Treatment of landfill leachate using a combined stripping, Fenton, SBR, and coagulation process

The leachate from Changshengqiao landfill (Chongqing, China) was characterized and submitted to a combined process of air stripping, Fenton, sequencing batch reactor (SBR), and coagulation. Optimum operating conditions for each process were identified. The performance of the treatment was assessed by monitoring the removal of organic matter (COD and BOD5) and ammonia nitrogen (NH3-N). It has been confirmed that air stripping (at pH 11.0 and aeration time 18 h) effectively removed 96.6% of the ammonia. The Fenton process was investigated under optimum conditions (pH 3.0, FeSO4.7H2O of 20 g l-1 and H2O2 of 20 ml l-1), COD removal of up to 60.8% was achieved. Biodegradability (BOD5/COD ratio) increased from 0.18 to 0.38. Thereafter the Fenton effluent was mixed with sewage at dilutions to a ratio of 1:3 before it was subjected to the SBR reactor; under the optimum aeration time of 20 h, up to 82.8% BOD5 removal and 83.1% COD removal were achieved. The optimum coagulant (Fe2(SO4)3) was a dosage of 800 mg l-1 at pH of 5.0, which reduced COD to an amount of 280 mg l-1. These combined processes were successfully employed and very effectively decreased pollutant loading.