Study And Forecast On Groundwater Pollution In Lingwu Landfill Of Ningxia

Municipal solid waste landfills, where most of the household refuse was treated, play a significant role for the urban development, the environment conservation and rational exploitation of resources. Landfill has been widely applied to waste disposal for its small investment, simple operation, mature technology and other features. However, at the same time, a large quantity of high concentrations of inorganic or organic leachate has been produced by biochemical reactions in the process of waste compaction and fermentation colluding with rainfall conditions, which may bring large problems to the groundwater environment and residents health. In this paper, Lingwu non-hazardous waste landfill, which located in the east of Lingwu City in Ningxia Autonomous Region, was selected as the study area. Based on the field investigation, related data collection and sampling analysis, water quality condition and health risk situation in the Lingwu non-hazardous waste landfill and its surrounding areas has been comprehensively evaluated. As element is proved as the major pollutant in leachate. Then, MODFLOW software was used to simulate As element traveling in groundwater in two cases:(1) All anti-seepage layer has not been damaged.(2) 5% of anti-seepage layer has been damaged. Some important conclusions could be summarized as following:(1) The supply-runoff-drainage condition in study area is simple, precipitation and side-runoff are the main recharge source, among which the precipitation is 7.79 ×104m3/a, accounting for about 30% in total recharge. Groundwater discharge form is lateral runoff, of which the excretion is about 24.47×104m3/a.(2) Groundwater evolution result showed that TDS, NH3-N, total hardness, permanganate index, fluoride and nitrite nitrogen indexes all exceeded the standards, corresponding to the excessive rates of 66.7%, 83.3%, 83.3%, 66.7%, 100% and 16.7%,which indicates that the water quality level in the study area is poor.(3) The carcinogenic risk value of As element in groundwater in the study area is about 1.99×10-6 while the skin cancer risk value is 3.41×10-11; The harm quotient of fluoride-containing groundwater in the drinking study area is 3.18, while the skin-contacting study area is 5.44×10-5. All water samples were non-cancer risk drinking way more than acceptable hazard quotient 1.(4) Taking the observed concentration of 0.295 mg/L as input, As element traveling in groundwater were simulated and predicted in three cases for 30 years: in seepage well controlled situation, the concentration of arsenic in groundwater has no limit; In the landfill area filter membrane damage 5%, permeability seepage control under the condition of normal, arsenic in groundwater is not standard, In the landfill area and permeability filter membrane are damaged 5% of cases, the concentration of arsenic in groundwater at the beginning of the leakage was overweight, and the concentration of arsenic as the growth of the simulation period. The model runs for 18 years, downstream of the landfill area 140 m within the scope of concentration of arsenic.