Hybrid Microbial-Photosynthetic Biofuel Cells for Simultaneous Bacterial Glycerol Biotransformation and Algal Carbon Dioxide Capture

Abstract

Power generation at bioanodes of Pseudomonas aeruginosa for glycerol biotransformation was coupled to the carbon dioxide capture in biocathodes of Chlorella vulgaris in hybrid photosynthetic biofuel cells (HPSBC). Biochemical parameters such as microbial growth, substrate consumption, production of bacterial pigments and CO2 capture were studied. Also electrochemical parameters of maxima current densities (Idmax), power output (Pdmax) and coulombic efficiencies (CE) were studied. Initially, both systems were evaluated in separate against the corresponding Fe3+|Fe2+ redox pair. In bacterial systems, important results in terms of Idmax of 42 ± 2.1 µA cm-2, CE of 48 ± 2.4% and Pdmax of 350 ± 17.5 mW cm-2 were achieved. Likewise, for isolated algal cathode systems, Idmax of 93 ± 4.65 µA cm-2, CE of 56 ± 2.8% and Pdmax of 3.2 ± 0.16 mW cm-2, were achieved. In contrast, when both systems were coupled, a lower Idmax of 48.5 ± 2.42 µA cm-2 was observed. Finally, bioelectrochemical conditions were improved based on substrate consumption, electrogenic products, cation transport and mediated electron transfer systems. Thus, higher average values for Idmax of 80 ± 4.0 µA cm-2, CE of 71.5 ± 3.57% and Pdmax of 650 ± 32.5 mW cm-2 were obtained.