Microbial fuel cells (MFCs)

Microbial fuel cells (MFCs) utilize electroactive microorganisms to generate electricity. Unlike conventional fuel cells, MFCs use carbon-rich substrates such as glucose, acetate, wastewater, or even urine as fuel. These substrates are broken down by anaerobic microorganisms, releasing electrons in the process. The electrons are transferred to the anode and subsequently flow to the cathode. This electron transfer creates an electric current, which can be used externally.

MFCs offer a wide range of applications, including:

• Energy production: Converting organic waste and renewable resources into electrical energy.
• Wastewater treatment: Removing organic pollutants from wastewater while simultaneously generating electricity.
• Sensor technology: Developing biosensors for environmental monitoring and diagnostics.

MFCs represent a promising approach in the field of renewable energy and sustainable resource utilization.

Within the anaerobic anodic chamber, microorganisms can either be suspended in the medium or be present as an electroactive biofilm adhered to the anode. Biofilms generally achieve significantly higher power densities compared to suspended cells because the electron transfer pathway to the anode is much shorter in biofilm systems. Utilizing the sol-gel process, electrode surfaces can be biofunctionalized to create artificial biofilms directly on the electrode. This approach significantly reduces startup times, which, for naturally developed biofilms, can take several days to weeks.

Additionally, the incorporation of redox mediators and conductive polymers further enhances system performance and improves electron transfer efficiency. These advancements open new avenues for optimizing MFCs, making them more viable for practical applications in energy production and environmental remediation.

In one of our recent projects, we employed electroactive microorganisms to develop a bioelectrochemical process aimed at enhancing biological reactions and microbial transformations under anoxic conditions in aquatic environments and sediments. By transferring the electrons generated to extracellular electron acceptors, microbial metabolism was improved, leading to faster oxidation of carbon-containing substrates and their degradation under anoxic conditions.

This method aligns with research demonstrating that electroactive microbes can enhance bioremediation or bioenergy production by facilitating electron transfer to external acceptors, speeding up the breakdown of organic matter even in oxygen-deprived environments like sediments or deep waters.

The project focused on two specific application areas for the bioelectrochemical system under development. One of the primary areas is the treatment of organically polluted lakes and ponds to ensure sustained high water quality, which is crucial for maintaining the proper functioning of aquatic ecosystems.

• Enhanced breakdown of carbon inputs through the transfer of electrons to the anode.
• Reduced sediment buildup by decomposing deposited plant biomass (leaves, decayed plant parts) under anoxic conditions.
• Decreased formation of foul gases (such as methane and hydrogen sulfide), which are typically produced during anaerobic processes in sediments.

The second application focuses on the treatment of sulfate-containing waters, particularly those influenced by mining activities, such as the waters found in the Lusatia region as a result of lignite mining.

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ANSPRECHPARTNER:
Dr. Ulrich Soltmann
Fachsektion Dresden – “Funktionelle Schichten”
Tel.: 0351 / 2695 343
E-Mail: soltmann@gmbu.de