This study was conducted for the efficient utilization of a scoria, which is abundantly found in cheju island, as filtration medium and the scoria was examined for its performance in clarification of waste water extracted from a brown algae(Ecklonia cava), the mian waste source of alginic acid. The smaller media and the longer HRT(hydraulic retention time) showed higher SS removal efficiency. Under the experi-ments of the same scoria size the SS removal effiiciency was shown more effective at lower initial concentration than at higher initial concentration. The higher HRT took longer time to reach headloss 3.0m and the accumu-lation of SS was suspected to have great influence on the headloss. The removal rate equation obtained from experiments was consistent with model equation. The filter capacity σ_u was 2.94-3.43g/l and clogging rate K was 2.34-2.66l/gㆍhr.