We found this YouTube about making a biodigester and found it to be both informative and entertaining enough to sit through the whole 14 minutes. The Urban Farming Guys have what looks to be a great setup for a backyard biodigester. You might want to what this a couple of times to pay attention to all the other stuff they have going on in their yard.
Watch the whole thing for an overview of the system they are building, the mistakes they made (so you won’t have to make the same mistakes), and an explanation and demonstration of how to install the fittings and pipes.
If you’d like to see an example of a huge biodigestion system and how it works, try to find Living With Ed, episode “For Better Or Worse” somewhere. Ed Begley, Jr and his wife Rachel Carson, visit a farm with a biodigester that produces its own electric power.
Or…here’s another YouTube with a brief overview of a system installed on a pig farm in Dodge, Nebraska,