Enhancing biogas production from municipal solid waste through recirculation of blended leachate in simulated bioreactor landfills

This study is an attempt to assess biogas production improvement from organic fraction of municipal solid waste in simulated bioreactor landfills through recirculation of blended landfill leachate. In this study, various old and new leachate blends (66.6%New/33.3%Old, 33.3%New/66.6%Old, 100%New and 100%Old) were recirculated through 6 laboratory-scale bioreactors using open-loop and closed-loops modes. Compared with the control bioreactor where 100% new leachate was recirculated and operated as a closed-loop, cumulative biogas production was improved by as much as 77.2 to 193.2% when a leachate blend of 33.3%New/66.6%Old was recirculated. Furthermore, comparison of the results from open-loop and closed-loop operated bioreactors indicated that there was approximately 28.3 to 65.4% more biogas in open-loop bioreactors. The Gompertz model produced a better fit (R-2 > 0.99) than first-order and logistic function models. Leachate blending reduced the lag phase by almost half and thus helps in alleviating the ensiling during the start-up phase.