Bioelectrochemical systems (BESs) are emerging as a technology with diverse future applications. Anode-associated microbial diversity and activity are known to change over time, but the consequences of these dynamics on BES functioning are poorly understood. A novel BES with exchangeable anodic electrodes that facilitates characterisation of microbial communities over time was constructed. The BES, received a mixture of volatile fatty acids and produced 0.13 mA cm(-2) of anodic electrode surface, leading to the removal of 14 g chemical oxygen demand per m(2) electrode per day at a coulombic efficiency of 76%. Pyrosequencing of 16S rRNA genes revealed no differences in the diversity of microbial communities associated with different electrodes within a single time point. This finding validates the design for temporal studies as changes in microbial diversity observed over time can be related to community development rather than spatial variation within the reactor. (C) 2012 Elsevier Ltd. All rights reserved.