Determination of leachate leakage around a valley type landfill and its pollution and risk on groundwater

Abstract

Landfill leachate has great pollution risk to groundwater, which is of practical significance to study the characteristics of leachate leakage and surrounding groundwater pollution and its harm to human health. Taking a typical valley-type landfill in South China as the research object, this paper ascertained the leakage area based on geophysical methods and groundwater sampling. A total of 21 parameters such as pH, total hardness (TH), total mineralization (TM), permanganate index (CODMn), ammonium (NH3-N), nitrites (NO3-N), nitrates (NO2-N), sulphates (SO4−), chloride (Cl−), fluorides (F−), volatile phenols, cyanide, and heavy metals (HMs) in groundwater and some indicators in leachate were tested, and the water quality and health risks were evaluated by using the Nemerow pollution index (NPI) method and BCRA (Rish-based Corrective Action) model. The results indicate that the leakage areas are existing in the middle of the landfill site, the middle and the south of the anti-seepage dam with a depth about 15-22m and main pollutants of CODMn and NH3-N. The main pollutants of pH, NH3-N, Fe and Mn were ranged from 5.80 to 6.70, 0.06 to 0.74 mg/L, 0.002–2.763 mg/L, and 0.003–1.181 mg/L, their rates exceed the class Ⅲ standard at 28.57%, 28.57%, 4.29% and 14.29%, respectively. The Nemerow pollution index showed that the groundwaters at ZK01 and ZK04 were seriously polluted. Groundwater quality was affected by leachate and natural geological background. The total non-carcinogenic risk of groundwater was ranked as LS102 < LS101 < ZK02 < ZK01 < ZK03 < ZK05 < ZK04, with Cl− and Mn as the main non-carcinogenic pollutants in the landfill. This rank reveals the rule that the closer to the waste body, the higher the risk.