Abstract
This study comparatively evaluated the potential of conventional plastic rings (Kaldnes) and two materials from the company LECA International (Saint Gobain), namely Filtralite® AIR 10-20 mm and Filtralite® Air AC, for the abatement of an odorous emissions (containing 22 ± 1.7 ppmv of H2S, 2.3 ± 0.4 mg toluene m-3 and 3.8 ± 0.3 ppmv of methyl mercaptan) in biotrickling filters. The PVC biotrickling filters (BTF) used were packed with 2.5 L of packing material and operated with a constant recirculation of mineral salt medium at 2 m/h, a liquid medium exchange rate of 2.5 L/g H2S fed and decreasing gas residence times (120, 60 30 and 15 s). The removal of H2S at gas residence times of 120, 60, 30 and 15 s was complete regardless of the packing material. Filtralite materials supported a more effective acclimation of the toluene degrading microbial communities, which completely degraded toluene (> 97%) by day 5, 12 and 35 in the BTF packed with Filtralite® Air AC, Filtralite® 10-20 mm and Kaldnes rings, respectively. The superior performance of Filtralite materials during toluene biodegradation was also confirmed under process operation at 15 s of gas residence time, where toluene removal efficiencies averaged 100 %, 98% and 71 % for Filtralite® Air AC, Filtralite® 10-20 mm and Kaldnes, respectively. Similar methyl mercaptan removal efficiencies were recorded in the three BTF evaluated. A complete removal of this odorant was only achieved at 120 and 60 s, which confirmed that methyl mercaptan removal was mass transfer limited. Interestingly, all packing materials provided comparable pressure drops at the different gas residence time tested. Finally, Filtralite® Air AC was able to buffer the recirculation medium and maintain the pH > 6. This study confirmed the superior performance of Filtralite materials as packing of biotrickling filter for odour abatement.
