Behavior of trickle-bed air biofilter for toluene removal: Effect of non-use periods

A laboratory-scale trickle bed air biofilter (TBAB) packed with synthetic, inorganic media for microbial attachment was used for toluene removal from an air stream. Three experimental strategies - including backwashing as the active biomass control and two non-use periods (starvation, which represents a period without toluene loading, and stagnant, which reflects no flow) - were considered in this study. The non-use periods can be considered as another means of biomass control for low VOC loadings (0.70 and 1.41 kg COD/ m ³·day), whereas at high VOC loading (>3.52 kg COD/m ³·day) backwashing is deemed essential to remove the excess biomass accumulation in the biofilter. As the toluene loading rate was increased, a considerably longer reacclimation period was unavoidable for biofilter performance to reach the 99% removal for all experimental strategies (backwashing, starvation, and stagnant). Because the biofilter response was strongly dependent on the active biomass in the system, biofilter response after the non-use periods was significantly different from that after backwashing.