Studies on the ·OH Inactivation of Non-native Aquatic Organisms and Potential Disinfection Byproduct Formation for Oceanic Environmental Safety

Abstract

This work was carried out based on the principles of biological effectiveness and environmental acceptability of the International Maritime Organization (IMO). The non-native red tide organisms Prorocentrum donghaiense and Scrippsiella trochoidea were selected to examine ·OH inactivation to meet the IMO standard of ballast water discharge (< 10 cells/mL). The effective quantum yield of photosystem II of algal chlorophyll rapidly decreased to zero within a contact time of only 6 s. Under scanning electron microscope (SEM) observation, the algal cells treated with the ·OH inactivation dose still had an intact shape and did not release cellular material, and thus, there are no risks associated with oceanic environmental safety. The potential disinfection byproducts (DBPs) from discharged ship’s ballast water at high salinity (33.7 PSU) treated at a maximum TRO dose of 2.41 mg/L were analyzed by 5-day storage experiments. The results indicated that the contents of bromate, trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) were below the WHO drinking water standards. Therefore, discharged ship’s ballast water with ·OH inactivation is safe for oceanic environments.