1. A dual-chamber microbial fuel cell (DMFC) system for simultaneous pharmaceutical wastewater treatment and bioelectricity generation, the system comprising: (a) an anode chamber configured to receive pharmaceutical wastewater; (b) a cathode chamber; (c) a proton exchange membrane positioned between the anode chamber and the cathode chamber; (d) an anode electrode and a cathode electrode comprising manganese cobalt oxide coated carbon veil (MnCo₂O₄-CV); and (e) an external electrical circuit connecting the anode electrode and the cathode electrode to allow electron flow and power generation during microbial degradation of the pharmaceutical wastewater.

2. The system as claimed in claim 1, wherein the MnCo₂O₄-CV electrodes are prepared by a hydrothermal synthesis process at a temperature ranging from 170°C to 190°C for a duration of 14 to 18 hours.

3. The system as claimed in claim 1, wherein each of the anode chamber and the cathode chamber has a working volume ranging from 450 mL to 550 mL.

4. The system as claimed in claim 1, wherein the MnCo₂O₄ coating is synthesized using manganese chloride, cobalt chloride, and urea dissolved in 70 mL to 90 mL of distilled water.

5. The system as claimed in claim 4, wherein the molar ratio of manganese chloride to cobalt chloride corresponds to the stoichiometric composition required for formation of MnCo₂O₄.

6. The system as claimed in claim 1, wherein pharmaceutical wastewater is supplied to the anode chamber at an organic loading rate ranging from 1.5 to 2.5 g COD L⁻¹.

7. The system as claimed in claim 6, wherein the system achieves a soluble chemical oxygen demand (SCOD) removal efficiency ranging from 85% to 92% during treatment of the pharmaceutical wastewater.

8. The system as claimed in claim 1, wherein the DMFC system is configured for continuous operation during wastewater treatment for extended operational periods.

9. The system as claimed in claim 1, wherein the system produces a peak power density ranging from 300 to 350 mW/m² during operation.

Description:The present invention provides a dual-chamber microbial fuel cell (DMFC) system incorporating a novel manganese-cobalt-oxide-coated carbon veil (MnCo₂O₄-CV) electrode. The invention simultaneously addresses the technical challenges of pharmaceutical wastewater (PWW) treatment and renewable energy recovery through a synergistic electrochemical and biological process.
Electrode Fabrication and Hydrothermal Synthesis
The core innovation resides in the multi-step hydrothermal synthesis of the electrode, ensuring optimal crystalline formation and adhesion of the catalyst to the substrate.
Substrate Selection: Carbon veil is utilized as the base substrate due to its high structural integrity, electrical conductivity, and porous architecture which facilitates biofilm attachment.
Precursor Preparation: A precursor solution is prepared by dissolving precisely measured stoichiometric ratios of Manganese Chloride (MnCl₂: 24.89 mg), Cobalt Chloride (CoCl₂: 70.1 mg), and Urea (CH₄N₂O: 19.1 mg) in 80 mL of distilled water. This specific ratio ensures the formation of the spinel MnCo₂O₄ nanostructure.
Synthesis Conditions: The carbon veil is submerged in the precursor solution and subjected to hydrothermal treatment at a critical temperature of 180°C for 16 hours within an autoclave.
Post-Processing: The synthesized electrodes are naturally cooled to room temperature to prevent thermal stress and delamination. They are subsequently rinsed with distilled water and vacuum-dried at 60°C for 24 hours to preserve the integrity of the nanostructured coating.
DMFC System Configuration and Design
The DMFC is constructed from chemically resistant and transparent plexiglass.
Chamber Specifications: The batch mode system chambers (anode and cathode) has a dimension of 11.2 × 7.0 × 6.0 cm³ with a working volume of 500 mL.
Electrode Assembly: Custom-fabricated MnCo₂O₄-CV electrodes (10 × 10 cm², 3 mm thickness) are installed in both chambers.
Proton Exchange: A Nafion 117 membrane (10 × 10 cm²) separates the chambers, facilitating selective proton transport while preventing oxygen or substrate crossover.
Anodic Environment: The anode is fed with 300 mL of pre-treated pharmaceutical wastewater and inoculated with 200 mL of anaerobic sewage sludge. To optimize the electrogenic community, 50 mM 2-bromoethanesulfonate (BES) is added to suppress methanogenesis.
Cathodic Environment: The cathode contains a phosphate buffer solution (PBS) optimized for ionic conductivity and pH stability, comprising KCl, NH₄Cl, Na₂H₂PO₄, and NaH₂PO₄·H₂O.
Operational Parameters and Best Mode
The invention operates optimally under the following conditions:
Temperature and pH: Maintained at 25 ± 2°C and a pH of 7.0 ± 0.2, respectively.
Acclimatization: A 30-day phase in open-circuit mode is conducted until a stable voltage of 180 mV is achieved.
Organic Loadings (OLs): The best mode for operation is identified at a OLs of 2.0 g COD L⁻¹. At this loading, the system achieves a peak power density of 325 mWm⁻² and a coulombic efficiency of 44%.
Stability: The system demonstrates robust continuous operation for 160 days, significantly outperforming conventional MFC systems.
Microbial Community Engineering
Metagenomic analysis (16S rRNA gene sequencing) confirms that the MnCo₂O₄ coating selectively enriches high-performing exoelectrogenic taxa.
Dominant Taxa: The community is dominated by Proteobacteria (primary exoelectrogens), Bacteroidetes (complex organic degraders), and Firmicutes.
Diversity: A Shannon diversity index exceeding 3.5 indicates a stable and resilient microbial ecosystem.
Novelty: The presence of a significant "No Relative" category (approx. 20%) suggests the enrichment of previously uncharacterized electroactive microorganisms specific to this electrode-wastewater interface.
Performance Validation
The synergistic effect of the MnCo₂O₄ / Mn-Co combination provides multiple electron transfer pathways (direct contact, nanowires, and mediators).
Power Enhancement: The system provides a 4.39-fold improvement in power density compared to unmodified carbon veil electrodes.
Pollutant Removal: At the optimal loading of 2.0 g COD L⁻¹, the system achieves:
oSCOD removal: 89% (1300 to 143 mg L⁻¹)
oTCOD removal: 87% (4500 to 260 mg L⁻¹)
oTSS removal: 82% (2000 to 360 mg L⁻¹) , Claims:We claim:
1. A dual-chamber microbial fuel cell (DMFC) system for simultaneous pharmaceutical wastewater treatment and bioelectricity generation, the system comprising:
(a) an anode chamber configured to receive pharmaceutical wastewater;
(b) a cathode chamber;
(c) a proton exchange membrane positioned between the anode chamber and the cathode chamber;
(d) an anode electrode and a cathode electrode comprising manganese cobalt oxide coated carbon veil (MnCo₂O₄-CV); and
(e) an external electrical circuit connecting the anode electrode and the cathode electrode to allow electron flow and power generation during microbial degradation of the pharmaceutical wastewater.
2. The system as claimed in claim 1, wherein the MnCo₂O₄-CV electrodes are prepared by a hydrothermal synthesis process at a temperature ranging from 170°C to 190°C for a duration of 14 to 18 hours.
3. The system as claimed in claim 1, wherein each of the anode chamber and the cathode chamber has a working volume ranging from 450 mL to 550 mL.
4. The system as claimed in claim 1, wherein the MnCo₂O₄ coating is synthesized using manganese chloride, cobalt chloride, and urea dissolved in 70 mL to 90 mL of distilled water.
5. The system as claimed in claim 4, wherein the molar ratio of manganese chloride to cobalt chloride corresponds to the stoichiometric composition required for formation of MnCo₂O₄.
6. The system as claimed in claim 1, wherein pharmaceutical wastewater is supplied to the anode chamber at an organic loading rate ranging from 1.5 to 2.5 g COD L⁻¹.
7. The system as claimed in claim 6, wherein the system achieves a soluble chemical oxygen demand (SCOD) removal efficiency ranging from 85% to 92% during treatment of the pharmaceutical wastewater.
8. The system as claimed in claim 1, wherein the DMFC system is configured for continuous operation during wastewater treatment for extended operational periods.
9. The system as claimed in claim 1, wherein the system produces a peak power density ranging from 300 to 350 mW/m² during operation.