Abstract
Most of algae which affect the filter clogging in water purification process for drinking water are slender type diatom. In this study, the filtration experiment has been performed using the practical slender diatoms to clear the mechanism of deposit in the filter. The ratio of filter grain size to the length of slender type diatom is closely related with the filter efficiency, the headloss profile in filter layer. As the results, it is indicated as follows: 1) the efficiency of filtration is higher comparatively under the filtration of filter grain size, d within about 15 times of length of slender type diatom, s, but it decreases with ratio of grain size to length of diatom, 2) on the penetration depth, which is correspond to the filter depth of the 95% headloss appearance to total headloss for the deposit in the filter, of diatoms into sand filter layer, under the condition such less than 15 in ratio, d/s, the number of thin filter layer having depth of grain size for the penetration depth is within about 50 only.
