REMOVAL EFFICIENCY OF HARMFUL RED TIDE BY NATURAL MINERALS

This study was carried out to find a new material having high removal capacity on harmful red tide, algae (Cochlodinium polykrikoides) grow very fast or "bloom" and accumulate into dense, visible patches near the surface of the seawater. Some Fe-oxides, clay minerals and Hwangto (Reddish soil consist of clay minerals and Fe-oxieds) are used to estimate removal efficiency of algaes. The determined sprinkling ratio of mineral and seawater containing around 5,000 cells/mL of Cochlodinium polykrikoides was 10g/L. In order to estimate the removal efficiency, living cells was measured by counting with intervals of 0, 10, 30, 60 minutes after sprinkling. In the result of five Hwangtos from different localities, high concentration in Fe and Al of Hwangto is more effective to remove algae. After sprinkling the Hwangto which is the highest of removal efficiency in lab testing, 99% of algaes were eliminated in 60 minutes. Kaolinite, 92% removal efficiency after 60 minutes, showed the highest of removal efficiency among clay minerals, and the following order of montmorillonite (91%) > zeolite (88%) > illite (81%). In addition, Fe-oxides like hematite, 99% removal efficiency after 30 minutes, and goethite, 99% after 60 minutes, also has high capability to get rid of algae from water. In particular, the removal efficiency with 1g/L ratio of earthy hematite and seawater was 99% after 60 minutes. According to these results, it can concluded that earthy hematite is the most effective natural mineral removing Cochlodinium polykrikoides from seawater.