Abstract: To comprehensively evaluate the quality and potential risks of urban food waste composting, four food waste treatment sites were selected, and four treatment processes were implemented: high-temperature aerobic composting, dynamic aerobic composting, rapid composting, and on-site composting. The results showed that the incoming food waste at the four treatment sites was rich in organic matter and nutrients, with low risk of heavy metal pollution, indicating high potential for resource utilization. The organic matter content and total nutrient content of the composting products from the four treatments met the limits specified in the NY/T 525—2021 standard. Through biodegradation and other treatment technologies, the food waste was converted into fertilizer rich in organic matter and various nutrients.As, Hg, Pb, Cd, and Cr were detected in samples from all four treatments. The single-factor pollution index of heavy metals in samples from high-temperature aerobic composting, dynamic aerobic composting, rapid composting, and on-site composting was less than 1.0, indicating a clean level. The Nemerow comprehensive pollution indices of the samples were 0.27, 0.25, 0.23, and 0.19, respectively, all below 0.7, indicating a safe level. The potential ecological risk indices of the samples were 18.57, 17.51, 11.76, and 14.16, respectively, all below 150, indicating a low potential ecological risk. The evaluation results could more accurately assess the quality of composting products and effectively prevent environmental pollution.

Key words: food waste, composting, heavy metals, risk assessment