Biogas

Biogas is a mixture of combustible gases, which are formed by the decomposition of organic substances in wet and lack of oxygen. Component of biogas is methane. The first descriptions of biogazuluisunt made ​​by Volta in the late seventeenth century. Volta first methane extracted from swamp gas. The process of formation of biogas, anaerobic digestion takes place at temperatures between 20-45 ° C in the presence of two species of bacteria  Bacillus cellulosae methanicus responsible for methane formation, and Bacillus cellulosae hidrogenicus responsible for the formation of hydrogen.

Later these two species were united under the common name methano-bacterium. As raw materials to biogas formation serves biomass, which represents residual plant material. Cellulose is the main component of the organic material used in the formation of biogas. Cellulose content in organicaeste matter of about 50%. Among other components, we can mention aquatic plants, algae, animal remains etc.

Currently there are about seven methods for recovering energy from organic waste equipment: anaerobic digestion at ambient temperature, high temperature anaerobic digestion, thermophilic anaerobic digestion, distillation distinctive, composting, incineration and heat transfer.

It has the greatest potential anaerobic fermentation process at temperatures around 40 ° C. By anaerobic microorganisms break down organic matter, releasing a series of metabolites, mainly carbon dioxide and methane. Depending on the feedstock, the amount of methane in biogas is 35-80%. The maximum amount of methane fermentation is obtained from animal carcasses, especially from poultry complexes.

Bigazul need to be processed before use. It is usually passed through special separators, where methane is separated from the gas. Using raw biogas  can lead to poisoning, as in the rest gas can contain toxic gases.

Among the chemical components of organic matter conversion highest levels in biogas have celluloses, hemicelluloses and fat.

Anaerobic digestion can not take place in the presence of light and oxygen, in the absence of a high humidity environment. The decomposition of organic matter fermentative microorganisms non participate: cellulose bacteria, lactic, acetic, sulfate-reducing and denitrifying, and numerous species of fungi and some yeasts. Microorganisms spend activity mentioned in the first phase of fermentation.

In the next phase, called methanogenesis, acts anaerobic methanogenic bacteria specialized in producing methane. Most metanobacteriilor used as a substrate only hydrogen and carbon dioxide. Methane is formed by reducing the carbon dioxide and hydrogen gas by oxidation of methanol, bacteria, using hydrogen. Quick reaction process is:

CO2 + 4H2O -> CH4 + 2H2O + Q (energy)

The energy removed from the process is small and usually is used for basic maintenance process, which has a higher productivity at temperatures of about 40 ° C, allowing winter carrying out the fermentation without external heat (does not require additional equipment).

Besides methane longer remove hydrogen, hydrogen sulphide, water vapor, ammonia, nitrogen, indole and skatole.

Methane is the component that gives biogas energy value. In pure form is a combustible gas, colorless, odorless, tasteless; lighter than air (M = 16); burning blue flame; has a calorific value of 97 MJ per milliliter (slightly more than diesel). Biogas as compared to pure methane, has a power of 25 MJ / ml, due to the presence in it of carbon dioxide and other gases. Fiaz not liquefied methane-ambient temperature (-20 ° C to + 40 ° C). Keep container at low pressures with high volume or pressure ridi-many in small volumes. For example, a bottle of 0.1 ml at a pressure of 200 barrels containing 28 ml of methane with a tractor can be operated 8 hours.

Uses methane.

a) methane are used as an energy. It is a superior fuel of coal and petroleum products even higher calorific power, operating costs and lower transport.

b) methane can be used in the production of hydrogen by decomposition

CH4 -> C + 2H2

or by oxidation, when carbon is obtained, water vapor, or carbon oxide and hydrogen

2CH4 + O2 -> 2CO + 4H2

c) is important chlorination of methane, after which we obtain chloromethane, dichloromethane, tricolormetan, tetrachloromethane

CH4 + Cl2 -> CH3Cl + HCl

The chlorination of methane are obtained some solvents and refrigerants.

The nitration of methane is obtained nitromethane used as solvent in organic synthesis by ammoxidation.

In phase methane by methane bacteria, anaerobic specialized in producing methane. In it there are also traces of hydrogen, hydrogen sulphide, mercaptans, water vapor, ammonia, nitrogen, indole and skatole.

Hydrogen and carbon dioxide substrate is a characteristic of methanogenesis. Most metanobacteriilor used as a substrate only hydrogen and carbon dioxide. Methane Carbon dioxide formed by reduction and oxidation of hydrogen gas (H +) by using hydrogen metanobacteriile:

CH4 + CO2 + 4H2O 2H 2 O + Ž energy

Methanogenic bacteria are very diverse in terms of morphological, but the unit of biochemically and physiologically. They are the only organisms that have a strictly anaerobic respiration and the ability to produce methane through metabolic processes. As life forms of the oldest on Earth, bacteria matanogene were included in the kingdom Archaebacteria.

Methane is the component that gives biogas energy value. In pure methane gas is a colorless gas, odor or taste, lighter than air, burns with a blue flame and has a calorific value of 37 MJ / ml, slightly higher than diesel. Compared to pure methane biogas has a calorific value of 25 MJ / ml, due to carbon dioxide which is mixed.

Storage of biogas, even for small time intervals is part of the anaerobic digestion plant. Since methane is not liquefy at ambient temperature regardless of the pressure used, it is kept at low pressures in large containers or high pressure low volume. For example, a bottle containing 0.1 ml to 28 ml pressure 200 bar biogas with a heavy tractor can run 8:00.

A large biogas plant, industrial consists of:

1 - wastewater pumping station

2 - gravitational settling

3 - Mud fattening

4 - distribution station sludge

5 - anaerobic digestion reactor equipped with a metal bell for capturing biogas.