Abstract: To mitigate the environmental odorous and safety risks during the excavation of aged municipal solid waste (MSW) in landfills, and to address the long processing duration drawback of conventional aerobic stabilization technologies,the aged MSW with a landfill age of approximately 5 to 10 years from a large-scale MSW landfill in South China was taken as the research sample, and a small-scale laboratory device for rapid aerobic environment simulation was constructed. Using reaction tanks with air flow rates of 15 L/min and 10 L/min, and the AERMOD atmospheric dispersion model was applied for simulation analysis to systematically investigate the variation laws and diffusion behaviors of malodorous pollutants during the rapid aerobic stabilization process. The results indicated that based on on-site monitoring data of the landfill, ammonia was identified as the representative pollutant for rapid aerobic pretreatment. The ammonia concentration exhibited a variation trend of “rapid decline in the initial phase, stabilization in the later phase, and rebound after shutdown”, which was attributed to the stage-specific degradation effect of aerobic treatment on NH3. AERMOD model simulation results showed that the post-attenuation ratios of ammonia at distances of 10 m, 100 m, and 300 m along the dominant diffusion direction were 93%, 23%, and 6%, respectively, with the attenuation rate slowing significantly as the distance increased. The solubility of ammonia was much higher than that of other malodorous pollutants, making it prone to migrate with moisture and expand the pollution scope. Based on these findings, it was recommended to prioritize an aeration rate of 15 L/min or higher, maintain intermittent aeration for a minimum of 1 344 hours, enhance ventilation in the initial phase and supplementary deodorization measures in the later phase and install drying devices during aeration. These measures could effectively improve the aerobic stabilization efficiency of the pretreatment process prior to aged waste excavation in the landfill and further mitigate the diffusion of odorous pollutants.

Key words: aged municipal solid waste, rapid aerobic stabilization, pretreatment； landfill gas, malodorous pollutants, AERMOD model