Description:FIELD OF THE INVENTION:
The present invention generally relates to microbial fuel cells (MFC). More specifically, the invention relates to buoyancy-based floating MFC for wastewater treatment and bioelectricity production.

BACKGROUND:
The increasing global demand for energy and effective wastewater management, there is a need for sustainable and low-cost solutions that address both challenges simultaneously. Waste sources rich in biodegradable organic matter offer significant potential for bioelectricity generation, while rapid industrialization has intensified waste disposal challenges. Addressing these issues efficiently is crucial for achieving environmental and energy sustainability goals.

India and several other nations have committed to carbon neutrality, emphasizing the need for practical solutions that optimize existing resources. Microbial Fuel Cells (MFCs) present a promising technology that utilizes microbial metabolism to convert organic waste into electricity while facilitating wastewater treatment. However, conventional MFCs suffer from high operational costs, external aeration requirements, and inefficient electrode positioning.

While advancements in wastewater treatment technologies have emerged, many remain costly and energy-intensive. MFCs offer an eco-friendly solution by using electrogenic bacteria to simultaneously treat wastewater and generate electricity. However, oxygen aeration and residual sludge processing contribute to high operational costs. Since wastewater itself contains stored energy, improving its conversion efficiency is key to making MFCs more viable.

Despite advancements in wastewater treatment, there is a need for integrating a floating, buoyancy-based MFC which eliminates the need for mechanical aeration and optimizes electrode function, making bioelectricity production more practical and scalable. Furthermore, interconnecting multiple units can enhance power output, making it suitable for decentralized applications.

While traditional MFCs have been explored in laboratory settings, buoyancy-assisted configurations are not widely adopted. The present disclosure provides a cost-effective, scalable, and energy-efficient solution for renewable energy production and wastewater treatment.

SUMMARY OF THE INVENTION:
The primary objective of the present invention is to provide a floating-type buoyancy microbial fuel cell (BFMFC) that efficiently generates bioelectricity while facilitating wastewater treatment.

Another objective of the present invention is to design a floating-type buoyancy microbial fuel cell with high mechanical and dimensional stability for long-term operation.

Yet Another objective of the present invention is to provide scalability, enhanced stability, improved conductivity and power generation efficiency.

According to an aspect of the present disclosure, a floating-type buoyancy microbial fuel cell (BFMFC) comprises a cathode, an anode electrically linked to the cathode, and a floating unit that enables the cell to remain on the wastewater surface. The cell incorporates a Proton Exchange Membrane (PEM) made of a composite material containing one or more cement-supported conductive salts. The membrane electrode assembly (MEA) is secured in a cathode container, allowing it to float using a buoyancy mechanism. The cathode is positioned at the upper region of the setup, acting as a buffer, while the anode is submerged in a high-electron-generation zone within the wastewater. The electrode wires facilitate electron flow from the anode to the cathode.

Another aspect of the present disclosure discloses a floating-type MFC based on Archimedes' principle, which states that a body immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid. The buoyancy mechanism ensures stable equilibrium, meaning the system returns to its original position when slightly displaced. The cathode-membrane-anode assembly is vertically aligned within the floating unit, with horizontally positioned anode electrodes extending outward. The anode is electrically connected to a data acquisition device (DAQ) for voltage monitoring and storage. The anode electrodes consist of graphite plates arranged in a balanced propeller-like configuration, improving floating stability.

In an embodiment, the floating-type microbial fuel cell may further incorporate a reactor top portion with an inlet/outlet port for an aerobic cathode, enhancing oxygen availability and bioelectricity production. The anode is immersed such that 75% of the graphite surface remains within the wastewater, while the cathode is housed in an empty space on the upper reactor surface. The ion exchange membrane (e.g., NCSCS/Nafion 117) is placed between the anode electrodes and the bottom of the cathode chamber. The entire 500ml buoyancy floating-type microbial fuel cell can be connected to the DAQ system for power storage and further applications.

BRIEF DESCRIPTION OF THE DRAWINGS:
FIG. 1 illustrates a perspective view of 2D reactor design of buoyancy float microbial fuel cell in accordance with an embodiment of the present disclosure;
FIGS. 2A and 2B illustrate a 3D diagram and experimental set up of parts of Buoy Floating MFC according to an exemplary embodiment of the present disclosure;
FIG. 3 illustrates a graphical representation of open circuit voltage production using BFMFC in a single unit floating in the wastewater tank;
FIG. 4 illustrates a graphical representation of current production using BFMFC in a single unit floating in the wastewater tank;
FIG. 5 shows an exemplary setup of an actual packaged BFMFC;
FIG. 6 illustrates a graphical representation of COD removal efficiency % and COD of buoyancy microbial fuel cell system;
FIG. 7 illustrates a graphical representation of Power density and current density polarization curve obtained from the BFMFC; and
FIG. 8 illustrates a graphical representation of cyclic voltammetry analysis of BFMFC attached electrodes.
 
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be comprehensively elucidated herein with reference to the accompanying drawings, which depict preferred embodiments of the invention. However, it should be noted that the invention can take various forms and is not limited to the embodiments described herein. In the drawings, an exemplary representation of a Buoyancy-based Floating Microbial Fuel Cell (BFMFC) is illustrated, where the unit is positioned on a wastewater tank for bioelectricity generation using a cost-effective method. The figures and descriptions serve to facilitate a better understanding of the invention without limiting its scope.

Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.

It must be noted that as used herein and in the appended claims, the singular forms "a", "and", and "the" include plural referents unless the context dictates otherwise. Thus, for example, reference to "a compound" includes a plurality of such compounds, and reference to "the step" includes reference to one or more steps and equivalents thereof known to those skilled in the art, and so forth.

The term “some” as used herein is defined as “none, or one, or more than one, or all.” Accordingly, the terms “none,” “one,” “more than one,” “more than one, but not all” or “all” would all fall under the definition of “some.” The term “some embodiments” may refer to no embodiments or to one embodiment or to several embodiments or to all embodiments. Accordingly, the term “some embodiments” is defined as meaning “no embodiment, or one embodiment, or more than one embodiment, or all embodiments.”

The terminology and structure employed herein is for describing, teaching and illuminating some embodiments and their specific features and elements and does not limit, restrict or reduce the spirit and scope of the claims or their equivalents.

More specifically, any terms used herein such as but not limited to “includes”, “comprises”, “has”, “consists” and grammatical variants thereof is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. The specification will be understood to also include embodiments which have the transitional phrase “consisting of” or “consisting essentially of” in place of the transitional phrase “comprising.” The transitional phrase “consisting of” excludes any element, step, or ingredient not specified in the claim, except for impurities associated therewith. The transitional phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps “and those that do not materially affect the basic and novel characteristic(s)” of the claimed disclosure.

The present disclosure pertains to a floating-type buoyancy microbial fuel cell (BFMFC) designed for bioelectricity generation from wastewater. The BFMFC comprises a cathode, an anode electrically connected to the cathode, and a floating unit that ensures the cell remains on the wastewater surface. A Proton Exchange Membrane (PEM), composed of a composite material containing cement-supported conductive salts, is integrated into the system to enhance ion exchange and electron transfer. The membrane electrode assembly (MEA) is securely placed within a cathode container, allowing it to float while maintaining operational stability. The cathode is positioned in the upper region, serving as a buffer, whereas the anode is submerged in a high-electron-generation zone within the wastewater. Electrode wires facilitate the flow of electrons from the anode to the cathode.

In accordance with the present disclosure, BMFC relies on Archimedes' principle, which states that a body immersed in a fluid experiences an upward buoyant force equal to the weight of the displaced fluid. This principle ensures stable equilibrium, meaning the system returns to its original position when slightly displaced. The cathode-membrane-anode assembly is vertically aligned within the floating unit, while the anode electrodes extend outward in a horizontal orientation, ensuring proper electron transfer. The anode is also connected to a data acquisition device (DAQ) for real-time monitoring of voltage and power generation.

According to an aspect of present disclosure, anode electrodes are composed of graphite plates arranged in a balanced propeller-like configuration, improving floating stability and electron harvesting. On the other hand, cathode electrodes are positioned in the upper chamber and exposed to air, enabling enhanced oxygen reduction. BMFC includes ion exchange membranes fixed between the anode electrodes and the cathode chamber, ensuring efficient proton transfer (e.g., NCSCS or Nafion 117 membrane).

In accordance with an embodiment, below table provides the different materials and dimensional specifications used in BMFC.

Material Surface area (cm3)
Anode Electrodes 12 x 2
Cathode electrode 7.85
NCSCS PEM 35.34
Cathode chamber 729
Length of external electrical wires (cm) 10 x 2

In one aspect, a reactor top portion includes an inlet/outlet port to enhance oxygen availability, thereby increasing bioelectricity production. A PVC pipe holder is used to fix the membrane within the cathode chamber, and an external electrode propeller ensures efficient floating. Further, electrodes are secured with non-conductive waterproofing gum, preventing short circuits while enabling efficient electron transport. The cathode chamber contains 60-70% phosphate buffer, improving bioelectricity generation by enhancing conductivity and reducing ohmic resistance.

According to an embodiment, FIG. 1 illustrates the exploded perspective view of a single BFMFC unit showing electrode and membrane assembly. FIGS. 2A & 2B depict the 3D diagram and experimental setup of BFMFC, including components such as anode wires, cathode container cap, cathode electrode, electrode fixation screws, and gas inlet/outlet. FIGS. 3 & 4 illustrate the graphs depicting variations in open circuit voltage and closed circuit current over time in different BFMFC configurations. FIG. 5 depicts the real-life image of the BFMFC floating on a wastewater tank. FIG. 6 illustrates the wastewater treatment performance analysis based on Chemical Oxygen Demand (COD) reduction.
FIG. 7 illustrates the power and current density graphs under different resistor conditions. FIG. 8 depicts the electrochemical characterization results using Cyclic Voltammetry (CV), showing oxidation-reduction activity of biofilm-attached electrodes.
According to one embodiment of the present disclosure, FIGS. 1 and 2 present perspective view of 2D of design of the BFMFC. Respectively, the buoyancy floating-type microbial fuel cell in accordance with an electrodes and membrane assembled. FIG. 2A depicts the 2D diagram of BMFC. As shown, the anode wires (202) connect the anode electrode attached biofilm (210) to the external circuit, allowing electron transfer from microbial oxidation in wastewater. The cathode electrode (206), housed within the cathode container cap (204), facilitates oxygen reduction and completes the electrochemical reaction. The screw (208) for electrode fixation ensures secure placement of electrodes, maintaining stability and efficient electron flow. The gas inlet or outlet (212) allows controlled aeration or removal of byproducts such as oxygen or hydrogen gas, optimizing cathodic reactions. A multimeter (210) is used to measure voltage, current, and resistance, enabling real-time monitoring of the BFMFC’s performance and bioelectricity generation efficiency. These interconnected components work together to maintain stable operation, enhance microbial activity, and optimize power output. FIGS. 3 and 4 provide evidence of bioelectricity in terms of voltage and current by the wastewater floating buoyancy microbial fuel cell device along with electrodes and membrane assembly.

According to an embodiment, when a buffer such as phosphate buffer (but not limited to it) is added, the average power generation increased to 0.204 mW/m2, approximately 1.5 times more than when it was not added (0.14 mW/m2). No appreciable difference in the final pH was observed with the addition of this phosphate buffer. The power generation period increased to 729 hours, nearly seven times longer than the existing generation's operating length (around 110 hours) without the added buffer Additionally, the buffer allowed the sludge substrate's conductivity to increase from 0.8 to 8.4 mS/cm, which reduced the ohmic resistances and increased power output. The both anode wires and top cathode wires were linked with the DAQ for collection of bioelectricity in the terms of voltage and current. The prepared design difference from the (membrane- electrode assembly

In accordance with an embodiment, an anode part of entire septic tank or wastewater tank contained higher COD, i.e. 2940 mg/L and it’s efficiently reduced up to 370mg/L within 63 days in the 15L Septic tank water Containing BFMFC single unit. The methanogenic and electrochemically active microorganism were attached in the anode electrode surface of both side of device. The microbial fuel cell involves floating in a substrate solution, where the substrate may be contaminated water containing organic contaminants. Exo electrogens, such as metal salt reducing bacteria, oxidize organic contaminants and transmit electrons to the anode. No mediator is needed in this process, avoiding issues related to mediator accumulation and toxicity. The EAB may include exoelectrogens, consortium of various electrogens using various electron acceptors.

Therefore, experimental results demonstrate the efficacy of the microbial fuel cell, with open circuit voltages initially producing 0.310 V in the single BMFC unit with buffer and 0.442 V in without buffer (bare cathode) BFMFC unit. After attachment of biofilms in the electrodes the voltage gradually increased up to 0.944 V of maximum in the 15th day by the single unit of with buffer BFMFC and 0.861V in 7th day by without buffer (bare cathode) BFMFC effective bioelectricity production by the floating on wastewater surface. The stable voltage achieved and maintained several days without any energy input. After achieving maximum voltage the closed circuit voltages current measured through the DAQ the maximum current production of 3.673 micro Amp producing by the single unit BFMFC without any external resistor. The floating BFMFC was adjusted and moved another surface of same wastewater may able to enhance voltage and current production. The ensuring optimization of the cathode buffer to the air cathode or buffer free empty cathode have also contributed sustained current production.

Hence, the present invention discloses a cost-effective approach to bioelectricity generation using floating microbial fuel cells. The use of cement-supported conductive salts in the PEM, optimized buffer solutions, and buoyancy stabilization mechanisms significantly enhances performance. The BFMFC can be scaled for larger wastewater treatment applications while simultaneously generating renewable energy.

Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the disclosure be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present disclosure are intended to be illustrative, but not limiting, of the scope of the disclosure, which is set forth in the appended claims. , Claims:1. An apparatus for bioelectricity generation from wastewater, comprising:
a. an anode electrode submerged in the wastewater, facilitating electron generation through microbial oxidation;
b. one or more anode wires (202) electrically connected to the anode electrode for conducting electrons;
c. a cathode electrode (206) positioned in an aerated region above the wastewater to enable oxygen reduction;
d. a proton exchange membrane (PEM) fixed between the anode electrode and the cathode electrode to facilitate proton transfer vertically;
e. a floating unit configured to support the cathode electrode and maintain the apparatus on the surface of the wastewater; and
f. a cathode container housing the cathode electrode and having a gas inlet or outlet for oxygen exchange.

2. The apparatus as claimed in claim 1, wherein the proton exchange membrane comprises a composite material containing cement-supported conductive salts to enhance ion conductivity and durability.

3. The apparatus as claimed in claim 1, further comprising one or more screws (208) for electrode fixation to secure the anode electrode within the floating unit and maintain structural stability.

4. The apparatus as claimed in claim 1, wherein the anode electrode is configured in a propeller-like arrangement to improve electron harvesting efficiency and floating stability.

5. The apparatus as claimed in claim 1, wherein the floating unit is designed based on Archimedes’ principle to provide buoyancy and self-adjustment in response to displacement.

6. The apparatus as claimed in claim 1, wherein the gas inlet or outlet (214) in the cathode container is configured to regulate oxygen flow, enhancing cathodic reactions and bioelectricity generation.
7. A method for bioelectricity generation from wastewater using a floating-type buoyancy microbial fuel cell, comprising:
a. submerging an anode electrode in wastewater to facilitate microbial oxidation and electron release;
b. transferring the electrons through an anode wire to a cathode electrode positioned in an aerated region above the wastewater;
c. facilitating proton transfer through a proton exchange membrane disposed between the anode and cathode electrodes;
d. maintaining the cathode electrode afloat using a floating unit while ensuring stability in the wastewater; and
e. optimizing oxygen availability at the cathode electrode via a gas inlet or outlet to enhance oxygen reduction reactions.

8. The method as claimed in claim 9, further comprising the step of securing the anode electrode using a screw for electrode fixation within the floating unit.

9. The method as claimed in claim 9, wherein the proton exchange membrane comprises cement-supported conductive salts to enhance ion exchange efficiency and durability.

10. The method as claimed in claim 9, further comprising optimizing buffer solution concentration in the cathode chamber to improve bioelectricity generation and reduce ohmic resistance.