Inconsiderable Amount of Phytoplankton Leakage by Algal Mat Peeling from a Slow Sand Filter

Abstract

Heavy algal mat of a filamentous diatom is sometimes observed in an open slow sand filter. Amount of particle leakage breaking through a slow sand filter was measured as an indicator of chlorophyll α concentration in filtrate water during the filter run. Chlorophyll α concentration decreased rapidly since the beginning of filter operation. Chlorophyll α concentration after ll days of filter run reached to inconsiderable amount of 0.005 Chl. α mg m^-3. This means the particle concentration breaking through the slow sand filter was negligibly small amount. Algal mat peeling during a continuous culture condition of filamentous diatom does not cause the particle leak through a slow sand filter.