Aerobic composting of food waste (FW) is constrained by delayed temperature increase initially. This study evaluated the use of high-solid anaerobic digestion (HSAD) biogas residue as a composting initiator. In the co-composting treatment containing biogas residue and FW (C3), the temperature peaked at 69.8 °C on day 5. In comparison, the FW composting alone (C1) reached a lower peak temperature of 67.1 °C on day 8. Similarly, C3 sustained the thermophilic phase (>55 °C) for 10 days, comparable to the 11 days observed in C1. The incorporation of biogas residue adjusted the pH of FW toward neutrality, helping to reduce nitrogen loss. C3 also demonstrated a distinctive phytohormone profile, with salicylic acid (SA) content reaching 42.62 ng g−1, significantly exceeding that of C1 (31.54 ng g−1), suggesting enhanced bio-stimulatory potential. Compared with C1, N2O emissions in C3 were both reduced and delayed, while cumulative CH4 emissions were lower than those in the biogas-residue-alone composting (C2). Biogas residue addition introduced thermotolerant microbes, reduced acidification by suppressing acidophiles, and enhanced humification via cooperative networks. Metagenomics revealed that C3 developed a denitrification gene profile favoring net N2O consumption under high pH. These results demonstrate that HSAD biogas residue can serve as an effective initiator for FW composting.
Chi et al. (Tue,) studied this question.