The subject of this research was the decomposition of pharmaceuticals (sulfamethazine and sulfathiazole) using an oxygen-based membrane biofilm reactor. The influent concentrations in pharmaceuticals feed-medium were (in ppb): sulfamethazine (40) and sulfathiazole (85). The oxygen-based membrane biofilm reactor system consisted of two membrane modules connected to a recirculation loop. The main membrane module contained a bundle of 32 hydrophobic hollow-fiber membranes inside a polyvinyl-chloride pipe shell, and the other module contained a single fiber used to take biofilm samples. Pure O-2 was supplied to the inside of the hollow fibers through the manifold at the base, and the O-2 pressure for both reactors was 13 kPa. (I kPa = 0.0099 atm = 0.145 psi). HRT was 3 It. The decomposition ratio of pharmaceuticals (sulfamethazine and sulfathiazole) using oxygen-based membrane biofilm reactor was (%): sulfamethazine (77 +/- 2), and sulfathiazole (87 +/-2). (C) 2009 Elsevier B.V. All rights reserved.