Peat biofilters in long-term experiments for removing odorous sulphur compounds

Peat was employed as a biological filter material for the removal of hydrog en sulphide (H2S) dimethyl sulphide (Me2S) and methyl mercaptan (MeSH) from odorous ventilation air. Removal of H2S was possible without the need to i noculate the filter material with oxidizing microbes whereas Me2S required inoculation for degradation. The removal of Me2S was decreased as a result of MeSH addition. Liming of the filter material, i.e., addition of calcium hydroxide, increased removal efficiency and activated the oxidation of H2S without any adaptation period. As a consequence of the poor Me2S removal ef ficiency of natural peat, a limed and inoculated biofilter was needed to pu rify mixtures of gases containing sulphur. The highest H2S load tested with limed but otherwise natural peat was 136 g-S m(-3) day(-1), yielding a 99 % reduction. The maximum Me2S elimination capacity with limed and inoculate d peat was 175 g-S m(-)3day(-)1, but removal became unstable when the load exceeded 150 g-S m(-3) day(-1). The maximum MeSH load tested was 107 g-S m( -3) day(-1), yielding 98 % removal.