Abstract
Several floc-forming bacteria and phenol-decomposing bacteria were isolated from a phenol-adapted activated sludge. Strain No. 12 was the best floc-former and the ratio of flocculated cells to total cells was 90% or more. A model floc was formed by the mixed culture of the strain No. 12 and No. 3, which was one of representative strains of phenol-decomposing bacteria. This model floc can successfully decompose such a high concentration of phenol as 700ppm, though the strain No. 3 in pure culture did not show any detectable phenol decomposition or did not even grow at that concentration of phenol.
