Due to widespread use of antibiotics in food production, it is highly likely that various antibiotic resistance genes (ARGs) are present in food waste.While a number of studies on ARGs fate other organic waste treatments exist, food waste as an ARG source remains understudied.In this study, the fate of different ARGs was compared among different types of food waste treatment. Thermal treatment (pyrolysis and incineration), composting, and anaerobic membrane bioreactor were investigated.Eight different ARGs (sul1, sul2, tetO, tetW, ermF, ermB, ampC, oxa-1), intI1, and rpoB were quantified in food waste derived from grocery stores in Los Angeles, CA and tested subsequently during and after treatment using qPCR. Pyrolysis and incineration were performed at three different conditions.Aerobic composting was tested with biochar amendment and in hyperthermophilic conditions. A bench-scale AnMBR was operated at 3 different operating conditions with varying organic loading rate (OLR) and solids retention time (SRT).ARG copy number ranged from 3.5 x 109 to 2.9x 106 copies/Kg with ampC being the least abundant and sul1 being the most abundant, respectively in untreated food waste samples. Overall, thermal treatment showed to be the best for ARG removal with no ARGs detected after treatment. From the three composting conditions tested, ARGs persisted only in early aerobic composting and hyperthermophilic composting. While all genes decreased in concentration in all AnMBR effluents, sul1 persistent the most, detected at the highest under 5 kg m-3 day-1 OLR and 100 days SRT with 8.0 x106 copies/L.Biosolids on the contrary, accumulated ARGs in all operating conditions, with ermF being the most abundant ARG in all operating conditions, detected the highest under 2.5 kg m-3 day-1 OLR and 150 days SRT with 1. x1010 copies/Kg. Results inform the risk associated with ARGs proliferation after food waste treatment with the evaluated methods.
