DYNAMICS OF THE ANAEROBIC UTILIZATION OF ORGANIC SUBSTRATES IN AN ANAEROBIC-AEROBIC SEQUENCING BATCH REACTOR

The operation of an anaerobic/aerobic Sequencing Batch Reactor (SBR) w ith synthetic feed (glucose as the sole organic substrate) demonstrate d periods of non-EBPR and EBPR operation in the absence of polyhydroxy alkanoate (PHA) storage. The glucose added as feed disappeared rapidl y (within 10 minutes) and none of the normal fermentation products wer e detected in the supernatant in either mode of operation. Anaerobic/a erobic batch trials using the biomass from the SBR were conducted to e xamine the processes taking place and a rapid uptake of glucose was co nfirmed and was accompanied by a fall in pH. The biomass also demonstr ated that anaerobic PHB storage occurred when acetate feed was used. T he biomass was characterized by a large population of ''G'' bacteria, the absence of filamentous microorganisms, compact flee structure and high total carbohydrate (ca 40% w/w). The supernatant was characterize d by low GOD, TOC and the virtual absence of the glucose substrate. Th e observations indicate that EBPR was possible under circumstances whi ch are not consistent with accepted mechanisms.