EFFECT OF ACCLIMATING SACCHARIDES ON THE ACTIVATED-SLUDGE BACTERIAL POPULATION - COMPOSITION ABNORMALITY OF ACTIVATED-SLUDGE ACCLIMATED TO GLUCOSE

The question of whether the substitution of glucose for starch in muni cipal sewage as an acclimating saccharide far activated sludge (AS) in the laboratory is valid was investigated using activated sludges accl imated to glucose (G-AS) and dextrin (D-AS), since the bacteria respon sible for starch (dextrin) removal in D-AS are verified to take up mal tose instead of glucose during dextrin removal. In G-AS, polysaccharid es are the major reserve materials, and large amounts of residual orga nic materials (ROM) are excreted from the AS. In contrast, in D-AS, ab out half of the reserve materials are low molecular weight saccharides , and no appreciable amount of ROM was detected. It is considered that most bacteria responsible for the removal of dextrin and glucose are Gram-negative and Gram-positive, respectively, based on the results of the chemical composition of AS and the type of reserve saccharide. As a result, in laboratory-scale AS precesses, maltose (disaccharide) or dextrin (polysaccharide), instead of glucose (monosaccharide), should be used as a substitute for starch. (C) 1998 IAWQ. Published by Elsev ier Science Ltd.