New Material for Digester

I have just recently received another email from Paul Harris of The University of Adelaide in Roseworthy, South Australia on the topic of what is best for an anaerobic digester. His reply to my email message writes:
"Pig or cow manure is best for bacteria (I have used pig manure). Or you may
be able to get some sludge from a sewerage treatment works or an operating
digester if there is one nearby.

You should burn the gas if possible, as methane is 23 times worse as a
greenhouse gas than carbon dioxide (not that you are making a huge amount!).
I have found that a 12mm (1/2") tube (metal!) makes a good burner for small
scale by using a 1mm (1/16") diameter gas jet and low pressure supply -
about 25mm (1") water pressure (there is a sketch on the web page http://www.adelaide.edu.au/biogas/fair/). All I do is run a tube from my
digester to the burner."

My next goal is to find a pretty local ranch or farm that I can get some cow manure from. I believe that this should be relatively easy to accomplish.

After that, my main problem is determining what type of gas is actually being produce and whether or not it is safe to burn. I do not want to have a flame any where near my project if it turns out that the gas will explode rather than burn.