[Potential and Mechanism of High-temperature Pretreatment Composting of Food Waste for Amendment of Cadmium and Lead-contaminated Soil].

To investigate the potential of high-temperature pretreatment composting of food waste for the amendment of cadmium （Cd） and lead （Pb）-contaminated soil, food waste subjected to high-temperature pretreatment composting （HC）, traditional composting （TC）, and only high-temperature pretreatment were combined with inorganic passivators （lime/zeolite） for an indoor passivation cultivation experiment. The results indicated that HC combined with the inorganic passivators group （HLZ） exhibited the most effective passivation potential for Cd and Pb in soil, achieving passivation rates of 76.92% and 86.29%, respectively. Additionally, the residual fraction of Cd and Pb in the soil increased by 10.65% and 19.94% compared to that of the control group （CK）. Fourier transform infrared spectroscopy analysis revealed that high-temperature pretreatment could facilitate the degradation of organic matter during aerobic composting, thereby improving the humification degree of organic fertilizer. As a result, the produced carboxylic acids and hydroxyl compounds were able to complex with more Cd and Pb ions, reducing their bioavailability and mobility. Moreover, the pH and electrical conductivity （EC） of the soil in the HLZ group significantly increased by 28.23% and 23.80%, respectively （<0.05）. Furthermore, the HLZ group exhibited the highest levels of available nitrogen, phosphorus, and potassium nutrients （1.62, 2.94, and 1.34 times higher than in CK）, as well as activities of urease, hydrogen peroxide enzyme, sucrase enzyme, and phosphatase enzyme （7.17, 2.09, 1.83, and 8.36 times higher than in CK）. Notably, phosphatase activity was positively correlated with the passivation rates of Cd and Pb （<0.05）. The HLZ group, characterized by high phosphatase activity （23.83 mg·g·d）, exhibited greater potential in passivating heavy metals Cd and Pb and improving soil ecological functions. Redundancy analysis of soil physicochemical indicators and the passivation effect of heavy metals indicated that soil pH, available nitrogen, organic matter, and EC significantly influenced the transformation of Cd and Pb fractions （<0.01）. The soil in the HLZ group possessed high pH, effective nitrogen, organic matter, and EC and particularly significantly higher levels of effective nitrogen content and EC compared to those in other treatment groups （<0.05）, which could be the primary reason for the optimal potential of HLZ in the amendment of Cd and Pb-contaminated soils. This study provides a feasible application of high-temperature pretreatment compost products from food waste and the amendment of heavy metal-contaminated soil.