Bio gas, its principle and production all you need to know.

1. BIO GAS
PRP
PRINCIPLE OF PRODUCTION

2. BIOCHEMICAL CONVERSION
• By the use of metabolic action of microbial organism on
biomass to produce liquid and gaseous fuels.
• There are two types….
o Fermentation process,
o Anaerobic digestion.

3. ANEAROBIC DIGESTION
• An anaerobic is a micro organism that can live and grow
without air or oxygen, it gets oxygen by the decomposition
of matter containing it.
• It involves wet biomass & animal waste into biogas through
decomposition process by the action of anaerobic bacteria.
• The biogas production depends on,
o The type of biomass used,
o Temperature,
o PH value of mixture etc.

4. Gas produced by the anaerobic digestion or fermentation
of organic matter under anaerobic conditions.
Typical biogas composition:
Methane, CH4 : 55-65%
Carbon dioxide, CO2 : 30-40%
Nitrogen, N2 : 1 %
Hydrogen Sulphide, H2S : 0.1 %
Hydrogen, H2 : 1-2 %
Oxygen, O2 : 0.1 %
• pH-value : 6.5 to 7.5
What is biogas?

5. PRINCIPLE OF BIOGAS PRODUCTION
• The production of biogas is achieved by the action of anaerobic
bacteria in the presence of moisture & in the absence of oxygen.
• The conversion process is called bio digestion.
• The bio chemical process take place in three stages.
o Enzymatic hydrolysis
o Acid formation
o Methane formation

6. ENZYMATIC HYDROLYSIS
• Complex compound such as fat, protein, carbohydrates are broken into
simple water soluble organic compounds through the influence of water
called hydrolysis.

7. ACID FORMATION
• Acid forming bacteria produced mainly acetic acid & Propionic
acid at low temperature and release of co2.
• Duration of 2 week and during this process large amount of co2 is
given off.

8. METHANE FORMATION
• Anaerobic bacteria called as methane formers converts organic acid into
biogas having main constituents as methane & carbon dioxide with other
small traces of hydrogen and nitrogen etc…
• These methane former bacteria are sensitive to PH changes.
• PH value in between 6.5 to 8 is the best for the fermentation

9. COMPLEX
ORGANIC
MATTER
SIMPLE
ORGANICS
ACETATE
H2 / CO2
METHANE and CARBON DIOXIDE
LOW ODOR EFFLUENT
LIQUEFACTION
PHASE
GASIFICATION
PHASE
ACIDOGENS METHANOGENS

10. FACTORS AFFECTING THE
PRODUCTION OF BIOGAS
• Temperature (Pshchrophilic-10-20, Mesophilic-35-38, -
Thermophilic40-45 degree centigrade. Gas stops if temp go beyond 10
degree)
• Pressure (2-200 psi)
• Solid concentration & HRT(8-10%,30,40,55 Days),
• Retention period (30-45 days), Winter-60 Days
• PH value(6-7)
• Nutrients composition ( Straw are added to increase the N content)
• Uniform feeding
• Diameter to depth ratio(16 feet depth & 4 to 5 m diameter)( 0.66-1.0)
• Carbon to nitrogen ratio(30:1)
• Toxicity due end product- should b harmful to bacteria
• Stirring or agitation of the content of digester
• Loading Rate- Should be kept const

11. BIOGAS PLANT
A STRUCTURE INSIDE WHICH ANAEROBIC DIGESTION OF ORGANIC
MATTER TAKES PLACE AND BIOGAS IS PRODUCED

15. Components of biogas plant
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

16. One m3 of biogas is equivalent to
0.7 m3 of natural gas,
0.7 kg of fuel oil,
0.6 kg of kerosene,
0.4 kg of benzene,
3.5 kg of firewood,
12 kg of manure
4 kWh of electric energy,
1.5 kg of coal,
0.433 kg of LPG
1.6 kg of CO2

17. Biogas consumption for different applications
Use Specification Quantity of gas
consumed (m3 /hr)
Cooking
2" burner 0.33
4" burner 0.47
6" burner 0.64
per person per day 0.24 m3/day
Gas lighting
mantle lamp of
100 Candle Power 0.13
Duel fuel engine 75-80% replacement
of diesel oil per B.H.P.
0.50
Electricity 1 kWh 0.21