Abstract:
The use of microbial fuel cells (MFCs) that generates energy from biodegradable substances
by means of microorganisms, has several applications, including wastewater
treatment, operation of remote sensing devices, and bioremediation. In terms of energy
generation, the ocean is a vastly underutilized yet potentially abundant resource. Because
of the rapid ionic movements and superior electrical conductivity of sea water, it is
a suitable medium for operating bio-electrochemical devices. The anode compartment’s
mixed consortium of marine microorganisms can perform robust extracellular electron
transfer and has to be fed an external substrate like glucose. In conventional MFCs
the cathode has to be coated with an expensive noble metal to efficiently catalyze
the oxygen reduction reaction (ORR) and it requires active aeration. Biofilm-forming
marine photosynthetic microorganisms (MPM) serve as electron donors and replace
the typical cathode catalyst in this marine photosynthetic MFC (mpMFC). This study
examined the use of seawater as a conducting medium in a two-chambered MFC to
enhance power production in conjunction with a marine photosynthetic bio-cathode
as an alternative to the abiotic chemical cathode. Using a modified BG11 medium,
MPMs were effectively transferred into the cathode compartment. After a significant
quantity of biomass had formed, it was prepared for use as an exo-electrogens-nourishing
extracellular feeding substrate. The effectiveness of marine MFC (mMFC) was evaluated
in three phases: before adding MPMs to the cathode compartment, after adding MPMs
into the cathode compartment, and while feeding ready-to-use substrate. Power current
plots and polarization curves were used to evaluate the efficiency of MFC. In mMFC,
maximum power density (Pdmax) was 147.84 mW/m2 and maximum current density
(Jmax) was 1311.82 mA/m2. In mpMFC, Pdmax was 104.48 mW/m2 and Jmax was
1107.27 mA/m2. The Pdmax in mMFC is increased by 178.2% and in mpMFC by 161.4%,
while the Jmax is increased by 96.6% and 120.65% respectively. Exo-electrogens were
proven to exist by observing a color change in anode samples cultivated in modified
chromogenic medium. We conclude that this mpMFC that is fully driven by sea water
along with a biocathode is a promising technology for the sustainable production of
electricity.
