Benzophenone biodegradation and characterization of malodorous gas emissions during co-composting of food waste with sawdust and mature compost

Abstract

Abstract Benzophenone (BP) and its derivatives are extensively used as ultraviolet filters in modern society and increasingly being released into the environment. Co-composting of food waste with sawdust and mature compost was successfully demonstrated to treat high BP concentration (927\xa0 ± \xa0229 mg kg−1), with a removal efficiency of 97% after 35 days of incubation. The highest biodegradation rate of 55\xa0mg\xa0kg−1day−1 was observed at the thermophilic stage. The biodegradation followed second-order kinetics, and the half-life of BP was 1.3 days during the co-composting process. Additionally, malodorous gas emissions from the co-composting process were also analyzed. The malodorous compounds, including ammonia (NH3), hydrogen sulfide (H2S), and volatile organic sulfide compounds (VOSCs), peaked at the thermophilic phase. NH3 and H2S were the main components contributing to 92% and 7.6% of the total malodorous concentration (617 ppm). Dimethyl disulfide (28.9 ppb) and dimethyl sulfide (23.5 ppb) concentrations accounted for ∼ 58.9% of the total VOSC emitted. The malodorous emissions were positively correlated with temperature, pH, and negative with oxygen content during the co-composting. Sawdust and mature compost enhanced oxygen penetration in the compost mixture and thereby reduced odor emission. These results support that co-composting could be a technically and economically feasible treatment technology for the degradation of BP and can be used to treat other emerging organic pollutants.