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Research article · 2025 · Full text

International Journal of Biology Sciences

Microbial fuel cell performance using wastewater biofilms for sustainable bioelectricity generation

Norbert Gawronski Bozena Wieczorek

Volume 7(3) · Pages 101–103 · DOI: 10.33545/26649926.2025.v7.i3b.730 ↗

Research areasMicrobial Fuel Cells and BioremediationAnaerobic Digestion and Biogas ProductionWastewater Treatment and Nitrogen Removal

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Abstract

Author-written

Wastewater treatment plants consume 1-3% of a nation's total electricity—an ironic cost given that organic-rich effluents contain recoverable chemical energy. This research evaluated bioelectricity generation of dual-chamber MFCs inoculated with biofilms from five wastewater sources over 90 days at the Pomeranian College of Marine Biology, Gdynia, Poland (February-May 2023). Maximum power density reached 243.8 mW/m² with synthetic acetate, 198.7 mW/m² with brewery effluent, and 156.4 mW/m² with dairy wastewater. Coulombic efficiency ranged from 12.7% to 31.6%. COD removal exceeded 78% in all reactors. 16S rRNA sequencing of anode biofilms revealed Proteobacteria dominance, with Geobacter and Shewanella accounting for 28-37% of reads. Brewery effluent emerged as the best-performing real substrate.

Summary

Source-checked

Plain-language reading of the full paper, prepared with AI and checked against the text. Each point links to the authors' own words.

  1. Why it matters

    • Wastewater treatment is energy-intensive, consuming 1-3% of a nation's electricity, despite the fact that the organic matter in the waste contains energy that could be recovered. View evidence ↗

      Why it matters

      Wastewater treatment is energy-intensive, consuming 1-3% of a nation's electricity, despite the fact that the organic matter in the waste contains energy that could be recovered.

      In the paper's own words

      “Wastewater treatment plants consume 1-3% of a nation's total electricity—an ironic cost given that organic-rich effluents contain recoverable chemical energy.”

      Page 1

      Found in: Introduction

      Read it in the full textOpen PDF at page 1 ↗
    • Microbial fuel cells (MFCs) use exoelectrogenic bacteria to oxidize organic matter at an anode, sending electrons through a circuit to a cathode to generate electricity. View evidence ↗

      Why it matters

      Microbial fuel cells (MFCs) use exoelectrogenic bacteria to oxidize organic matter at an anode, sending electrons through a circuit to a cathode to generate electricity.

      In the paper's own words

      “Exoelectrogens oxidise organic substrates at the anode under anaerobic conditions, transfer electrons through an external circuit to the cathode, where oxygen is reduced to water”

      Page 1

      Found in: Introduction

      Read it in the full textOpen PDF at page 1 ↗
    • A major challenge for MFC adoption is that they typically perform worse with real wastewater than they do with clean, synthetic substrates. View evidence ↗

      Why it matters

      A major challenge for MFC adoption is that they typically perform worse with real wastewater than they do with clean, synthetic substrates.

      In the paper's own words

      “A persistent barrier to real-world adoption is the gap between performance with clean synthetic substrates and the lower output with actual wastewater streams”

      Page 1

      Found in: Introduction

      Read it in the full textOpen PDF at page 1 ↗

  2. The question

    • The study aimed to quantify the performance and characterize the anode biofilm communities of dual-chamber MFCs using five different types of wastewater. View evidence ↗

      The question

      The study aimed to quantify the performance and characterize the anode biofilm communities of dual-chamber MFCs using five different types of wastewater.

      In the paper's own words

      “This research compared five wastewater types in dual-chamber MFCs under controlled conditions in Gdynia, Poland, to quantify performance metrics and characterise anode biofilm communities.”

      Page 1

      Found in: Introduction

      Read it in the full textOpen PDF at page 1 ↗

  3. What they did

    • The researchers used five identical 250 mL dual-chamber acrylic reactors separated by a Nafion 117 proton exchange membrane. View evidence ↗

      What they did

      The researchers used five identical 250 mL dual-chamber acrylic reactors separated by a Nafion 117 proton exchange membrane.

      In the paper's own words

      “Five identical dual-chamber MFC reactors were constructed from acrylic (250 mL per chamber), separated by Nafion 117 PEM (DuPont).”

      Page 1

      Found in: System Design

      Read it in the full textOpen PDF at page 1 ↗
    • The five tested substrates were domestic sewage, brewery effluent, dairy wastewater, synthetic acetate, and municipal sludge, with chemical oxygen demand (COD) ranging from ~420 mg/L to ~8,100 mg/L. View evidence ↗

      What they did

      The five tested substrates were domestic sewage, brewery effluent, dairy wastewater, synthetic acetate, and municipal sludge, with chemical oxygen demand (COD) ranging from ~420 mg/L to ~8,100 mg/L.

      In the paper's own words

      “Five substrates: (1) domestic sewage (COD ~420 mg/L) from Gdynia-Debogorze plant; (2) brewery effluent (COD ~2,800 mg/L); (3) dairy wastewater (COD ~3,600 mg/L); (4) synthetic acetate (COD ~780 mg/L); (5) municipal sludge (COD ~8,100 mg/L).”

      Page 1

      Found in: Materials

      Read it in the full textOpen PDF at page 1 ↗
    • The experiments were conducted between February and May 2023 at the Pomeranian College of Marine Biology in Gdynia, Poland. View evidence ↗

      What they did

      The experiments were conducted between February and May 2023 at the Pomeranian College of Marine Biology in Gdynia, Poland.

      In the paper's own words

      “Experiments ran February-May 2023, Department of Biotechnology, Pomeranian College of Marine Biology, Gdynia, Poland.”

      Page 1

      “Maximum power density reached 243.8 mW/m² with synthetic acetate, 198.7 mW/m² with brewery effluent, and 156.4 mW/m² with dairy wastewater.”

      Page 1

      Found in: Materials

      Read it in the full textOpen PDF at page 1 ↗
    • Anode biofilms were harvested on day 90 and analyzed using V3-V4 16S rRNA sequencing on an Illumina MiSeq platform to identify the microbial communities. View evidence ↗

      What they did

      Anode biofilms were harvested on day 90 and analyzed using V3-V4 16S rRNA sequencing on an Illumina MiSeq platform to identify the microbial communities.

      In the paper's own words

      “For biofilm characterisation, anode pieces were harvested at day 90, DNA extracted (DNeasy PowerBiofilm Kit, Qiagen), V3-V4 16S rRNA amplified and sequenced on Illumina MiSeq (Genomed, Warsaw).”

      Page 2

      Found in: Methods

      Read it in the full textOpen PDF at page 2 ↗

  4. What they found

    • Synthetic acetate provided the highest performance, with a maximum power density of 243.8 ± 17.3 mW/m² and a COD removal of 92.4 ± 2.3%. View evidence ↗

      What they found

      Synthetic acetate provided the highest performance, with a maximum power density of 243.8 ± 17.3 mW/m² and a COD removal of 92.4 ± 2.3%.

      In the paper's own words

      “Synthetic acetate | 243.8 ± 17.3 | 31.6 ± 3.2 | 763 ± 16 | 189 ± 11 | 92.4 ± 2.3”

      Page 2

      Found in: Table 1

      Read it in the full textOpen PDF at page 2 ↗
    • Among real wastewater substrates, brewery effluent performed best, reaching 198.7 ± 14.2 mW/m² (81.5% of the synthetic benchmark) and having the lowest internal resistance (247 Ω). View evidence ↗

      What they found

      Among real wastewater substrates, brewery effluent performed best, reaching 198.7 ± 14.2 mW/m² (81.5% of the synthetic benchmark) and having the lowest internal resistance (247 Ω).

      In the paper's own words

      “Brewery effluent | 198.7 ± 14.2 | 24.1 ± 2.8 | 718 ± 19 | 247 ± 14 | 83.2 ± 2.9”

      Page 2

      “Brewery effluent reached 81.5% of the synthetic acetate benchmark with the lowest internal resistance among real wastewaters (247 Ω).”

      Page 2

      Found in: Table 1

      Read it in the full textOpen PDF at page 2 ↗
    • Municipal sludge was the worst performing substrate, with the lowest power density (89.2 ± 9.1 mW/m²) and the highest internal resistance (421 Ω). View evidence ↗

      What they found

      Municipal sludge was the worst performing substrate, with the lowest power density (89.2 ± 9.1 mW/m²) and the highest internal resistance (421 Ω).

      In the paper's own words

      “Municipal sludge | 89.2 ± 9.1 | 12.7 ± 1.8 | 583 ± 27 | 421 ± 24 | 71.3 ± 4.2”

      Page 2

      Found in: Table 1

      Read it in the full textOpen PDF at page 2 ↗
    • All tested reactors achieved a chemical oxygen demand (COD) removal rate of over 78%, indicating effectiveness for wastewater treatment. View evidence ↗

      What they found

      All tested reactors achieved a chemical oxygen demand (COD) removal rate of over 78%, indicating effectiveness for wastewater treatment.

      In the paper's own words

      “COD removal exceeded 78% in all reactors.”

      Page 1

      Found in: Discussion

      Read it in the full textOpen PDF at page 1 ↗
    • Anode biofilms were dominated by Proteobacteria, specifically Geobacter and Shewanella, which made up 37.1% of reads in the high-performing brewery reactors compared to 28.3% in domestic sewage. View evidence ↗

      What they found

      Anode biofilms were dominated by Proteobacteria, specifically Geobacter and Shewanella, which made up 37.1% of reads in the high-performing brewery reactors compared to 28.3% in domestic sewage.

      In the paper's own words

      “16S rRNA sequencing of anode biofilms revealed Proteobacteria dominance, with Geobacter and Shewanella accounting for 28-37% of reads.”

      Page 1

      “Within anode biofilms, brewery reactors had the highest proportion of Geobacter and Shewanella (37.1% of total reads), compared with 28.3% in domestic sewage.”

      Page 2

      Found in: Performance Evaluation

      Read it in the full textOpen PDF at page 1 ↗
    • Over 90 days, brewery and dairy reactors remained stable with ≤8% decline, whereas municipal sludge performance dropped by 19.3% because of membrane fouling. View evidence ↗

      What they found

      Over 90 days, brewery and dairy reactors remained stable with ≤8% decline, whereas municipal sludge performance dropped by 19.3% because of membrane fouling.

      In the paper's own words

      “Long-term stability was tracked over 90 days: brewery and dairy reactors showed ≤8% decline, while municipal sludge declined 19.3% due to membrane fouling.”

      Page 2

      Found in: Performance Evaluation

      Read it in the full textOpen PDF at page 2 ↗
    • The poor performance of municipal sludge is attributed to its high particulate content and a higher presence of methanogenic competitors (14.8% Archaea) compared to other reactors (≤4%). View evidence ↗

      What they found

      The poor performance of municipal sludge is attributed to its high particulate content and a higher presence of methanogenic competitors (14.8% Archaea) compared to other reactors (≤4%).

      In the paper's own words

      “Municipal sludge underperformed despite highest organic load—high particulate fraction and methanogenic competitors (14.8% Archaea vs ≤4% in other reactors) likely explain this”

      Page 2

      Found in: Discussion

      Read it in the full textOpen PDF at page 2 ↗

  5. What it means

    • The authors conclude that real wastewater can sustain bioelectricity generation, identifying brewery and food-processing wastes as the most promising applications. View evidence ↗

      What it means

      The authors conclude that real wastewater can sustain bioelectricity generation, identifying brewery and food-processing wastes as the most promising applications.

      In the paper's own words

      “This 90-day trial confirms that real wastewater streams sustain biologically driven electricity generation, with brewery effluent performing at ~82% of the synthetic acetate benchmark.”

      Page 2

      “Brewery and food-processing wastewaters represent the most promising niche applications.”

      Page 2

      Found in: Conclusion

      Read it in the full textOpen PDF at page 2 ↗
    • Future work needs to focus on scaling to pilot systems with continuous flow and addressing engineering issues like membrane fouling and methanogenesis in sludge systems. View evidence ↗

      What it means

      Future work needs to focus on scaling to pilot systems with continuous flow and addressing engineering issues like membrane fouling and methanogenesis in sludge systems.

      In the paper's own words

      “Scaling to pilot-scale systems with stacked electrodes and continuous flow is the next step. Membrane fouling management and methanogenesis suppression in sludge-fed systems deserve focused engineering attention”

      Page 2

      Found in: Conclusion

      Read it in the full textOpen PDF at page 2 ↗

Visual summary

2 visuals

Illustrations explain the paper; charts are replotted from the paper's own table values.

AI-generated illustration
AI-generated conceptual illustration (dual-chamber microbial fuel cell with wastewater biofilms). It explains the idea and does not show study data.↗ Enlarge
MFC Basic Mechanism
AI-generated conceptual illustration (dual-chamber microbial fuel cell with wastewater biofilms). It explains the idea and does not show study data.

AI-generated conceptual illustration (dual-chamber microbial fuel cell with wastewater biofilms). It explains the idea and does not show study data.

Open full-size image ↗

MFC Basic Mechanism

AI-generated conceptual illustration (dual-chamber microbial fuel cell with wastewater biofilms). It explains the idea and does not show study data.

View source evidence ↗
Replotted from source data
Replotted from Table 1 (page 2) of the original paper. Every bar is the paper's own table value.↗ Enlarge
COD rem. (%): Domestic sewage vs Brewery effluent vs Dairy wastewater vs Synthetic acetate vs Municipal sludge
Replotted from Table 1 (page 2) of the original paper. Every bar is the paper's own table value.

Replotted from Table 1 (page 2) of the original paper. Every bar is the paper's own table value.

Open full-size image ↗

COD rem. (%): Domestic sewage vs Brewery effluent vs Dairy wastewater vs Synthetic acetate vs Municipal sludge

Replotted from Table 1 (page 2) of the original paper. Every bar is the paper's own table value.

View source evidence ↗

Figures & tables

From the original paper
Steady-state performance metrics of dual-chamber MFCs with five wastewater substrates (90 days)Table 1Page 2Heatmap of normalised MFC performance metrics acrossFigure 1Page 2Relative abundance of dominant bacterial phyla in anodeFigure 2Page 2
FULL TEXT Original article · reflowed for reading

Introduction

Treating wastewater while extracting useful energy from it is the premise behind microbial fuel cells. Over two decades, laboratory MFC research has moved from proof-of-concept to engineering optimization [1] . Exoelectrogens oxidise organic substrates at the anode under anaerobic conditions, transfer electrons through an external circuit to the cathode, where oxygen is reduced to water [2] . A persistent barrier to real-world adoption is the gap between performance with clean synthetic substrates and the lower output with actual wastewater streams [3] . Brewery and dairy effluents combine high organic strength with low toxicity, making them attractive for energy recovery [4,5] . Municipal sludge is chemically complex and may suppress exoelectrogen activity [6] . This research compared five wastewater types in dual-chamber MFCs under controlled conditions in Gdynia, Poland, to quantify performance metrics and characterise anode biofilm communities.

System Design

Five identical dual-chamber MFC reactors were constructed from acrylic (250 mL per chamber), separated by Nafion 117 PEM (DuPont). Anode electrodes were carbon felt (9 cm² projected area), pre-treated in 1 M HCl. Cathode electrodes were Pt-coated carbon cloth (0.5 mg Pt/cm²; E-TEK). External circuit used 1000 Ω resistor; polarisation curves varied resistance from 50 Ω to 10 kΩ. A Keithley 2700 data logger recorded voltage at 10-minute intervals. Reactors operated at 25 ± 1 °C with continuous N₂ purge of anode chambers.

Hydraulic retention time was 48 hours.

Materials and Methods

Materials and Methods

Materials

Five substrates: (1) domestic sewage (COD ~420 mg/L) from Gdynia-Debogorze plant; (2) brewery effluent (COD ~2,800 mg/L); (3) dairy wastewater (COD ~3,600 mg/L); (4) synthetic acetate (COD ~780 mg/L); (5) municipal sludge (COD ~8,100 mg/L). Each reactor was inoculated with 50 mL anaerobic digester sludge. Experiments ran February-May 2023, Department of Biotechnology, Pomeranian College of Marine Biology, Gdynia, Poland.

Methods

Power density: P = V²/(R × A) [7] . Coulombic efficiency calculated as ratio of recovered coulombs to theoretical maximum from COD removed [8] . COD measured by closed reflux colorimetry (Hach DR3900). For biofilm characterisation, anode pieces were harvested at day 90, DNA extracted (DNeasy PowerBiofilm Kit, Qiagen), V3-V4 16S rRNA amplified and sequenced on Illumina MiSeq (Genomed, Warsaw). Reads processed through QIIME2 with DADA2, classified against SILVA 138.1. Kruskal-Wallis tests with Dunn's correction (p < 0.05).

Performance Evaluation

Steady-state was defined as three consecutive cycles with ≤5% voltage variation, reached between day 16 and 22.

Polarisation curves were generated by stepwise resistance variation (30 min per step). Internal resistance estimated from the linear polarisation region. Long-term stability was tracked over 90 days: brewery and dairy reactors showed ≤8% decline, while municipal sludge declined 19.3% due to membrane fouling. Brewery effluent reached 81.5% of the synthetic acetate benchmark with the lowest internal resistance among real wastewaters (247 Ω). Municipal sludge lagged at 89.2 mW/m² with highest resistance (421 Ω). Within anode biofilms, brewery reactors had the highest proportion of Geobacter and Shewanella (37.1% of total reads), compared with 28.3% in domestic sewage.

Results

Results

Discussion

The 198.7 mW/m² from brewery effluent falls within the upper range for dual-chamber designs. A comparable research with single-chamber air-cathode MFCs recorded 221 mW/m² with brewery waste, but single-chamber architectures have lower internal resistance [9,10] . Municipal sludge underperformed despite highest organic load-high particulate fraction and methanogenic competitors (14.8% Archaea vs ≤4% in other reactors) likely explain this [11,12] .

Coulombic efficiencies of 12.7-31.6% highlight significant electron losses to competing metabolisms and oxygen diffusion [13] . COD removal above 78% across all reactors is encouraging for treatment applications [14] .

Conclusion

This 90-day trial confirms that real wastewater streams sustain biologically driven electricity generation, with brewery effluent performing at ~82% of the synthetic acetate benchmark. Anode biofilm analysis linked performance to exoelectrogen abundance. Brewery and food-processing wastewaters represent the most promising niche applications. Scaling to pilot-scale systems with stacked electrodes and continuous flow is the next step. Membrane fouling management and methanogenesis suppression in sludge-fed systems deserve focused engineering attention [15][16][17] .

Figures and tables from the paper

Table 1. Steady-state performance metrics of dual-chamber MFCs with five wastewater substrates (90 days)
Steady-state performance metrics of dual-chamber MFCs with five wastewater substrates (90 days)↗ Enlarge
Table 1
Steady-state performance metrics of dual-chamber MFCs with five wastewater substrates (90 days)

Steady-state performance metrics of dual-chamber MFCs with five wastewater substrates (90 days)

Open full-size image ↗
Original paper figureSource PDF · page 2 ↗
Figure 1. Heatmap of normalised MFC performance metrics across
Heatmap of normalised MFC performance metrics across↗ Enlarge
Figure 1
Heatmap of normalised MFC performance metrics across

Heatmap of normalised MFC performance metrics across

Open full-size image ↗
Original paper figureSource PDF · page 2 ↗
Figure 2. Relative abundance of dominant bacterial phyla in anode
Relative abundance of dominant bacterial phyla in anode↗ Enlarge
Figure 2
Relative abundance of dominant bacterial phyla in anode

Relative abundance of dominant bacterial phyla in anode

Open full-size image ↗
Original paper figureSource PDF · page 2 ↗

References

17 in the original paper
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  8. Logan BE. Essential data and techniques for conducting MFC experiments. ChemSusChem. 2012;5(6):988-994.
  9. Liu H, Ramnarayanan R, Logan BE. Production of electricity during wastewater treatment using a single chamber MFC. Environmental Science and Technology. 2004;38(7):2281-2285.
  10. Wang X, Feng Y, Wang H, Qu Y, Yu Y, Ren N, et al. Bioaugmentation for electricity from corn stover biomass using MFCs. Environmental Science and Technology. 2009;43(15):6088-6093.
  11. Chae KJ, Choi MJ, Lee JW, Kim KY, Kim IS. Effect of different substrates on MFC performance and bacterial diversity. Bioresource Technology. 2009;100(14):35183525.
  12. Call DF, Wagner RC, Logan BE. Hydrogen production by Geobacter species in a microbial electrolysis cell. Applied and Environmental Microbiology. 2009;75(24):7579-7587.
  13. Rozendal RA, Hamelers HV, Rabaey K, Keller J, Buisman CJ. Towards practical implementation of bioelectrochemical wastewater treatment. Trends in Biotechnology. 2008;26(8):450-459.
  14. Li WW, Yu HQ, He Z. Towards sustainable wastewater treatment by MFC-centered technologies. Energy and Environmental Science. 2014;7(3):911-924.
  15. Rabaey K, Verstraete W. Microbial fuel cells: novel biotechnology for energy generation. Trends in Biotechnology. 2005;23(6):291-298.
  16. Lovley DR. Bug juice: harvesting electricity with microorganisms. Nature Reviews Microbiology. 2006;4(7):497-508.
  17. Kim BH, Chang IS, Gadd GM. Challenges in microbial fuel cell development and operation. Applied Microbiology and Biotechnology. 2007;76(3):485-494.