Because effluents to atmosphere from sewage treatment typically include hydrogen sulfide (H2S) among other malodors, and because H2S is a light gas, it is commonly assumed that unmodified (“virgin”) activated carbon, which acts largely by physical adsorption, is inadequate for such applications. Instead, 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 airborne component. Our laboratory and full-scale comparative studies question this assumption and practice, and strongly support the advantages of virgin over impregnated or other special carbons for control of H2S as well as for general odor removal. In this report, we suggest that biofiltration in the carbon bed helps achieve such favorable outcomes.