Science Buddies: "Ask an Expert"

Hi
I am creating a hybrid device, by combining microbial fuel cell and electrolysis cell powered by wind. The function of my MFC will be to purify sewage water, and the voltage produced by it will be used to supplement the electrolysis cell. The electrolysis cell will be powered by a wind-simulation device, and voltage from MFC. What I am testing is amount of hydrogen gas produced when various liquids are electrolyzed. Water will be the control, and variables will be added to water to see which when helps produce more hydrogen. The variables I will use are vinegar, liquid ammonia and hydrogen peroxide. The will keep all the aspects of the MFC constant. Does this sound like a good project for a seventh grader?
The questions I have are:
1. I am using a single chambered MFC, I will be making it at home. Is the single-chambered MFC better in any way than the double-chambered MFC? If so, then how? Where can I read more about it?
2. I am also making a mediator-less MFC, is this better, in any way, than the one that uses mediators. How is one better than the other. I am guessing, in the one without mediator minimal electrons will be lost. Please also tell me where I can read more about different types of MFCs and which one is better than other.
Since the focus of my experiment is mainly the electrolysis cell, and the amount of hydrogen produced... I don't want to use a very complicated MFC. What would be your suggestion. Also I will be keeping the MFC and all its aspects constant... is that viable?
How long can an MFC run continuously without exhausting the bacteria?
Any other suggestions you have about this project, pls let me know.
Also, is this both a physical science and life science project or just physical science?!!!!???
Thanks

Hi, I have one more question related to chemistry;

I am electrolyzing various liquids in my project, in order to obtain hydrogen gas. I will be measuring the hydrogen gas (that is the goal of my experiment).

The liquids I am hydrolyzing are: water, hydrogen peroxide, liquid ammonia and vinegar.

My question is; for liquid ammonia and vinegar is it possible that some other gas like carbon dioxide might get produced, and if so how do I separate it from hydrogen and measure only the hydrogen and not the other gas.

I know the hydrogen gas will be collected at the cathode, so may be the other gasses might get collected at the anode.... but I'm still not sure how I can distinguish which gas is being produced, as all of them will be appearing as bubbles.

Please let me know, if those gasses will be produced, and how to avoid measuring them while measuring hydrogen.