BACKGROUNDAnaerobic technology is one of the most highly efficient methods for the biological treatment of dye wastewater by means of the reductive cleavage of the azo linkages. Dissimilatory Fe(III)-reducing microorganisms play crucial roles in a number of processes of environmental concern. The main objective of the study was to investigate the novel Fe(III)-reducing strain isolated from a BES enhanced by addition of Fe(OH)(3). RESULTSIn this study, a new electrogen, Sphingomonas strain DJ, was isolated from a microbial electrochemical reactor with Fe(OH)(3) added. The iron-reduction and the dye decolorization efficiencies of this strain achieved 69.04% and 97.65%, respectively. Cyclic voltammetry showed that strain DJ had electrochemical activity. The dye concentration, operating temperature and pH had obvious effects on the performance of the strain. Addition of Fe(III) into the medium further enhanced the decolorization efficiency. The possible pathway of the reduction of AO7 with the new strain was proposed. CONCLUSIONThe model developed for this study could provide a new method for enriching electroactively Fe(III)-reducing bacteria to treat other refractory wastewaters. (c) 2013 Society of Chemical Industry