A microbial desalination cell was developed that contained a stack of membranes packed with ion exchange resins between the membranes to reduce ohmic resistances and improve performance. This new configuration, called a stacked microbial electro-deionization cell (SMEDIC), was compared to a control reactor (SMDC) lacking the resins. The SMEDIC+S reactors contained both a spacer and 1.4 +/- 0.2 mL of ion exchange resin (IER) per membrane channel, while the spacer was omitted in the SMEDIC-S reactors and so a larger volume of resin (24 +/- 0.2 mL) was used. The overall extent of desalination using the SMEDIC with a moderate (brackish water) salt concentration (13 g/L) was 90-94%, compared to only 60% for the SMDC after 7 fed-batch cycles of the anode. At a higher (seawater) salt concentration of 35 g/L, the extent of desalination reached 61-72% (after 10 cycles) for the SMEDIC, compared to 43% for the SMDC. The improved performance was shown to be due to the reduction in ohmic resistances, which were 130 Omega (SMEDIC-S) and 180 Omega (SMEDIC+S) at the high salt concentration, compared to 210 Omega without resin (SMDC). These results show that IERs can improve performance of stacked membranes for both moderate and high initial salt concentrations. (C) 2014 Elsevier B.V. All rights rcserved