Oxidation of Gas Mixtures Containing Dimethyl Sulfide, Hydrogen Sulfide, and Methanethiol Using a Two-Stage Biotrickling Filter

ABSTRACT

A biofiltration technique was developed for removing a mixture of hydrogen sulfide (H₂S), methanethiol (MeSH), and dimethyl sulfide (Me₂S) from waste gases. Since H₂S, especially at high concentrations, disturbs the removal of Me₂S, two biotrickling filters with different microbes and operating pH levels were connected in series to create a two-stage system. Different loads of these gases were studied in order to determine their impact on the removal capacity of the system. The microbial consortia for these filters were enriched from the sludge of a Finnish refinery with bubbling H₂S or Me₂S. Acclimation for Me₂S took 2 weeks, though no acclimation time was needed for the other gases. The first filter, at a pH of 2, removed most of the H₂S and some of the MeSH and Me₂S. The second filter, at a pH of ~6.5, removed the rest of the MeSH and most of the Me₂S. The total maximum loads of the whole two-stage biotrickling filter were 1150 g/m³/day for H₂S-S (suffix S indicates the results are counted as sulfur amounts), 879 g/m³/day for Me₂S-S, and 66 g/m³/day for MeSH-S treated in a gas mixture. The average removal efficiencies for all gases tested were 99% or higher.