Completed unit. I have removed the gas pipe, so that the joints will get cured without any stress:
Wait for a day or two before feeding the system, allowing all joints to get cured and become leak-proof.
Initially, cow-dung mixed with water will be fed in to the system, which will start the gas formation process. Subsequently, food waste, decomposable organic material and kitchen waste will be diluted with water and used to feed the system. The gas holder will rise along the guide pipes based on the amount of gas produced. We can add some weight on top of the gas holder to increase the gas pressure. When we feed the system, the excess digested slurry will fall out through the outlet pipe, which can be collected, diluted and used as organic manure.
Initial production of gas will consist of oxygen, methane, carbon di oxide and some other gases and will not burn. These gases can be released to the atmosphere by opening the ball valve at least three / four times.
Subsequent gas will consist of about 70 to 80 percent methane and the rest carbon di oxide, which can be used in a single bio-gas burning stove or a Bunsen burner.
Total cost of this proto-type system is about one thousand Indian Rupees (about 20 dollars)
This is a basic prototype of a Bio-gas system using the food waste, decomposable organic material and kitchen waste to produce gas. An one thousand litre capacity Digestion tank will be sufficient for a small household for daily cooking purpose. The bigger commercial models provide a water seal between the digestion tank and gas holder tank.
You can get further information on kitchen waste based mini Bio-gas plant at the following links: