Dynamics of the anaerobic utilization of organic substrates in an anaerobic/aerobic sequencing batch reactor

Abstract

The operation of an anaerobic/aerobic Sequencing Batch Reactor (SBR) with synthetic feed (glucose as the sole organic substrate) demonstrated periods of non-EBPR and EBPR operation in the absence of polyhydroxy alkanoate (PHA) storage. The glucose added as feed disappeared rapidly (within 10 minutes) and none of the normal fermentation products were detected in the supernatant in either mode of operation. Anaerobic/aerobic batch trials using the biomass from the SBR were conducted to examine the processes taking place and a rapid uptake of glucose was confirmed and was accompanied by a fall in pH. The biomass also demonstrated that anaerobic PHB storage occurred when acetate feed was used. The biomass was characterized by a large population of “G” bacteria, the absence of filamentous microorganisms, compact floc structure and high total carbohydrate (ca 40% w/w). The supernatant was characterized by low COD, TOC and the virtual absence of the glucose substrate. The observations indicate that EBPR was possible under circumstances which are not consistent with accepted mechanisms.