Removal kinetics of hydrogen sulfide, methanethiol and dimethyl sulfide by peat biofilters

Abstract

The biological degradation rates of odorous sulfur compounds, such as hydrogen sulfide (H 2S), methanethiol (MT) and dimethyl sulfide (DMS) on peat biofilters were measured. First, peat was acclimated with each gas alone, then the removal rate was measured 2 h after the sulfur load was changed by altering the inlet concentration and space velocity (SV = aerated volume at standard state/packed volume of peat). A Michaelis-Menten type equation was applied and the maximum removal rate ( V m) and saturation constant ( K s) were calculated. For single gases, these constants were as follows: V m(H 2S) = 5.0 g-S/d kg-dry peat, K s(H 2S) = 55 ppm, V m(MT) = 0.9 g-S/d kg-dry peat, K s(MT) = 10 ppm, V m(DMS) = 0.38 g-S/d kg-dry peat, K s(DMS) = 10 ppm. Second, after acclimation by each gas alone, different gases were supplied and the removal rate was measured using the same method described above. Third, mixed gases were passed through the peat acclimated by a single gas, and kinetic analysis was carried out. H 2S and MT were degraded on peat irrespective of the acclimating gas, and their maximum removal rates were unaffected by the presence of DMS. DMS was degraded only in DMS acclimated peat. The removal rate of DMS in mixed gas experiments on DMS acclimated peat decreased significantly 2 h after changing the inlet conditions of the peat, followed by a low constant removal rate after 7–8 h. The same phenomenon was observed in MT when MT and H 2S mixed gases were supplied to MT acclimated peat.