19. AVAILABILITY OF SORBED SUBSTRATE FOR MICROBIAL DEGRADATION ON GRANULAR ACTIVATED CARBON

Abstract

The availability of sorbed substrate for microbial degradation on granular activated carbon was investigated in comparative studies of substrate utilization and biological growth in fluidized-bed batch-recycle reactors containing GAC, coal and sand. The substrates used were o-cresol, acetophenone, phenol and benzoic acid. These differed greatly in adsorbability. The specific microbial growth rates were found to be the same on the two non-adsorbing media. However, an enhanced biodegradation rate and a higher specific growth rate was measured on GAC. Then on the non-adsorbing media. This enhanced growth rate is a function of substrate availability. Experiments showed that an increase in sorbed substrate concentrations and a decrease in particle diameter increased the specific growth rate. A maximum enhanced rate is approached for each particle size as sorbed substrate increases.