Odor characteristics and health risks during food waste bioconversion by housefly (Musca domestica L.) larvae

Abstract

Bioconversion by housefly (Musca domestica L.) larvae is a novel technology for reducing and recycling food waste. In this study, odor characteristics and health risks of gaseous pollutants from food waste bioconversion by housefly larvae were investigated and compared with other treatment technologies for the first time. Air samples were collected from different areas in a full-scale food waste bioconversion facility (50 t/d). The chemical compositions of the air samples were quantitatively and qualitatively analyzed, the odor contribution and annoyance were assessed with the odor activity values and their sum, and the health risks (carcinogenic and non-carcinogenic risks via inhalation and other risks) were evaluated. The total concentrations of volatile compounds were significantly higher in the breeding and biodegradation areas than in the other areas. Ethanol was the dominant odorant in the unloading, pretreatment, substrate storage, and breeding areas, while that was ammonia in the biodegradation and product areas. The sums of odor activity values in the breeding and biodegradation areas were the highest (1171 and 756, respectively) with trimethylamine as the key odorant. Carcinogenic risk in the breeding area was unacceptable with acetaldehyde as the key carcinogen, and possible carcinogenic risks existed in the other areas except for the substrate storage area. Non-carcinogenic risk existed in the order of breeding area > biodegradation area > product area > pretreatment area with acetaldehyde, ethyl acetate, hydrogen sulfide, and ammonia as the dominant contributors. The bioconversion technology showed different odor characteristics and health risks from other treatment technologies. Therefore, odor control and health protection measures should be taken based on the odor and health risk evaluation, especially in the breeding area. Suggestions on gas collection and treatment method selection were proposed. The findings provide a scientific basis for odor control and health protection in food waste bioconversion facilities.