Abstract
Buoyant density of floe can be obtained by simultaneous use of Odén balance method and photoextinction method, provided that the relationship between size and settling velocity of floe is known, and that flocculation and redispersion of floes do not occur significantly during settling.
By use of this method the following result is obtained. Settling velocity of activated sludge and floe formed by bentonite and alum can be represented by a settling velocity equation for solid spheres.
