Treatment of Red Tide in Ocean Using Non-Thermal Plasma Based Advanced Oxidation Technology*

A Pilot-scale experiment for the treatment of red tide in the enclosure was done in sea area of Shandong Province, P.R. China on Aug. 25, 2002. With the method of micro-gap discharge, O2 in air and H2O in seawater are ionized and dissociated into large numbers of OH• radicals, and then dissolved into a part of seawater to form OH• solution of high concentration. With OH• concentration of 0.68 mg/L, the kill efficiencies of 29 kinds of red tide organisms such as Chaetoceros lorenzianus and so on reached 99.89%, in which bacterium and vibrio were reduced below the detection limit, also Gonyaulax cysts and Prei. Cysts with the crust were done the lowest limit of test. At the same time, the content of chlorophyll-a was decreased below the detection limit. DO (dissolved oxygen) saturation of seawater was greatly increased to 100% because the residual OH• radical was decomposed into H2O and O2 after 20 min. Therefore the treatment of red tide using OH• radicals is a kind of advanced oxidation technology, which realizes zero pollution, zero emission and zero residual in the process of the production of OH• radicals and the treatment of red tide.