•OH Treatment for Killing of Harmful Organisms in Ship's Ballast Water with Medium Salinity Based on Strong Ionization Discharge

A novel discharge mode consisting of alternate discharge of a micro-streamer and micro-glow was developed to induce the formation of center dot OH radicals in ballast water. A series of center dot OH killing experiments were then conducted using medium salinity ballast water. Five species of algae from three different phyla and three kinds of bacteria were killed by center dot OH radicals in compliance with the D-2 ballast water standard of International Maritime Organization. Moreover, the chlorophyll-a was fully discolored when the total reactive oxidants was 2.5 mg/L, indicating that the algae had died. Overall, the quality of medium salinity ballast water with heavy pollution was greatly improved. These results indicate that the use of center dot OH radicals is an effective method for the treatment of ship's ballast water.