Biogas, as the name suggests, is the gas in the swamp. People often see bubbles coming out in swamps, sewage ditches or septic tanks. If we scratch a match, we can ignite it. This is the biogas that naturally occur in nature. Biogas is a combustible gas produced by various organic substances that is isolated from the air (reduction conditions) and must be appropriately temperature and humidity.

Biogas is a mixture of multiple gases, generally containing 50-70% methane, and the rest are carbon dioxide and a small amount of nitrogen, hydrogen and hydrogen sulfide. Its characteristics are similar to natural gas. If biogas contains 8.6-20.8% (by volume) of biogas, an explosive mixture will be formed. In addition to direct combustion for cooking, drying agricultural and sideline products, heating, lighting and gas welding, biogas can also be used as fuel for internal combustion engines and the production of chemical raw materials such as methanol, formalin, and carbon tetrachloride. The material liquid discharged after fermentation by the biogas device and

Sediment contains rich nutrients and can be used as fertilizers and feed. Biogas is a combustible gas produced by some organic substances that isolate air (such as using biogas tanks) under certain temperature, humidity and acidity conditions. It contains a small amount of hydrogen sulfide, so it has a slight odor. Fermentation is a complex biochemical change, and many microorganisms participate. The reaction is roughly divided into two stages: (1) Microorganisms degrade sugars, fats, and proteins in complex organic substances into simple substances, such as low-grade fatty acids.

, alcohols, aldehydes, carbon dioxide, ammonia, hydrogen and hydrogen sulfide. (2) The action of methanogen species turns some simple substances into methane. To produce biogas normally, good conditions must be created for microorganisms so that they can survive and reproduce. The biogas tank must meet multiple conditions. First, the biogas tank must be closed. Fermenting organic matter into biogas is the result of a variety of anaerobic bacteria activities, so it is necessary to create an oxygen-deficient environment for anaerobic bacteria activities. When building biogas tanks, be careful to isolate air, not breathable, and not water seepage. Secondly, in the biogas tank

It is necessary to maintain 20-40℃ because the gas production rate is usually the highest at this temperature. Third, the biogas tank must have sufficient nutrients. For microorganisms to survive and reproduce, nutrients must be absorbed from the fermentation substances. In the fermentation raw materials of the biogas tank, human and animal feces can provide nitrogen, and celluloses such as crop straw can provide carbon. Fourth, the fermentation raw materials must contain appropriate amounts of water. Generally, the fermentation raw materials in the biogas tank contain about 80% of the water. Too much or too little is not good for gas production. Fifth, the pH value of the biogas tank is generally controlled at 7-8.5.

Methane, the main component of biogas, is an ideal gas fuel. It is colorless and odorless. It is burned after mixing with an appropriate amount of air. The maximum heat of pure methane per cubic meter is 34,000 kJ, and the heat of biogas per cubic meter is about 20,800-23,600 kJ. That is, after 1 cubic meter of biogas is completely burned, it can generate heat equivalent to 0.7 kilograms of anthracite. Compared with other gases, its explosion resistance is better and it is a good cleaning fuel.

Biogas was discovered in the swamp by Italian physicist A. Volta in 1776. In 1916, the first strain of methanobacteria (but not purebred) was isolated by the Russians. China successfully isolated methanebasicus in 1980. Currently, nearly 20 isolated methanobacteria species in the world.

Biogas was discovered in the swamp by Italian physicist A. Volta in 1776. In 1916, the Russians Β.П Omelensky isolated the first strain of methanobacteria (but not purebred). China successfully isolated methane Ò.Asians. In 1980, nearly 20 strains of methanobacteria have been isolated in the world. The world's first biogas generator (also known as automatic purifier) ​​was improved by French L. Mura in 1860. In 1925, in Germany, in 1926, digestive pools with heating facilities and gas collection devices were built in the United States, which is a prototype of a modern large and medium-sized biogas generator. After World War II, biogas fermentation technology was developed in some Western European countries, but it was affected by the influx of cheap oil into the market.

Later, with the emergence of the global energy crisis, biogas attracted people's attention again. In 1955, the new biogas fermentation process - high-rate anaerobic digestion process - was produced. It broke through the traditional process flow, and the gas production per unit pool (i.e. gas production rate) was increased from 1 cubic meter per day to 4 to 8 cubic meter of biogas at medium temperature, and the residence time was shortened from 15 days or more to a few days or even a few hours. In the early 1920s, Luo Guorui built the first biogas pool in Chaomei area of ​​Guangdong Province, and then established the China Ruigas headquarters to promote biogas technology. At present, the number of household biogas pools in rural China has reached 13 million. The high-speed anaerobic digestion process productivity test equipment has been operating normally in sugar factories and wineries.

Biogas fermentation microorganisms are a general term, including five major groups of fermented bacteria, hydrogen-producing acetic acid bacteria, hydrogen-producing acetic acid bacteria, hydrogen-producing acetic acid bacteria, hydrogen-producing methanogens, and acetic acid-producing methanogens. The five major groups of bacteria form a food chain. Judging from the impact of the physiological metabolites of each group of bacteria or their activities on the pH value of the fermentation broth, the biogas fermentation process can be divided into hydrolysis, acid-producing and methanogenic stages. The activities of the first three groups of bacteria can cause organic matter to form various organic acids, so they are collectively called non-methanogenic bacteria. The activities of the latter two groups of bacteria can convert various organic acids into methane, so they are collectively called methanogenic bacteria.

(1) Methanogenic bacteria and methanogenic bacteria can turn complex macromolecular organic matter into simple small molecular weight substances. They are of various types, and they are divided according to the active matrix, including fibrous decomposition bacteria, hemicellulose bacteria, starchy decomposition bacteria, protein decomposition bacteria, fat decomposition bacteria and some special bacteria, such as hydrogen-producing bacteria and acetic acid-producing bacteria. (2) Methanogenic bacteria are the main component of biogas fermentation - the producer of methane. They are the core of biogas fermentation microorganisms. They are strictly anaerobic and are very sensitive to oxygen and oxidants. The most suitable pH range is neutral or slightly alkaline. They rely on carbon dioxide and hydrogen to grow and discharge methane in the form of waste. They are the simplest microorganisms that require the growth substances.

There are many types of organic species used as raw materials for biogas fermentation, such as poultry and livestock manure, crop straw, food processing waste and wastewater, as well as alcohol waste, etc. The main chemical components are polysaccharides, proteins and lipids. Among them, polysaccharides are the main components of fermentation raw materials, including starch, cellulose, hemicellulose, pectin, etc. Most of these complex organic matter cannot be dissolved in water. They must first be hydrolyzed by extracellular enzymes secreted by fermented bacteria to soluble sugars, peptides, amino acids and fatty acids before being absorbed by microorganisms. After fermenting bacteria absorb the above soluble substances into cells, they will convert them into fatty acids such as acetic acid, propionic acid, butyric acid and alcohols, as well as a certain amount of hydrogen and dioxide.

Carbon. During the biogas fermentation and determination process, the total amount of acetic acid, propionic acid and butyric acid in the fermentation broth is called medium volatile acid (TVA). Protein substances are decomposed into amino acids by fermented bacteria, and can be used by bacteria to synthesize cellular substances. When excess is added, they can be further decomposed to produce fatty acids, ammonia and hydrogen sulfide. The amount of protein content directly affects the content of ammonia and hydrogen sulfide in the biogas. The organic acids generated during amino acid decomposition can continue to be converted to form methane, carbon dioxide and water. Under the action of bacterial lipase, lipid substances are first hydrolyzed to form glycerol and fatty acids. Glycerol can be further decomposed according to the sugar metabolism pathway, and fatty acids are further decomposed into multiple acetic acids by microorganisms.

Biogas fuel cells are the latest clean, efficient, and low-noise electrical devices. Compared with biogas generators, they not only have high power output efficiency and energy utilization, but also have low vibration and noise, and low concentration of nitrogen oxides and sulfides. Therefore, they are a promising biogas utilization process. Using biogas for fuel cell power generation is an important way to effectively utilize biogas resources. my country's fuel cell research began in 1958. However, due to the small amount of investment in fuel cell research over the years, there is still a big gap with developed countries in terms of the overall level of fuel cell technology. The emergence and development of fuel cells will bring a profound revolution to portable electronic devices, and will also affect centralized power supply systems in the automotive industry, residential and social aspects.

Biogas is a combustible gas produced by organic matter in an anaerobic environment under certain temperature, humidity, and pH conditions. Since this gas was first found in swamps, lakes, and ponds, people call it biogas. Biogas contains a variety of gases, the main component is methane (CH4). The process of biogas bacteria decomposing organic matter and producing biogas is called biogas fermentation. According to the role of various bacteria during biogas fermentation, biogas bacteria can be divided into two categories. The first type of bacteria is called decomposition bacteria, and its function is to decompose complex organic matter into simple organic matter and carbon dioxide (CO2).

Among them, there are those who specialize in decomposing cellulose, called fibrolytic bacteria; there are those who specialize in decomposing proteins, called protein-decomposing bacteria; there are those who specialize in decomposing fats, called fat-decomposing bacteria; the second type of bacteria is called methane-containing bacteria, usually called methane, and its function is to oxidize or reduce simple organic matter and carbon dioxide to methane. Therefore, the process of organic matter turning into biogas is like two processes in a factory to produce a product: first, decompose bacteria and process complex organic matter such as feces, straws, weeds into semi-finished products—compounds with simple structures; then, under the action of methane bacteria, simple compounds are processed into products—that is, to produce methane.

To enable the biogas tank to start normally, first, choose the time to feed the material, then prepare the appropriate fermentation raw materials, mix the raw materials evenly after entering the pond, and the water sealing plate must be tightly sealed. Generally, the gas pressure gauge can be observed the second day after feeding the biogas tank, indicating that gas has been produced in the biogas tank. Initially, the generated gas must be released (until the gas pressure gauge drops to zero). When the gas pressure gauge rises again, ignite on the stove. If it can be ignited, it means that the biogas tank has started normally. If it cannot be ignited, try again according to the above method. If it is not possible, check whether the biogas material liquid is acidified or other reasons. After checking that the sealing performance of the biogas tank meets the requirements, the feed can be fed. When feeding the biogas tank, the water volume should be calculated according to the fermentation liquid concentration as required and poured into the pool. When feeding the biogas tank, the water volume should be calculated according to the fermentation liquid concentration as required and poured into the pool.
Chapter completed!