Impact of incineration slag co-disposed with municipal solid waste on methane production and methanogens ecology in landfills

[Display omitted] •CH4 concentration was positively correlated with the proportion of slag added.•Leachate and refuse pH were strongly and positively correlated with CH4.•Methanosarcina played a vital role in CH4 production in the colandfilling process.•CO2-reducing and acetoclastic methanogenesis were the main methanogenesis pathways. Co-landfill of incineration slag and municipal solid waste (MSW) is a main method for disposal of slag, and it has the potential of promoting methane (CH4) production and accelerating landfill stabilization. Four simulated MSW landfill columns loaded with different amount of slag (A, 0%; B, 5%; C, 10%; D, 20%) were established, and the CH4 production characteristics and methanogenic mechanisms were investigated. The maximum CH4 concentration in columns A, B, C and D was 10.8%, 23.3%, 36.3% and 34.3%, respectively. Leachate pH and refuse pH were positively correlated with CH4 concentration. Methanosarcina was the dominant genus with abundance of 35.1%∼75.2% and it was positively correlated with CH4 concentration. CO2-reducing and acetoclastic methanogenesis were the main types of methanogenesis pathway, and the methanogenesis functional abundance increased with slag proportion during stable methanogenesis process. This research can help understanding the impact of slag on CH4 production characteristics and microbiological mechanisms in landfills.