Biofiltering action on hydrogen sulfide by unmodified activated carbon in sewage treatment plants

Because effluents to atmosphere from sewage treatment typically include hyd rogen sulfide (H2S) among other malodors, and because H2S is a light gas, i t is commonly assumed that unmodified ("virgin") activated carbon, which ac ts largely by physical adsorption, is inadequate for such applications. Ins tead, caustic-impregnated and other modified carbons have been used in the U.S.A., Europe. and Israel for odor control where H2S is an expected airbor ne component. Our laboratory and full-scale comparative studies question this assumption and practice, and strongly support the advantages of virgin over impregnate d or other special carbons for control of H2S as well as for general odor r emoval. In this report, we suggest that biofiltration in the carbon bed hel ps achieve such favorable outcomes.