Treatment of landfill leachate by coagulation process using Red Earth as coagulant

Abstract

Leachate is one of the significant environmental issues since it is highly contaminated wastewater which consists of organic and inorganic matters. Coagulation-flocculation treatment is widely applicable for treating stabilized landfill leachate. However, this method requires chemical based coagulant as treating agents which are non-environmental friendly and possess potential hazard to the environment quality. Therefore, red earth is suggested to be developed for replacing the use of existing chemical coagulant such as aluminium sulphate (alum) in order to achieve sustainable development. In this study, the comparative suitability of red earth and alum as coagulants in the treatment of stabilized leachate from Padang Siding Landfill Site were evaluated via a series of Jar Test experimental works with rapid mixing speed of 100 rpm for 3 minutes, slow mixing speed 30 rpm for 10 minutes and settling time of 30 minutes. Besides that, sludge volume index (SVI) of the treated leachate samples were determined under optimized conditions. The red earth able to effectively removed 53.9% of COD, 90.0% of turbidity and 46.7% of NH3-N at optimal pH value of 2.0 with favourable dosage of 8000 mg/L. On the other hand, the optimal pH 5.0 of alum with optimal coagulant dose of 9000 mg/L induced a 66.9% COD reduction, 96.2% turbidity removal and 43.3% NH3-N removal from the same leachate sample. Besides that, the SVI of alum coagulant was 42.21 whereas red earth gave value of 3.73 for SVI with relatively ratio of alum to red earth of 11.3:1. Hence, red earth could be proposed as plentiful and viable coagulant which is enriched with metal cationic ions such as aluminium, iron and silica elements for leachate treatment.