This paper presents a new integrated model of an immersed membrane bioreactor (iMBR) for wastewater treatment. The model is constructed out of three previously published sub models describing the bioreactor, the membrane, and the interface between them. The bioreactor submodel extends a conventional activated sludge model with soluble and bound biopolymers which have been found to cause irreversible and reversible fouling. The membrane model describes fouling as a function of biopolymer concentrations, permeate flow, and shear stresses on the membrane surface. The interface describes the dependency of oxygen transfer rate on suspended solids concentrations and calculates shear stresses on the membrane surface from air-scour rates. The paper serves three purposes. First, the integrated model is simulated on a plant layout of a previously published MBR benchmark model which did not consider any interactions between the submodels. Hence, this paper presents a new and upgraded MBR benchmark model. Secondly, the simulation results showcase how simulations with an integrated model can be used to optimise plant performance and minimise energy consumption. Finally, the paper introduces new measures of fouling which can be used for benchmarking different MBR plant layouts and control strategies. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.