In-situ emission characteristics of odorous gases from two food waste processing plants

Odorous gas emission is the main environmental concern of food waste treatment. Two typical food waste processing plants, one for animal feed production by hydrothermal hydrolysis + aerobic fermentation (Plant A), and the other for biogas production by anaerobic digestion (Plant B), were selected to conduct in situ monitoring of fugitive odorous gas emission for five consecutive days, and the emission characteristics of NH₃ and total volatile organic compounds (TVOC) were compared in this paper. The results showed that the two processes had different emission characteristics of odorous gases. Closed-operated hydrothermal hydrolysis had positive effects on overall fugitive odor control in plant A. Meanwhile, more fugitive odor gases may be released into the environment during the pretreatment with high-temperature and seemingly-open facilities in plant B. The emission strength of odor gases at night was generally lower than that in the day since more fresh food waste was received in the day and the higher temperature and lower air pressure in the day were favorable to gas emission. In general, the process of hydrothermal hydrolysis + aerobic fermentation was more advantageous in controlling odor than the process of anaerobic digestion.