MFC Experimental Trials

Prototype 1 - Double Chamber MFC (11/12/20)

Goals:

Gain a clearer understanding of how an MFCs function
Identify any potential problems and improvements to the MFC

After conducting each trial for at most 7 minutes, it was observed that the alcohol content discouraged the microbes from producing much voltage. Upon removing it, the voltage improved, and more trials were conducted to identify ammonia's impact on the voltage. Since it serves as a catalyst that encourages yeast fermentation, it encouraged cellular respiration to occur and a higher voltage was produced.

Details:

A double chamber MFC was constructed using PVC pipes and connectors. Each chamber was occupied by an anode and cathode.
Two sponges were soaked to make it easier to puncture a hole through. A wire was then passed through to allow the the wire to pass through each electrode brush.
The wire poking out of the anode chamber is then connected with an alligator clip to a voltmeter to measure the voltage produced (in mV). It is important to note that the anaerobic (without air) chamber was sealed with a PVC tube cap to prevent too much air from entering the system.

Double Chamber MFC built from PVC pipes and connectors.

Salt bridge made from saturated solution of gelatin and sugar.

Cathode (C) is submerged in a saturated salt solution, whereas the anode (A) is submerged within the wastewater dupe.

Recipe for Brewery Wastewater Dupe:

- 300 mL of bottled water

- 5 tsp of yeast

- 4 tsp of cornstarch

- 50 mL ammonia (catalyst to encourage yeast fermentation)

Max Voltage Measured 3.6 mV
(w/ Ammonia)

Trial 1a: 400ml of bottled water with 2 tsp of yeast, 2 tsp cornstarch, 5 tsp of sugar, 40ml of 70% ethyl alcohol.
Trial 2a/2b: 300ml of bottled water with 5 tsp of yeast, 4 tsp cornstarch, 8 tsp of sugar.
Trial 3a/3b: 300ml of bottled water with 5 tsp of yeast, 4 tsp cornstarch, 10 tsp of sugar, 50ml ammonia.

Prototype 2 [Trial 1]- Cube Reactor MFC (12/01/20)

Goals:

Create and test a cube reactor MFC design
Determine its effectiveness using wastewater collected from our college's brewing class

After constructing the cube reactor, about 28 mL of wastewater was poured through the two holes from the top of the MFC. Both of the wires were then connected to a breadboard, which was then connected to a voltmeter. A 10k Ohm resistor was also connected

There was a substantial improvement to the voltage produced, which can be attributed to its tight compact design and materials (3D printed parts, electrodes, sheets, and tight compact design). It can also be attributed to the fact that the brewery wastewater contained more sugar for the microbes to consume.

Details of Cube Reactor:

For this prototype, the MFC was constructed with 3D printed parts, made from Autocad. Those parts were fixed together with 8cm long screws and sealed tight with wing knots.
Carbon paper was then cut out in a square-shape (length of 4cm) and then placed at the front of the cube (anode side).
The paper also had 1cm diameter holes in the corners for the screw to insert in. On the other side, a nafion sheet and aluminum paper sheet were both cut out in a square-shape (length of 4cm).
The nafion is connected directly to wastewater (cathode). The two sheets also had holes for the screw to insert into. The plate with the hole is for the air anode side. The other plate is solid, so the aluminum and nafion sheets are held tightly together.
The screws are used to seal the 3 pieces and electrode sheets together, two wires are passed into the two holes from the top of the cube.

3D Printed Parts For Cube Reactor

Fully Assembled Cube Reactor (Top View)

Fully Assembled Cube Reactor (Side View)

Maximum Voltage from Open Circuit (mV)

Maximum Voltage from Closed Circuit (mV)

Setting Up Voltmeter to Cube Reactor

Results

Observations

The voltmeter reading wasn't initially consistent since it read 20 mV (theoretical max). After leaving the wastewater for 25 minutes, the voltage became consistent and read 6.8mV.

The wastewater used was diluted by a lot of water to obtain a liquidy texture.
The breadboard contributed some resistance as well.
The brewery wastewater used smelt like alcohol, which had probably reduced the amount of bacteria in the water.

Prototype 2 [Trial 2, 3, & 4] - Cube Reactor MFC (12/09/20)

Goals:

Determine the voltage produced from brewery wastewater collected from Wild East Brewing
Get a higher voltage (closed circuit) than the voltage from Trial 1. Ideally, the power should be ~0.2 W per m^3.

Trial 2 Improvements: Used Brewery Wastewater

Used brewery wastewater from Wild East Brewing Co.
Notes on wastewater:
- The brewery wastewater was fresh out the vat and was steaming hot.
- It didn’t have the alcoholic smell that Cooper Union's brewing class wastewater had, which likely suggests that this wastewater contained more bacteria.
Breadboard was not used as it created more resistance in the circuit.
The voltage took some time until it became consistent, we measured two voltages until it stabilized at about 220 mV.

Trial 3 & 4 Improvements: Improved Electrode Connection

Still used Wild East Brewing Co. Wastewater
The yellow wires in the cube reactors were bent, so they can touch two ends of the MFC. The yellow wire connected to the red wire of the voltmeter to the anode. The yellow wire also connected to the black wire of the voltmeter to the cathode. The yellow wire's ends were then bent into a circle, so they can touch their two respective electrode.

Initial Voltage in mV (Trial 2)
[Closed Circuit with Resistance of 10k Ohms]

Voltage in mV (Trial 2)

After Stabilization

Max Voltage in mV (Trial 2)
[Closed Circuit with Resistance of 10k Ohm]

Voltage in mV (Trial 3)

After Stabilization

Wastewater Collected From Brewery

Results

Prototype 3 [Trial 1 & 2] - Cube Reactor MFC (12/09/20)

Goals:

Trial 1:
- Used Wild East Brewing Co. brewery wastewater
- This prototype was created to confirm whether second prototype using the cube reactor worked. Data from both Trials 1 and Trials 2 of this prototype were done using an open circuit. The voltage produced was lower than expected (200 mV and above). This could be attributed to the fact that the screws weren't tightly fixed, causing the water to leak. It could have also been due to the lower volume of wastewater used.
Trial 2:
- Followed the same conditions, but the cube's faces were screwed tighter, and more wastewater was poured, so it filled the cube to the top. The voltage appeared to
- Same conditions but with the cube tightly held together by the screws and wastewater filling the cube to the top. Trials 1&2 measurements are open circuit ones.

Trial 1 Max Voltage (mV)

Trial 2 Max Voltage (mV)

Trial 3 Max Voltage (mV)

Results

Observations

For Trial 1a and 1b, the voltage produced was lower than expected (200 mV and above). This could be attributed to the fact that the screws weren't tightly fixed, causing the water to leak. It could have also been due to the lower volume of wastewater used.
Trial 2 remains consistent with the previous prototype's data. It appears to be slightly higher in voltage.

Prototype 4 - Cube Reactor MFC (12/09/20)

Goals:

To build another cube reactor and collect data to verify past results

Setting Up Voltmeter to Cube Reactor

Trial 1 Max Voltage (mV)

Results

Conclusion

Our fourth prototype was the best as we knew what the optimal settings were from past prototypes. The best circuit trial was trial 1 which measured 418mV with a 10k ohm resistor. Trial 2 measured 388mV with a 10k resistor. We were still using the brewery wastewater sample from the Wild East brewery.

Water Cleanliness Trial Using Cube Reactor (12/09/20)

Goals:

To confirm the effectiveness of using MFCs to clean wastewater by measuring the pH and alkalinity of wastewater before and after it was treated.
The wastewater was left in the MFC for 3 days before it was remeasured.

Result:

Conclusion:

The pH of the water has decreased but is still within a range that is not too acidic or basic. The average alkalinity of domestically used water is less than 100 ppm, which is well over the tested value of the wastewater. This proves that the MFC efficiently treats the pH and alkalinity of wastewater, but there are still trials to be done to test other factors that affect the "cleanliness of water", such as the concentration of solids and chemicals that it includes. Moreover, the color of the treated sample showed little change, possibly indicating more testing might be necessary.

MFC Experimental Trials

Prototype 1 - Double Chamber MFC (11/12/20)

Goals:

Gain a clearer understanding of how an MFCs function

Identify any potential problems and improvements to the MFC

​

​

Details:

A double chamber MFC was constructed using PVC pipes and connectors. Each chamber was occupied by an anode and cathode.

Two sponges were soaked to make it easier to puncture a hole through. A wire was then passed through to allow the the wire to pass through each electrode brush.

The wire poking out of the anode chamber is then connected with an alligator clip to a voltmeter to measure the voltage produced (in mV). It is important to note that the anaerobic (without air) chamber was sealed with a PVC tube cap to prevent too much air from entering the system.

Double Chamber MFC built from PVC pipes and connectors. Salt bridge made from saturated solution of gelatin and sugar. Cathode (C) is submerged in a saturated salt solution, whereas the anode (A) is submerged within the wastewater dupe.

Recipe for Brewery Wastewater Dupe: - 300 mL of bottled water

- 5 tsp of yeast

- 4 tsp of cornstarch

- 50 mL ammonia (catalyst to encourage yeast fermentation)

Max Voltage Measured 3.6 mV (w/ Ammonia)

Prototype 2 [Trial 1]- Cube Reactor MFC (12/01/20)

Goals:

Create and test a cube reactor MFC design

Determine its effectiveness using wastewater collected from our college's brewing class

​

After constructing the cube reactor, about 28 mL of wastewater was poured through the two holes from the top of the MFC. Both of the wires were then connected to a breadboard, which was then connected to a voltmeter. A 10k Ohm resistor was also connected

​

Details of Cube Reactor:

For this prototype, the MFC was constructed with 3D printed parts, made from Autocad. ​Those parts were fixed together with 8cm long screws and sealed tight with wing knots.

Carbon paper was then cut out in a square-shape (length of 4cm) and then placed at the front of the cube (anode side).

The paper also had 1cm diameter holes in the corners for the screw to insert in. On the other side, a nafion sheet and aluminum paper sheet were both cut out in a square-shape (length of 4cm).

The nafion is connected directly to wastewater (cathode). The two sheets also had holes for the screw to insert into. The plate with the hole is for the air anode side. The other plate is solid, so the aluminum and nafion sheets are held tightly together.

The screws are used to seal the 3 pieces and electrode sheets together, two wires are passed into the two holes from the top of the cube.​

3D Printed Parts For Cube Reactor

Fully Assembled Cube Reactor (Top View)

Fully Assembled Cube Reactor (Side View)

Maximum Voltage from Open Circuit (mV)

Maximum Voltage from Closed Circuit (mV)

Setting Up Voltmeter to Cube Reactor

Results

Observations

The voltmeter reading wasn't initially consistent since it read 20 mV (theoretical max). After leaving the wastewater for 25 minutes, the voltage became consistent and read 6.8mV.

​

Prototype 2 [Trial 2, 3, & 4] - Cube Reactor MFC (12/09/20)

Goals:

Determine the voltage produced from brewery wastewater collected from Wild East Brewing

Get a higher voltage (closed circuit) than the voltage from Trial 1. Ideally, the power should be ~0.2 W per m^3.

​

Trial 2 Improvements: Used Brewery Wastewater

Used brewery wastewater from Wild East Brewing Co.

Notes on wastewater:

The brewery wastewater was fresh out the vat and was steaming hot.

It didn’t have the alcoholic smell that Cooper Union's brewing class wastewater had, which likely suggests that this wastewater contained more bacteria.

Breadboard was not used as it created more resistance in the circuit.

The voltage took some time until it became consistent, we measured two voltages until it stabilized at about 220 mV.​

Initial Voltage in mV (Trial 2) [Closed Circuit with Resistance of 10k Ohms]

Voltage in mV (Trial 2)

After Stabilization

Max Voltage in mV (Trial 2) [Closed Circuit with Resistance of 10k Ohm]

Voltage in mV (Trial 3)

After Stabilization

Wastewater Collected From Brewery

Results

Prototype 3 [Trial 1 & 2] - Cube Reactor MFC (12/09/20)

Goals:

Trial 1:

Used Wild East Brewing Co. brewery wastewater​

Trial 2:

Followed the same conditions, but the cube's faces were screwed tighter, and more wastewater was poured, so it filled the cube to the top. The voltage appeared to

Same conditions but with the cube tightly held together by the screws and wastewater filling the cube to the top. Trials 1&2 measurements are open circuit ones.

Trial 1 Max Voltage (mV)

Trial 2 Max Voltage (mV)

Trial 3 Max Voltage (mV)

Results

Observations

​For Trial 1a and 1b, the voltage produced was lower than expected (200 mV and above). This could be attributed to the fact that the screws weren't tightly fixed, causing the water to leak. It could have also been due to the lower volume of wastewater used.

Trial 2 remains consistent with the previous prototype's data. It appears to be slightly higher in voltage.

Prototype 4 - Cube Reactor MFC (12/09/20)

Goals:

To build another cube reactor and collect data to verify past results

Setting Up Voltmeter to Cube Reactor

Trial 1 Max Voltage (mV)

Results

Double Chamber MFC built from PVC pipes and connectors.

Salt bridge made from saturated solution of gelatin and sugar.

Cathode (C) is submerged in a saturated salt solution, whereas the anode (A) is submerged within the wastewater dupe.

Recipe for Brewery Wastewater Dupe:

- 300 mL of bottled water

Max Voltage Measured 3.6 mV
(w/ Ammonia)

For this prototype, the MFC was constructed with 3D printed parts, made from Autocad. Those parts were fixed together with 8cm long screws and sealed tight with wing knots.

The screws are used to seal the 3 pieces and electrode sheets together, two wires are passed into the two holes from the top of the cube.

The voltage took some time until it became consistent, we measured two voltages until it stabilized at about 220 mV.

Initial Voltage in mV (Trial 2)
[Closed Circuit with Resistance of 10k Ohms]

Max Voltage in mV (Trial 2)
[Closed Circuit with Resistance of 10k Ohm]

Used Wild East Brewing Co. brewery wastewater

For Trial 1a and 1b, the voltage produced was lower than expected (200 mV and above). This could be attributed to the fact that the screws weren't tightly fixed, causing the water to leak. It could have also been due to the lower volume of wastewater used.