Enrichment of extremophilic exoelectrogens in microbial electrolysis cells using Red Sea brine pools as inocula

Abstract

Applying microbial electrochemical technologies for the treatment of highly saline or thermophilic solutions is challenging due to the lack of proper inocula to enrich for efficient exoelectrogens. Brine pools from three different locations (Valdivia, Atlantis II and Kebrit) in the Red Sea were investigated as potential inocula sources for enriching exoelectrogens in microbial electrolysis cells (MECs) under thermophilic (70°C) and hypersaline (25% salinity) conditions. Of these, only the Valdivia brine pool produced high and consistent current 6.8±2.1A/m-anode in MECs operated at a set anode potential of +0.2V vs. Ag/AgCl (+0.405V vs. standard hydrogen electrode). These results show that exoelectrogens are present in these extreme environments and can be used to startup MEC under thermophilic and hypersaline conditions. Bacteroides was enriched on the anode of the Valdivia MEC, but it was not detected in the open circuit voltage reactor seeded with the Valdivia brine pool.

Understanding the cumulative effects of salinity, temperature and inoculation size for the design of optimal halothermotolerant bioanodes from hypersaline sediments

“…It is therefore accepted that the successful application of BES to the treatment of highly saline and/or hot wastewater is based on the identification and characterization of exoelectrogenic bacteria that are both tenacious and resilient under these particularly extreme conditions. Halothermophilic microorganisms are thus suitable candidates for the treatment of the high saline wastewaters generated, for example, in the seafood processing (8 to 20 g/L), textile dyeing (2 to 10 g/L), petroleum (few g/L to 300 g/L), and tannery industries (40 to 80 g/L) [17,18]. Some halophilic and/or thermophilic bacterial species isolated from extreme natural or industrial environments have been reported to display electroactive properties [19,20].…”

“…Some halophilic and/or thermophilic bacterial species isolated from extreme natural or industrial environments have been reported to display electroactive properties [19,20]. In particular, sediments from salt marsh [7,8], saline microbial mats and salt lakes [21], saline ponds [22], the Red Sea [17], the Great Salt Lake [2], and Sambhar Lake [6] have been investigated to select electroactive bacterial biofilms. In the majority of these studies, a positive correlation between salinity and current generation has been demonstrated.…”

Catalyst Development of Microbial Fuel Cells for Renewable-Energy Production

“…An example of an improved current generation at a high temperature (60°C) is a marine sediment MFC that generated 209-254 mA/m 2 compared with 10-22 mA/m 2 at 22°C [76]. Recently, an MFC with a higher operating temperature (70°C) has generated 6800 mA/m 2 [77]. Furthermore, the hyperthermophilic MFCs were operated at above 80°C [78].…”

Microbial Fuel Cells 2018

“…MEC gets noticeable attention as a sustainable wastewater treatment system with energy recovery [33], and many research teams built pilot scale MEC facilities to validate that MEC can be utilized in real industry [34][35][36][37][38][39]. In recent studies, various modified MEC structures are suggested for different applications, such as microbial electrodialysis cell (MEDC) [40], microbial reverse-electrodialysis electrolysis cell (MREC) [41,42], microbial electrolysis struvite-precipitation cell (MESC) [43][44][45], microbial electrolysis desalination and chemical-production cell (MEDCC) [46][47][48][49], and microbial saline-wastewater electrolysis cell (MSC) [50][51][52].…”