Assessment of the ozonation against pathogenic bacteria in the effluent of the quarantine station

This study investigated how ozone treatment can successfully inactivate pathogenic bacteria in both artificial seawater and effluents discharged from the fishery quarantine station in Pyeongtaek Port, Korea. Vibrio sp. and Streptococcus sp. were initially inoculated into the artificial seawater. All microbes were almost completely inactivated within 10 min and 30 min by injecting 6.4 mg/min and 2.0 mg/min of ozone, respectively. It was discovered that the water storing Pleuronichthys, Pelteobagrus, and Cyprinus imported from China contained the indicator bacteria, Vibrio sp., Enterococcus sp., total coliforms, and heterotrophic microorganisms. Compared to the control, three indicator bacteria were detected at two to six times higher concentrations. The water samples displayed a diverse microbial community, comprising the following four phyla: Bacteroidetes, Proteobacteria, Firmicutes, and Actinobacteria. Almost all indicator bacteria were inactivated in 5 min at 2.0 mg/min of ozonation; comparatively, 92.9%-98.2% of the less heterotrophic microorganisms were deactivated within the same time period. By increasing the dosage to 6.4 mg/min, 100% deactivation was achieved after 10 min. Despite the almost complete inactivation of most indicator bacteria at high doses after 10 min, several bacterial strains belonging to the Proteobacteria have still been found to be resistant under the given operational conditions.