Enhancement of photocatalytic-based processes by mono- and bimetallic (CuPd) rutile loaded nanoparticles for antibiotic resistance genes and facultative pathogenic bacteria removal

The aim of the study was the strong reduction of facultative pathogenic bacteria (FPB), and clinically relevant antibiotic resistance genes (ARGs) from secondary effluent. To evaluate the ARGs removal efficiency comparative study of individual unit processes and combined AOPs has been performed. The present work investigated: i) removal of selected ARGs, namely blaTEM, ermB, qnrS, tetM, five FPB as well as 16S rDNA and the integrase gene intl1 involved in horizontal gene transfer; ii) bacterial regrowth potential after treatment; (iii) the removal of the total genomic DNA content, by mono- and bimetallic TiO2-CuPd rutile photocatalysts under visible light radiation in real secondary effluent. The nanoparticles were characterized by UV–vis, XRD, HRTEM, Raman and XPS. TiO2-CuPd/VIS inactivation gives the highest (more than 2 log units removal) efficiency for almost all targets (blaTEM, ermB, tetM, intl 1, and 16S rRNA) compared to monometallic catalysts. The highest efficiency toward blaTEM was achieved after ozonation and TiO2-CuPd/O3/VIS (3.22 and 3.23 LRV, respectively). It was found that despite similar FPB inactivation, lower DNA destruction was found after O3 compared to TiO2-CuPd/O3/VIS treatment. The blaTEM and enterococci were completely removed during TiO2-CuPd/O3/Vis and TiO2-Cu/O3/Vis. While, catalytic ozonation leads to only slightly blaTEM removal (0.64 and 0.44 LRV for TiO2-CuPd/O3 and TiO2-Cu/O3, respectively). Photocatalytic ozonation with the application of TiO2-CuPd leads to significant removal of FPB and ARGs due to synergistic effect between Pd and Cu, which leads to acceleration of ozone – catalysts reaction. Photocatalytic ozonation has the greatest potential giving promising possibilities for eliminating AMR.