Biogas Plants
24-03-2014
Biogas Plants
• Part of the carbon is oxidized and another part reduced to produce CO2 and CH4.
• These bacteria live and grow without oxygen.
• They derive the needed oxygen by decomposing biomass.
• The process is favored by wet, warm and dark conditions. • The airtight equipment used for conversion is known as a biogas plant or digester, which is constructed and controlled to favour methane production. i. Stage I:
• The original organic matter containing comlex compounds, e.g., carbohydrates, protein and fats is broken down through the influence of water
(known as hydrolysis) to simple water soluble compounds. • The polymers (large molecules) are reduced to monomers (basic molecules).
• The process takes about a day at 25oC in an active digester. Biogas production from waste biomass:
• Biomass if left to decompose in open air, is acted upon by aerobic bacteria (bacteria that require oxygen for their survival and growth) to produce mainly CO2 and NH3.
• The total carbon component completely gets oxidized to produce CO2 and no fuel is produced.
• Some form of nitrogen is also lost in the form of ammonia. • Biogas is produced from wet biomass with about
90-95% water content by the action of anaerobic bacteria. • The conversion process is known as anaerobic fermentation (or biodigestion).
• Nutrients such as soluble nitrogen compounds remain available in solution and provide excellent fertilizer and humus.
• The energy available from the combustion of biogas is 60-90% of the input dry matter heat of combustion.
• The energy conversion efficiency of the process is 60-90%.
• The biochemical processes proceed in three stages as shown in figure (next slide).
ii. Stage II:
• The micro-organisms of anaerobic and facultative (that can live and grow with or without oxygen) groups, together known as acid formers, produce mainly acetic and propionic acids.
• This stage also takes about one day at
Biogas Plants
• Part of the carbon is oxidized and another part reduced to produce CO2 and CH4.
• These bacteria live and grow without oxygen.
• They derive the needed oxygen by decomposing biomass.
• The process is favored by wet, warm and dark conditions. • The airtight equipment used for conversion is known as a biogas plant or digester, which is constructed and controlled to favour methane production. i. Stage I:
• The original organic matter containing comlex compounds, e.g., carbohydrates, protein and fats is broken down through the influence of water
(known as hydrolysis) to simple water soluble compounds. • The polymers (large molecules) are reduced to monomers (basic molecules).
• The process takes about a day at 25oC in an active digester. Biogas production from waste biomass:
• Biomass if left to decompose in open air, is acted upon by aerobic bacteria (bacteria that require oxygen for their survival and growth) to produce mainly CO2 and NH3.
• The total carbon component completely gets oxidized to produce CO2 and no fuel is produced.
• Some form of nitrogen is also lost in the form of ammonia. • Biogas is produced from wet biomass with about
90-95% water content by the action of anaerobic bacteria. • The conversion process is known as anaerobic fermentation (or biodigestion).
• Nutrients such as soluble nitrogen compounds remain available in solution and provide excellent fertilizer and humus.
• The energy available from the combustion of biogas is 60-90% of the input dry matter heat of combustion.
• The energy conversion efficiency of the process is 60-90%.
• The biochemical processes proceed in three stages as shown in figure (next slide).
ii. Stage II:
• The micro-organisms of anaerobic and facultative (that can live and grow with or without oxygen) groups, together known as acid formers, produce mainly acetic and propionic acids.
• This stage also takes about one day at