MFC ProjectAustin Bartley

Ashleigh HoughKatie Bickle

Kristina McLaren

Intro - Problem/Need❏ Design a sediment microbial fuel cell (MFC) reactor

to produce a recoverable electrical power of 1 Watt per cubic meter of anode volume.

Intro - Goals❏Process

❏ Biological: oxygen amount in the cathode, microorganism respiration, natural bacteria growth

❏ Chemical: “...chemical system for power generation based on the exploitation of biocatalytic reactions…” (Rashid)

❏Structural❏ surface area of anode, conductivity of anode material, large

cylindrical PVC design, depth of water, volume of anode chamber

❏Mechanical❏ no mechanical elements

Intro - Constraints & Considerations

Constraints❏ Skills

❏ fabrication skills varied❏ Budgetary

❏ $20 limit❏ 25% of materials can be

new❏ Other

❏ had to have all materials by 11/11

Considerations❏ Safety

❏ tools and methods used to design

❏ Ethical❏ creating an original idea

❏ Environmental❏ biologically compatible

materials❏ location

❏ Life Cycle/Ultimate Use❏ durable materials❏ ability to reuse❏ able to be put in water

and still measure power

Literature Review - Hard DataPower generation using an activated carbon fiber felt cathode in an upflow microbial fuel cell

❏ Crushed graphite and multiple graphite rods

RBC - MFC❏ cathode disks made out of graphite woven felt, mounted on graphite rod

(Sayess)

Bioresource Technology❏ Wire mesh strength and porosity, roughened graphite

Literature Review - Past Experience/HeuristicsPast Experience

❏ Oyster shells as aggregates

❏ Fabrication experience

Heuristics❏ Knowledge of the basic

components of an MFC❏ Knowledge of successful

design traits of MFC’s tested prior to ours.

Literature Review - Description/Graphic

Design Methodology and Materials - AnalysisPre-Project AnalysisFrom viewing examples of previous MFC’s built by students, we decided that we wanted to follow their general model, but wanted to make ours bigger and better. We were also required to test them in the aquaculture ponds, a much different environment than the controlled lab environment that had previously been the test site. Seeing the pricing sheets for the available supplies, we decided that we would have to use as many reclaimed materials as possible to keep us under the budget while making a larger scale MFC. We decided that we also wanted to use pluff mud from the coast, as it was thicker, would provide the anode with even less oxygen, and it has had good results in past experiments.

Design Methodology and Materials - MaterialsMaterials❏ Refurbished PVC pipes (12.5 and 1 inch diameters)❏ PVC connectors, elbow and T joints (1 inch diameter)❏ Wire ❏ Alligator clamps❏ Duct tape ❏ Crushed graphite❏ Graphite rods❏ Wire mesh sheet❏ Wire nuts❏ Play sand❏ Oyster shells

Design Methodology and Materials - Fabrication

The main MFC chamber was reclaimed and sealed at the bottom, so it did not need fabrication. We did need to create the anode and cathode, as well as the pipes that would separate the wires from the water. To create the anode and cathode, we cut 6x6 inch sheets of fine wire mesh. We then stapled the sides and bottoms of the sheets together to create a pouch. We then filled the pouches with 365 ounces of crushed graphite. We connected graphite rods-two for each pouch- by wrapping them with copper wire. The pairs of rods were then inserted into the tops of the pouches, into the crushed graphite. We then stapled the tops of the pouches shut and caulked around the tops of the pouches and the openings where the rods were inserted. For extra security, we then wrapped rubber bands around the bags and over the wire connecting the two rods. We then connected the copper wires from the anode and cathode to wires using wire nuts. For the pipes bringing the wires to the surface, we started by drilling a hole in the side of the MFC for the anode wires. We did not have the correct drill bit, so we used one that was smaller than needed, then used other bits to make the hole the desired size. We then assembled the pipes by connecting PVC pipe with PVC connectors and using primer and glue to secure the connections. We then ran the wires up the pipes, and installed the pipes into the MFC by gluing the anode tube into the hole that we had drilled. Finally, we connected alligator clips to the end of the anode and cathode wires for easier use while recording feedback.

Fabrication: Removing the mesh covering and drilling holes for wires

Design Methodology and Materials - Synthesis❏ Synthesis

❏ Main MFC chamber chosen for lack of fabrication and materials needed and a strong resemblance to sample MFC’s.

❏ Oyster shells and sand chosen for ability to make a good membrane, were also curious towards possible positive effects of oyster shells.

❏ Alternatives and Improvements❏ Put in an area that is easily accessible to gather information.❏ Make the wires longer for easier gathering of readings.❏ Shorten the MFC for improved water flow through the cathode.❏ Better and less obtrusive clips for easier readings. ❏ Different ratio of membrane to anode material or different

membrane/membrane materials.

Installing the MFC and retrieving the first set of data

Results & Discussion - Polarization Curves (V = IR)

Initial UpdatedResistance [Ω] Voltage [V] Current [mA]

20.7 .002 0.096618

78.9 .009 0.114068

240.4 .021 0.087354

741 .031 0.041835

2360 .050 0.021186

4388 .054 0.012094

Resistance [Ω] Voltage [V] Current [mA]

4680 0.071 0.015171

4950 0.069 0.013939

10.6 0.002 0.188679

349.3 0.037 0.105926

1320 0.058 0.043939

4680 0.071 0.015171

Results & Discussion - Polarization Curves

Initial Updated

Results & Discussion - Power v. Current

Results & Discussion - Power over Time

Results & Discussion - P = IV

Date Temp [oC] Resistance [Ω] Voltage [V] Current [mA] Power [mW]

11/11 17.6 614 .010 0.016287 0.000163

11/13 11.1 594 .027 0.045455 0.001227

11/15 12.8 603 .041 0.067993 0.002788

11/17 16.1 608 .058 0.095395 0.005533

11/18 16.8 349 .037 0.105926 0.003919

11/22 15.9 393 .066 0.167939 0.011084

11/25 15.6 382 .059 0.154289 0.009103

11/26 5.6 321 .068 0.211838 0.014405

Results & Discussion - PDV = IV/V

Highest power reading - 0.014405 mW

Volume of Anode Chamber - 0.0206 m3

Reusable Power Produced - 0.700 mW/m3

Results & Discussion - Improvements

❏ The time frame of the MFC testing did not allow for improvements to the system, but we came up with some ways to improve it. These ideas were shown and discussed in the alternatives section of the design slides. Given time, these improvements would be carried out and the MFC would be tested again.

ConclusionsThe highest recorded power density we had was .700 mW/m3. Although our results did not meet our desired goal, we were satisfied. Our design showed good qualities, such as ease of fabrication and cost for size. Although we had errors in design, measurement, and possibly in calculation, we think that we can meet the goal with improvements and better techniques.

References1. Drapcho, Caye. “Lecture 6: Engineering Design Method.” Handout. Fundamentals of Biosystems Engineering. (Dr. Caye

Drapcho). Clemson University. November 2013. Print (unpublished).

2. Drapcho, Caye. “Presentation Format.” Handout. Fundamentals of Biosystems Engineering. (Dr. Caye Drapcho.) Clemson University. November 2013. Print (unpublished).

3. Q. Deng, et al., J. Power Sources (2009), doi:10.1016/j.jpowsour.2009.08.092

4. Sayess, Rassil R., Pascal E. Saikaly, Mutasem El-Fadel, Dong-Li, Lucy Semerjian. “Reactor performance in terms of COD and nitrogen removal and bacterial community structure of a three-stage rotating bioelectrochemical

contactor.” Elsevier. Water Research. November 2013. Online.5. Wei, J., Liang, P., Huang, X., Recent progress in electrodes for microbial fuel cells, Bioresource Technology (2011), doi:

10.1016/j.biortech.2011.07.0196. Rashid, Naim, Yu-Feng Cui, Muhammad SaifUr Rehman, Jong-In Han. “Enhanced electricity generation by using algae

biomass and activated sludge in microbial fuel cell.” Elsevier. Science of the Total Environment. November 2013. Online.

Appendix A - Procedure for Polarization

- Attach potentiometer to multimeter and set resistance- Attach MFC to potentiometer and record voltage- Detach MFC from potentiometer and repeat for various resistances- Graph data and determine MFC internal resistance by calculating slope of trendline

Appendix B - Polarization Curve

Maximum power density can be achieved when internal resistance matches that of the external load, therefore; polarization curves were used to obtain the resistance of the MFC.

ex.

Slope of the graph represents the internal resistance of the MFC, which we then matched to the resistance of the potentiometer.

Appendix C - Power Density

Power Density = Current * Voltage / Anode Chamber Volume

PDV = I*V / VPDV = P / V

PDV = 0.014405 mW / 0.0206 m3

PDV = 0.700 mW/m3

Appendix D - Ohm’s Law

Voltage = Current * Resistance V = I * R

Power = Current * Voltage P = I * V P = I * (I * R)