THE ROLES OF INTRACELLULAR ORGANIC STORAGE MATERIALS IN THE SELECTION OF MICROORGANISMS IN ACTIVATED-SLUDGE

The nature of organic energy reserves, and their relation to the microbial selection in activated sludge were of interest. The cellular carbohydrate and PHB were first examined in relation to their accumulation and degradation with activated sludge cultivated on glucose under batch and continuous feeding conditions. Then, CH accumulation was related with substrate uptake rate using activated sludge bearing different amounts of storage materials for both sludge. The cellular carbohydrate and PHB were of prime importance with both activated sludge. However, cellular carbohydrate was accumulated and decomposed more readily compared with PHB. The accumulation of cellular carbohydrate retarded its synthesis as well as glucose uptake. While no such relation was observed with PHB. The cellular carbohydrate accumulation capacity and attainable maximum specific substrate uptake rate were far greater for the batch-wise-fed activated sludge. Thus, the ability to accumulate cellular carbohydrate was found to be a prime selective advantage for floc formers in batch-wise-fed activated sludge. On the other hand, a sudden drastic stimulation of Sphaerotilus natans in the continuously-fed activated sludge could not be well explained even though aided with Chudoba's kinetic selection theory.