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With China's rapid urbanization, rural development, rural sewage emissions is growing, high COD, high N content of sewage water pollution caused by emissions from a large number of issues become increasingly prominent. Has a large amount of rural sewage, emission dispersion, high pollution levels, water quantity and quality changes, away from large municipal wastewater treatment plant outfall network and other characteristics, generally without any treatment into nearby rivers and lakes, causing serious environmental pollution. Rural sewage pollution of natural water has become an important factor for the characteristics of rural sewage water purification process miniaturization has become urgent. Wetland water purification system due to simple process, low energy consumption, easy to disperse construction and management advantages, especially for China's vast rural areas and small towns sewage treatment status, becoming rural sewage treatment process is one of the best. Constructed wetlands for nitrogen removal rely mainly on microbial ammonification, nitrification and denitrification, which are mainly ammonification and nitrification in aerobic environment, while denitrification is dependent on anaerobic conditions to complete. Traditionally constructed wetland due to structural constraints, can not itself provide both aerobic and anaerobic conditions, a single type of constructed wetland TN removal is often not high, generally between 40% -55%. To fundamentally solve this problem, the water must be designed to ensure that there is sufficient oxygen to complete the NH4-N nitrification, and denitrification bacteria also make appropriate anaerobic hypoxic environment and adequate sources of organic matter in order to protect denitrification process smoothly, in order to improve NH4-N and TN removal effect. To solve this problem, this study is aimed at optimizing the traditional distribution of subsurface flow wetland dissolved state, the greatest degree improve wetland fill the lower oxygen distribution and improved aerobic and anaerobic microbial number and activity in order to improve their quality of sewage purification efficiency. In this study, the traditional subsurface wetlands of different sections of the division, its structure optimization and enhanced features designed different structures aerobic / anaerobic Tandem constructed wetland to study the aerobic / anaerobic ratio position, artificial aeration, adding water and other factors on the impact of water quality, and subsurface flow wetlands with conventional purification comparison. The results showed that when the hydraulic retention time of 5d, the average concentration of influent COD was 184.55mg · L-1, NH4-N was 21.72mg · L-1, TN is 22mg · L-1, the traditional subsurface wetlands COD, NH4 -N and TN removal rate were 70.3%, 18.4% and 40.6% in aerobic / anaerobic / aerobic segment in series with front and rear aeration and make undercurrent of anaerobic treatment wetlands (ie OAO exposure gas group) removal rate was 90.1%, 99.7% and 50.7%, and further optimize the structure and proportions OBAAO multi-point water aeration group removal rates were 91.6%, 100% and 87.7%. Seen in the experimental conditions OBAAO aeration influent group multi-point maximum contaminant removal efficiency, the improved wetlands can purify process optimization needs. Since the same structure SFCWs different aeration state, there are significant differences in water quality, aeration can improve the COD and NH4-N removal. In the aeration state wetland structure and aeration position of the segment of COD and NH4-N removal has a significant influence. DO, carbon, etc. are affected denitrification important factor, adding water, the removal rate of TN wetlands have improved significantly.
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