organic waste management

1. METHANE PRODUCTION
SHARMILA. C
18UT18

2. Biogas
• Biogas is a methane rich flammable gas that results from the
decomposition of organic waste material.
• Biogas is produced by anaerobic digestion or fermentation of
biodegradable materials such as biomass , manure , sewage , municipal
waste , green waste , plant material and energy crops.
• Biogas also called as Marsh gas.
• Biogas is a type of biofuel.
• This type of biogas comprises primarily methane and carbon dioxide.

3. Composition of biogas
• Biogas is generated by the activity of anaerobic bacteria
• Composition depends on : the composition of raw material , organic
loading to digesters , time and temperature of anaerobic digestion.

4. Biochemical reactions
• Organic matter -------------> CH4 + CO2 + H2 + NH3 + H2S
• Stages of anaerobic digestion :
• Liquefaction by hydrolytic enzymes
• Acid formation
• Methane formation with methanogen production

5. Liquefaction by hydrolytic enzymes
• Complex organic matter is degraded to basic structure by hydraulic
bacteria
 Protein – polypeptide and amino acid
 Fat - glycerin and fatty acid
 Amylose – monosacride and polysacride

6. Acid production
• Also called the acidogenesis
• Simple organic matters are converted into acetic acid , H2 , and CO2
• Acting bacteria in this process are called hydrogen producing bacteria
and acid producing bacteria

7. Methane production
• Also called methanogenesis
• In this process , acetic acid , H2 , CO2 , are converted into CH4
• Methane producing bacteria have strict pH requirement and low
adaptability to temperature
• Organism used is Methanococcus jannaschii , Methanobacterium
thermoautotrophism

8. Flow chart of anaerobic digestion

9. Modes of operation
• Batch
• Semi – continuous - regular feeding of digester and decrease of
organic matter at intervals
• Continuous – for liquid waste treatment

10. Batch – fed system
• The simplest design
• Low cost
• The feedstock is loaded one batch at time
• Irregular biogas production
• Can operate on high solid content
• Requires manual labour.

11. Continuous - fed system
• Suited for large – scale manure substrate bioreactor
• Steady biogas production can be expected
• Many require auxiliary equipments
• Requires high liquid content
• Temperature , loading rate and solid content need to be carefully
monitored

12. Factors affect yield and production of biogas
• Many factors affecting the fermentation process of organic
substances under anaerobic condition are ,
 The quantity and nature of organic matter
 The temperature
 Acidity and alkanity [pH ] of substrate
 The flow and dilution of material

13. General features of biogas

14. Advantage of biogas
• Large amount of methane gas
• Free flocking thick sludge
• Odourless sludge
• Sludge can be used as fertilizer and soil conditioner
• Sanitary way for human and animal waste disposal
• Conservation of scarce resources like wood

15. Disadvantages
• Explosion chances
• High capital lost
• Incorrect handling of liquid sludge causes pollution
• Requires control and maintenance
• Needs proper condition
• Use as a fuel rquires removal of CO2 and H2S

16. THANK YOU