I have constructed a 2 chamber MFC for my senior research assignment and it has yet to produce any voltage. I used nafion as a PEM membrane and used graphite brushes as the electrodes. I have the bioanode filled with waste water that was about 2 weeks old and the cathode filled with tap water. The anode is capped and airtight while the cathode is uncapped to allow O2 into the chamber. I have let the MFC sit with the waste water in it for about 24 hours and there is still no current being generated.
I suppose there may be problem related to the start-up of your MFC. Precisely, the bioanode needs much attention. Try adding small quantities of seeding material (eg. Cow dung slurry) so that there is ensured microbial growth.
Did you let your system in OCV for sometimes and connect an external resistor?
Did you make sure that your system reached to steady state? There are some hints for you to go back and double-check your system again:
1) Measuring COD to make sure that bacteria consume the feeding substrate.
2) How did you connect your electrodes? Have ever measured the resistance of the connection of electrode and the connector (titanium wire)?
3)Measuring the ORP (oxidation reduction rate) of anodic side to make sure that the values is about (-300 mV) for anaerobic environment, hence, there is not presence of oxygen.
4) Was there any biofilm deposited on surface of electrode?
5) Tap water has low conductivity. You should switch to another type of catholyte solution.
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