A biofilter media has one or more of a set of desired physical characteristics. The set of physical characteristics includes a sphericity of 0.75 to 1, a particle size of 1 to 16 or 4 to 8 mm, a uniformity coefficient of 2 or less and a surface area of 800 to 2000 m.sup.2/m.sup.3 of media. The media is coated, supports microorganisms and is used to treat a waste gas stream.