Explain the principle and working of a biogas plant using a labelled schematic diagram.
Biogas is produced as a result of anaerobic fermentation of biomass in the presence of water.Construction Back to Top
The biogas plant is a brick and cement structure having the following five sections:
- Mixing tank present above the ground level.
- Inlet chamber: The mixing tank opens underground into a sloping inlet chamber.
- Digester: The inlet chamber opens from below into the digester which is a huge tank with a dome like ceiling. The ceiling of the digester has an outlet with a valve for the supply of biogas.
- Outlet chamber: The digester opens from below into an outlet chamber.
- Overflow tank: The outlet chamber opens from the top into a small over flow tank.
Fixed Dome type Biogas PlantWorking Back to Top
- The various forms of biomass are mixed with an equal quantity of water in the mixing tank. This forms the slurry.
- The slurry is fed into the digester through the inlet chamber.
- When the digester is partially filled with the slurry, the introduction of slurry is stopped and the plant is left unused for about two months.
- During these two months, anaerobic bacteria present in the slurry decomposes or ferments the biomass in the presence of water.
- As a result of anaerobic fermentation, biogas is formed, which starts collecting in the dome of the digester.
- As more and more biogas starts collecting, the pressure exerted by the biogas forces the spent slurry into the outlet chamber.
- From the outlet chamber, the spent slurry overflows into the overflow tank.
- The spent slurry is manually removed from the overflow tank and used as manure for plants.
- The gas valve connected to a system of pipelines is opened when a supply of biogas is required.
- To obtain a continuous supply of biogas, a functioning plant can be fed continuously with the prepared slurry.