Killing of Red Tide Organisms in Sea Enclosure Using Hydroxyl Radical-Based Micro-Gap Discharge

A pilot-scale experiment for killing red tide organisms in a sea enclosure was done in Bohai Sea off Dalian City, China, in August 2003. With the physical method of micro-gap gas discharge, an OHmiddot solution of 24.3 mg/L was produced by the ionization of O₂ in air and H₂O at gas state and then dissolved into one part of seawater. When the OHmiddot concentration was 0.68 mg/L in the sea enclosure, the total kill efficiencies of 26 kinds of red tide organisms reached 99.8%, in which the bacterium and vibrio were reduced below the detection limit, meanwhile Gonyaulax cysts and Prei. Cysts with the cell crust were decreased to under the test limit. In addition, the content of chlorophyll-a was decreased below the test limit. The dissolved oxygen saturation of seawater was greatly increased to 430%. Therefore, the treatment of red tide using OHmiddot radicals is a kind of advanced oxidation technology, which realizes zero pollution, zero emission, and zero residual