Biogas fermentation is accomplished by the co-fermentation of various methanogenic and non-methanogenic bacteria. In the first stage of biogas fermentation, cellulose and starch are hydrolyzed into monosaccharides by anaerobic and facultative anaerobic hydrolytic bacteria or fermentative bacteria, and acetone is further formed; protein is hydrolyzed into amino acids and ammonia of organic acids is further formed; lipids are hydrolyzed into glycerol and fatty acids, and propionic acid, acetic acid, butyric acid, ethanol and so on are further formed. In the second stage, the bacteria producing hydrogen and acetic acid utilize the organic acid produced in the first stage to oxidize and decompose into acetic acid and molecular hydrogen. In the third stage, the bacteria producing methangens are strictly anaerobic. The biogas purification company reminds us that in this complex mixed fermentation system, non-methanogenic bacteria provide the matrix for methanogenic bacteria to grow and produce methane, create appropriate redox conditions and remove toxic substances; methanogenic bacteria release feedback inhibition for the biochemical reaction of non-methanogenic bacteria, create thermodynamic favorable conditions; and the two types of bacteria maintain together. The suitable pH value in the environment. Methane-producing bacteria and non-methanogenic bacteria can form methane efficiently through mutual cooperation.
整个厌氧消化过程是一个产甲烷细菌和非产甲烷细菌相互作用，相互制约的动态平衡过程。用于厌氧消化的原料几乎都是不溶性有机大分子的碳水化合物、脂肪和蛋白质等，只有通过水解酶把它们分解成较小的分子后才能被产氢产乙酸菌和产甲烷细菌利用，终产生甲烷。
The whole anaerobic digestion process is a dynamic equilibrium process in which methanogenic bacteria and non-methanogenic bacteria interact and restrict each other. The raw materials used for anaerobic digestion are almost all insoluble organic macromolecules such as carbohydrates, fats and proteins, which can be utilized by hydrogen-producing Acetobacteria and methanogenic bacteria only after they are decomposed into smaller molecules by hydrolytic enzymes, and finally methane is produced.
水解过程通常较缓慢，因此是含高分子有机物或悬浮物废液厌氧降解的限速阶段。影响水解速度与水解程度的因素很多。胞外酶能否有效接触到底物是影响水解速率的关键。因此大颗粒比小颗粒底物降解要缓慢得多。许多微生物可以产生胞外酶，其中主要的水解酶有脂肪酶、蛋白酶和纤维素酶等。它们的作用是将复杂的大分子水解为可被微生物同化的单体。在有机聚合物占多数的废物厌氧生物处理中，水解作用是整个过程的限速步骤。
The hydrolysis process is usually slow, so it is the limited stage of anaerobic degradation of wastewater containing macromolecule organic matter or suspended matter. There are many factors affecting the hydrolysis rate and degree. Whether extracellular enzymes can effectively contact the substrate is the key to affect the hydrolysis rate. Therefore, the degradation of large particles is much slower than that of small particles. Many microorganisms can produce extracellular enzymes, including lipase, protease and cellulase. Their function is to hydrolyze complex macromolecules into monomers that can be assimilated by microorganisms. Hydrolysis is a speed-limiting step in the anaerobic biological treatment of wastes with organic polymers as the majority.
近10年来的研究发现，产氢产乙酸菌包括互营单胞菌属、互营杆菌属、梭菌属、暗杆菌属等。这类细菌能把各种挥发性脂肪酸降解为乙酸和H2。利用乙酸的产甲烷细菌有索氏甲烷丝菌和巴氏甲烷八叠球菌，两者的生长速率差别较大。在一般的厌氧反应器中，约70%的甲烷由乙酸分解而来，30%由氢气还原二氧化碳而来。在厌氧反应器中，甲烷产量的70%是由乙酸歧化菌产生的。在反应中，乙酸中的羧基从乙酸分子中分离，甲基终转化为甲烷，羧基转化为二氧化碳。
In the past 10 years, it has been found that hydrogen-producing acetic acid bacteria include Mutual Bacillus, Mutual Bacillus, Clostridium, Acinetobacter and so on. These bacteria can degrade various volatile fatty acids into acetic acid and H2. Methanogenic bacteria utilizing acetic acid are Methanothrix soxhlii and Methanococcus Pasteuri, and their growth rates are quite different. In general anaerobic reactors, about 70% of methane is decomposed from acetic acid and 30% from hydrogen to carbon dioxide. In an anaerobic reactor, 70% of methane production is produced by disproportionate acetic acid bacteria. In the reaction, the carboxyl group in acetic acid is separated from the acetic acid molecule, methyl is eventually converted to methane, and carboxyl is converted to carbon dioxide.
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