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• The property of AMRs biochar has been improved by H 3 PO 4 -modification. • The using of PBC as carrier to load nZVI improved the agglomeration of Fe particles. • PBC and nZVI/PBC enhanced biogas yield by more than 20% in AD of corn straw. • The nZVI/PBC exhibited higher ability in maintaining the stability of AD system. Antibiotic mycelial residues (AMRs), as recyclable hazardous waste, can realize efficient utilization by reasonable treatment. To solve the problems of undeveloped pore structure and low specific surface area existed in AMR biochar, this study first modified biochar by phosphoric acid (H 3 PO 4) to prepare PBC (H 3 PO 4 -modified biochar). Then, PBC was used as carrier to load nano zero-valent iron (nZVI) for preparation of nZVI/PBC. Finally, the biochar materials were used to promote anaerobic digestion (AD) of corn straw. The results showed that H 3 PO 4 -modification can effectively improve the specific surface area, pore structure, and electron donating capacity of AMRs biochar. The using of PBC as carrier to load nZVI attenuated the agglomeration of nZVI particles. Both PBC and nZVI/PBC improved the AD process, with biogas yield enhanced by 29.63% and 29.26%, respectively. The nZVI/PBC exhibited higher ability in maintaining the stability of AD system and promotion of fiber degradation than PBC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Established a high lignocellulosic dry-wet combined anaerobic digestion system. • The kinetic parameters of the whole anaerobic digestion process were revealed. • Synergism between Clostridiales and methanogens was evaluated via network analysis. • Syntrophy between SFOB and methylotrophic Methanospirillum was observed. • The number of key acidogenic Clostridium was increased by 80.77–107.11%. Dry-wet combined anaerobic digestion is a novel approach for treating lignocellulosic waste by increasing the organic load of reactor while accelerating the conversion of organic acids. Here, we investigated the effect of regulated substrate ratios and initial pH in the dry acidogenesis stage on the bioconversion efficiency of dry-wet combined anaerobic digestion. Our data revealed microbial interactions and further identified key microbes based on microbial co-occurrence network analysis. On day three of acidification, the kinetic hydrolysis rate and acidification yield reached 1.66 and 60.07%, respectively; this was attributed to enhancement of the synergistic effect between Clostridiales and Methanosaeta , which increased the proportion of corn straw in the substrate or lowered the initial spray slurry pH to 5.5–6.5. With increased acidification capacity, acetoclastic methanogens were enriched in the wet methanogenesis stage; the syntrophic effect of Syntrophomonadales , Syntrophobacterales and Methanospirillum , meanwhile, was enhanced, leading to an overall improvement in biogas production. [ABSTRACT FROM AUTHOR]