Abstract
This study aimed to elucidate the effects of coagulation on filtration treatment for picophytoplankton removal. We analyzed the treatment and coagulation characteristics observed during filtration treatments by using a coagulation-sedimentation filtration experiment with cultured picophytoplankton. We found that the particle size distribution of leakage from the coagulation-sedimentation filtration was observed with a peak of 4.2 μm, revealing that the leakage had formed a fine floc rather than non-coagulation. In the coagulation treatment of picophytoplankton, when a low coagulant dose was injected, particle size of the floc was formed ＜ 10 μm, and if a high coagulant dose was injected, particle size of the floc was formed ＜ 10 μm through re-dispersion of the floc. The results clearly show that injecting the optimal coagulant dose to maintain the size of the floc infiltrating the filter layer at ＞ 10 μm would play a vital role in preventing filtration leakage.
