Multistage biological contact oxidation for landfill leachate treatment: Optimization and bacteria community analysis

Landfill leachate is a wastewater contained solid waste and is hard to treat due to its complex composition. The most effective treatment is biological method among leachate transfer, biological treatment, and physical and chemical methods, however, the chemical oxygen demand (COD) removal efficiency of present biological treatment has not been more than 90% at influent COD concentration of 2000 mg/L to 5000 mg/L. In this study, the multistage biological contact oxidation (MBCO) is performed for treating landfill leachate. The optimized parameters as followed achieve 91.28% COD removal efficiency: influent COD landfill leachate concentration of 4000 mg/L; 0.1 L/min·L (reactor volume) aeration rate; temperature (T) of 35 °C and hydraulic retention time (HRT) of 24 h and also obtained 318.64 mg/L ammonium nitrogen (NH3-N) effluent concentration, Besides, biofilm community structure show that Proteobacteria, Bacteroidetes and Firmicutes are identified as the dominant in phylum. All the results indicate that the MBCO is an effective technology for landfill leachate treatment.