Evaluation of coagulation-flocculation in the leachate treatment using FeCl₃ and Al₂(SO₄)₃

Abstract

Suspended solid (SS), ammoniacal nitrogen (NH3-N), turbidity and chemical oxygen demand (COD) are the main form of pollutants in landfill leachate. In this study, the main objectives is to evaluate the coagulation-flocculation process in the leachate treatment by using Ferric Chloride [FeCl₃] and Aluminium Sulphate [Al₂(SO₄)₃] as coagulant. The coagulation-flocculation processes is carried out to investigate the efficiency of coagulation-flocculation processes for removal of SS, NH3-N, turbidity and COD which present in significant quantity in the leachate of Padang Siding Landfill in Perlis, Malaysia. Then, the effect of initial pH, coagulant dosage and mixing time are evaluated. The coagulation-flocculation process was done with standard jar test apparatus for pH, coagulant dosage and mixing time, then 150 rpm mixing speed and 60 minutes settling time. The highest percentages of removal efficiency for NH3-N and COD are 35% and 8% for FeCl₃ whereas 16% and 3% for Al₂(SO₄)₃. FeCl₃ achieved the highest removal efficiency in NH3-N, turbidity and COD. While Al₂(SO₄)₃ was categories as low removal efficiency in leachate treatment but Al₂(SO₄)₃ is more effective in removing of SS. In summary, the FeCl₃ was found more effective coagulant compared the Al₂(SO₄)₃.