Coagulation process for semi-aerobic leachate treatment using poly-aluminum chloride

Sanitary landfill leachate is considered as heavily polluted industrial wastewater, which has extremely high pollution load that may pollute subsoil and ground water. Special attention must be paid to its efficient treatment and disposal. In this study, performance of coagulation and flocculation process was evaluated for semi-aerobic municipal solid waste leachate collected from Pulau Burung Landfill Site in Penang, Malaysia. Poly-aluminum chloride (PAC) was used as coagulant which has not been a common coagulant in leachate treatment. Effects of chemical and physical variables (concentration, pH, speed and time of rapid mixing and slow mixing) were examined by Jar-test experiments. The optimum pH and dosage of poly-aluminum chloride were obtained as 7.5 and 1.9 g/L, respectively. The most efficient rapid and slow mixing speeds were 80 for 45 seconds and 30 rpm for 15 minutes, respectively. The
optimum settling time was 30 minutes. Results showed that 97% removal of colour, 61% reduction of chemical oxygen demand (COD), and almost complete removal of suspended solids (SS) and turbidity were obtained under optimum conditions.