Aerobic co-treatment of landfill leachate with domestic wastewater

Addition of landfill leachate to a domestic wastewater treatment system may have negative impacts since leachate is a highly concentrated wastewater both in terms of inorganic and organic pollutants. The aim of this study was to investigate the effluent quality in the cotreatment of sanitary landfill leachate and domestic wastewater and the improving effect of powdered activated carbon (PAC). The volumetric ratio of leachate was varied from 5 to 25% (v/v). Batch activated sludge (AS) reactors were fed with leachate and domestic wastewater. Parallel AS + PAC reactors also contained PAC, which was added at the dose of 100-3,500 mg L-1. The nonbiodegradable soluble COD (SCOD) in leachate was decreased to very low levels by this addition. Experiments were also conducted in Semi-Continuously Fed Batch (SCFB) and Continuous-Flow (CF) activated sludges with recycle. In both types of operations, effluent COD and ammonium nitrogen concentrations increased when the leachate input increased. In all cases, the positive effect of PAC addition became more apparent at high leachate inputs. The study revealed that the negative impact of leachate on a municipal wastewater treatment system could be prevented by the addition of PAC. Particularly, if the leachate contribution in a publicly owned treatment work (POTW) exceeds 10%, or in the case of shock leachate loadings, the effluent quality may be considerably improved with PAC addition.