The Study Of Groundwater Pollution By Sewage Irrigation At Malong County

When the economic development and the process of urbanization, the more density of population, the more shortage of resources, especially the problem of water shortages. China is a country that serious water shortages, so the use of reclaimed water in the country to get the attention and it is more important that reclaimed water irrigation in China.Under the conditions that Yunnan Province drought three consecutive years, we research the drought area at Malong County in Qiujing.The sewage treatment plant of Malong County for reclaimed water irrigation of alfalfa to assess the feasibility of reclaimed water irrigation of alfalfa. This will not only save the operating cost of Marlon County sewage treatment plant, reduce the use of chemical fertilizers, but also significant savings in water resources in the arid conditions; then set two analog experimental field with recycled water and well water for irrigation, when irrigation one year, he analysis test renewable water pollutants TN, TP, ammonia, CODcr, Cu, Cb, Pb and Zn in soil and irrigation after one year of pollutants in the soil vertically downward migration of the number m, affect the number of m of the soil, and well water for irrigation, which is more suitable for irrigation; distilled water leaching the soil column experiment simulation of atmospheric precipitation, to see whether the pollutants in the soil with the transit downward migration of water deep into the soil and groundwater. Finally, use of recycled water washout filter soil column to simulate forecast irrigation with reclaimed water for three years, the impact on groundwater. Reclaimed water in future in Malone County irrigation alfalfa provides a scientific basis. The main conclusions of the study are as follows:(1) the feasibility of recycled water for irrigation in Malone County:The area that Malong County sewage treatment plant reclaimed water irrigation is yellow soil, the lithology is sandy clay and the permeability coefficient is0.01-1m/d, it is belong to poor permeability; the deep depth of shallow groundwater water that is15-20m.The quality of irrigation water after Marlon County sewage treatment plant to achieve "urban sewage treatment plant pollutant discharge standards," a subject of water quality is of a scientific irrigation. Malone County study area is suitable for the use of recycled water for irrigation is feasible. (2) reclaimed water irrigation impact on soil after one year:Recycled water in irrigation after one year, contaminants, TN, TP, ammonia, CODcr, Cu, Cb, Pb and Zn accumulated mainly in the surface layer of the soil0-15cm;15-30cm in depth when the pollutant content declined sharply to reachsoil environmental quality standards;30-60cm soil levels of pollutants are small and meet the standards;60cm thickness of the unsaturated zone TP, TN and ammonia nitrogen removal rate reached98.2%,67.7%and89.3%, the removal ratehigh,60cm of soil vadose zone structure the effect of removing pollutants. The year irrigation pollutants affect up soil0-30cm at60cm below the soil is not received pollution and irrigation with reclaimed water vertically downward migration of contaminants in the soil30cm.(3)the influence of reclaimed water irrigation after one year of groundwater:Recycled water for irrigation year, contaminants in soil TN, TP, ammonia, CODcr and heavy metals Cu, Cd, Pb, Zn only through the30cm at the vadose zone and not with the transit of moisture migration down to15m groundwatergo, and cross-boundary water pollutant concentration gradually decreased, down to a minimum last stabilized, not found in reclaimed water irrigation of alfalfa plots lead to groundwater quality change, and the concentration of pollutants in the oozing liquid are standard, so the groundwatersmall influence.(4)And well water for irrigation, recycled water and well water are not of soil and groundwater pollution, and recycled water for irrigation of alfalfa growth more vigorous irrigation with reclaimed water saving natural resources and economic resources, reclaimed water is more suitable for alfalfa irrigation.(5) predicted impact on groundwater recycled water for irrigation after three yearsA number of indicators integrated pollution index method to predict the use of recycled water for irrigation of alfalfa Three years later, the shallow groundwater of the study area will not be affected.In summary, the application of Malong County reclaimed water for irrigation of alfalfa have a good impact and the impact on groundwater.