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Monday, May 21, 2012

Biogas is the mixture of gas produced by Methanogenic bacteria while acting upon biodegradable materials in an anaerobic condition. This gas is principally composed of methane (CH4) and carbon dioxide (CO2). Methane is virtually odorless and colorless. It burns with a smokeless clear blue flame and is non toxic. 

The approximate composition of the Biogas is presented in the Table

Average Composition of Biogas Composition
Methane (CH4)
50 - 70
Carbon dioxide (CO2)
30 - 40
Hydrogen (H2)
5 - 10
Nitrogen (N2)
1 - 2
Water Vapour (H2O)
Hydrogen Sulphide (H2S)
                                                                                     Source: Karki & Dixit (1984)
What bio gas can do:
  • 1m3 of Biogas can give as much light as a 60-100 Watt bulb for 6 hours.
  • 1m3 of Biogas can cook 3 meals for a family of 5 - 6.
  • 1m3 of Biogas can replace 0.7 kg of petrol.
  • 1m3 of Biogas can generate1.25 kilowatt hours of electricity.


Bio gas is a mixture of a few gases, such as methane (50-60%) carbon- dioxide (40-50%), hydrogen and ammonia etc., formed as a result of anaerobic digestion (absence of oxygen) of organic waste. A bio gas is commonly described as underground masonry well shaped fermentation tank (Digester) connected with inlet and outlet tanks and covered by an inverted floating or fixed gas storage tank.

Biogas is a BioMethanation plant for producing bio gas from kitchen and vegetable. The plant works on similar principles of traditional floating drum type bio gas plant with a few modification and comes in two deigns : both PORTABLE AND FIXED . The portable unit is entirely made of fiber glass or LLDPE (plastic) material. These plants have a user-friendly design and are suited for both urban and rural environment.

  • It provides an effective alternative to LPG as coking gas.
  • It provides an effective solution for waste disposal : it is a very good for bio gas degradable waste management system.
  • It improve the hygiene with no Odour and no disease causing vermin
  • Methane is an important green house gas (GHG). If the organic waste are left outside all that methane will escape to the atmosphere and thus the plant helps in arresting GHG emission.
  • The digested outlet  slurry is good as an organic manure : it increases interest in kitchen gardening.
  • Its user-friendly design is suitable for both rural and urban areas.
  • Its available in wide –range of volumes (from 500 liters to any amount of volume) allows user to choose depending upon the volume of domestic waste their household generate.
  • It’s easy to handle and maintain.
  • It can be kept in any place including terrace (which makes it usable even in urban apartments.)

How it work:
The main digester is initially fed with cattle dung as it is rich Methanogenic bacteria. it produce methane from starchy material subsequently , cattle dung is not required . Afterwards, one can start feeding the plant daily with kitchen/ vegetable waste. The ratio of waste to water should be 1:1 .this will facilitate easy flow of waste through inlet into the digester. The value of pH of the kitchen waste should be ideally kept in the range of 6.8 to 7.5 for optimum production of bio gas. About 5 kg. Of kitchen waste with the help of plant. Gas coming out of the slurry coming out from the outlet can as manure. the gas generated will have 60 to 70% methane, same amount of water vapour (moisture) and the balance will be carbon- di-oxide and very little amount of trace gases. 

The waste generated from the kitchen:
  • Cooked waste                                           Rice, chapati, Dal, Subji etc.      
  • Non Veg.Waste                                         Fish and meat etc
  • Vegetable Waste                                      Wastage from Vegetable Cuttings
  • Flour Mill Waste                                        Wheat, Rice, Cereal Etc
  • Starch Material                                         Tapioca, Maize and Grams Etc.,
  • Waste Used Tea and Coffee Powder  KANJI (Water from Boiled Rice), Water from Cleaning the   Rice, Vegetable Etc

Methane content will vary as per type of feed. Starchy material as well as Non-Veg feed having more fat will give more methane, whereas vegetable like pumpkin, cucumber will gives less gas.

We have to make a distinction between cooked waste and uncooked waste. In case of cooked waste, fermentation has already started and thus it is easy for microbes to react. however , in case of vegetables waste (uncooked material ),fermentation is achieved by keeping the material for a day or two in water (better hot water ) or in the output slurry after crushing to get better results.


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