Study On Odors Emission In The Process Of Converting Food Wastes Into Feedstuffs

Food waste, with the dual attribute of pollution and resource, is the hotspot and difficultyof municipal solid waste management. Currently, one of the major processing methods offood waste treatment is producing feeds, the typical craft of which is hydrothermal hydrolysis+aerobic fermentation. During the treatment process, it is unavoidable that microbialdegradation will release some second pollutant, especially odor gases during the processingtechnology. On the one hand, odor pollution can make people feel disgusting; on the otherhand, odor gases, such as, hydrogen sulfide, mercaptan, NH₃, phenols, and benzenecompound which are harmful to human health and cause some damage for respiratory systemand nervous system.This article chose a food waste treatment plant with hydrothermal hydrolysis+aerobicfermentation as its key craft, aimed at different processes and involved areas in the plant area,carried out multi-period monitor of odor gases through stationing sampling points, studied theproduce and release rules ofNH₃, H₂S, TVOC. Moreover, total components of odor gasesfrom intensive pollution emission sources were analyzed, in order to identify the main smellycomponents and pollutants with high environment risk, and then offer supports for the odorpollutant and environment risk controlling of feed-producing craft. The results showed that:1. Among various in-organization emission sources in the whole craft production line,the release of NH₃mainly come from aerobic fermentation vessel; the release of TVOC ismainly caused by hydrothermal reactor and aerobic fermentation vessel. Due to the influenceof numerous factors, the release density of other in-organization emission sources is relativelylow, therefore, the hydrothermal reactor and aerobic fermentation vessel are regarded as thekey odor control areas.2, There is no odor pollutants which are monitored in the living quarters, office area andother area of factory, which shows that the measures of liquid medicine spray and negativepressure suction have good effects on control of odor pollutants.3. Odor pollutants include sulfocompounds, aromatic compounds, halogenated hydrocarbons, alkanes, olefins, oxygenated compounds and terpenes. In which, oxygenatedcompounds, aromatic compounds, halogenated hydrocarbons and alkanes were mainly carriedby food waste itself, while sulfocompounds, olefins, and terpenes were mainly produced byfollow-up treatment process.4. Odor strength in different process sections was as following: Discharge bin:acetaldehyde> hydrogen sulfide> methanethiol> dimethyl disulfide> ethanol; Crusher:methyl mercaptan> acetaldehyde> hydrogen sulfide, Hydrothermal reactor: acetaldehyde>methanethiol> hydrogen sulfide, Aerobic fermentation vertical: acetaldehyde> methylmercaptan. Hydrothermal reactor is the most heavily odor polluted area.5. Considering no matter the cancer risk or non-cancer risk, hydrothermal reactor is thestrongest release source. Moreover, hydrogen sulfide, acetaldehyde and propionaldehyde arethe potential contributing pollutants for non-cancer risk, while benzene is the contributingpollutant for cancer risk.