Electrochemical and chemical enrichment methods of a sodicesaline inoculum for microbial fuel cells K. Sathish-Kumar a , O. Solorza-Feria b,a , J. Tapia-Ramı´rez c , N. Rinderkenecht-Seijas d , H.M. Poggi-Varaldo e, * a Doctoral Program of Nanoscience and Nanotechnology, Centro de Investigacio ´n y de Estudios Avanzados del IPN, Mexico D.F., Mexico b Depto. Quı´mica, Hydrogen and Fuel Cells Group, Centro de Investigacio ´n y de Estudios Avanzados del IPN, Me ´xico D.F., Mexico c Dept. of Genetics and Molecular Biology, Centro de Investigacio ´n y de Estudios Avanzados del IPN, Mexico D.F., Mexico d ESIQIE-IPN, Division Basic Science, Campus Zacatenco, Mexico D.F., Mexico e Centro de Investigacio ´n y de Estudios Avanzados del Instituto Polite ´cnico Nacional, Dept. Biotechnology and Bioengineering, Environmental Biotechnology and Renewable Energies R&D Group, P.O. Box 14-740, 07000 Me ´xico D.F., Mexico article info Article history: Received 30 August 2012 Received in revised form 27 November 2012 Accepted 30 November 2012 Available online xxx Keywords: Electrochemical active bacteria Electrolysis Enrichment Exocellular electron transfer Iron (III) Microbial fuel cell abstract In microbial fuel cells (MFCs) efficient extracellular electron transfer microbes, also known as anode-respiring bacteria, play an important role on cell performance. This type of microbes can be developed by application of enrichment procedures. The objective of this study was to compare a chemical (only C, final terminal electron acceptor Fe(III)), an electrochemical (only E), and a hybrid method (H, i.e., E followed by 3 serial transfers in iron (III) citrate medium) enrichment methods departing from a salineesodic soil inoculum. In the electrochemical enrichment procedure in an electrolysis cell, the inoculum was sub- jected to a continuous electrical stress continually by posing the cell at 150 mV/SCE (þ94 mV/SHE). The only C enrichment method delivered powers superior to the only E one (higher values of P An,max ¼ 49 mW m 2 and P V,max ¼ 558 mW m 3 of C compared to 33 and 379 of only E). Interestingly, overall resistance as determined by EIS was lower for only E (1240 U) than for only C (1632 U). Yet, the hybrid H method, showed electrochemical characteristics consistently superior to both only C and only E methods (higher P An,max and P V,max , lower internal resistance). Further detailed electrochemical studies of only E- method showed that the anodic resistance decreased with the time of operation of the electrolysis cell that would be consistent with the adaptability/enrichment purpose of the method. Also, Cyclic voltammetry peaks with values close to those reported for bacterial cytochromes appeared with time of cell operation. To the best of our knowledge, this is the first time that it is reported that serial transfers with Fe(III) as electron acceptor to an inoculum previously enriched in an electrolysis cell, leads to improved characteristics of MFC and increased Fe(III)-reducing capability of the inoculum. Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: þ5255 5747 3800x4324; fax: þ5255 5747 3313. E-mail address: hectorpoggi2001@gmail.com (H.M. Poggi-Varaldo). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2012) 1 e10 Please cite this article in press as: Sathish-Kumar K, et al., Electrochemical and chemical enrichment methods of a sodicesaline inoculum for microbial fuel cells, International Journal of Hydrogen Energy (2012), http://dx.doi.org/10.1016/ j.ijhydene.2012.11.147 0360-3199/$ e see front matter Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2012.11.147