Fixed Dome type – Janata Model Biogas Plant Construction

Biogas can be a great alternative of fossil fuels. It is already in use in many rural areas. Biogas plants use animal waste, plant waste and human waste. All this wastes have great combustible property. Biogas is an excellent renewable energy source. It is produced by the digestion of waste materials by the means of anaerobic reaction. Anaerobic means the absence of Oxygen. In most of the rural areas cow and buffalo dungs is used as biomass fuel for producing gas. The typical composition of biogas is

Methane - CH₄  (55 - 65 %)
Carbon dioxide CO₂  (30-40%) 

H_{2 ,} H₂S , N₂      (< 10%) 

Biogas Technology involves the bacterial breakdown of the waste materials to produce Methane, Carbon Dioxide and Water . The process involves the following three steps - 

Hydrolysis 

Organics materials contains mainly carbohydrate mainly in the form of cellulose, hemicellulose and lignin. These have very complex structure which is not suitable for absorption. So these matters are converted into simple soluble materials by the action of celluolytic or hydrolytic bacteria. Concentration of bacteria in the organic materials, temperature and pH controls the rate of hydrolysis. pH between 6 to 7 and temperature between 30-40 degree Celsius is good for bacteria to work. 

Acid Formation 

Simple organic materials are turned into acid by acetogenic bacteria. 

Methane Formation 

Methanogenic bacteria turns the acid into methane, carbon dioxide, hydrogen, nitrogen and oxygen. The methane content is 60%. It has high calorific value. Very good for combustion and producing energy. 

Biogas plants 

Biogas plant converts the organic wastes like dung, human waste and plant wastes into a inflammable and it also produces a high quality organic manure as a by product. Most popular two designs of biogas plant is 

1. Fixed Dome Type Biogas plant (Janata Model) (Operates in constant volume)

2. Floating Drum type Biogas plant. (Operates in constant pressure)

In this article I will discuss about the first one - The Fixed Dome type or Janata Model biogas plant. 

Fixed Dome Type Biogas Plant - Janata Model 

This type of biogas plant is very economical is design. It works with the constant volume principle. The main structure is made up of brick and cement masonry. This type of plant doesn't have any moving parts so it is safe from wear and tear. The operating pressure varies from 0 to 100 cm of water column. It is also known as Janata model.