bio gas

What  is  biogas? 

 Biogas  is  produced  after  organic  materials (plant  and  animal  products)  are  broken  down by  bacteria  in  an  oxygen-free  environment,  a process  called  anaerobic  digestion.  Biogas systems  use  anaerobic  digestion  to  recycle these  organic  materials,  turning  them  into biogas,  which  contains  both  energy  (gas), and  valuable  soil  products  (liquids  and solids).   Anaerobic  digestion  already  occurs  in nature,  landfills,  and  some  livestock  manure management systems,  but  can  be  optimized,  controlled,  and  contained  using  an  anaerobic  digester.  Biogas  contains roughly  50-70  percent  methane,  30-40  percent  carbon  dioxide,  and  trace  amounts  of  other  gases. solid  digested  material, called digestate,  is  frequently  used as  a soil  amendment.

Biogas is a clean, nonpolluting and low contains about 55 to 75 per cent methane, which is inflammable. Biogas can be produced from cattle dung, human waste and other organic matter by a process called "anaerobic digesti  cost fuel. It on" in a biogas plant. The digested material, which comes out of the plant is an inreached manure.

Typical waste streams for Anaerobic Digestion  

• Fruit & Veg waste 

• Restaurant waste 

• Agricultural waste such as livestock manure, silage • Abattoir waste 

• Fat trap/clarifier waste from food industry and           restaurants

• Activated sewage sludge 

• Paper sludge 

Biogas technologies

The development of biogas technologies in Georgia started in 1993-1994 with the assistance of GTZ (Technical Cooperation Agency of Germany). Technical support provided by GTZ allowed Georgian experts and engineers to study advanced designs and adapt technologies to Georgian climatic and economic conditions. 

The process of biogas production takes place in anaerobic conditions and in different temperature diapasons. There are psychrophilic (temperature diapason 10-250C), mesophilic (25-400C) and thermophilic (50-550C) regimes of bioconversion. Biogas production in a thermophilic regime is much higher than for the mesophilic and psychrophilic regimes. Modern thermophilic bioreactors can produce 2-6 m3 per m3 of installation, which amounts to 5-15 kg of waste on a dry mass base (or 50-150 kg of wet mass). For mesophilic biogas installations, these values are 0.2-0.4 m3 per m3 of installation and 0.5-1 kg on a dry mass base (or 5-10 kg of wet mass). Biogas reactors, working in a thermophilic regime, can be introduced in agricultural farms where the number of livestock exceeds 5. Biogas produced on such farms can be used not only for cooking and heating water, but for dairy production as well.

Working

From the above, in the inlet tank animal waste slurry is prepared containing cow dung and waste in the ratio as 1:1 to 1:1.25 the feeding of animal waste slurry is usually done once in a day.
The sludge comes out with the built up of gas pressure in the dome above the partition wall & flows out to the outlet tank the th’ A C outlet pipe. This sludge is an excellent fertilizer which can be again fed to the soil. At the top of the gas holder , the accumulated gas is drawn from the pipe through gas value. The bifurcation of digestion chamber through a partition wall providers optimum conditions for growth of acid formers & methane forms as the PH valve requirement for these bacteria are different. Therefore, this gives a good yield of biogas. It operates naturally under constant pressure. The diameter of the digester of a gas plant rangers from 1.2 to 6m. & its height varies from 3m to 6m.
The mild steel gas holders are prone to corrosion thus needs painting at regular intervals. This problem can be overcome by using fiber glass reinforced plastic (FRP) material for construction of gas holders. However it is constly.

Advantages of Biogas

• It's a Clean & Renewable Energy Source.
• It Reduces Soil & Water Pollution. 
• Prevents Health Problems & Biodiversity Loss. 
• Generates Organic Fertilizer. 
• It's A Simple and Low-Cost Technology That Encourages A Circular Economy. 
• Healthy Cooking Alternative For Developing Areas.

Application of biogas

There are many application of biogas. Given structure of biogas.

Dangers

The air pollution produced by biogas is similar to that of natural gas. The content of toxic hydrogen sulfide presents additional risks and has been responsible for serious accidents.Leaks of unburned methane are an additional risk, because methane is a potent greenhouse gas.
Biogas can be explosive when mixed in the ratio of one part biogas to 8–20 parts air. Special safety precautions have to be taken for entering an empty biogas digester for maintenance work. It is important that a biogas system never has negative pressure as this could cause an explosion. Negative gas pressure can occur if too much gas is removed or leaked; Because of this biogas should not be used at pressures below one column inch of water, measured by a pressure gauge.
Frequent smell checks must be performed on a biogas system. If biogas is smelled anywhere windows and doors should be opened immediately. If there is a fire the gas should be shut off at the gate valve of the biogas system.