Intensified disinfection of aquaculture matrices by Ga2O3/UV-C photocatalysis coupled with peracetic acid

This study explores the effectiveness of Ga₂O₃/UV-C photocatalysis for disinfecting recirculating aquaculture system (RAS) effluents, focusing on the inactivation of Enterococcus faecalis . After material characterization, the research optimized key parameters, including UV-C irradiation intensity, Ga₂O₃ dosage, and oxidant selection (peracetic acid and peroxymonosulfate). The Ga₂O₃/UV-C/peracetic acid (PAA) system was identified as the most effective configuration, significantly enhancing disinfection kinetics and halving treatment time compared to the Ga₂O₃/UV-C system alone. In contrast, the addition of potassium peroxymonosulfate (PMS) exhibited an antagonistic effect, indicating non-productive radical consumption pathways. Mechanistic considerations through scavenging experiments revealed that singlet oxygen ( 1 O₂) played a dominant role in the bacterial disinfection for the Ga₂O₃/UV-C system, while hydroxyl radicals (HO • ) were the primary oxidative agents in the PAA-intensified process. The study confirmed the recyclability of Ga₂O₃ over multiple treatment cycles, showing sustained disinfection performance without significant loss of activity. Long-term assessments demonstrated fewer regrowth suppression in the Ga 2 O 3 /UV-C/PAA system, likely due to residual oxidants like peracetic acid and its by-products, which retain antibacterial properties post-treatment. Furthermore, validation in real aquaculture effluents confirmed the robust performance of the optimized systems, showcasing faster inactivation yields in fish tank water compared to simulated aquaculture water, attributed to differences in organic load. Toxicity considerations, featuring DBPs, water quality parameters measurement and phytotoxicity assessment, indicated promising results. This research positions Ga₂O₃/UV-C photocatalysis, particularly when paired with PAA, as a technically viable and sustainable alternative to conventional chemical disinfectants for RAS applications.