FLOC FORMATION IN ACTIVATED SLUDGE

I. FLOC-FORMING ACTIVITIES OF REPRESENTATIVE BACTERIA ISOLATED FROM ACTIVATED SLUDGE

Abstract

The activated sludge tested contained about 10¹¹ bacterial cells per g of dry matter. The bacterial strains isolated from the activated sludge were classified into 21 groups by their morphological and physiological properties. Depending upon the floc-forming activities, the representative 12 strains which seemed to be dominant in number were distinguished into the following three types: (A) Floc former as cultured singly, (B) floc former as cultured in combination with strains other than type A, and (C) restrainer of floc formation if combined with type B. The bacteria isolated and the original sludge showed only a weak activity in oxygen consumption with glucose, but the sludge and some of bacteria belonging to types B and C consumed large or noticeable amounts of oxygen with peptone.