Can coagulation–flocculation be an effective pre-treatment option for landfill leachate and municipal wastewater co-treatment?

Coagulation–flocculation as pre-treatment option for co-treatment of landfill leachate (LL) and municipal wastewater (MW) was investigated using ferric chloride as coagulant along with a novel flocculant namely polyacrylamide grafted gum ghatti (GGI-g-PAM). Experiment at different coagulant doses with constant flocculant dose was performed at different LL to MW at ratios of 1:20, 1:10, 1:7 and 1:5. Pre-treatment process's efficiency evaluation was based on removal of chemical oxygen demand (COD), total suspended solids (TSS), turbidity and colour. LL and MW characterization revealed that LL was old with low BOD5/COD ratio, high ammonia and TSS concentration while MW had moderate COD concentration. FeCl3 optimum dose was 970 mg/L with 100 mg/L of GGI-g-PAM flocculant. Best pre-treatment was at a ratio of 1:7 where 79% COD, 93% turbidity and 90% TSS removal was recorded. Colour removal was found to decrease with increase in FeCl3 dose at all the ratios tested except at 1:20. Results indicated that coagulation–flocculation can be useful pre-treatment option for LL and MW co-treatment