Cat-C that Im familiar with is Granulated Anthracite media. Its catalytic in that it uses adsorption along with heavy meatals in the caol to catalyze the H2S.
Still, the H2S can come in several forms from conservative to colloidal and bacterial.
The cheapest is always oxidation and Cl is the cheapest oxideizer.
Is the ASTM standard for cat Carbon 6646? I dont have a new 09 standards book yet.