Subject: In anerobic digestion, what is the chemical reaction taking place?

I have set up two biogas generators in our shed at home and am trying to find 
out which kind of manure produces the most methane gas. I have a couple of 
problems that I need help on though. One of them is that the balloons in 
which  I'm collecting the gas being produced are getting water in them (from 
the water/manure mixture in a large water bottle, which is attached to tubes 
leading to the balloons) - How can I prevent this? I got the method of making 
the generators from the internet, it was quite easy, and I followed it exactly.
I also need to know what chemical reaction is going on, in order to produce 
this gas. Is is gas that is produced right away or just air or carbon dioxide? 
How can I check if it is gas ?? I was going to use a bunsen burner to see if 
it would burn using the gas I produce.
How can I make my experiment more efficient???
Help!! I am getting tangled up in this experiment and my mum is getting mad at 
me for the poop factor!
Thank you, From Danial

Re: In anerobic digestion, what is the chemical reaction taking place?