The Removal Irechnics Of Antibiotic Resistante Bacteria And Antibiotic Resistance Genes In Water Environment

Inactivating antibiotic resistant bacteria(ARB) and removing antibiotic resistance genes(ARGs) from wastewater treatment plant effluent is very important to prevent their spread into environment. Previous effo rts have been taken to eliminate ARB and ARGs from aqueous solution and sludges, however, few satisfying results have been obtained. This study investigated whether H2O2, UV and photocatalysis by TiO2 can reduce the levels of two ARGs, mecA and ampC in extracellular and intracellular forms within host ARB, methicillin-resistant Staphylococcus aureus(Gram-positive, MRSA) and Pseudomonas aeruginosa(Gram-negative, P.aeruginosa), respectively.In order to lessen the interference caused by TiO2 powder on ARB detecting and ARGs extracting, TiO2 catalytic films were synthesized by using sol- gel method. XRD analysis showed that the synthesized TiO2 thin films were crystal of anatase TiO2 with the most efficient photocatalyst than the other crystal forms; SEM analysis found that TiO2 particles in synthesied TiO2 thin films were ball and less than 300 nm revealed that synthesized TiO2 thin films had a larger surface area and mihgt have a photocatalytic efficiency.For ARB, 2.1-2.2 and 2.2-2.5 log ARB reductions were achieved by 100 mmol/L H2O2 and 12mJ/cm2UV254 fluence dose, respectively. Approximately 3.77-4.56 log MRSA reductions and 3.67-3.78 log P.aeruginosa reductions were achieved by 100 mmol/L H2O2 and 12 mJ/cm2 UV254 fluence dose respectively. 5.76-5.86 log MRSA reductions and 5.66-5.74 log P.aeruginosa reductions were achievedunder 12 mJ/cm2 UV254 fluence dose in the presence of TiO2.5.98-5.99 log MRSA reductions and 5.8-5.89 log P.aeruginosa reductions were achievedunder 12 mJ/cm2 UV254 fluence dose and 100 mmol/L H2O2 in the presence of TiO2. Matrix have little effect on ARB inactivating. P.aeruginosa was easier inactived than MRSA.For ARGs, 0.75 logmecA reductions and 0.88 logampC reductions were achieved by 100 mmol/L H2O2 and 2.30 logmecA reductions and 1.40 logampC reductions were achieved by 12mJ/cm2UV254 fluence dose. Approximately 2.95 logmecA reductions and 2.17 logampC reductions wereachieved by 100 mmol/L H2O2 and 120 mJ/cm2 UV254 fluence dose.5.7-5.9 logmecA reductions, 4.6-4.8logampC reductions,5.24 logINC-mecA reductions, 3.27 logEXC-mecA reductions 4.42 log INC-ampC reductions 2.64 logEXC-ampC reductions were achievedunder 120 mJ/cm2 UV254 fluence dose in the presence of TiO2.5.7-5.9 logmecA reductionsand 4.6-4.8 logampC reductionswere achievedunder 120 mJ/cm2 UV254 fluence dose and 100 mmol/L H2O2 in the presence of TiO2.Increasing addition of H2O2 enhanced the removal efficiencies of ARB and ARGs. H2O2 showed a better effect on ARB inactivation than ARGs removal, whereas UV irradiation showed a converse effect. MRSA was more resistant than P.aeruginosa under the same treatment condition, while the amp C was easier damaged than mecA.