Dynamics of toluene degradation in biofilters

Biodegradation processes have been validated as a promising alternative to other conventional air pollution control technologies. The objective of this research was to systematically investigate the transient behavior of shut down and restart-up operation and shock loading of the biofilter. Experiments were conducted in three laboratory-scale biofilters with mixtures of chaff/compost, D.E. (diatomaceous earth)/compost, and GAC (granular activated carbon)/compost, respectively as the filter materials. Toluene was used as the gas pollutant in this study. The response of each biofilter to shock loading was studied by abruptly changing the concentration or flow rate of the inlet gas. For each transient operation, toluene concentration was continuously measured until a new steady state was achieved. The results indicated that the biofilters responded effectively to the shut down and restart-up operation and shock loading of toluene concentration or gas flow rate. Moreover, the highly adsorptive GAC could improve the biofilter performance, especially for the treatment of less water soluble compounds such as toluene. Therefore, the GAC/compost biofilter had the highest maximum elimination capacity of 97 (g hr{sup {minus}1} m{sup {minus}3}). 17 refs., 8 figs.