METHANIZATION.- - Methanization or biogas is a process of anaerobic fermentation of organic components of MSW waste where organic matter decomposes in several steps until you get the final product, biogas, a mixture of carbon dioxide (CO2 ) and methane (CH4). The fermentation is caused by bacteria or microorganisms that thrive in environments lacking oxygen. This degradation involves the action series about certain families of bacteria:
> Phase hydrolytic: organic matter is dissolved and in contact with the bacteria.
> Acetogenic phase: the molecules are converted into simple acids.
> Methanogenic phase: the phase in which the bacteria convert acetic acid into methane and CO 2.
For the operation of this process and anaerobic bacteria is necessary to develop an atmosphere without oxygen, which forces to confine the waste to be treated, in closed and impermeable called digesters.
In the crowd involved digestion of bacterial strains whose composition is determined by the conditions inside the digester (waste to feed the plant, temperature, pH, etc.).. These microorganisms carry out the biological process, which is the basis of this treatment anaerobic (without oxygen).
During the process of transformation of organic matter (digestion) these bacteria produce a gas called biogas in origin, which is composed primarily of methane (CH4) and carbon dioxide (CO2). Participation rates of these gases are variable and depend on the physicochemical conditions in which it develops the "digest" organic material.
It can be seen that biogas is a mixture of gases which basically consists of: • Methane (CH4): 40/70% vol. • Carbon dioxide (CO2): 30/60% vol. • Hydrogen (H2): 0 / 1% vol. • Hydrogen sulfide (H 2): 0 / 3% vol.
Biodigestores In certain conditions are controlled pH, pressure and temperature to obtain the best performance of the anaerobic reaction.
It is performed with residence times of 10-15 days with temperatures of 55/60 ° C. The digester is basically a cylinder or sealed container, where they enter to treat organic materials, suitably wet. Within the digester no oxygen and anaerobic bacteria multiply and process organic matter, methane gas production. After the water returns to be recirculated and reused for new processes. Finally, the biogas produced should undergo a cleansing process through which separates methane from carbon dioxide and other gases that appear to a lesser extent, the effects of energy use according to current standards.
The calorific value of biogas is about 6 KW/h/m3 corresponding to approximately 0.5 liters of diesel fuel.
The biogas has the advantage of reducing the odor produced by the decay and pollution load of organic matter itself. As a process in the absence of oxygen is reduced microorganisms that can cause disease in humans and animals to safe levels in less time than other treatments. Besides generating biogas fuel, anaerobic fermentation of organic matter produces a residue called COMPOST excellent fertilizers, their composition varies according to the waste used. Compost is the second product resulting by-product of anaerobic process of solid waste (MSW). Compost is a nutrient that improves soil structure, helps reduce erosion and helps the absorption of water and nutrients by plants.