| Biosolids from wastewater treatment plant(WWTP)are environmental reservoirs of antibiotic resistance genes(ARGs),which attract great concerns on their efficient treatments.Furthermore,biosolids from pharmaceutical(antibiotic production)WWTPs contain a higher concentration of ARGs(109?1013 copies/g TS).Thus,effective treatment of waste sludge may represent a strategy for reducing ARGs in the environment.Anaerobic digestion(AD)is widely used for sewage sludge treatment but its effectiveness is limited due to the slow hydrolysis.Ozone and thermal hydrolysis pretreatments were employed to improve AD efficiency and reduce ARGs in municipal and pharmaceutical waste sludge in this study.Sludge solubilization achieved 42.9-68.8%after pretreatment by detecting concentrations of SCOD,TN,TP and protein in supernatant.Thermal hydrolysis could improve the dewaterability of sludge,while ozonation increased the capillary suction time(CST).The dewaterability/filterability could be improved by pretreatments combined AD.Both pretreatments improved cumulative methane production and the enhancements were greater on PWS than MWS.Removal rates of VS in combined treatment could achieve more than 55%,and the production of methane were increased by 1.31?5.71.Five tetracycline-resistant genes(tet A,tetG,tetQ,tetW,tetX),two sulfonamide-resistant genes(sul?,sul?),two ?-lactam-resistant genes(blaTEM,blaNDM-1)and one mobile element(intll)were qPCR to assess pretreatments.Pretreated sludge reduced more ARGs than raw sludge for both ozonation and thermal hydrolysis by absolute concentrations and relative abundances during AD.Results of this study help support management options for reducing the spread of antibiotic resistance from biosolids. |
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