Anaerobic co-digestion of chicken manure and cardboard waste: Focusing on methane production, microbial community analysis and energy evaluation

[Display omitted] •Biomethane was enhanced 14.2% at optimal ratio at 35% CM: 65% CB.•The potential mechanism of co-digestion to improve stability was revealed.•Cellulose degradation caused humic acid accumulation and low energy production.•Energy balance exhibited a significantly synergetic improvement of co-digestion.•Full scale assessment of co-digestion of CM and CB was performed. This study aimed to investigate the synergistic effect and microbial community changes between chicken manure (CM) and cardboard (CB) during anaerobic co-digestion. Meanwhile, the energy balance of biogas engineering was extrapolated based on the batch tests. In batch tests, co-digestion system achieved the highest improvement (14.2%) and produced 319.62 mL CH4/gVS with a 65:35 ratio of CB: CM. More extracellular polymeric substance secretion promoted the electron transfer for acidogenesis and more hydrolase was provided with 31.6% improvement. The microbial analysis illustrated that higher acetoclastic Methanosaeta abundance was achieved, leading to 211% enhancement of acetoclastic pathway. Moreover, associated network illustrated that the higher methane production was mainly achieved through matching of hydrolytic bacteria and acidogenesis bacteria. As for energy balance, the synergistic effect increased the energy output by 38% and energy recovery to 46.4%.