Stepwise Process of Biogas Production and Microbial Stages
We have become so advanced in technology that we are able to use the organic waste and produce a gas that can be used by the people living in that society, thus saving on the increased exploitation of the natural resources. Biogas energy is one such example of innovations. There are certain bacteria that are known to grow under anaerobic conditions, and they produce a lot of methane, carbon dioxide, and hydrogen. And this mixture of gases can be used for a variety of chores. Methanogens are the bacteria that produce the gaseous mixture. One such methanogen is Methanobacterium, which is present in the cattle food. The cattle digest these bacteria with the food, and the dung produced by the cattle contain these methanogens that are used in the production of gobar gas.
A mixture of gases that are produced by the anaerobic decomposition of the organic matter like municipal waste, plant residue, agricultural waste, food waste, etc. is called biogas. Biogas is usually composed of carbon dioxide, methane, and a small amount of hydrogen sulphide and moisture.
Biogas Plant
It is a dome-like structure in which the production of the biogas takes place. The biogas plant has a source to supply the feedstock, a digestion tank to produce biogas, a biogas recovery unit to separate the biogas that is produced and the heat exchanger to maintain the temperature of the digester that is required for the production of the biogas. The digester is a sealed chamber in which the biowaste and the slurry are decomposed using anaerobic decomposition. The slurry is then covered with a floating cover so that the gas produced due to microbial activity can make the cover rise upwards. The biogas thus produced is drawn out through the pipes and then supplied to the respective places through the connected pipes. This slurry is removed through an outlet and then later used as a fertilizer. This biogas can be used for cooking or lighting.
(image will be uploaded soon).
Biogas Production in Landfill
Besides the gobar gas plant, biogas can also be produced in the Landfills. The organic matter present in the landfills decomposes naturally, and the biogas is produced as a result of the activity of these microbes. Methanobacteria that are present in the organic waste decompose the waste and produce a mixture of gases called biogas. There is a network of interconnected pipes present in the landfill to collect the biogas that is produced—the composition of the gas changes with time. After a year of production, the composition of methane and carbon dioxide changes to 60% and 40%, respectively. This is gaining popularity and acceptance as this method prevents the explosion that could be caused due to the collection of methane gas in the landfill, and it also prevents the loss of methane into the atmosphere. The biogas produced in landfills is used to create electricity.
Substrates Required in Biogas Production
Advantages of Biogas
The advantages of the biogas are: -
Renewable Source of Energy: Biogas is a renewable source of energy because the production of the biogas is dependent on the generation of the waste, which is an endless process.
Cheaper Technology: The installation of the biogas requires a very small cost, and it becomes self-sufficient in a duration of about 3-4 months.
Non - Polluting: The biogas burns without smoke, and thus no harmful gases like carbon dioxide, carbon monoxide, sulphur dioxide, and nitrous oxide are released.
Generates Employment: The setup of biogas creates a work opportunity for thousands of people in rural areas.
Reduces Landfills: The slurry that is leftover after the production of biogas is used as a fertilizer. The method of disposal is safe and environmentally friendly, and so no space is wasted in the form of landfills.
Disadvantages of Biogas
The disadvantages of biogas are:
Contains Impurities: The biogas contains several impurities which are difficult to remove even after a number of rounds of purification. Biogas, when compressed to be used as fuel, proves to be highly corrosive to the container.
Unstable and Hazardous: When methane comes in contact with oxygen, it reacts to produce carbon dioxide. The highly inflammable nature of the methane makes it prone to explosions.
Not Efficient on a Large Scale: Since it is not easy to enhance the efficiency of biogas, it is not viable economically to use biogas on a huge scale.
FAQs on Production of Biogas in Anaerobic Digestion Systems
1. What is the production of biogas?
The production of biogas is the biological process in which organic waste is broken down by microorganisms in the absence of oxygen to produce a combustible gas mixture. This process is called anaerobic digestion.
- Occurs in oxygen-free conditions
- Uses organic materials like cow dung, sewage, and plant waste
- Produces biogas mainly composed of methane (CH₄) and carbon dioxide (CO₂)
2. How is biogas produced step by step?
Biogas is produced through four main stages of anaerobic digestion carried out by microorganisms.
- Hydrolysis – Complex organic matter is broken into simple soluble molecules.
- Acidogenesis – Simple molecules are converted into organic acids.
- Acetogenesis – Organic acids are converted into acetic acid, hydrogen, and CO₂.
- Methanogenesis – Methanogenic bacteria convert these products into methane gas.
3. What are the main components of biogas?
The main components of biogas are methane and carbon dioxide.
- Methane (CH₄) – 50–70% (responsible for fuel value)
- Carbon dioxide (CO₂) – 30–40%
- Small amounts of hydrogen sulfide (H₂S), hydrogen, and water vapor
4. What raw materials are used for biogas production?
Biogas production uses biodegradable organic materials as raw materials.
- Cow dung and animal manure
- Agricultural waste and crop residues
- Kitchen waste and food scraps
- Sewage sludge
5. What is the role of methanogenic bacteria in biogas production?
The role of methanogenic bacteria is to convert acetic acid, hydrogen, and carbon dioxide into methane during the final stage of anaerobic digestion.
- They belong to the group Archaea.
- They function in oxygen-free environments.
- They are responsible for methane formation in the methanogenesis stage.
6. What conditions are required for biogas production?
Biogas production requires specific environmental conditions for efficient microbial activity.
- Absence of oxygen (anaerobic conditions)
- Optimal temperature (30–40°C for mesophilic bacteria)
- Neutral pH (around 6.8–7.5)
- Proper moisture content
7. What is a biogas plant and how does it work?
A biogas plant is a facility that produces biogas by decomposing organic waste in an airtight digester.
- Organic waste is mixed with water to form slurry.
- The slurry is fed into a sealed digester.
- Microorganisms break down the waste anaerobically.
- Biogas accumulates in a gas holder and is used as fuel.
8. What are the advantages of biogas production?
Biogas production offers environmental, economic, and agricultural benefits.
- Provides renewable and clean energy
- Reduces greenhouse gas emissions
- Manages organic waste efficiently
- Produces nutrient-rich organic manure
9. What is the difference between biogas and natural gas?
The main difference between biogas and natural gas is their origin and methane purity.
- Biogas is produced by anaerobic digestion of organic waste and contains 50–70% methane.
- Natural gas is a fossil fuel formed over millions of years and contains about 85–95% methane.
10. Why is biogas production important for the environment?
Biogas production is environmentally important because it converts organic waste into renewable energy while reducing pollution.
- Prevents methane release from open decomposition
- Reduces dependence on fossil fuels
- Lowers greenhouse gas emissions
- Produces eco-friendly organic fertilizer
