The removal of phenols from wastewater has been investigated under various operational conditions using hydrophobic hollow fiber membrane contactors. Experimental overall mass transfer coefficients were obtained in both handmade and Liqui-Cel modules. Model predictions based on a resistance in series model with solvent-filled membrane pores matched well with experimental values for tributyl phosphate/Shellsol extraction systems. However, the predictions were in poor agreement with experimental data obtained when 50% pentanol/xylene was used to treat industrial wastewater in the handmade module. Further analysis showed that the operational pressure on the aqueous side and the breakthrough pressure for the two solvents probably influenced the position of the interface within the membrane pores. This change in wetting patterns resulted in significant differences in mass transfer and solute recovery which can be accounted for by adjusting the position of the interface within the membrane fiber. (C) 2012 Elsevier B.V. All rights reserved.