Stabilization of leachates from municipal solid waste landfill by sedimentation

The purpose of this study is to show the results of the physicochemical treatment of leachates from a municipal solid waste (MSW) landfill sited in Madrid (Spain). Different techniques of contamination elimination were studied to reduce the concentration of contaminants in solution and suspended matter. The reagents used were precipitating agents such as lime slurry and caustic soda and coagulant-flocculant agents, to facilitate sedimentation, like FeCl3. 6H(2)O and Al-2(SO4)(3). 18H(2)O. The parameters studied to evaluate the contamination removal efficiency were: turbidity, chemical oxygen demand (COD), suspended solids (SS) and heavy metals. The best results were obtained with lime slurry if a value of pH=12 was reached, but a high quantity of agent was necessary (about 7300-7900 ppm) to eliminate 90% of turbidity and SS. The COD removal was 35%. SS, COD and turbidity removal efficiency attained was lowest when salts of Fe3+ were added., Al3+ yielded better results than Fe3+, but lower than lime slurry. COD removal was about 25% if the cation concentration was 236 ppm.