Works best on hot climates
Bio gas is usually methane that comes from rotting biological carbon based matter
An effective and simple bio gas generator can be made by getting a barrel and cutting the bottom open – (or if the barrel has no lid just turn it upside down)
if using this method there is no need to feed the digester or have a sludge outlet .. cause its setup to use batches.
but this pretty much sums it up
Plumb in some gas fittings with a tap to control the flow so that you can close them for the period needed to start the procedure
Dig a trench (the reason for the trench is to do more then one barrel at a time in the same area to provide enough gas and you can space them apart in time so that you always have some usable gas ) in the ground as big as you need to fit the barrel inside without touching the walls – and almost as deep as the barrel is high (don’t want the plumbing clogged with the slop) – the ditch or trench can be dug to include a number of barrels in a row, line the trench with clay , or plastic sheeting and fill with pig/chicken manure or any other material and water in a sloppy mixture about the consistency of loose oats porridge (experimentation gives results of what works and what doesn’t)
place the barrels open side down into the mixture with the taps open so as to form a seal with the slop,
and close the taps ( the weight of the barrel provides even pressure)
leave for a few days, the barrels should begin to rise out of the slop, open the taps and release the gas that is formed – this will be mostly CO2 – close them again
leave them a few more days.
the barrels will rise out of the slop as they get filled with gas, release the gas again … do this for the next 3 weeks ( depending on temperature, higher goes faster 30 -45 degrees C is optimal )
Test each day after the first 3 weeks have passed for combustibility.
they should produce usable gas for 2 months or so
When the gas is no longer being produced, take the barrels out and let the muck dry out and cover the holes in with dirt and dig a new trench for the next batch – dig these holes up after a year or so and use the rich fertilizer left behind for farming,