Effect of operating conditions and temperature on efficiency of aged refuse bioreactor and microbial community structure analysis

The aged refuse from Shanghai Laogang landfill were used as carriers to build the bioreactor. The removal efficiency on NH₃-N, TN, BOD₅ and COD of the mature leachate in terms of various hydraulic loads, recirculation ratios and different temperatures as well as the microbial community structure were investigated. The results show that when hydraulic load of aged refuse bioreactor increases from 8.5 L/(m³·d) to 17 L/(m³·d), removal efficiency of NH₃-N and BOD₅ change less, and that of COD and TN increase significantly, which indicating hydraulic load has limited effect on enhancing efficiency of reactor. While it would be impossible to improve the efficiency of denitrification by adding the circulation. When the temperature increases from 15℃ to 30℃, NH₃-N and BOD₅ can be completely removed. The removal efficiency of TN increases from 27.3% to 43.7% and that of COD increases from 73.1% to 80.5%, showing that increasing temperature could improve performance of reactor. The result of the bacterial community structure shows that adding circulation has a little effect on community structure, while increasing hydraulic load enhances diversity of community structure in the top of the reactor. When increasing temperature, the bacterial amounts in both top and bottom of reactor increase. It is concluded that the temperature plays greater effect on performance and community of aged refuse bioreactor.