Abstract With a methanogenic reactor using treated leachate recirculation, the effects of 12 effective microorganisms (EMs), isolated from Hangzhou Tianzhiling landfill, on the degradation of municipal solid waste (MSW) were investigated. The preliminary experiment indicated that the EMs increased the biodegradability of MSW, enhanced 24% of organic mass effluent from the landfill reactor, and shortened methane production period to about 91 days in the bioreactor landfill system. The total gas production volumes for the landfill only with leachate recirculation, the bioreactor landfill system with and without EMs inoculation were 65.7, 620.9 and 518.6 l, respectively, after 105 days operation. The average methane concentration of the gas formed in the bioreactor landfill system was above 70%. These showed that a combination of EMs and methanogenic reactors using treated leachate recirculation might be a good way to increase the degree of MSW stabilization, and enhance the rate and quality of gas production for energy recovery.