Influence of fermentation time and heating rate on gaseous pollutants from municipal solid waste combustion

The influence of fermentation pretreatment (1–7 days) and heating rates (5, 10, 20 K/min) on the relative release characteristics of key gaseous products (CO 2 , NO, CO, NO 2 ) during municipal solid waste (MSW) combustion was systematically investigated using thermogravimetry-mass spectrometry (TG-MS). The results indicated that CO 2 and NO 2 were primarily released during the fixed-carbon combustion stage (360–590 °C), whereas CO and NO exhibited significant bimodal release peaks. Fermentation duration non-linearly affected the gas evolution: the relative cumulative release initially increased, peaking at day 3, driven by the intense microbial breakdown of organics into highly reactive small molecular intermediates. Specifically, the relative cumulative ion intensity of CO 2 at day 3 was ~ 55% higher than that of 7-day fermented samples. Subsequently (days 4–7), the relative cumulative releases of NO, CO, and NO 2 decreased by 30–45%. This late-stage reduction in nitrogen pollutants is hypothesized to be associated with potential fuel-N loss via intense aerobic ammonification during the pretreatment phase, effectively achieving a source-reduction effect. Consequently, under the specific TG-MS conditions investigated, an optimal fermentation window of approximately 3 days was identified as a potential theoretical baseline to balance energy efficiency and environmental protection.Furthermore, increased heating rates exacerbated the thermal hysteresis effect, shifting peak temperatures higher by ~ 10 °C per doubled rate. While the intense localized thermal shock exponentially increased instantaneous relative peak intensities by 20–50%, the severely shortened residence time restricted complete oxidation, ultimately reducing the overall relative cumulative release by 10–30%. This study provides critical mechanistic insights for optimizing MSW storage and incineration parameters to improve efficiency and reduce emissions.