Water-evaporation-induced efficient high-temperature aerobic fermentation of food waste

Aerobic fermentation is an effective approach for reducing, stabilising, and recovering resources from food waste. However, its performance is often constrained by poor oxygen transfer within the fermentation substrate. In this study, we investigated the inductive mechanism of water evaporation enhancing aerobic fermentation of food waste. It was observed that water evaporation, as the primary driving force, promoted microscale moisture redistribution and pore structure optimization, leading to an 84.8% (p < 0.01) increase in the average pore diameter and an 8.7% (p < 0.01) increase in porosity. As a result, a significant increase in the oxygen mass transfer coefficient (+250.1%) was achieved within the food waste. This improved microenvironment steered microbial community succession toward thermophilic functional groups dominated by Bacillus and Diutina, prolonging the thermophilic phase by 167% (p < 0.05) and facilitating the degradation of major organic components. Among them, the degradation rate of lipids was significantly increased by 57.1% (p < 0.01). Consequently, the humic substance content in the fermentation product increased by 18.8% (p < 0.05) and the corresponding germination index increased by 41.4% (p < 0.05). These results were further confirmed by the metagenomic analysis, which indicated that water evaporation induced the significant enrichment of functional genes associated with the tricarboxylic acid cycle and electron transport chain in the aerobic fermentation. These findings offer new mechanistic insights into leveraging microscale moisture regulation to optimize aerobic bioconversion.