Significant Improvements in Biofilter Performance for H2S and VOC Removal Using Biotrickling/Bioscrubber Technology in the Aeration Distribution Plenum System

Biofilters can handle the removal challenge of a diverse mix of complex odors and VOCs. However, there are significant limitations in handling levels of hydrogen sulfide (H2S) loadings above 10 ppm. High levels of H2S loading in biofilters will create an increase in the acidithiobacillus colony causing an overproduction of acid. This will destroy all other biodegrading microorganisms and fungi in the organic media that feed on the more complex odor compounds. A loss of treatment efficiency, premature media replacement, compaction and channeling of the organic media will occur.The objective of this pilot study was to mitigate the high H2S problems in biofilters and improve organic media life and removal efficiency by using porous lava rock media instead of typical washed stones. Porous lava rock media has been widely used in biotrickling/bioscrubber applications and has shown high removal efficiency of H2S in the range of 98-99%. The concept was to use the porous lava rock media as the first ecosystem layer for removal of H2S and use as a second ecosystem the organic media for removal of remaining odor compounds and VOCs. This is essentially a two-stage treatment in one cell without additional footprint.Results of the testing indicate that when high levels of H2S are present the porous lava rock media (stage one) achieved average H2S removal efficiency above 99%. The polishing through the organic media achieved 99.9% removal levels of H2S and non-detectable levels of VOCs and sulfur compounds (stage one and two).