The Paddy Fields Of Different Designs To Deal With The Effectiveness And Impact Of Rural Sewage

Paddy wetland is both the source of agricultural nonpoint source pollution, but also the sink of N and P pollution. Development and utilization of paddy wetlands to deal with the N and P in sewage have high economic and social value. This study take sewage treatment trials in paddy field of Taihu Lake Basin, experimental field was divided into three plots, were designed to overflow water plot,"串"type plot and "弓" type plot. Investigated three plots N emissions after fertilizer, relatively low concentrations of N and P in sewage for irrigation and drainage under each plot of N and P removal, compared to increase sewage treatment flow cell N and P removal, inspection growing and harvest yield of rice in the plot run, the plot sewage treatment impact on the microbial community in the system. The results showed that:(1) Five days after fertilization is an important period for control soil pollution,5days after the plot drainage TN concentrations are stabilized at about1.0mg·L-1, DON become the main form of paddy wetland N emissions, accounting and TN70%or more. Furrow irrigation design area of the treatment effect of NH4+-N was significantly better than the overflow plot.(2) Three plots low concentration wastewater (TN<10mg·L-1, TP<1.0mg·L-1) continuous water (4m3/d) deal with the TN removal efficiency of70%-80%, drainage TN concentrations are stable, no significant differences between the three plots. The consumptive mainly of N and P role in the front of the system, compared with the "串"type plot,"弓"type plot of HRT is shorter, so deal with the same amount of waste water of the paddy area is also large, The consumptive of TP in"弓" type plot significant than the other two plot.(3)Increase the sewage(5m3/d), sewage flow rate accelerated, the consumptive needs of sewage N and P in paddy increases."弓”type plot has a higher hydraulic loading, the consumptive capacity of TN and TP was significantly greater than other plot.(4) Each plot of rice growth showed significant differences along the flow direction of the sewage, the front-end rice plant biomass and the harvest was significantly better than the end. Overflow plot prone to sewage flow of poor nutrient accumulation with sewage somewhere’‘串”type plot effluent N and P removal are more concentrated and the front of the system:compared to "弓"type plot nutrients with the sewage flow and distribution Therefore, the‘弓’’type plot of rice per mu is the highest. (5) High concentrations of sewage input helps to maintain the structural and functional diversity of soil microbial communities at a higher level, affected by N and P inputs, the microbial community of the plot at the end of a different bias in the choice of substrate utilization significant differences between community structure and functional diversity.