Use of alum and ferric sulphate for treating landfill leachate via coagulation Process: A comparative study

Abstract

Landfill leachate is a complex wastewater which may give potential problems to the environment. Besides the new treatment processes that has been implemented, coagulation and flocculation treatment are considered as the most widely used method in treating landfill leachate to reach requirements specification for the discharge of leachate. Regularly, aluminium sulphate (alum) is used as a chemical coagulant to enhance the removal contaminants in this treatment process. Besides alum, ferric sulphate also shows their ability in leachate treatment. Hence, this study has been carried out to examine the comparison between both chemical coagulants in treating leachate form Padang Siding Landfill Site. The optimum pH and coagulant dosage was evaluated by a series of Jar Test experiment. In addition, the Sludge Volume Index (SVI) test also determined for the treated leachate under optimized conditions. Ferric sulphate with optimum pH 3.0 and coagulant dosage of 6000 mg/L was successfully removed of 58.9% of COD, 72.9% of turbidity and 46.1% of suspended solid. Meanwhile, alum coagulant was able to removed 69.4% of COD, 94.5% of turbidity and 84.3% of suspended solid under optimum pH 5.0 and 8000 mg/L of optimum coagulant dosage. Besides that, SVI of alum was 46. 8 mL/g and ferric sulphate gave the value of 32.5 mL/g for SVI. Hence, ferric sulphate is recommended to replace alum as a coagulant in landfill leachate treatment process since the efficiency is almost the same as alum.