Porosity-dependent absorption capacity of red tide algae by ceramic absorbers

Abstract

Cochlodinium red tides occur over a wide area in South Korea, from the south coast to the east coast, and last from Augustuntil October. The damage to fisheries caused by these red tides amounts to tens of billions per year. Chemical spray,sedimentation, and red clay spray methods can prevent red tides, but the most practical method, the red clay spray method,also has a negative effect on marine ecosystems. Therefore, to protect marine life from a Cochlodinium red tide withoutaffecting the marine ecosystem, six ceramic absorbers were applied to a pontoon system, a type of cage fish farm, to comparetheir absorbing capacity for red tide algae that is dependent on the porosity of the ceramic absorber. This experiment wasperformed to determine which ceramic absorber can effectively prevent red tide penetration. Previous studies have shown thatmost fish die when exposed to 8.0 × 103 cells/mL of Cochlodinium polykrikoides for 8 hrs. From the results of this experiment,the concentration of red tide algae that passed through ceramic absorber D (average porosity 60.3%), was 0.14 × 103 cells/mL. For ceramic absorber L (average porosity of 57.3%) it was 0.18 × 103 cells/mL. These two values were the highest red tideabsorption rates recorded in this study. Even when the average porosity was as low as 34.6%, such as in ceramic absorberK that had a small particle size, a high absorption efficiency of 0.18 × 103 cells/mL was observed.