ADSORPTION OF TOXIC SHOCKS ON CARRIERS IN ANAEROBIC BIOFILM FLUIDIZED-BED REACTORS

The influence of different carrier materials on the performance of sin gle stage anaerobic biofilm fluidized bed reactors by toxic shock load ings was studied in parallel experiments. The carrier materials invest igated were porous glass (Siran), quartz sand, pumice, shale, activate d carbon and anthracite. Since the composition and morphology of the b iofilm is influenced by the individual wastewater, vapor condensate fr om a sulfite cellulose process and mixed brewery wastewaters were used as substrates. The phenol adsorption characteristics were measured on bare and biofilm-coated carriers. Biofilm-coated carriers adsorbed la rger amounts of phenol than bare carriers. It was observed that the bi ofilm morphology and the corresponding adsorption capacity of biofilm carriers depended on the individual wastewater characteristics. It was also shown that activated carbon (and partly anthracite) adsorbed lar ge amounts of phenol, mostly irreversibly. The performance of the indi vidual reactors was studied under short-term dynamic phenol shocks (co nstant hydraulic retention time (HRT) 10 h, loading rate increase from 12 to 20 kg COD/m3d during the shock period of ca. 10 h). During the toxic loading in continuous operation, an increase of phenol concentra tion was observed in the effluent, coupled with an up to 20% decrease in the gas production rates. During this period, acetic acid accumulat ion was also observed, indicating the inhibition of methane formation. Following the shock, all reactors showed a relatively rapid recovery to the original activity after 2-3 hydraulic retention times.