A molecular transformation study on the humus soil biomaterial promoting effects on the humification process in an...

Biopolymers with different biodegradability result in the asynchronous production of humus precursors during anaerobic digestate composting, which hinders humus formation. This study aimed to improve the humification process of digestate composting with Humus Soil Biomaterial (HSB) as ameliorant, and unveiled corresponding humification mechanisms. Results indicated that HSB containing pumice stone, phenolics, and native microbes promoted the humification process of digestate composting and contributed to higher aromaticity and humification degree. HSB provided additional phenolics as aromatic skeleton to polymerize with amine-N to rapidly form humic substances, which avoided the adverse effects of lignin rate-limiting decomposition on humification process while reducing mineralization of amine-N precursors. Pumice stone and native microbes in HSB improved microbial composition by increasing microbial abundance and diversity, respectively, which strengthened the interactions between microorganisms and organics to accelerate humus formation and composting maturity. This study proposed a novel rapid humification option for the resourceful treatment of anaerobic digestate.