Oxidation of gas mixtures containing dimethyl sulfide, hydrogen sulfide, and methanethiol using a two-stage biotrickling filter

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 o f Me2S, two biotrickling filters with different microbes and operating pH l evels were connected in series to create a two-stage system. Different load s of these gases were studied in order to determine their impact on the rem oval 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 fo r 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 similar to6.5, 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/m(3)/day for H2S-S (suffix S indicates the results are counted as sulfur amounts), 879 g/m(3)/ day for Me2S-S, and 66 g/m(3)/day for MeSH-S treated in a gas mixture. The average removal efficiencies for all gases tested were 99% or higher.