In a recent study, researchers from South-West University “Neofit Rilski”explored the influence of light irradiation on the sediment microbial fuel cell’s (SMFCs) electrical outputs. The experiments at both natural and artificial illumination firmly show that current grows up during the photoperiods. The intensity the current increases was shown to depend on the duration of the photoperiod as well as on the wavelength of the monochromatic light source applied.

The highest influence of the light irradiation was obtained at wavelengths corresponding to the absorption peaks of essential pigments in the light-harvesting system of oxygenic photosynthesizing microorganisms. The decreased values as well as the discontinued fluctuations of the current as a result of suppressed illumination or substitution of the biocathode with a new one suggest that photosynthesizing microorganisms, co-existing in the cathodic biofilm consortium, contribute to the overall SMFC performance.

The microscopic observations confirm the existence of chlorophyll-containing microorganisms on the cathode surface. The amplicon-based microbial profiling results support the hypothesis that the current enhance during the photoperiods is due to the in situ bio-oxygen production on the cathode surface, thus lowering the mass transport limitations for the oxygen reduction reaction.

 

Reference
I Bardarov, M Mitov, D Ivanova, Y Hubenova (2018) Light-dependent processes on the cathode enhance the electrical outputs of sediment microbial fuel cells Bioelectrochemistry. doi: 10.1016/j.bioelechem.2018.02.009 [abstract]

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