INFLUENCE OF THE RATIO OF THE INITIAL SUBSTRATE CONCENTRATION TO BIOMASS CONCENTRATION ON THE PERFORMANCE OF A SEQUENCING BATCH REACTOR

Biomass behaviour and COD removal in a benchscale activated sludge rea ctor have been studied alternating anaerobic and aerobic conditions. P articular attention has been paid to the influence of the ratio of the initial substrate concentration (S-0) to the initial biomass concentr ation (X(0)) on the reactor performance. Tests at very low ratios (S-0 /X(0)<2) demonstrate the existence of a threshold below which the reac tor performance is seriously affected (S-0/X(0)=0.5). Under conditions of total suppression of cell duplication, substrate maintenance requi rements have also been calculated for the microbial consortium present in the activated sludges. The results obtained show that stressed bio mass can survive conditions of substrate lack better than unstressed b iomass.