Response Surface Methodology Optimization of Composting Pretreatment: Enhanced Lignin Degradation, Reduced Greenhouse Gases, and Improved Product Quality

The lignin in chestnut rose waste restricts composting efficiency. This study aimed to optimize lignin degradation in feedstock pretreatment using response surface methodology (RSM) and evaluate the effects on composting efficiency and greenhouse gas emissions. A Box–Behnken design with three factors (temperature, time and biochar) was used to determine optimal conditions. The RSM-optimized pretreatment was then compared against biochar pretreatment, high-temperature pretreatment without biochar, and no pretreatment to evaluate their effects on composting efficiency. The results showed that the RSM-supported optimal pretreatment (79.2 °C, 5.2 h, 10.3% biochar, R2 = 0.9970, p < 0.0001) degraded 59.31% of lignin in chestnut rose waste. The optimized pretreatment condition increased the lignin degradation rate by 31.5% during composting compared to a lack of pretreatment. The quality of the compost was significantly improved, with the total N and NO3− contents increasing by 22.0% and 65.2%, respectively. Furthermore, the optimized pretreatment reduced cumulative CH4 and N2O emissions by 37.5% and 36.5%, respectively. These findings suggest that RSM-optimized pretreatment effectively enhances composting efficiency and mitigates the environmental impacts of chestnut rose waste composting. However, this study was limited to laboratory-scale conditions, and further field-scale validation is needed.