Microbial Fuel Cell

[ResearchTopic]

I'm planning to construct a microbial fuel cell for my science project to test how much electricity is produced under different conditions. Some variables I'm considering are different types of microorganisms, whether it is mediator/mediator-less, and what area in the water source the wastewater comes from. I have read the article about microbial fuel cells on here, but I'm looking for more info. What types of microorganisms are safe to use, easy to find, and are effective, like yeast? Are there any other variables that could be tested? Also, are there any precautions I should take to ensure that the MFC works properly, such as with usage and construction? Thanks!

[deleted-71417]

Hi,

I understand the Science Buddies project you are trying to use is:

https://www.sciencebuddies.org/science- ... p026.shtml

Here is a brief article mentioning useful bacteria:

http://www.technologyreview.com/Energy/16921/?a=f

If you haven’t seen this book, it might prove helpful:

http://www.amazon.com/Microbial-Fuel-Ce ... 0470239484#

Thies articles are more recent than the project writeup, so might be useful:

http://www.nature.com/nrmicro/journal/v ... o2113.html

http://www.plosone.org/article/info:doi ... ne.0006570

Here is another project description set with recent comments:

http://www.instructables.com/id/Simple- ... -An-Algae/

http://www.instructables.com/id/Make-a- ... C-Part-II/

This website lists some of the active research groups in this area and outlines their research directions:

http://www.microbialfuelcell.org/www/in ... h-America/

I hope this helps a little.

Best regards,

Barrett Tomlinson

[ResearchTopic]

In MFCs, is the purpose of the carbon cloth electrodes to act as a bridge for the electrons to pass from the anode to the cathode? Also, how can a multimeter be attached to each electrode (anode and cathode) so that it can read the voltage of the electric current?

[deleted-71588]

The efficiency of using two carbon element electrodes will be significantly less than using a metal container as one of the electrodes. In order to prevent metalic material oxidation, you want to consider "cathodic protection" aspects. This would suggest that the metal container be the cathode and use the carbon cloth for the annode.

The purpose of ANY electrode associated with a chemical reaction is to prove an external circuit connection to either draw power from the electrolyte (battery operation) or to inject current flow in the electrolyte to recharge or cause electro-plating.

In order to make a good connection between any two conductors, you need clean surface contact. The larger the contact area, the lower the resistance and the more current the connection will allow. In most cases, you want something that applies mechanical pressure to the contact area. You also want to avoid intruducing additional metals into the electrolyte.

Something like a couple of fender washers on either side of the fabric, a spade or ring wire lug with wire attached, and a bolt/nut/lockwasher through the other parts might work.

Simple alligator clips might even work if the amount of current is very small.

[ResearchTopic]

Thanks! This has helped a lot to clear up some issues. Instead of using a metal container, which I think may be difficult to drill a hole in for the proton exchange membrane, is there an alternative way to increase the efficiency of the electrodes while still using plastic containers? I mean as in something like lining the containers with metal foil? For the carbon cloth electrodes, are ready-made ones (with wires already attached to carbon cloth) efficient enough or should I still attach washers to the sides?

[deleted-71588]

For the carbon cloth electrodes, are ready-made ones (with wires already attached to carbon cloth) efficient enough

This is a good question that can't be answered without experimentation. If the ready-made carbon cloth electrodes were designed for your kind of application, then one would hope that the manufacture did their homework (aka research) and produced an efficient design you can use as is.

Efficient contacts to aluminum foils is a problem to solve. You have different metals, contact pressure, mutual surface area, gas tight, and other aspects to solve but it can be done.

[ResearchTopic]

I have collected the voltage readings for my control (purified water), mud, pond water, and ground food at different time intervals (from 5 min. to 36 hours)and I have 7 trials for each type of organic waste. I was wondering how I should display my data on graphs. I'm going to create 1 graph per type of organic waste I used, with the voltage readings at different times. I also have the average voltage readings of all trials of each type of organic waste for each different time (ex. average of all 7 voltage readings of pond water samples at 12 hours). I also have the averages for all trials of each type of organic waste for all times (average of all the voltage readings I have for each typ eof organic waste). I'm also going to find the regression line for the original set of data with the voltage readings at different times. How should I display my data? Should I show all of the original data for each type of organic waste along with the averages, or should I separate the averages?

On a different topic, I also collected readings for resistance, along with voltage, of each trial. Should I use this to calculate current, or will showing the voltage only be sufficient?

Thanks!