Study On Sloping-Subsurface Flow Wetland For Treating Cattle Sewage

The paper reviews the wetland science and constructed wetland sewage treatment technologies at home and abroad , raised the purpose and significance of research. Unlike conventional biological wastewater treatment technology, natural transmission oxygen supply play an important role in the process of degradation of pollutants. Traditional undercurrent wetland known as anaerobic bed,oxygen-restricted restricted the removal of pollutants further. The paper start on the degradation of nitrogen, proposed a step-by-step nitrification and denitrification of the two-phase denitrification process.The entire system is composed of water distribution sedimentation tanks, three aerobic wetlands, an anaerobic bed and a stabilization pond put Pistia stratiotes L and silver carp.there are some elevation difference between every aerobic wetlands and connect through overflow weir,small aspect ratio and the local soil, anaerobic bed high aspect ratio and greater depth .Wetlands filled limestone matrix and planting cattail and scirpus crassipes.After nearly six months of operation come to the following conclusions:①Compared Scirpus crassipes, cattail can better adapt to the growth along the Yangtze River in Chongqing environment Because along the Yangtze River often strong winds and high hollow thin Scirpus crassipes easily be blown over.②10cm/d, 20cm/d, 40cm/d three hydraulic loading, limestone can be pH value of less than 7.0water rose to 7.4-7.7.③Overflow weir drop water aeration system, which enables the effective sewage reoxygenation.DO 0.2 mg/L effluent around through aeration can be increased to 4.0mg/L around.3-oxygen aeration total of about 12mg/L, the concentration of water is not conducive to reoxygenation.④When the hydraulic loading of 20cm/L, the average TN concentration of Influent water is 6.67mg/L,The average removal rate was 89.4%;the average TP influent concentration of 3.541mg/L, with an average removal rate of 82.8%;average CODcr influent concentration of 343.1mg/L, with an average removal rate was 85.4%.In the hydraulic loading of 40cm/d, every export value have a certain degree of fluctuation, but still maintained a high removal rate.⑤20cm/d, 40cm/d two hydraulic load, the average effluent concentration of chlorophyll a value of 8.07μg/L, with an average removal rate was 58.5%.In both hydraulic loading, the system of turbidity removal is relatively stable, and the effluent turbidity 4.83 NTU, the average removal rate of 62.7%, Influent and effluent values of a positive correlation.⑥Floating plants Pistia stratiotes L is suitable for the application of easy control small-scale surface.Pistia stratiotes L outputs can be used as the auxiliary chicken feed. 50 yuan invested , the output of about 150 yuan, with ecological and economic effects of the double.⑦the degradation of TN, TP, CODcr in the wetland system are better follow First-order kinetic mode (R2 are greater than 0.9).through the slope of degradation equation,obtained TN, TP and CODcr based on the size of First-order kinetic removal rate constant value, respectively 100.1,59.9and118.0m/y.provide a theoretical reference to similar wetlands designThe article finally done a project area of wetland example, and put forth suggestions for further research directions.