Metagenomics insights into the effect of co-landfill of incineration fly ash and refuse for bacterial community succession and metabolism pathway of VFAs production.

With the development of incineration technologies, incineration has become the most common treatment method of municipal solid waste in China. However, stabilized fly ash may enter landfills during the transition from landfill to incineration, which caused uncertain impact on landfill waste stabilization. Two simulated co-landfill columns were constructed based on different co-landfill methods (layer co-landfill and mixed co-landfill) to investigate the effect of stabilized fly ash co-landfilled municipal solid waste for bacterial community succession and change in metabolic pathways during hydrolysis-acidogenesis stage. The mixed co-landfill method resulted in higher degree of organic matter degradation, and the concentrations of volatile fatty acids (VFA) and chemical oxygen demand (COD) in leachate were higher. The dominant phyla were Firmicutes in the layered co-landfill column and Bacteroidetes in mixed co-landfill column. The dominant genera for the total bacterial composition and VFA production were different, Pseudomonas and Propionibacterium, Proteiniphilum and unclassified Bacteroides were the dominant genera responsible for VFA generation in the layered and mixed co-landfill columns. The genes for butyrate production were enriched in the layered co-landfill column, whereas those related to acetate production were enriched in mixed co-landfill column. However, the layered co-landfill inhibited the microbial metabolic activity at the end of the co-landfill process.