The students designed a sediment-based microbial fuel cell to produce 1.25 W/m3. Their initial design used PVC piping, graphite rods, gravel, and duct tape. Testing showed their design did not meet the power goal. They then made improvements like relocating the fuel cell and securing the wiring. While power was produced, further design changes would be needed to increase the output. The students concluded additional testing of design modifications could help optimize the design to better meet the goals.

1. Microbial Fuel Cell
BE 2120
Alena Senf, Casey McCarroll,
Kaitlyn Hillard, & Karla Diviesti

2. Introduction: Recognition of Problem/Need
● Primary Goal - Create more
sediment-based MFCs
○ Produce 1.25 W//m3
● Will replace lab-scale MFCs already
in use for BE 2120 and aid students
during their senior design problems
(1)

3. Introduction: Specifics of Problem
● Produce 1.25 W//m3
● Be able to withstand the weather issues surrounding
Aquaculture System
● Space constraints
○ Water layer of 0.5-1 feet
○ Sediment layer of 0.5 feet
● 25% of materials (by weight) can be new & man-made
○ Total of $10.00
● Biologically compatible with algae/organic specimens

4. Introduction: Governing Equations
● V = IR
● P = IV
● PDV = IV/SA
● ρ = m/V

5. Introduction: Goals
● Process Goals
○ Non-reactive, non-toxic
○ Does not interfere with local wildlife, organisms, bacteria or
algae
● Structural Goals
○ Placed within sediment and water level constraints
○ Easy access to resistor to allow for proper readings
○ Certain parts may remain waterproof
● Mechanical Goals
○ Waterproofed parts remain buoyant above the water level
○ Withstands all type of reasonable weather
○ This goal will have to be in tune with structural goals

6. Introduction: Constraints
● Simple tools and hands-on design
● Budget of $10.00
○ 25% of design can be new materials
■ Recycle most materials
● Structural issues of design, based upon goals
● Logistics of building process between students
○ Must align free time
○ Building abilities

7. Introduction: Considerations
● Must be safe = non-negotiable
○ For students and local environment
● Ethical issue
○ Should not look like garbage/litter
● Environmental
○ Non-toxic, non-reactive, doesn’t disrupt local environment
● Life Cycle
○ Ability to reuse pieces of MFC
● Ultimate Use
○ Example: being able to supply enough energy to power a
light for the end of a dock
● Sustainability
○ Use of recycled products

8. Literature Review
MFC Designs from Literature (2)
● PVC pipe
● Graphite felt anode
● Platinum coated carbon cloth cathode
● Stone gravel and glass wool to prevent oxygen diffusion
Information from Research Article
● No significant impact of aeration on power generation- a cathode
chamber open to the air to have some natural aeration
Past Experience and heuristics
● Lab experience using Voltmeters & MFCs
● Basic ability to create parts using power tools
● Advanced ability creating systems and recognizing mechanical needs

9. Design Materials
Material Amount Purpose Cost ($)
4 in diameter PVC
pipe
2 ft Main body of MFC $3.00
4 in diameter
coupling
1 unit Middle of MFC $2.01
12-gauge wire 3 ft Connection $0.87
Crushed graphite 1.5 cups Anode/Cathode $0.42
Gravel 2 cups Buffer Free
Window screen 1 ft2 Anode/Cathode $0.28
Pool noodle 1 unit Floatation $1.00
Tupperware 1 unit Water protection Free
Total Cost: $7.58

10. Design Methodology

11. Design Methodology
Not a pipe bomb
Mid-design changes
- Graphite rod addition to
anode/cathode
- Duct tape pool noodle to the
top
- Plastic bag covering top of
reactor
- Increase in PVC Diameter and
reactor height

12. And then tragedy struck…..

13. Design Methodology Alternatives
- No pool noodle
- Or fully submerged reactor
- Wider diameter PVC pipe
- Larger Anode/Cathode
- Different anode/cathode shape
- Supplemental nutrients in anode
- More stable wire connection (3)

14. Calculations (Volume)
Anode = 12.27 g
ρ Graphite = 2.266 g/cm3
V= m/ρ = 12.27 (g) / 2.666 (g/cm3) = 5.41 cm3
5.41cm3 * (1 m)3 / (100 cm)3 = 5.41 * 10-6 m3
Max power: (1.8 * 10-6 ) W
PDV = (1.8 * 10-6)W / (5.41 * 10-6) m3
PDV Max = 0.3327 W/m3
Min Power: (4.5 * 10-8) W
PDV Min = (4.5 * 10-8) W / (5.41 * 10-6) m3
PDv Min = 0.0083 W/m3
Average Power: (4.75 * 10-7) W
PDV AVG = (4.75 * 10-7) W / (5.41 * 10-6) m3
PDV AVG = 0.0878 W/m3

15. Calculations (Surface
Area)
Anode = 12.27 g
ρ Graphite = 2.266 g/cm3
SA = 2 * (0.5*L*H) = 2*(0.5*1*1) = 2 cm2
2cm2 * (1 m)2 / (100 cm)2 = 2 * 10-4 m3
Max power: (1.8 * 10-6 ) W
PSA MAX = (1.8 * 10-6)W / (2 * 10-4) m2
PSA Max = 0.009 W/m2
Min Power: (4.5 * 10-8) W
PSA Min = (4.5 * 10-8) W / (2 * 10-4) m2
PSA Min = 0.000225 W/m2
Average Power: (4.75 * 10-7) W
PSA AVG = (4.75 * 10-7) W / (2 * 10-4) m2
PSA AVG = 0.002375 W/m2

16. Ideal Calculations
Goal : 1.25 W/m3
Anode = 12.27 g
ρ Graphite = 2.266 g/cm3
V= m/ρ = 12.27 (g) / 2.666 (g/cm3) = 5.41 cm3
5.41cm3 * (1 m)3 / (100 cm)3 = 5.41 * 10-6 m3
PDv = P/V
P = PDV * V
P = (1.25 W/m3) * ( 5.41 * 10-6 m3)
P = 6.76 * 10-6 W
V = (P*R)½
V = ( (6.76 * 10-6 W)*(1125 ohms))½
V = 0.087 V
I = P/V
I = (6.76 * 10-6 W) / (0.087 V)
I = 7.77 * 10-5A

17. Results: Initial
Polarization Curve

18. Results: Power Calculations

19. Results: Final Polarization Curve

20. Discussion
Redesign Methods Used
● Relocation of entire MFC
● Taping pool noodle and tupperware to the top of the PVC
● Reattached wires to cathode rod to make more secure
● Placed bag over top of MFC
Suggestions for Future Improvements
● Easier accessibility
○ Closer to wall
○ Taller
● Location change
● Addition of supplemental nutrients

21. Conclusion
Our design produced power, but did not meet the goal.
Improvements would need to be made in order to increase the power
output.
Additional design changes could be made to test plausible ways to
increase power output, since there is a baseline to compare against.

22. References
(1) http://pubs.rsc.org/en/content/articlehtml/2015/RA/C5RA15279H
(2) “Performance assessment of aeration and radial oxygen loss assisted cathode based integrated
constructed wetland-microbial fuel cell systems” by Pratiksha Srivastavaa, Saurabh Dwivedi, Naresh
Kumar, Rouzbeh Abbassi, Vikram Garaniya, and Asheesh Kumar Yadav
(3) Https://www.researchgate.net,www.researchgate.net/figure/315416169_fig1_Fig-1-MFC-
reactor-concepts-A-SEDSED-MFC-sedimentsediment-MFC-B-BLAir-MFC-bulk.

23. Appendices
Initial Polarization Curve Data

24. Appendices
Power Calculation vs. Time Data

25. Appendices
Final Polarization Curve Data

26. Thank you!
Kaitlyn’s Joke:
“And thanks for all the fish.”