In Korea, in particular the south coast, the marine industry has been gradually damaged by red tide. The pollution of offshore regions and the death of wild and offshore fish-farm fishes have resulted in significant economic losses to fishermen. The primary approach employed to remove red tide domestically is to spray red clay. However, not only is it hard to find the effect, but phosphorus and a trace quantities of metal in red clay promote the proliferation of red-tide algae. Therefore, the use of red clay is not ideal. In this study, a laboratory-sized mock-up test is performed to predict the efficiency of red-tide removal, water current, and flow velocity in the case where an artificial float with its membrane filled with ceramic carriers is installed around the perimeter of an offshore underwater fish farm. Mock-up devices are classified as circular and scaled-down types. Based on the test with the circular type, the flow velocity had a reduction rate of 78% after the passage of layer 1, and it had increased to 81~82% after the passage of layer 2. The reduction rate of red tide was initially 2000 cell/ml at the time it passed layer 1, and had reduced to between 400 cell/ml and 800 cell/ml after passing layer 2. In the test with the scaled-down type, the reduction pattern of the flow velocity was the same as that of the circular type. In conclusion, the artificial float with a ceramic membrane was effective at removing red tide and reduced the flow velocity between membrane layers to increase the stay time of red tide. It was verified that an actual artificial float could secure a sufficient time to remove red tide by causing the red tide to remain for a longer time between layers to increase the concentration, pumping red-tide microorganisms, and then removing the red tide through a filter press. It is expected that the use of artificial floats will become an effective measure to remove red tide.

Keywords: Mock-up test, Ceramic membrane, Ceramic carrier, Red tide, Chattonella.