Leachate Treatment by Coagulation and Precipitation

When sanitary landfills are constructed with provisions for collection and treatment of leachates, chemical treatment may be one of the treatment processes employed. The research described herein was conducted to determine the ability of chemical treatment to remove suspended solids, biochemical oxygen demand, chemical oxygen demand, iron, calcium, and magnesium from leachate. Chemical treatment studies were conducted in the laboratory using alum, lime, and ferric chloride. Preliminary results indicate that lime precipitation was most effective. Additional studies revealed that suspended solids, color, and some multivalent cations can be effectively removed from raw leachate using lime. However, significant removals of soluble biochemical oxygen demand were not observed and extremely high lime concentrations in the 300–600 mg/L range were required to obtain a relatively clear supernatent resulting in relatively large amounts of sludge.