The combination of ultrafiltration and activated carbon adsorption is an attractive alternative for removal of organic xenobiotics from water even in comparison with GAC fixed bed adsorbers. Results from a lab-scale investigation of combined out/in ultrafiltration and powdered activated carbon adsorption (PAC) for removal of p-nitrophenol (c(0) = 1 mg/L) are presented. The behavior of different types of carbons in conditions with and without air scouring was assessed. The most efficient carbon was the one with the smallest particle size and the fastest kinetics. Efficiency showed a decreasing trend with increasing carbon particle diameter and apparent density regardless of air scouring application. On the other hand, the effect of air scouring was different for different carbons. It was absent when the carbon with the fastest kinetics was applied. Activated carbons with slower rates of adsorption showed different behavior. Addition of coagulant in the PAC/UF system with smallest particles increased removal efficiency. Furthermore, the system was tested for the removal of carbamazepine (4 mu g/L) and xenobiotics uptake by the membrane was assessed. (C) 2010 Elsevier B.V. All rights reserved.