Study on improving anaerobic co-digestion of cow manure and corn straw by fruit and vegetable waste: Methane production and microbial community in CSTR process

•The new concept of available carbon was introduced in anaerobic co-digestion.•The available carbon released rate of FVW was high and that of straw was low.•Available carbon quickly released substrate could improve the hydrolysis process.•The methane yield of anaerobic co-digestion of cow manure and corn straw increased.•The microbes changed and FVW enhanced the variation of the bacterial communities. Based on continuous anaerobic co-digestion of cow manure with available carbon slowly released corn straw, the effect of adding available carbon quickly released fruit and vegetable waste (FVW) was explored, meanwhile microbial community variation was studied in this study. When the FVW added was 5% and 1%, the methane production of the cow manure and corn straw was improved, and the start-up process was shortened. With higher proportion of FVW to 5%, the performance was superior with a mean methane yield increase of 22.4%, and a greater variation of bacterial communities was observed. FVW enhanced the variation of the bacterial communities. The microbial community structure changed during fermentation and showed a trend toward a diverse and balance system. Therefore, the available carbon quickly released FVW was helpful to improve the anaerobic co-digestion of the cow manure and available carbon slowly released corn straw.