Coagulation-flocculation process for landfill leachate pretreatment and optimization with response surface methodology

摘要

The present paper aimed to characterize and treat a landfill leachate using a coagulation-flocculation process. The leachate was obtained from a landfill in the city of Sousse, Tunisia. Its physicochemical characterization showed high levels of chemical oxygen demand (COD), ammonium, and heavy metal contents. The coagulation-flocculation process was applied as pretreatment effluent to reduce these pollutants. The key operating parameters (pH, coagulant dose, flocculant dose, and mixing speed in the flocculation step) on the coagulation-flocculation process were optimized using response surface methodology to investigate COD removal in landfill leachate. In this regard, a hybrid design was carried out to seek optimal conditions which were as follows: pH: 3.36; concentration of coagulant: 0.87g/l; concentration of flocculant: 26mg/l; and mixing speed: 48rpm. These conditions have been proved experimentally.