PRELIMINARY STUDIES ON THE GRANULAR ACTIVATED CARBON-SEQUENCING BATCH BIOFILM REACTOR

The Granular Activated Carbon-Sequencing Batch Biofilm Reactor (GAC-SBBR), a system which combines a submerged membrane oxygenation system to support a biofilm with granular activated carbon (GAC), and the Sequencing Batch Biofilm Reactor (SBBR), a comparable system containing no GAC, were investigated to determine the efficiency of each for the treatment of wastewaters containing volatile components. Toluene, at feed concentrations between 100 and 200 mg/L, was reduced to less than 10-mu-g/L in both systems. In the GAC-SBBR, biodegradation and adsorption were responsible for 92% and 8%, respectively, of the toluene removal, while in the SBBR, all of the toluene was removed by biodegradation. The quantity of toluene volatilized from the GAC-SBBR over a 10 week period of operation was approximately 0.003% of the toluene introduced. The major consideration for long-term, efficient operation of these systems is selection of an operating strategy which results in the supply of sufficient oxygen to the biomass. Both biomass wasting and purging of the membrane oxygenation system were critical for maintaining adequate oxygen transfer to the biofilm in the GAC-SBBR and in the SBBR.