The ultrafiltration (UF) membrane in membrane bioreactor (MBR) technology is the most suitable in a wastewater treatment plant (WWTP). In MBR systems, bacteria consume organic waste for energy to survive. Hence, the membranes should be non-toxic to the bacteria but still possess antifouling capability. In this study, carbon nanotube (CNT)- and sulphonated CNT (SCNT)-blended ultrafiltration polyvinylidene fluoride (PVDF) membranes were fabricated with the aim of conserving the bacterial population. The successful sulphonation of CNTs was observed by X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy. The porosity of PVDF-CNT and-SCNT membranes was 81 and 84%, respectively. The mean pore size was 50 and 60 nm, respectively, and the corresponding water flux experiment was 360.43 and 680 L m(-2) h(-1). The fouling recovery ratio (FRR) of the CNTs and SCNTs were 72.74 and 83.52%, respectively. In addition, the BSA (bovine serum albumin) rejection was 90% in the PVDF-SCNT. The CNTs and SCNTs (150 mu g/m L) had a significant antibacterial effect against Escherichia coli, Pantoea agglomerans, and Pseudomonas graminis isolated from full scale MBR with 60% cell viability. On the other hand, PVDF-CNT and-SCNT membranes were nontoxic (90%, p < 0.0001) to the bacterial population. Therefore, the fabricated UF membranes have sustainable antifouling properties and are non-toxic to bacteria. This study suggests that PVDF-CNT and-SCNT are promising materials for MBR systems in WWTPs. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.