Science Buddies: "Ask an Expert"

Hi,
I assembled a MFC (MFC1) on 12/26/14 and it started blinking on 12/27/14 at night. Next day the power was at 3 micro-watts and I thought my experiment was going very well. The next day however the power went down to 2 micro-watts. The following day it stopped blinking and has not blinked ever since.
I assembled a second MFC (MFC2) on 12/27/14. This is the one I intend to add urine to later and use the MFC1 as control. MFC2 has not blinked yet.
What should I do with MFC1? Should I redo it? Why would it blink so early? Why would it stop? Will it blink again?
My project is due on Jan 25th and I am starting to worry about the success of this project.
Thanks for your help.
MWE

Hi MWE,

I do not think that you will need to redo MFC1 because in a science fair project, you must have multiple trials. If the other trials show different results from the first trial then you can assume that a mistake might have occurred in the first trial.

Good Luck. If you have any more questions feel free to ask.
nikhita8

Hi MWE,

I posted a reply to your questions on the Phys Science forum January 1 with several suggestions to test. Did you try them and what was the result? This information is necessary for other experts to help you effectively.

1. Did you try measuring the voltage on MFC2? Did you take the lid with the hacker board and LED from MFC1 and try it on MFC2. Equipment failure is always a possibility.
2. Oxygen may be getting to the anode and blocking the current flow. This could also explain why MFC1 stopped producing current. Where did you get the soil to make the mud? Any pesticide residues or run-off from something like oil or solvents could be toxic to the soil bacteria. Did you use distilled water when you made the mud? Chlorinated water can harm the soil bacteria.
3. Did you try using fresh mud from a different location?

Please answer the questions and provide an update on the current status of your MFCs. Thanks.

Sybee

Hi Sybee,
Please see my responses below:
1. Did you try measuring the voltage on MFC2? Did you take the lid with the hacker board and LED from MFC1 and try it on MFC2. Equipment failure is always a possibility.
I have been measuring the voltage on both MFCs with a multimeter and got readings. So there is no equipment failure. I just don't have enough power in MFC1 to light up the LED which I did initially. Today MFC2 started blinking. Will see how long this lasts.
2. Oxygen may be getting to the anode and blocking the current flow. This could also explain why MFC1 stopped producing current. Where did you get the soil to make the mud? Any pesticide residues or run-off from something like oil or solvents could be toxic to the soil bacteria. Did you use distilled water when you made the mud? Chlorinated water can harm the soil bacteria.
No visible voids in the MFCs. Both soil samples were from our organic garden. They contain some level of bunny waste which we use to fertilize, and organic compost. We have been building our soil for the past two years. It should be ideal for this experiment. It works great for growing food.
3. Did you try using fresh mud from a different location?
No. The soil should be ideal according to all descriptions I came across.
Thanks.
MWE

I agree that soil amended with organic materials, animal manures and compost is great for growing vegies, but it may not be so good for creating the anaerobic environment that the MFC bacteria need. Even a very small amount of oxygen can inhibit the microbial electron transfer. If you are still getting erratic voltage readings I would try a mucky soil that is more dense.

Good luck!

Sybee

Anybody has any suggestions on how to display data for this project? I have different resistors with different voltage and power measurement over many days for two diferent MFCs. Not sure what to compare and what to show in my charts, highest power per day, powers across same resistor, to compare or not the two MFCs on the same graph…. to complicate it even more, I will have new data after adding urine. I also have blinks per second to display. Please suggest ways to organize this data in an easy way to interpret.
thanks.
MWE