Lagooning microbial fuel cells: A first approach by coupling electricity-producing microorganisms and algae

• An algae cathode of a MFC has been used without artificial mediators or catalysts.
• To perform a lagooning wastewater treatment coupled with energy-producing MFC.
• The producing electricity operates under day/night irradiation cycles, is shown.

The paper focused on the start-up and performance characterisation of a new type of microbial fuel cell (MFC), in which an algae culture was seeded in the cathodic chamber to produce the oxygen required to complete the electrochemical reactions of the MFC, thus circumventing the need for a mechanical aerator. The system did not use mediators or high cost catalysts and it can be started-up easily using a straightforward three-stage procedure. The start-up consists of the separate production of the electricity-producing microorganisms and the algae cultures (stage I), replacement of the mechanical aeration system by the algae culture (stage II) and a change in the light dosage from a continuous input to a dynamic day/night profile. The MFC was operated under a regime of 12 h light and 12 h dark and was also operated in batch and continuous substrate-feeding modes. The same cell voltage was achieved when the cathode compartment was operated with air supplied by aerators, which means that this configuration can perform as well as the traditional one. The results also show the influence of both the organic load and light irradiation on electricity production and demonstrate that this type MFC is a robust and promising technology that can be considered as a first approach to perform a lagooning wastewater treatment with microbial fuel cells.

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