Dynamic Behavior of Biofilters Degrading Pulping Odors and VOCs: Hydrogen Sulfide, 1998 Environmental Conference Proceedings

Altaf H. Wani, Richard M.R. Branion, Anthony K. Lau

The University of British Columbia

Results of a systematic study about the transient behavior of biofilters, treating reduced sulfur pulping odors and VOCs, to variations in contaminant loading, and the effects of periods of starvation on biofilter dynamics and performance are reported. Three bench-scale biofilters with different filter media were used. Filter media materials used were the mixtures of compost/perlite (4:1), hog fuel/perlite (4:1), and compost/hog fuel/perlite (2:2:1). Hydrogen sulfide, the main malodorous gas produced from kraft pulping processes, was used as the test contaminant. The response of each biofilter to variations in contaminant mass loading was studied by abruptly changing the concentration and/or flow rate of the inlet waste air stream, to mimic the real world conditions. Concentration spikes were applied to study the effects of shock loading on the biofilter removal rates. The starvation period comprised of an “idle phase” when no air was passing through the biofilters. Contaminant concentration was continuously measured until a new steady state, for each stage, was achieved. Biofilters responded effectively to H2 S concentration variations and shock loads by rapidly recovering to their original removal rates within 2 - 8 hours. The re-acclimation times to reach the full capacity, after a starvation period of 3 months, were very short ranging between 120 and 140 hours, as compared to initial start-up time.