At present, the basic principle of biological treatment is widely accepted as syllogism. This principle
The complex anaerobic biochemical process can be roughly divided into three stages, namely hydrolysis and development.
Fermentation stage; Hydrogen production and acetic acid production stage; Methane production stage. Therefore, anaerobic fermentation micro
Organisms are divided into three categories: fermentation bacteria, hydrogen-producing acetic acid-producing bacteria and methanogenic bacteria.
Bacteria. These three stages are independent and interrelated.
The first stage is hydrolysis and fermentation. At this stage, complex organic matter is anaerobic.
Under the action of extracellular enzymes, bacteria first decompose into simple organic matter, such as cellulose, through water.
Break down into simpler sugars; Protein is converted into simpler amino acids; Lipid transfer
Into fatty acids and glycerol, etc. Then, under the action of acid-producing bacteria, these simple organic substances
pass by
Wait a minute.
Anaerobic fermentation and oxidation are converted into fatty acids and alcohols, such as acetic acid, propionic acid and butyric acid.
The hydrolysis and fermentation involved in this stage are mainly anaerobic bacteria and facultative anaerobic bacteria.
The second stage is hydrogen production and acetic acid production. At this stage, hydrogen-producing bacteria and acetic acid-producing bacteria are removed.
Intermediate products produced in the first stage except acetic acid, formic acid and methanol, such as propionic acid and butanol.
Fatty acids such as acids and alcohols are converted into acetic acid and hydrogen, and CO2 is generated.
The third stage is methane production stage. At this stage, methanogenic bacteria put the first stage
Acetic acid, H2 and CO2 produced in the second stage are converted into methane.
According to the three-stage theory, methanogens cannot utilize acetic acid, H2/CO2 and methanol.
Organic acids and alcohols, long-chain fatty acids and alcohols other than hydrogen must be produced to produce acetic acid.
Bacteria can only be used by methanogens after being converted into acetic acid, Hz and CO2.
Almost at the same time of putting forward the three-stage theory, some scientists put forward the four-flora.
Go ahead. According to this theory, there are four kinds of anaerobic microorganisms in the process of anaerobic nitrification of complex organic matter.
Group participation means that the homotype (hydrogen-consuming) acetic acid-producing flora increases and its metabolic characteristics increase.
It can synthesize acetic acid from H2/ CO2.
The process of degradation of organic matter by three-stage theory and four-flora theory is shown in Figure 72.
organic matter
1 1 fermentation bacteria
Fat base, alcohol, etc.
acetic acid
methane
Three-stage theory and four-species theory of anaerobic reaction in the 72 nd circle
Explanation: 1 I, II and III are three-stage theories, and I, II, III and IV are four-group theories.
2. The resulting porous material is not shown in the figure.
The slowest step in anaerobic treatment is characterized by the substrate before the rate-limiting step.
Accumulate. If the substrate is in the form of a non-acidic organic substance, such as ethanol, the whole
Microbial communities have no adverse effects. - 。
The slowest member of the microbial population is usually propionic acid or acetic acid utilizing bacteria.
The accumulation of propionic acid and acetic acid will offset the salinity of bicarbonate in the system for operation.
Failure may reduce the pH value of the system, thus further affecting the whole microbial community.
The impact of profits. At the same time, low pH will only affect the utilization of propionic acid and B ..
Acid has the greatest inhibitory effect on microorganisms.
It can be inferred from the series of methane-producing reactions that there are only microorganisms in each sequence.
Organic intermediates for things are as fast as these intermediates, which is disgusting.
The oxygen process can be carried out well.