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

Peat was employed as a biological filter material for the removal of hydrogen sulphide (H(2)S) dimethyl sulphide (Me(2)S) and methyl mercaptan (MeSH) from odorous ventilation air. Removal of H(2)S was possible without the need to inoculate the filter material with oxidizing microbes whereas Me(2)S required inoculation for degradation. The removal of Me(2)S 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 H(2)S without any adaptation period. As a consequence of the poor Me(2)S removal efficiency of natural peat, a limed and inoculated biofilter was needed to purify mixtures of gases containing sulphur. The highest H(2)S load tested with limed but otherwise natural peat was 136 g-S m(-3) day(-1), yielding a 99 % reduction. The maximum Me(2)S elimination capacity with limed and inoculated 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.