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A strategy for power generation from bilgewater using a photosynthetic microalgal fuel cell (MAFC)
Citation:
Hwang, J., H. Ryu, K. Rodriguez, S. Fahad, J. SantoDomingo, A. Kushima, AND W. Lee. A strategy for power generation from bilgewater using a photosynthetic microalgal fuel cell (MAFC). JOURNAL OF POWER SOURCES. Elsevier Science Ltd, New York, NY, 484:229222, (2021). https://doi.org/10.1016/j.jpowsour.2020.229222
Impact/Purpose:
Bilgewater is oily wastewater found in the bottom chamber of ships, which generally contains fuels, oil, grease, detergents, and seawater. The discharge of oil < 15 ppm into the ocean is strictly regulated by U.S. federal and state government agencies and the international community. However, chemically stable emulsions formed by surfactant-stabilized micelles are difficult to treat using traditional methods such as gravity-driven oil water separator, often requiring secondary treatment to meet regulatory guidelines. Bioelectrochemical systems (BES) can provide a sustainable alternative as electroactive microorganisms can produce direct electrical energy, while treating wastewater as an electron donor. Given the oil biodegradation potential of green alga, we evaluated the use of microalgae as active biomass in the anode as well as a biocathode for effective O2 supply and catalytic reduction in a single-chamber microalgal fuel cell (SMAFC) as an alternate BES for bilgewater emulsion treatment. In this study, a SMAFC was constructed using Chlorella sorokiniana as an activate biomass in the anode to treat synthetic bilgewater containing surfactant as a substrate. The performance of the SMAFC was evaluated in terms of chemical oxygen demand reduction as oil removal, biomass production, electron acceptors, power (voltage) generation, current density, and power density. A double-chamber microalgal fuel cell, directly fed with O2 produced by microalgal photolysis at a separated cathode chamber, was also operated to compare the performance of MFC between the two different reactor configurations.
Description:
Microbial fuel cells (MFCs) have recently advanced towards a new initiative of electricity generation from oily wastewater. Although MFCs that utilize microalgae as a self-supporting oxygen (O2) supply at the cathode have been well discussed, microalgae at the anode as an active biomass for treating wastewater and producing electrons is still poor studied. Here, we demonstrated a bilgewater treatment using single- and double-chamber microalgal fuel cells (SMAFC and DMAFC) capable of generating energy using a novel microalgal strain (Chlorella sorokiniana) that was originally isolated from oily wastewater. Compared to previous MFC studies using green algae, relatively high voltage output (151.3–160.1 mV, 71.3–83.4 mV m-2 of power density) was observed in the SMAFC under O2 controlled systems (i.e., acetate addition or light/dark cycle). It was assumed that, under the O2 depletion, alternative electron acceptors such as bicarbonate may be utilized for power generation. A DMAFC showed better power density (up to 23.9%) compared to the SMAFC due to the separated cathode chamber, fully utilizing O2 as an electron acceptor. Both SMAFC and DMAFC removed 67.2–77.4% of soluble chemical oxygen demands (SCOD) from the synthetic bilgewater. This study demonstrates that algae-based MFC is a feasible strategy to treat oil-in-water emulsion and generate electricity.
URLs/Downloads:
DOI: A strategy for power generation from bilgewater using a photosynthetic microalgal fuel cell (MAFC)
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