Abstract
In microbial fuel cells (MFCs), the oxidation of organic compounds catalyzed by microorganisms (anode) generates electricity via electron transfer to an external circuit that acts as an electron acceptor (cathode). Microbial fuel cells differ in terms of the microorganisms employed and the nature of the oxidized organic compound. In this study, a consortium of anaerobic microorganisms helped to treat the secondary sludge obtained from a sewage treatment plant. The microorganisms were grown in a 250 mL bioreactor containing a carbon cloth. The reactor was fed with media containing acetate (as the carbon source) for 48 days. Concomitantly, the electrochemical data were measured with the aid of a digital multimeter and data acquisition system. At the beginning of the MFC operation, power density was low, probably due to slow microorganism growth and adhesion. The power density increased from the 15th day of operation, reaching a value of 13.5 μW cm–2 after ca. 24 days of operation, and remained stable until the end of the process. Compared with data in the literature, this power density value is promising; improvements in the MFC design and operation could increase this value even further. The system investigated herein employed excess sludge as a biocatalyst in an MFC. This opens up the possibility of using organic acids and/or carbohydrate-rich effluents to feed MFCs, and thereby provide simultaneous effluent treatment and energy generation.
Highlights
Current energy production relies on fossil fuel consumption, which limits energy generation and dramatically contributes to climate change and environmental deterioration (Levin et al, 2004)
In microbial fuel cells (MFCs), the oxidation of organic compounds catalyzed by microorganisms generates electricity via electron transfer to an external circuit that acts as an electron acceptor
This study reports on the use of a consortium of microorganisms obtained from a biodigestor employed to treat excess sludge from an activated sludge wastewater treatment plant
Summary
Current energy production relies on fossil fuel consumption, which limits energy generation and dramatically contributes to climate change and environmental deterioration (Levin et al, 2004). Given this scenario, the development of technologies to obtain cleaner and renewable energy is highly desirable. The use of biological systems for energy production has attracted the attention of researchers worldwide With these systems, wastewater and organic residues with high concentration of pollutants can be applied as raw material to generate energy. Even in the absence of oxygen, certain bacteria can transfer electrons from organic compound oxidation to systems outside the cell These bacteria, known as exoelectrogenic bacteria, have found application as biological catalysts in MFCs. These bacteria, known as exoelectrogenic bacteria, have found application as biological catalysts in MFCs. (Logan, 2009; Rachinski et al, 2010)
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