Reverse electrodialysis (RED) is an emerging technology that can generate electricity from the mixing of two water streams (i.e., the concentrated and the diluted streams) with salinity gradient. In RED, the higher salinity gradient between water streams yields the higher power production. Therefore, water sources containing a high concentration of salts such as reverse osmosis brine, hypersaline lakes, and produced water from hydraulic fracturing could be considered as feed streams for enhancing energy production in RED. However, these water sources contain not only NaCl but also various multivalent ions, which are likely to increase electrical resistance of ion exchange membranes (IEMs) and potentially decrease power generation. In this study, we investigated the effects of divalent cations in the concentrated stream, including magnesium, calcium, and barium ions on electrical resistance of IEMs in static mode. The electrical resistance of IEMs in static mode was found to be correlated to power production in a bench-scale RED process during continuous operation. As a result, it was found that divalent cation with the smaller hydrated radius showed the higher electrical resistance in the static mode and the increased electrical resistance of cation exchange membrane (CEM) resulted in power reduction during the continuous operation of the bench-scale RED process.

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A lactic acid bacterium presenting antimicrobial activity against a Lactobacillus acidophilus strain used for eradication of acid inhibition was isolated from a natural cheese. The 16S rRNA gene sequence of the isolate best matched with a strain of L. rhamnosus and was designated L. rhamnosus CJNU 0519. The antimicrobial activity of the partially purified bacteriocin of CJNU 0519 was abolished when treated with a protease, indicating the protein nature of the bacteriocin. The partially purified bacteriocin (rhamnocin 519) displayed a narrow antimicrobial activity against L. acidophilus, Listeria monocytogenes, and Staphylococcus aureus among several tested bacterial and yeast strains. Rhamnocin 519 in particular showed strong bactericidal action against L. monocytogenes.