Due to high chemical oxygen demand (COD) and its low biodegradability, molasses wastewater is usually classified as a high-strength industrial wastewater. The possibility and efficiency of a membrane bioreactor (MBR), containing lab-made membrane modules, in treating molasses containing wastewater was studied. The research was conducted in two phases, namely a first period of fed-batch operation followed by a second with continuous MBR operation. The results showed that more than 80,90 and 30%, respectively, of the COD, total nitrogen (TN) and color were removed. There was a clear influence of the membrane pore size on trans-membrane pressure (TMP) build-up. Scanning electron microscopy and Fourier transformed infrared (FT-IR) analyses revealed no significant differences in organic constituents between the membrane cake layer and the activated sludge. (C) 2010 Elsevier B.V. All rights reserved.