Energy is neither created nor destroyed, it transforms from one form energy to another. Every body is well versed with this law of thermodynamics. So it leads to a number of questions about what happens to organic matter when it decomposes. What can be done to harness the energy that is created owing to organic matter decomposition? To put it simple, energy production from organic matter decomposition is the most ideal outcome that can be expected from any best out of waste strategy!
When an organic material undergoes decomposition, it follows either aerobic digestion or anaerobic digestion pathway depending upon the availability of air and environmental conditions. Aerobic means in the presence of oxygen and anaerobic means devoid of oxygen. Being two completely different types of processes, both the process of digestion is carried out by different set of bacteria and results in different end products. The energy released during biodegradation of the organic waste can be harnessed to and transformed into a useful product. The controlled aerobic digestion of organic material can provide us with nutrient rich fertilizer known as compost. Similarly the process of anaerobic digestion can lead to biogas production which can be an entremely useful energy source directed towards a myriad of applications.
The natural process of anaerobic digestion occurs in stomachs of ruminants or in swamps. In an anaerobic process, microorganisms degrade the organic material to produce biogas, which is mixture of methane (CH4), carbon di oxide (CO2), hydrogen sulfide (H2S), carbon monoxide (CO), Hydrogen (H2), nitrogen (N2) and water vapor. From all the end products obtaining from anaerobic digestion, methane is the most interesting gas due to its characteristics. Methane generated from biogas is combustible and can be used as a source of energy.
The process of biogas production is a multistep process carried out by different set of bacteria at each step. The organic material undergoes a chain of degradation steps viz. hydrolysis, acidogenesis, acetogenesis and methanogenesis. At the end of this chain of processes, the organic matter is converted into methane and other end products, and this process is known as biogas production.