Abstract
Three oxidants (sodium hypochlorite [NaClO], ozone, and ultraviolet rays) were combined with powdered activated carbon (PAC) and ultrafiltration (UF) for advanced treatment of the secondary effluent of sewage treatment plants. This study investigated the optimal oxidant dosing in the combined process, tested the removal efficiency of antibiotic resistance genes (ARGs) in the secondary effluent, and explored the removal of cell-associated and cell-free ARGs in the secondary effluent by the three combined processes. The results showed that the three combined processes could effectively reduce ARGs in the secondary effluent. The NaClO-PAC-UF process removed 3.02–4.07-log of ARGs (tetA, tetC, tetG, sulI, sulII), Class I integron-integrase (intI1) and 16S rRNA in the secondary effluent with the best reduction effect. Cell-associated ARGs were not detected in the membrane effluent of the three preoxidation-PAC-UF combined processes. The NaClO-PAC-UF combined process had the best removal effect on cell-free ARGs with a removal amount of 3.02–3.28-log. The three oxidants combined with PAC and UF can be used as a combined process to effectively reduce ARGs in secondary effluent.
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