Simulated Testing of the Characteristics and Environmental Impacts of Disinfection By-Products Generated by Ballast Water Management Systems in Ports during Phytoplankton Blooms

Ballast water management systems (BWMSs) using active substances (AS) have been subjected to land-based tests with artificially increased dissolved organic matter (DOM) and cultured species according to the International Maritime Organization G9 guidelines before the BWMS Code revision. Therefore, data on the environment risk assessment (ERA) of disinfection by-products (DBPs) for actual port DOM and natural species are limited. This study was conducted using seawater from Jangmok Bay, South Korea, during a phytoplankton bloom. In treated water with a high biological content (Group A), the DBPs concentration increased as the initial AS concentration increased. However, in treated water with a low biological content (Group B), the DBPs concentration did not increase as the initial AS concentrations. The higher the residual AS concentration on day 5, the more the DBPs concentration increased, and the composition ratio of the DBPs was also affected. The ERA to individual DBP was evaluated as low given <1 for the ratio of the predicted environmental concentration to the predicted no-effect concentration in port environments exposed to DBPs in discharged ballast water. This result may suggest that the ERA of IMO G9 performed with cultured species and additives could substitute the outcome obtained with natural plankton assemblages.