Evaluation of sulfur toxicity and media capacity for hydrogen sulfide removal in biofilters packed with both natural and commercial media

Two types of media, a natural media (wood chip) and a commercially engineered media, have been evaluated for sulfur inhibition and capacity for removal of hydrogen sulfide from air streams. Sulfate was artificially added (40, 65, 100 mg-S/g-media) to test its effect on removal efficiency, biofilms and media. A humidified gas stream of 50 ppmv H₂S was passed through the media columns and effluent readings for H₂S at the outlet were measured continuously. Pressure drop across the all of the media columns was very stable. The overall H₂S baseline removal efficiencies of the natural media column and the commercial media columns remained greater than 95% even with the accumulated sulfur species. Added sulfate at a concentration high enough to saturate the biofilter moisture phase did not appear to affect the H₂S removal process efficiency. Additional experiments were completed with a commercial granular media and the results also demonstrated that the accumulation of large amounts of sulfate sufficient enough to saturate the moisture phase of the media did not have a significant effect on H ₂S removal. When biofilter media pH was lowered to 4, H ₂S removal efficiency did drop to 36%. Sorption experiments with autoclaved media demonstrated that some H₂S removal was caused by physical processes, however, significant biotic removals were also occurring that were uninhibited by the accumulated sulfate.