Microbes in Production of Biogas

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Introduction

Microbes in Production of Biogas
Biogas is a mixture of gases (containing predominantly methane) produced by microbial activity and which may be used as fuel. Major component of biogas is methane (50-70%) which is highly inflammable, other gases are carbon dioxide (30-40%) and mixture of other gases H2, H2 S etc. (10%). Calorific value of biogas in 4429 kcal/m3 at 50% methane content.
(1) Certain bacteria, which grow anaerobically on cellulosic material, produce large amount of methane along with CO2 and H2 . These bacteria are collectively called Methanogens, e.g. Methanobacterium.
Methanogens
(2) These bacteria are commonly found in anaerobic sludge sludge during sewage treatment. These bacteria are also present in the rumen of cattle where they help in the breakdown of cellulose and play an important role in the nutrition of cattle. Thus, the excreta (dung) of cattle, commonly called gobar, is rich in these bacteria. Dung can be used for generation of biogas, commonly called gobar gas.
(3) The technology of biogas production was developed in Indian mainly due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission
Microbes in Production of Biogas-A typical biogas plant
A typical biogas plant
(4) The biogas plant consists of:-
(i) A concrete tank, 10-15 feet desp, in which bio-wastes are collected and a slurry of dung is fed.
(ii) A floating cover is placed over the slurry, which keeps on rising as the gas is produced in the tank due to microbial activity. It has an outlet, which is connected to a pipe to supply biogas to nearly houses.
slurry,
(5) Cattle dung is available in large quantities in rural areas where cattles are used for a variety of purposes. So, biogas plants are more often built in rural areas. The biogas thus produced, is used for cooking and lighting.
Hydrolysis: In this initial stage, hydrolytic bacteria break down complex polymers such as carbohydrates, proteins, and fats into simpler monomers like sugars, amino acids, and fatty acids. This is a crucial step as it makes the organic material more accessible for further microbial action.
Acidogenesis: The products of hydrolysis are then converted into volatile fatty acids, alcohols, hydrogen, and carbon dioxide by acidogenic bacteria. This stage is also known as fermentation, where a diverse group of facultative and obligate anaerobes participate.
Acetogenesis: Acetogenic bacteria further process the volatile fatty acids and alcohols into acetic acid, hydrogen, and carbon dioxide. This step is vital for providing the substrates required by methanogens
Methanogenesis: The final stage is carried out by methanogenic archaea, which convert acetic acid, hydrogen, and carbon dioxide into methane and water. Methanogens are strictly anaerobic and are sensitive to changes in environmental conditions such as pH, temperature, and the presence of inhibitors.
The biogas produced primarily consists of methane (CH4) and carbon dioxide (CO2), with traces of hydrogen sulfide (H2S), ammonia (NH3), and other gases. The efficiency of biogas production can be influenced by several factors, including the composition of the microbial community, substrate type, digester design, and operational parameters.
Advancements in microbiology and biotechnology have led to the development of strategies to enhance biogas production. These include microbial consortia optimization, genetic engineering of microbes, and the use of microbial additives to boost specific stages of the digestion process. Understanding and harnessing the power of these microbes not only improves the efficiency of biogas systems but also contributes to sustainable waste management and energy production.
Biogas production involves a diverse group of microbes, including hydrolytic bacteria, acidogenic bacteria, acetogenic bacteria, and methanogenic archaea. Each group plays a specific role in breaking down organic matter and producing methane.
Methanogenic archaea are crucial in the final stage of biogas production, known as methanogenesis. They convert intermediate products such as acetic acid, hydrogen, and carbon dioxide into methane and water, which are the primary components of biogas.
The efficiency of biogas production can be affected by several factors, including the composition of the microbial community, the type of substrate used, digester design, and operational conditions such as pH, temperature, and the presence of inhibitors.
Yes, the microbial community can be optimized through various strategies, such as selecting or engineering specific strains of microbes, adding microbial inoculants to enhance particular stages of digestion, and adjusting environmental conditions to favor the growth and activity of beneficial microbes.
The anaerobic digestion process in biogas production consists of four main stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Each stage involves different microbes that break down complex organic materials into simpler compounds, eventually leading to the production of methane and carbon dioxide.

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