Release characteristics of NH₃ and VOCs during short-term fermentation of municipal solid waste

To investigate the release characteristics of NH₃ and volatile organic compounds (VOCs) during the short-term storage and fermentation of municipal solid waste, a 7-day short-term fermentation system was established using simulated municipal solid waste under 30, 40 and 50 °C conditions. NH₃ was quantitatively monitored using an online monitoring method, while typical VOCs were qualitatively identified by GC-MS and semi-quantitatively analyzed based on normalized peak areas. The results showed that the pile temperature increased and the moisture content decreased during fermentation, indicating the continuous occurrence of microbial metabolism, moisture migration and organic matter degradation. NH₃ concentration accumulated continuously with fermentation time, and increasing temperature significantly promoted NH₃ release. The normalized peak-area responses of different VOC categories showed distinct variations: aromatic hydrocarbons were mainly released in the early and middle stages; halogenated hydrocarbons exhibited relatively high responses in the presence of plastic components; oxygenated VOCs increased markedly during the middle fermentation stage; alkanes were mainly characterized by continuous volatilization; and alkenes showed clear stage-dependent variations. The theoretical odor activity value (OAV) calculated from the quantitative NH₃ concentration indicated that NH₃ was a priority odor component requiring control during short-term fermentation. These results provide a reference for odor control, priority component screening and ventilation management in waste storage pits of municipal solid waste incineration plants.