Biofiltration of air contaminated with toluene

In industrial activities, operation of air biofilters may be interrupted fo r a long period of time. In order to examine the effect of shut-down on the performance of biofilters, a pilot scale biofiltration unit was restarted up after a non-use duration of eight months. After a reacclimation period o f eight days, the biofilter reached an elimination capacity of 35 g.m(-3).h (-1) compared to 38 g.m(-3).h(-1) before shut-down, for the same operating conditions. The results obtained indicate that the microorganism activity w as completely restored and this was confirmed by the microbial count tests performed on filter bed material samples. The impact of varying the inlet c oncentration of toluene on biofilter performance was also investigated. A m aximum elimination capacity of 120 g.m(-3).h(-1) was achieved, compared to 135 g.m(-3).h(-1) before shut-down. The biofilter removal efficiency exceed ed 96% for inlet concentrations up to 1.8 g.m(-3);. Temperature measurement s revealed that the filter bed temperature depends strongly on the intensit y of microbial activity and the biofilter effectiveness in eliminating tolu ene. Experimental data were compared with the calculations of a mathematica l model. Comparison showed that the theoretical model was successful in pre dicting the performance of the biofiltration unit.