Abstract: prevention of marine biological invasion is a major demand of our country, and the ballast water treatment system of ships, based on hydroxyl radicals, has been developed. According to the advanced oxidation process principle, a novel method was proposed for  OH radical generation by using strong electricfield discharge under atmospheric pressure, and a non-equilibrium plasma generator was built. Oxygen and gas phase water were ionized by high energy electron, and then dissociated into free active radicals or ions. These active radicals or ions were mixed well with water, followed by serious plasma chemical reaction to form  OH radicals. The onboard trial was carried out on “Yulong” ship with the treatment capacity of 250 m 3/h. The biological efficacy and relevant chemicals analysis were investigated. The test results indicate that the application of hydroxyl radicals is found to be an effective method to kill algae and bacteria; the results meet the standards set by regulation D-2 of the Convention; the concentration of tribromomethane as the main disinfection byproducts is 88.14 μg/L; no significant differences are obtained from water qualities, except dissolve organic carbon (DOC), particle organic carbon (POC) and total suspended solid (TSS); the DOC increases over time; on the contrary, POC  decreases; TSS decreases over time. The  OH ballast water treatment system provides a successful example during voyage and technical support for the development of global shipping market.

Key words: hydroxyl radicals; strong electricfield discharge; ballast water; onboard trial