natural wetland was established to treat the high salinity domestic sewage of Wucheng Town.The result showed that there was better effect to treat the high salt sewage combining the constructed wetlands and natural wetlands in lakeside area. The concentration range of Wucheng domestic sewage pollutants were large(coefficient of variation range was 0.278-0.572), COD(150-417)mg/L 、 TN(32-162)mg/L 、NH3-N(18-149)mg/L and TP(4-21)mg/L, and the sewage with higher salinity(665.92-1564.51)mg/L on the morning from September to December, 2014; the wetland system(natural wetlands adding constructed wetlands) removal efficiency of pollutants were COD>TN>NH3-N>TP, the respectively removal rates were 66.61%、57.12%、49.16% and 41.31%, and bacteria removal efficiency was better(above 50 percentages) by artificial wetland. The temperature and dissolved oxygen were significant factors to affect the constructed wetlands total removal efficiency of pollutants. The removal efficiency of pollutants had seasonal rules, the basis was autumn > spring > winter, pollutants(except COD) emissions showed seasonal patterns: autumn > winter > spring, TP and COD removal efficiency showed autumn > spring > winter seasonal pattern. Salinity in a certain range(measured in Cl-) had great influence on the removal rate of NH3-N and TP, and weaker effect on the removal of TN, and the effect on COD removal efficiency was ignored.In General, the pollutants degradation of horizontal subsurface flow constructed wetlands is horizontal plug-flow, the removal rates of pollutants(except TP) were higher in the forepart, and followed was slower degradation, which was primarily controlled by dissolved oxygen. As for the TP, if temperature was higher, the adsorption interception by microorganism was more than that by substrates and plants; in contrast, temperature was low, the adsorption interception by substrates and plants was more than that by microorganism.