Floating Gas-holder Type

A digester tank or a well is made out of concrete and it is called the digester tank, which has two parts: the inlet and the outlet. The inlet is from where slurry is transported to the tank, which has a cylindrical dome made of stainless steel. This dome floats on the slurry and collects the gas generated. That is why such a biogas plant is known as floating gas holder type. Fermentation of the slurry takes about 50 days. The pressure inside increases when more gas is formed by bacterial fermentation. The gas is then transported out through outlet pipe. The decomposed matter moves into the next chamber in the tank. By using the outlet pipe this is then removed to the overflow tank, which is used as manure for cultivation purposes.

Fixed Dome Type

Here also, a well and a dome are made out of concrete, which is called the digester tank. Since the dome is fixed, this gas plant is known as fixed dome type. The manufacturing process is similar to the floating holder type bio gas plant, where the slurry expands and overflows into the overflow tank.

Bag Type

The bag-type biogas plant is a portable unit. Made of rubberized nylon fabric, such a plant can be easily placed at any location. The appropriate type is selected on the basis of technical requirements like distance between kitchen and cattle shed, location, availability of dung and water, preferences of the beneficiaries etc.

Components of Biogas Plants

Inlet pipe: The slurry is moved into the digester through the inlet pipe/tank.

Mixing tank: The feed material like dung is gathered in the mixing tank. Using sufficient water, the material is thoroughly mixed till a homogeneous slurry is formed.

Digester: Inside the digester, the slurry is fermented. Biogas is produced through bacterial action.

Gas holder or gas storage dome: The biogas thus formed gets collected in the gas holder. It holds the gas till the time it is transported for consumption.

Outlet pipe: The slurry is discharged into the outlet tank. This is done through the outlet pipe or the opening in the digester.

Gas Pipeline: The gas pipeline carries the gas to the utilization point like a stove or lamp.