Despite the low removal efficiencies reported by previous studies, electro-flotation still stands out among other microalgae removal methods for its economical and environmental benefits. To enhance removal efficiency, the important factors that limit the performance of this method must be investigated. In this study, the possible ways of increasing the removal efficiency of microalgae have been explored by investigating the effects of several important variables in electro-flotation. Eight parameters, namely flotation time, rising time, current density, pH, conductivity, electrode distance, temperature and initial concentration were evaluated using a one-parameter-at-a-time approach. Results revealed that the operational parameters that greatly affected the removal efficiency of microalgae were electro-flotation time, current density, pH, and initial concentration. The effect of conductivity, electrode distance, and temperature on removal efficiency were insignificant. However, they exhibited positive an indirect positive effect on power demand, which is nowadays considered an equally important aspect in the running of a feasible and economically efficient electro-flotation process.

For the proposal of Microcystis aeruginosa control technique by coagulants, removal effects of coagulants were carried out using isolated strain and collected water bloom of M. aeruginosa on Downstream of the Nakdong River. Both of purified and field-collected M. aeruginosa were entirely sedimented by the addition of the coagulant Ceramic-Zeolite type Co 100 (1.5 ㎎/ℓ) within 24 hr, but Yellow loess (10 ㎎/ℓ) was less effective for the removal of M. aeruginosa within 24hr. Thus it was concluded that Ceramic-Zeolite type Co 100 was the most effective coagulant.