A single-chamber microbial fuel cell system for electricity generation from wastewater

Abstract

A microbial fuel cell system with a chamber for generating electricity from wastewater, the system comprising: a cylindrical glass chamber containing the electrode and wastewater, the cylindrical glass chamber acting as the main body of the system; a rubber cork with drilled holes placed on top of the cylindrical glass chamber to seal the chamber openings and maintain airtight conditions, the drilled holes allowing the insertion of electrodes and wires; a plurality of rod-shaped carbon electrodes serving as anode and cathode, the anode being placed in the cylindrical glass chamber and the cathode being placed outside the cylindrical glass chamber; a Nafion proton exchange membrane (PEM) placed between the anode chamber and the air cathode assembly, the cathode being placed in the cylindrical glass chamber, the Nafion proton exchange membrane being configured to enable enhanced proton transfer; and a plurality of rubber-insulated copper wires for connecting the electrodes to external voltage measuring devices, thereby completing the external circuit, the rubber-insulated copper wires being connected externally through the drilled holes in the rubber cork used to seal the cylindrical glass chamber.

Description

FIELD OF THE INVENTION

[0001] The present disclosure relates to a bioelectrochemical system, in particular a microbial single-chamber fuel cell system for generating electricity from wastewater. In particular, the present disclosure relates to a microbial single-chamber fuel cell system (MFC) as a sustainable technology for simultaneous wastewater treatment and electricity generation. The developed system utilizes the metabolic activity of electrogenic microorganisms to degrade organic pollutants in wastewater and thus generate bioelectricity as a byproduct. BACKGROUND OF THE INVENTION

[0002] Microbial fuel cells (MFCs) are bioelectrochemical systems that harness energy from microbial metabolism to generate electricity. Early MFC designs used dual-chamber configurations with separate anode and cathode compartments connected by salt bridges or proton exchange membranes. While these systems proved feasible for generating bioelectricity, they suffered from high internal resistance, complex operation, and increased construction costs.

[0003] To overcome these limitations, single-chamber MFCs (SCMFCs) were developed, eliminating the need for a separate catholyte chamber by exposing the cathode directly to atmospheric air. This design reduces operating energy requirements by utilizing atmospheric oxygen as the terminal electron acceptor in the oxygen reduction reaction (ORR).

[0004] In SCMFCs, electrogenic bacteria such as Geobacter sulfurreducens and Shewanella oneidensis oxidize organic substrates at the anode, generating electrons and protons. Electrons flow through an external circuit, generating electricity, while protons migrate through a proton exchange membrane (PEM) to the cathode, where they react with oxygen to form water.

[0005] Despite these advances, existing SCMFC technology faces significant technical challenges, including low power density, membrane fouling, high internal resistance, and degraded cathode performance. While conventional electrode materials are biocompatible, they often exhibit suboptimal conductivity and surface properties. Conventional PEMs, particularly Nafion-based membranes, possess excellent proton conductivity but are prohibitively expensive and prone to biofouling and oxygen crossover.

[0006] Current SCMFC systems typically achieve chemical oxygen demand (COD) removal efficiencies of over 80% while generating only modest electricity yields. However, scalability remains limited due to reactor-related challenges and insufficient substrate utilization efficiency.

[0007] There is a need in the art for an improved SCMFC design that addresses the above limitations while maintaining effective wastewater treatment capability and improved power generation performance.

[0008] To address the unmet need for an improved SCMFC system, the present invention provides a single-chamber microbial fuel cell system for power generation from wastewater. It utilizes the metabolic activity of electrogenic microorganisms to degrade organic pollutants in wastewater, generating bioelectricity as a byproduct. Summary of the invention

[0009] The present disclosure relates to a single-chamber microbial fuel cell system (SCMFC) for generating electricity from wastewater. The developed single-chamber microbial fuel cell system offers a sustainable technology for simultaneous wastewater treatment and electricity generation. The system utilizes the metabolic activity of electrogenic microorganisms to degrade organic pollutants in wastewater, thus generating bioelectricity as a byproduct. The proposed system features a simple architecture and reduced operating costs, while simultaneously operating efficiently for wastewater treatment and energy generation. Thus, the proposed system addresses both critical challenges: the need for clean water and the demand for renewable energy. The system harnesses the potential of microbial fuel cells to promote ecological sustainability and advance decentralized, environmentally friendly energy systems.

[0010] The disclosure relates to providing a microbial fuel cell system with a chamber for generating electricity from wastewater. The system comprises: a cylindrical glass chamber containing the electrode and wastewater, the cylindrical glass chamber serving as the main body of the system; a rubber stopper with drilled holes placed on top of the cylindrical glass chamber to seal the chamber openings and maintain airtight conditions, the drilled holes allowing the insertion of the electrode and wire; a plurality of rod-shaped carbon electrodes serving as anode and cathode, the anode being located in an anode chamber and the cathode being located outside the cylindrical glass chamber;a Nafion proton exchange membrane (PEM) between the anode chamber and the air cathode assembly, placed as the cathode in the cylindrical glass chamber, wherein the Nafion proton exchange membrane is configured to enable enhanced proton transfer; and a plurality of rubber-insulated copper wires for connecting the electrodes to external voltage measuring devices, thereby completing the external circuit, wherein the rubber-insulated copper wires are connected externally through the drilled holes in the rubber cork used to seal the cylindrical glass chamber.

[0011] An object of the present disclosure is to provide a microbial fuel cell system with a chamber for generating electricity from wastewater.

[0012] Another object of the present disclosure is to provide a microbial fuel cell system having a chamber, an air cathode, and a Nafion proton exchange membrane (PEM) for simultaneous wastewater treatment and power generation.

[0013] Another object of the present disclosure is to utilize the metabolic activity of electrogenic microorganisms for water treatment and power generation.

[0014] Another object of the present disclosure is to develop a bioelectrochemical system with improved and simplified design and construction that saves operating costs while maintaining effective treatment and energy delivery.

[0015] Another object of the present disclosure is to provide a bioelectrochemical system that meets the need for clean water and the demand for renewable energy, and in which the system converts waste into valuable resources, thereby promoting environmental sustainability and advancing decentralized, environmentally friendly energy systems.

[0016] To further clarify the advantages and features of the present disclosure, the invention will be explained in more detail with reference to specific embodiments illustrated in the accompanying drawings. These drawings illustrate only typical embodiments of the invention and are therefore not to be construed as limiting its scope. The invention will be described and explained in more detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE CHARACTERS

[0017] These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters represent like parts throughout. Fig. 1 shows a block diagram of a microbial fuel cell system with a chamber for generating electricity from wastewater according to an embodiment of the present disclosure. Fig. 2 shows diagrams illustrating various stages of development of the single-chamber microbial fuel cell system according to an embodiment of the present disclosure; and Fig. 3 is a diagram illustrating the final design of the single-chamber microbial fuel cell system according to an embodiment of the present disclosure.

[0018] Those skilled in the art will also appreciate that the elements in the drawings are shown for convenience and are not necessarily to scale. For example, the flowcharts illustrate the method by key steps to enhance understanding of aspects of the present disclosure. Moreover, with respect to device construction, one or more components of the device may be represented in the drawings by conventional symbols, and the drawings may show only the specific details relevant to understanding embodiments of the present disclosure in order not to clutter the drawings with details that would be readily apparent to those skilled in the art after reading the present description. DETAILED DESCRIPTION:

[0019] For a better understanding of the principles of the invention, reference is made below to the embodiment illustrated in the drawings and described in specific language. However, the scope of the invention is not limited thereby. Changes and further modifications to the illustrated system, as well as further applications of the principles of the invention, are possible, as would normally occur to one skilled in the art to which the invention pertains.

[0020] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be limiting thereof.

[0021] References in this specification to "one aspect," "another aspect," or similar expressions mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, the occurrences of the terms "in one embodiment," "in another embodiment," and similar expressions throughout this specification may or may not all refer to the same embodiment.

[0022] The terms "comprises," "having," or other variations thereof are intended to cover non-exclusive inclusion, such that a process or method comprising a list of steps not only includes those steps, but may also include other steps not expressly listed or inherent in such process or method. Likewise, the statement "comprises" with respect to one or more devices, subsystems, elements, structures, or components does not exclude, without further limitation, the existence of other devices, other subsystems, elements, structures, or components, or additional devices, additional subsystems, additional elements, additional structures, or additional components.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. The system, methods, and examples provided herein are for illustrative purposes only and should not be considered limiting.

[0024] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0025] Fig. 1 shows a block diagram of a microbial fuel cell system (100) with a chamber for generating electricity from wastewater according to an embodiment of the present disclosure.

[0026] Referring to Fig. 1, the system (100) comprises: a cylindrical glass chamber (102) accommodating the electrode and the wastewater, the cylindrical glass chamber (102) acting as the main body of the system (100); a rubber cork (104) having drilled holes placed on top of the cylindrical glass chamber (102) to seal the openings of the chamber (102) and maintain airtight conditions, the drilled holes allowing the insertion of the electrode and wire; a plurality of rod-shaped carbon electrodes (106) serving as anode and cathode, the anode (106a) being placed inside the cylindrical glass chamber (102) and the cathode (106b) being placed outside the cylindrical glass chamber (102);a Nafion proton exchange membrane (PEM) (108) placed between the chamber with anode (106a) and air cathode assembly, the cathode (106b) being placed in the cylindrical glass chamber (102), the Nafion proton exchange membrane (108) being configured to enable enhanced proton transfer; and a plurality of rubber-insulated copper wires (110) for connecting the electrodes (106) to external voltage measuring devices, thereby completing the external electrical circuit, the rubber-insulated copper wires (110) being connected externally through the drilled holes in the rubber cork (104) used to seal the cylindrical glass chamber (102);

[0027] In one embodiment, the cylindrical glass chamber (102) is filled with a wastewater sample serving as a substrate and providing organic matter and microbes for power generation and wastewater treatment, wherein the carbon anode (106a) is completely immersed in the wastewater within the cylindrical glass chamber (102).

[0028] In one embodiment, the system (100) further comprises a multimeter (112) serving as an external voltage measuring device and configured to measure the voltage and current generated by the microbial fuel cell, wherein no external load or resistor is connected, and wherein the generated voltage is used as an indicator of the microbial activity and performance of the system.

[0029] In one embodiment, adhesives and sealants are used to secure components, seal gaps, and ensure tight assembly of the chamber and electrodes.

[0030] In one embodiment, the cylindrical glass chamber (102) comprises a first chamber (102a) with clamps for holding electrodes alone and a second chamber (102b) equipped with a slot for placing the Nafion membrane (108).

[0031] In one embodiment, the Nafion proton exchange membrane (PEM) (108) is installed on the side of the cathode (106b), thereby enabling proton transfer while minimizing oxygen diffusion into the chamber (102) with the anode (106a), the membrane (108) being attached to the cathode side with adhesive or sealant.

[0032] In one embodiment, the anode electrode (106a) is stored within the cylindrical glass chamber (102) and fully immersed in the wastewater sample to maintain anaerobic conditions, while the cathode electrode (106b) is stored outside the cylindrical glass chamber (102) to maintain aerobic conditions.

[0033] In one embodiment, the system (100) performs two main functions simultaneously during operation, namely the treatment of wastewater and the generation of electricity. The system (100), with carbon-based electrodes (106) for optimal conductivity and biocompatibility, coupled with a Nafion proton exchange membrane (108), facilitates proton transfer while maintaining separation between the anode and cathode environments.

[0034] The present invention relates to a single-chamber microbial fuel cell system for electricity generation from wastewater. The proposed system enables wastewater treatment while simultaneously harnessing the metabolic activity of naturally occurring microbes to generate electricity. The proposed system features a single-chamber architecture with carbon-based electrodes coupled with a Nafion proton exchange membrane for efficient proton transfer while simultaneously separating the anode and cathode environments. The system functions as both a bioelectric generator and a wastewater treatment plant and is therefore well suited for industrial applications, particularly in areas with highly organically loaded wastewater.

[0035] Fig. 2 shows diagrams illustrating various stages of construction of the single-chamber microbial fuel cell system according to an embodiment of the present disclosure.

[0036] Fig. Figure 2 shows that the carbon electrodes are integrated into the cylindrical glass chamber to ensure proper placement and conductivity. The Nafion membrane separates the anode and cathode, facilitating proton transfer. Proper sealing and installation of the electrical connections enables current measurement.

[0037] Fig. 3 is a diagram illustrating the final design of the single-chamber microbial fuel cell system according to an embodiment of the present disclosure.

[0038] According to Fig. 3, the single-chamber microbial fuel cell system mainly consists of: a glass chamber, a rubber cork, carbon electrodes, and a Nafion proton exchange membrane (PEM).

[0039] The cylindrical glass chamber, which serves as the main body of the system, is designed to accommodate the electrodes and wastewater, with the wastewater sample serving as a substrate and providing organic matter and microbes for power generation and wastewater treatment.

[0040] The rubber stopper is used to seal the chamber openings to maintain airtight conditions. Holes are drilled into the rubber stopper to facilitate electrical connection to the electrodes.

[0041] The carbon electrodes have a rod shape and include an anode and a cathode electrode, which were selected for their high conductivity, chemical stability and biocompatibility.

[0042] The rubber-insulated copper wires are used to connect the electrodes to external measuring devices and to close the external circuit. A multimeter is used to measure the voltage and current generated by the microbial fuel cell.

[0043] The Nafion proton exchange membrane (PEM) is placed between the anode chamber and the air cathode to enable improved proton transfer.

[0044] The adhesives and sealants are used to fix components, seal gaps and ensure the tight assembly of chambers and electrodes.

[0045] In one embodiment, the system comprises two chambers. One chamber consists solely of clamps for electrode support, while the other is equipped with a slot for placement of the Nafion membrane. The rubber plugs are provided with holes that allow the electrode and wire to be inserted into the chamber. The Nafion proton exchange membrane (PEM) is cut to size and installed on the cathode side to enable proton transfer while minimizing oxygen diffusion into the chamber containing the anode electrode. The sealant ensures the tightness of the assembly.

[0046] In one embodiment, rod-shaped carbon electrodes were obtained, cleaned with distilled water and ethanol to remove impurities, and dried before use. The rubber-insulated copper wires are prepared to make secure external electrical connections. A digital multimeter is used to measure the voltage (potential difference) across the electrodes. Other support materials such as adhesives, sealants, and structural supports were selected based on material compatibility. Wastewater samples were collected from a sewer. Initial characterization of the wastewater included: pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), electrical conductivity (EC), total dissolved solids (TDS), total organic carbon (TOC), bacterial count, specific bacterial count, etc.These baseline parameters were recorded to evaluate the quality of the substrate with regard to microbial activity.

[0047] The carbon anode is immersed in the wastewater of the cylindrical glass chamber and completely submerged, while the carbon cathode is positioned near the Nafion membrane and faces outward to the atmosphere (air cathode setup). The copper wires are connected externally via cork gaskets. The glass chamber is securely sealed to maintain anaerobic conditions around the anode and aerobic conditions at the cathode. A leak test is performed before commissioning the system to ensure its integrity.

[0048] In an exemplary embodiment, system operation includes a stabilization phase for microbial adhesion and biofilm formation on the anode. To measure system performance, the open-circuit voltage (OCV) or potential difference is measured at regular intervals using a multimeter with no external load or resistance connected and only voltage measurements recorded. The voltage values ​​are recorded regularly over 5 days, and the generated voltage is used as an indicator of microbial activity and system performance.

[0049] In an exemplary embodiment, the treated wastewater is analyzed after operation of the system, with post-treatment parameters including pH, BOD reduction, COD reduction, electrical conductivity, TDS reduction, TOC reduction, total nitrogen content, microbial count (mg / ml), and specific microbial count (E. coli, Streptococcus, Enterobacter), and the obtained results are compared with the original measured values ​​to evaluate the water treatment efficiency of the SMCFC system.

[0050] The developed single-chamber microbial fuel cell (SCMFC) with integrated air cathode demonstrated significant potential as a multipurpose system capable of both generating electricity and treating wastewater. During the experiment, the SCMFC demonstrated a clear operating profile characterized by three distinct phases of voltage output. Within the first 15 hours, the system exhibited a low voltage range between 0 and 7 mV, indicating a lag phase during which electroactive bacteria acclimated and began to form a biofilm on the anode surface. As the microbial community stabilized and substrate oxidation improved, a significant increase in voltage output was observed, reaching 24 mV after 20 hours, 46 mV after 25 hours, and a peak of 120 mV after approximately 70 hours. This exponential phase confirmed the formation of an active electroactive biofilm and efficient electron transfer processes.From this point on, the voltage values ​​steadily decreased, reaching 8 mV after 120 hours. This decrease is due to substrate depletion, biofilm destruction, and increasing internal resistances within the system. The overall electrical performance confirms that SCMFCs can reliably generate power in the millivolt range and are particularly suitable for low-energy applications in decentralized environments.

[0051] At the same time, the SCMFC demonstrated effective wastewater treatment. To evaluate the efficiency of the bioelectrochemical treatment, several key water quality parameters were monitored. The pH of the wastewater decreased slightly from 7.2 to 6.8, a change indicating a buildup of organic acids as a result of anaerobic microbial metabolism. The biochemical oxygen demand (BOD) decreased significantly from 350 mg / L to 145 mg / L, indicating substantial degradation of biodegradable organic matter. A similar trend was observed for the chemical oxygen demand (COD), which decreased from 600 mg / L to 213 mg / L, reflecting the oxidation of a wider range of organic compounds, including some refractory substances. The total carbon content was reduced from 227 mg / L to 98 mg / L, demonstrating the system's efficiency in degrading carbon-rich organic pollutants.The nitrogen content decreased from 70 mg / L to 37 mg / L, indicating microbial assimilation for biomass formation and possible partial denitrification processes. While the total dissolved solids (TDS) content showed a slight increase from 1236 to 1275 mg / L, this was consistent with the accumulation of soluble byproducts from microbial metabolism.

[0052] Microbiological analyses further confirmed the bioelectrochemical robustness of the system. The total microbial population increased significantly from 2.31 × 10 8 cells / ml to 3.56 × 10 9cells / ml, highlighting the favorable conditions for microbial growth within the SCMFC. Proliferation of specific strains such as E. coli, Streptococcus, and Enterobacter was observed, indicating the presence of facultative and anaerobic niches that support various microbial metabolic processes critical for power generation and pollutant degradation.

[0053] Overall, the SCMFC proved to be a technically feasible solution for simultaneous energy recovery and wastewater remediation. The generation of a constant voltage profile, coupled with significant reductions in BOD, COD, carbon, and nitrogen levels, demonstrates the system's ability to convert organic waste into electrical energy while simultaneously purifying the water. Despite the performance decline after peak periods, the results confirm the need for operational strategies such as regular substrate feeding and maintenance to ensure long-term functionality. The findings underscore the potential of the SCMFC as a sustainable and decentralized bioelectrochemical technology for integrated environmental and energy applications.

[0054] The drawings and the foregoing description illustrate examples of embodiments. Those skilled in the art will recognize that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be separated into multiple functional elements. Elements of one embodiment may be added to another embodiment. For example, the order of the processes described herein may be changed and is not limited to the manner described herein. Furthermore, the actions of a flowchart need not be implemented in the order shown; nor do all actions need to be performed. Also, actions that are not dependent on other actions may be performed in parallel with the other actions. The scope of the embodiments is in no way limited by these specific examples.Numerous variations, whether explicitly stated in the specification or not, such as differences in structure, dimensions, and use of materials, are possible. The scope of the embodiments is at least as broad as indicated in the following claims.

[0055] Advantages, further benefits, and solutions to problems have been described above with reference to specific embodiments. However, the advantages, advantages, solutions to problems, and any components that may result in an advantage, advantage, or solution occurring or becoming more apparent are not to be construed as critical, required, or essential features or components of any or all of the claims. REFERENCES 100 A single-chamber microbial fuel cell system for electricity generation from wastewater. 102 Cylindrical glass chamber 104 rubber cork 106 Several rod-shaped carbon electrodes 106a Anode 106b cathode 108 Nafion proton exchange membrane (PEM) 110 Several rubber-insulated copper wires 112 multimeters

Claims

[1] A microbial fuel cell system with a chamber for generating electricity from wastewater, the system comprising: a cylindrical glass chamber containing the electrode and the wastewater, with the cylindrical glass chamber acting as the main body of the system; a rubber stopper with drilled holes, placed on the top of the cylindrical glass chamber to seal the chamber's openings and maintain airtight conditions, with the drilled holes allowing the insertion of electrodes and wires; a multitude of rod-shaped carbon electrodes serving as anode and cathode, with the anode being placed inside the cylindrical glass chamber and the cathode being placed outside the cylindrical glass chamber; a Nafion proton exchange membrane (PEM) placed between the chamber with anode and air cathode assembly, the cathode being placed in the cylindrical glass chamber, the Nafion proton exchange membrane being configured to allow improved proton transfer; and a multitude of rubber-insulated copper wires for connecting the electrodes to external voltage measuring devices, thereby completing the external circuit, the rubber-insulated copper wires being connected externally through the drilled holes in the rubber cork used to seal the cylindrical glass chamber. [2] System according to claim 1, wherein the cylindrical glass chamber is filled with a wastewater sample which serves as a substrate and provides organic substances and microbes for power generation and wastewater treatment, wherein the carbon anode is completely immersed in the wastewater within the cylindrical glass chamber. [3] System according to claim 1, further comprising a multimeter serving as an external voltage measuring device and configured to measure the voltage and current generated by the microbial fuel cell, wherein no external load or external resistance is connected and wherein the generated voltage is used as an indicator of the microbial activity and performance of the system. [4] System according to claim 1, wherein adhesives and sealants are used to fasten components, seal gaps and ensure a tight assembly of the chamber and the electrodes. [5] System according to claim 1, wherein the cylindrical glass chamber comprises a first chamber with clamps for holding electrodes alone and a second chamber which is equipped with a slot for placing the Nafion membrane. [6] System according to claim 1, wherein the Nafion proton exchange membrane (PEM) is installed on the side of the cathode and enables proton transfer while minimizing oxygen diffusion into the chamber containing the anode, wherein the membrane is attached to the cathode side with adhesive or sealant. [7] System according to claim 1, wherein the anode electrode is held inside the cylindrical glass chamber and is fully immersed in the wastewater sample to maintain anaerobic conditions, while the cathode electrode is held outside the cylindrical glass chamber to maintain aerobic conditions. [8] System according to claim 1, wherein the system performs two main functions simultaneously during operation, namely the treatment of wastewater and the generation of electricity, wherein the system with carbon-based electrodes for optimal conductivity and biocompatibility, coupled with a Nafion proton exchange membrane, facilitates proton transfer while maintaining separation between the anode and cathode environments.

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