Primary Treatment of Landfill Leachate Effects on Heavy Metal and Soil Chemical Properties in Kwashe Industrial Area in Duhok Province, Kurdistan Region of Iraq

Leachate is a major problem created from municipal solid waste (MSW) landfills and is considered the worst source of surface water and groundwater pollution. Kwashe industrial area as one of the most fast developing and polluted industrial area in Kurdistan region with many factories has a large solid waste separation factory that receives approximately 900 tons of municipal solid waste, out of which about 50% is organic kitchen waste. Samples of leachate were randomly collected from different sites downward drain of landfill and treated by aeration and filtration processes over a month. The results revealed that the soil was affected highly by soluble salts like Na and K from landfill; consequently, the electrical conductivity was 6.37(ds/m), 6 folds greater than the acceptable ranges. The primary treatment of landfill leachate by aeration and filtration reduced all heavy metals to acceptable ranges except Fe and Al, which remained relatively high over allowable ranges because the behavior and reaction of heavy metals in leachates is complicated as many acids are formed during the acidogensis of organic waste biodegradation that increases the solubility of these cationic heavy metals. The extractable forms of calcium, magnesium, sodium, potassium, sodium, and lithium are within acceptable ranges, which indicated not being enough to cause a threat in deteriorating soil and environmental chemistry. The results also showed that there was a close correlation between landfill leachate content of heavy metals and soil content affected by this leachate of Zn, Fe, Cu, Al, and Co at (P ≤ 0.01), but the soil downward landfill leachate fortunately did not reach the hazardous limits of their content in heavy metals and also did not exceed the standard ranges in soil.