Removal of Propylene and Butylene as Individual Compounds with Compost and Wood Chip Biofilters: Fid-Bau Portal

Removal of Propylene and Butylene as Individual Compounds with Compost and Wood Chip Biofilters

Rani, Madhu / Sattler, Melanie L.

Propylene and butylene are highly reactive volatile organic compounds (HRVOCs) in terms of ground-level ozone formation. This study examined the effectiveness of biofiltration in removing propylene and butylene as separate compounds. Specific objectives were (1) to measure maximum removal efficiencies for propylene and butylene and the corresponding microbial acclimation times, which will be useful in the design of future biofilters for removal of these compounds; (2) to compare removal efficiencies of propylene and butylene for different ratios of compost/hard wood-chip media; and (3) to identify the microorganisms responsible for propylene and butylene degradation. Two laboratory-scale polyvinyl chloride biofilter columns were filled with 28 in. of biofilter media (compost/wood-chip mixtures of 80:20 and 50:50 ratios). Close to 100% removal efficiency was obtained for propylene for inlet concentrations ranging from 2.9 × 10⁴ to 6.3 × 10⁴ parts per million (ppm) (232–602 g/m³-hr) and for butylene for inlet concentrations ranging from 91 to 643 ppm (1.7–13.6 g/m³-hr). The microbial acclimation period to attain 100% removal efficiency was 12–13 weeks for both compounds. The lack of similar microbial species in the fresh and used media likely accounts for the long acclimation time required. Both ratios of compost/wood chips (80:20 and 50:50) gave similar results. During the testing, media pH increased slightly from 7.1 to 7.5–7.7. None of the species in the used media that treated butylene were the same as those in the used media that treated propylene, indicating that different microbes are adept at degrading the two compounds.

This study is the first, to the authors’ knowledge, to demonstrate the effectiveness of a compost/wood-chip biofilter for propylene and butylene removal. Propylene and butylene are HRVOCs that are very efficient at forming ground-level ozone. This research determined removal efficiency values, microbial acclimation times, and microbial species responsible for compound degradation that will all be useful in the design of future biofilters for the removal of these compounds.