Enhancing aquaculture management: Utilizing cu-doped ZnO/graphene nanocomposite for effective reduction of antibiotics and antibiotic-resistant Bacteria in shrimp culturing ponds

Shrimp culturing ponds, and enclosed breeding environments, contribute to the dissemination of antibiotics and antibiotic-resistant bacteria (ARBs) in aquatic ecosystems. This study focuses on the synthesis of a ternary nanocomposite photocatalyst, comprising Cu-doped ZnO and reduced graphene oxide (GP), using a one-step microwave-assisted hydrothermal method. The photocatalyst was employed to effectively eliminate antibiotics and inactive ARBs from aquaculture water. The structure, morphologies, and optical properties of the synthesized composites were investigated. Tetracycline (TET) and florfenicol (FLO) were the most frequently detected antibiotics in shrimp pond water, followed by sulfamethoxazole and tiamulin. Photo-degradation efficiency of TET and FLO using composite significantly improved under both UV and simulated solar irradiation. After 60 and 180 min of irradiation, the removal percentages for TET were 87.5% and 80.3%, while for FLO they were 89.5% and 92.1% respectively. The Cu-ZnO/GP composite demonstrates potent antibacterial activity against both Gram-positive (E. faecalis V583) and Gram-negative (E. coli K12 MG1655) antibiotic-resistant strains under light exposure. Its photocatalytic properties augment reactive oxygen species (ROS) generation, thereby enhancing bacterial inhibition. After 24 h of light exposure, E. coli growth was inhibited by 78%, while E. faecium growth was suppressed by 92%. The composite achieved the highest inactivation levels for E. coli (Ln-3.8) and E. faecalis (Ln-2.8) after 15 min of light exposure. The efficacy of Cu-ZnO/GP composite treatments in bacterial inactivation was notable in both ultrapure water (UPW) and real wastewater (RWW) matrices, achieving significant inactivation levels after a 1-h treatment. These findings underscore the potential of Cu-ZnO/GP composites to improve aquaculture management practices, thereby mitigating antibiotic proliferation in aquaculture waters and the surrounding environment.