The treatment of food waste (FW) via anaerobic digestion (AD) is frequently plagued by a low methane yield and ammonia (NH4+) inhibition. This study demonstrates that the addition of elemental sulfur (S0) effectively mitigates both of these issues. Through batch and continuous experiments, it was found that the specific methane yield was enhanced by up to 48.1% and the NH4+ concentration decreased by 26.9% at the optimal S0 dosages of 20 mg/L. Metagenomic analysis revealed a dual mechanism underlying this enhancement: at low dosages, S0 provides a sulfur-containing functional group for the biosynthesis of methyl-coenzyme M, thereby accelerating the rate-limiting "methyl-transfer" step in methanogenesis; at high dosages, it promotes the biosynthesis of coenzyme A, which markedly enhances acidogenesis. Furthermore, S0 alleviates NH4+ inhibition by fostering a synergistic interaction between sulfate-reducing bacteria and anammox bacteria, which convert NH4+ to N2. Continuous operation over 140 days confirmed the long-term stability and effectiveness of this S0 addition strategy. This study provides mechanistic insights into S0-driven methanogenesis in complex organic waste (FW) and offers a cost-effective, sustainable approach to enhancing AD efficiency and stability.
Qiao et al. (2026) studied this question.