In order to meet the animal-derived protein requirement of the increasing population day by day, it has become necessary to make intensive animal husbandry. However, the modernization and intensive management in the rapidly developing livestock enterprises brought along some problems. Waste, which is also an important economic potential, is a major problem for the environment along with the number of animals. If the necessary precautions are not taken, the wastes and wastewater generated in livestock farms appear as potential pollutants.
As a result of the processing of fertilizers and other organic wastes arising from livestock activities in biogas facilities, eliminating the negative effects of the wastes in question on the soil and surface water, generating electricity and heat energy by burning the biogas, protecting the climate by replacing fossil fuels and using the material from the biogas plant in agricultural practices is holistic. It is considered as a waste management approach.
In order to prevent idle investments, a detailed research should be carried out before establishing a biogas plant and it should be decided whether the investment is economical or not with the feasibility study to be conducted. As the name suggests, “bio” gas is produced by a biological process. By being deprived of oxygen (called anaerobe), a mixture of gases called biogas emerges from the organic mass. This process, which is common in nature, also takes place, for example, in marshes, sea floors, slurry pits and ruminant ruminants. Meanwhile, organic mass is almost entirely converted into biogas by a number of microorganisms. In addition, certain amounts of energy (heat) and new biomass are formed.
Biogas consists of methane (50-75% Vol.) And carbon dioxide (25-50% Vol.). In addition, biogas contains low amounts of hydrogen, hydrogen sulphide, ammonia and trace amounts of other gases. The composition is mainly determined by the materials used, the fermentation process and different technical applications. The process of formation of biogas takes place in many stages. In the meantime, the individual degradation stages must be very compatible with each other in order for the whole process to develop in a way that does not cause any negative effects.
During the first stage, “hydrolysis”, the complex structures of the raw material (eg carbohydrates, albumin, fats) are converted into simpler organic structures (eg amino acids, sugar, fatty acids). The hydrolytic bacteria involved in it release enzymes that biochemically break down the material.
The intermediate products formed are decomposed into low fatty acids (acetic, propion and butric acid), carbon dioxide and hydrogen by fermenting (acid forming) bacteria in the “acetogenesis stage”. Meanwhile, small amounts of lactic acid and alcohols are also formed. The type of product formed at this stage is determined by the density of the hydrogene formed.
From All Kinds of Organic Waste
Biogas Production is Possible.
Biogas Energy Equivalents
Energy Equivalents of 1 m3 Biogas
In the phase of acetogenesis, ie “acid formation”, these products are converted into precursors of biogas (acetic acid, hydrogen and carbon dioxide) by acetogenic bacteria. In this context, partial pressure of hydrogen is of great importance. The excessive amount of hydrogen prevents the intermediates of acetogenesis from degradation for energetic reasons. As a result, organic acids such as propionic acid, isobutyric acid, isovalerian acid and capron acid are enriched and prevent the formation of methane. Acetogenic bacteria (hydrogen forming) therefore have to establish a close life partnership with methanogenic archaea, which use hydrogen to generate methane gas with carbon dioxide (hydrogen transfer between species) and thus create acceptable environmental conditions for bacteria that produce acetic acid and consume hydrogen.
In “methanogenesis”, which is the last stage of biogas formation, acetic acids, hydrogen and carbon dioxide are converted into methane by absolute anaerobic methanogen archaea. While methanogens using hydrogen produce methane from hydrogen and carbon dioxide, acetoclastic methane generators decompose acetic acid to form methane. Under the conditions prevailing in agricultural biogas plants, methane formation occurs mainly by hydrogen synthesis reaction at high ambient pressure, and by the decomposition reaction of acetic acid at relatively low ambient pressure. The information obtained from the wastewater sludge fermentation that methane is formed as a result of the decomposition of 70% acetic acid and the synthesis of 30% hydrogen is valid for high pressure fermenters with very short waiting times in agricultural biogas plants in any case. New research shows that hydrogen transfer between species will be the determining stage.
The four stages of anaerobic decomposition actually occur simultaneously in a single-step process in parallel. However, since the bacteria of each degradation stage have different habitat demands (eg pH value, temperature), a compromise has to be created in terms of process technique. Because methanogenesis microorganisms are the weakest link in biogenesis due to their low growth rate and react very sensitively to disturbing effects, environmental conditions must be adapted to the demands of methane-forming bacteria. The attempt to separate hydrolysis and acid formation from methane formation with two separate process stages (two-stage process application) is practically limited, because despite a low pH value (pH <6.5) in the hydrolysis stage, partial methane formation still occurs. The resulting hydrolysis gas contains methane as well as carbon dioxide and hydrogen, so the hydrolysis gas needs to be evaluated or treated to avoid adverse environmental impacts and safety risks.
Depending on the construction and operating style of the biogas plant, as well as the properties and concentration of the raw material used as a material, different environmental conditions can be created in each fermenter step in multi-stage processes. Environmental conditions also affect the composition and activities of microbiological biogenesis and thus directly affect the products of metabolism.
[Km ‘de %]
|KO||Biyogaz Üretimi [Nm 1/2 YM]||CH VERİMİ [Nm 1/2]||CH Verimi [Nm 1/2 OKM]|
|Sıvı sıgır gübresi||10||80||3,5||1,7||6,3||25||14||210|
|Sıvı domuz gübresi||6||80||3,6||2,5||2,4||28||17||250|
|Samansız at gübresi||28||75||veri yok||veri yok||veri yok||63||35||165|
|Yeşil çavdar silajı||25||90||150||79||324|
|Yemlik pancar||16||90||veri yok||veri yok||veri yok||90||50||350|
|Ayçiçegi silajı||25||90||veri yok||veri yok||veri yok||120||68||298|
|Sudan otu||27||91||veri yok||veri yok||veri yok||128||70||286|
|Şeker darısı||22||91||veri yok||veri yok||veri yok||108||58||291|
|Yeşil çavdar||25||88||veri yok||veri yok||veri yok||130||70||319|
|ürün işletme sanayisi atıkları|
|Meyve şilempesi||2,5||95||veri yok||0,7||veri yok||15||9||285|
|Ham gliserin||veri yok||veri yok||veri yok||veri yok||veri yok||250||147||185|
|Prenslenmiş Kolza Küspesi||92||87||24,8||660||317||396|
|Z- pres posası||24||95||veri yok||veri yok||veri yok||68||49||218|
|Üzüm posası||45||85||2,3||5,8||veri yok||260||176||448|
|Budama ve çim biçme artıkları|
|Budama artıkları||12||87,5||2,5||4.0||veri yok||175||105||369|