The role of TiO2 and gC3N4 bimetallic catalysts in boosting antibiotic resistance gene removal through photocatalyst assisted peroxone process

Abstract

Antibiotics are extensively used in human medicine, aquaculture, and animal husbandry, leading to the release of antimicrobial resistance into the environment. This contributes to the rapid spread of antibiotic-resistant genes (ARGs), posing a significant threat to human health and aquatic ecosystems. Conventional wastewater treatment methods often fail to eliminate ARGs, prompting the adoption of advanced oxidation processes (AOPs) to address this growing risk. The study investigates the efficacy of visible light-driven photocatalytic systems utilizing two catalyst types (TiO₂-Pd/Cu and g-C₃N₄-Pd/Cu), with a particular emphasis on their effectiveness in eliminating bla_TEM, ermB, qnrS, tetM. intl1, 16 S rDNA and 23 S rDNA through photocatalytic ozonation and peroxone processes. Incorporating O₃ into photocatalytic processes significantly enhances target removal efficiency, with the photocatalyst-assisted peroxone process emerging as the most effective AOP. The reemergence of targeted contaminants following treatment highlights the pivotal importance of AOPs and the meticulous selection of catalysts in ensuring sustained treatment efficacy. Furthermore, Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analysis reveals challenges in eradicating GC-rich bacteria with TiO₂ and g-C₃N₄ processes, while slight differences in Cu/Pd loadings suggest g-C₃N₄-based ozonation improved antibacterial effectiveness. Terminal Restriction Fragment Length Polymorphism analysis highlights the efficacy of the photocatalyst-assisted peroxone process in treating diverse samples.

Keywords: Antibiotic-resistant bacteria; Antibiotic-resistant genes; Bimetallic catalysts; Photocatalyst-assisted peroxone process; Photocatalytic ozonation; Regrowth.

Fig. 1

DRS UV-Vis spectra of (a) Pd/Cu-TiO₂, (b) Pd/Cu-g-C₃N₄ photocatalysts and HR-SEM images of (c) Pd/Cu-TiO₂ and (d) Pd/Cu-g-C₃N₄ photocatalysts.

Fig. 2

Influence of visible-light photocatalytic-based disinfection and processes on the absolute abundance of 16 S rDNA, intl1, bla_TEM, 23 S rDNA: photocatalytic oxidation ((Pd/Cu)^1%catalysts/VIS), photocatalytic ozonation ((Pd/Cu)^1%catalysts/O₃/VIS) and photocatalyst-assisted peroxone process ((Pd/Cu)^1%catalysts/O₃/H₂O₂/VIS *Blank column: below quantification/detection limit.

Fig. 3

Comparison of the influence of applied AOPs’ ((Pd/Cu)^1%catalysts/O₃/VIS and (Pd/Cu)^1%catalysts/O₃/VIS/H₂O₂) on the absolute abundance of the genes ermB, qnrS, tetM, bla_TEM, 16 S rDNA, 23 S rDNA, intl11. *Blank column: below quantification/detection limit.

Fig. 4

Comparison the performance of Cu/Pd^1%(TiO₂-based and g-C₃N₄-based) photocatalytic ozonation (with/without H₂O₂) in suppressing bla_TEM, 16 S rDNA, 23 S rDNA, intl1, ermB, qnrS, tetM regrowth. *Blank column: below quantification/detection limit.

Fig. 5

Comparison the performance of Cu/Pd^1% (TiO₂-based and g-C₃N₄-based) photocatalytic oxidation in suppressing bacterial regrowth. *Blank column: below quantification/detection limit.

Fig. 6

Nine discrete population analyses were independently conducted employing the PCR-DGGE methodology. Specifically, the eubacterial primers GC27F and 517R were utilized to amplify the V1–V2 variable regions of the 16 S rDNA.