Microbiology of Biogas Production

Dr.Jitender Kumar

Dept.of Biotechnology

• INTRODUCTION
• PRODUCTION
• COMPOSITION
• ANAEROBIC DIGESTOR
• SUBSTRATES
• BENEFITS

Introduction

• Biogas is produced from anaerobic breakdown of animal or plant or sewage waste etc. with the help of microbial activity
• Four types of microbial species are involved

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Advantages

• Renewable energy source like wind, solar etc.
• Can be produced from other raw material like sugarcane wastes etc.

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Fermentor/Digestor

• Digester tank is a system that brings decomposition of waste material of animal, plant origin.
• It produces biogas, generated through the process of anaerobic digestion.
• Biogas generated can be used for cooking, heating, electricity generation, and running a vehicle.

Microbial Activity

• Reduce �- Smell�- Greenhouse gas�- Pathogen level
• Produce methane, carbon di oxide, hydrogen gas etc.
• Produces fertilizers

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Methodology

• Dilution of waste material
• Hydrogen production Production
• Acetate Production
• Methane Production
• Formate production

Decomposition

• Complex organic matter is degraded to basic structure by anaerobic group of bacteria and protein are degraded to polypeptide and amino Acid, complex carbohydrates to simple carbohydrates

Acid Production

• Also called the acidogenesis
• Simple organic matters are converted into acetic acid
• Bacteria involved in this process are called hydrogen-producing bacteria and acid-producing bacteria.

Production of Acetate

• Process is called acetogenesis.
• The short-chain fatty acids are metabolized by acetogenic and homoacetogenic bacteria into acetate, carbon dioxide, and hydrogen.

Methane Production

• Process is called methanogenesis
• In this process, acetic acid, H₂, CO₂, are converted into methane
• Methane-producing bacteria have strict PH requirement and low adaptability to temperature.

Features of Biogas

• Biogas is generated by the activity of anaerobic bacteria.
• Biogas is comprised of about 60% of methane, 40% of carbon dioxide, and small amount of hydrogen sulfide, nitrogen, and hydrogen.
• The heating value of biogas is about 60% of natural gas and about 25% of propane.
• Biogas has corrosive nature and storage of biogas is not practical.

Application of Biogas

• The technology of biodigester is widely used in developing countries like India
• Anaerobic digester can be used in remote areas to recycle organic waste
• Can be used to produce electricity.

Mode of Operation

• Continuous-fed culture system in which nutrient are continuously fed in the digestor
• Batch-fed culture system are based on adding nuytrients at once only.

Continuous-fed System

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

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.
• Less susceptible to fluctuation of factors.
• Requires manual labor.

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Small scale Biodigester

• The idea is to make a small-scale, low-cost biodigester plant so that anyone in the world can make it and produce biogas.

Preparation

• Feed the digester with the effluent
• Add some extra nutrients in the form of manure
• Allow them to incubate
• Fermentation

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Operation

• Optimize environmental conditions
• The generator requires little maintenance besides occasional stirring.
• For the next batch, apply about 10% of the previous batch to activate the new batch.

References

• General Microbiology by Stanier
• Microbiology by R.P.Singh

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Thanks