ABSTRACT

Despite a growing interest in advanced oxidation processes (AOPs) for the inactivation of harmful microorganisms, there is relatively little research on the inactivation of harmful protozoa in aquaculture water. The research investigated the effectiveness and mechanisms of UV/chlorine, UV/monochloramine (UV/NH2Cl) and UV/chlorine dioxide (UV/ClO₂) inactivatingUronemamarinum(U.marinum), and assessed the feasibility of these processes in marine aquaculture. Three AOPs effectively inactivatedU.marinumin the following sequence: UV/ chlorine>UV/NH2Cl>UV/ClO₂. Furthermore, the concentrations of free radicals (•OH,•Cl, and•ClO) generated in the three AOPs exhibited the same order. In the investigation of the inactivation mechanism ofU.marinum, transcriptomic analysis results indicate that the effects of chlorine-based AOPs on the transcription, translation, and lipid metabolism ofU.marinummay be critical factors of the inactivation ofU.marinum. Additionally, the feasibility of chlorine-based AOPs for inactivating protozoa in marine aquaculture was assessed through pathological analysis of fish. The results indicate that compared to UV/chlorine and UV/NH₂Cl treatments, tilapia cultured in seawater treated with UV/ClO₂had lower mortality rates and minimal damage. This study provides valuable fundamental information for the selection and operation of AOPs to deactivate harmful microorganisms in marine aquaculture water.