Effects of Calcium Peroxide Dosage on Physicochemical Parameters, Organic Matter Degradation, Humification, and Microbial Community Succession During Food Waste Composting

To verify the possible roles of calcium peroxide (CaO₂) in addressing the key challenges of aerobic composting of food waste, including long composting duration, poor compost product quality, and gas emissions during composting, this study conducted a 38-day composting experiment using artificially blended food waste. Five containers were employed for investigating the effects of five doses of CaO₂ (0%, 5%, 10%, 15%, and 20%, <i>w</i>/<i>w</i>) on physicochemical parameters, organic matter (OM) degradation, and humification during composting. Additionally, more evidence from a microbial perspective was provided by analyzing the effects of CaO₂ additions on microbial community succession. The results indicated that CaO₂ additions increased the relative abundance of mineralization bacteria, accelerated the temperature increase of compost in the early composting stage, and elevated the peak temperature. It also facilitated the decomposition of OM and enhanced the synthesis of humic acid during the early composting stage. However, the addition of CaO₂, especially at relatively high doses, impacted the humification process. Compared with the control, only the 5% CaO₂ treatment had a significantly greater humification coefficient, reaching 1.73 ± 0.11. Moreover, adding CaO₂ reduced the total ammonia emissions from composting by 17.1% to 59.7%. Overall, CaO₂ is an effective additive for ameliorating key issues in food waste composting.