Study On Sewage Treatment With Yellow Soil-Clay Soil Double Layer Land Treatment System

Paper based on the research of a project of land treatment system,which is used to treat the wewage water in Heng Fa Chuen Nongjiale of Longquan.According to the climatic conditions, soil, vegetation distribution and water features, we build a yellow soil-clay soil double layers land treatment system. In the Start-up period,We researched the varivation about concentration of the pollutants in water and removal efficiency curve.And by changing the influent hydraulic loading, explore the affection on the pollutant removal rate and the depth of penetration; Finally,by comparing the effluent concentration and accumulation in blank and plant equipment, analysis the purification ability of the japonicus on removement of nitrogen and phosphorus.At the first cycle in Start-up period, the concentration of pollutants in the water is jumped and larger; at the second cycle, although showing a downward trendcy, the decline was not obvious; at the third and the fourth cycle, the concentration of pollutants and the trendcy of the pollutants curve has been basically the same. Finally, the removal rates of COD, NH3-N, TN, TP in plant area can reacheed 79.16%,96.01%,90.83%,89.47%; and blank area can reached 77.22%,95.46%,84.42%,82.89%. By comparing with Pollutant removal curves near the 2# and3# outlet in the plant and the blank arear,we found that there usually have a inflection point between te yellow soil layer and cayl soil layer.After the system is stable, under the conditions of ratio of 2:1 for the wet and dry and four hydraulic loadings,such as 0.04m3/m2·d,0.06m3/m2·d, 0.08m3/m2·d and 0.10m3/m2·d, the study found that at the hydraulic loading of 0.08m3/m2·d, the removal of pollutants is best, and the penetration depth is Minimum, it's range between 24cm～40cm.In the contrast part of the experiment, Focus on the purification of sewage effect about japonicus.The results show that:the nitrogen and phosphorus in wastewater which was assimilated by japonicas was 16.8% and 21.1% of the total removal in the land treatment system,while the assimilation of COD is less than 1%. So purification of TN, TP of japonicus is more effected than COD.In this study, based on the classic a kinetic equation of Eckenfelder, we have built some models. After verified by the fitting, there have little deviation between the Analog value and the real value, and the value of COD, NH3-N, TN, TP concentrations of pollutants are less than the A target requirements in"municipal wastewater treatment plant emission standards" (GB19918-2002).