Coagulation and electrocoagulation for co-treatment of stabilized landfill leachate and municipal wastewater

Landfill leachate and municipal wastewater at various ratios (1:20, 1:10, 1:7 and 1:5) were subjected to coagulation and electrocoagulation (EC). Alum was used in conventional coagulation at pH 6 and aluminum plate as electrode was used in EC at a current density of 386 A/m2 with 5 cm inter electrode spacing. Treatment efficiency was assessed from removal of chemical oxygen demand (COD), total suspended solids (TSS), turbidity, ammonia, nitrate and phosphate. At 1:5 ratio of landfill leachate to municipal wastewater, highest COD removal was with 3.8 g/L alum whereas highest turbidity removal was with 3.3 g/L alum during coagulation. EC exhibited almost similar removal efficiency for all the parameters at different ratios tested except for COD which was considerably higher at 1:20 ratio. Aluminum consumption from electrode was 0.7 g/L following EC as compared to 3.8 g/L alum used in coagulation. The amount of sludge produced was found to be higher with EC as compared to coagulation which could be due to the fact that the electrochemical method was performed for a longer duration than conventional coagulation. For minimal sludge generation, EC reaction time should be ∼30 min. Further studies with EC process on costing and sludge generation will help to advance the technology for wastewater treatment.