The amount of gas produced, the stability of operation and the level of CH4 content are closely related to the control of process conditions in the fermentation process. Due to the high dry material concentration of fermentation materials, problems such as difficulty in production, uneven heat transfer quality, and acidosis have become technical difficulties in dry anaerobic fermentation technology. They conducted in-depth research at home and abroad. The main factors that affect the stable operation of dry anaerobic fermentation include: substrate composition, substrate pretreatment, inoculation amount, organic load, pH value and temperature, and stirring. What are the main factors that affect the dry anaerobic fermentation process?

What are the main factors affecting the dry anaerobic fermentation process?

The amount of gas produced, the stability of operation and the level of CH4 content are closely related to the control of process conditions in the fermentation process. Due to the high dry material concentration of fermentation materials, problems such as difficulty in production, uneven heat transfer quality, and acidosis have become technical difficulties in dry anaerobic fermentation technology. They conducted in-depth research at home and abroad. The main factors that affect the stable operation of dry anaerobic fermentation include: substrate composition, substrate pretreatment, inoculation amount, organic load, pH value and temperature, and stirring. What are the main factors that affect the dry anaerobic fermentation process?

What are the main factors affecting the dry anaerobic fermentation process?

1. Model substrate composition due to different substrate characteristics, fermentation of biogas production is larger, many studies have shown that the anaerobic fermentation substrate C/N ratio should be 20~30. Gas generation rate. If the C/N ratio is too high, a large amount of organic acids will accumulate during the fermentation process; if the C/N ratio is too low, the decomposition of organic matter will be suppressed, and a large amount of NH3 suppresses the activity of methane dysentery.

2. Chair Pretreatment For anaerobic fermentation of high solid content organic waste, the hydrolysis phase of the substrate is in the rate-limiting phase of the overall anaerobic fermentation process. The hydrolysis rate of the substrate is not only related to its own characteristics, but also related to its physical structure, properties and the ease of contact between the container and the substrate. Through certain pretreatment technology, reducing the diameter of substrate particles and improving the affinity between substrate and enzyme can not only promote the decomposition of organic matter, but also create a suitable environment for the growth and reproduction of microorganisms, increase the contact area between microorganisms and fermentation substrate, but also significantly increase the hydrolysis of substrate and gas production.

There are several kinds of dry anaerobic treatment methods?

At present, the more common pretreatment methods are physical pretreatment methods, chemical pretreatment methods and biological pretreatment methods.

1. Physical Pretreatment Method The physical pretreatment method is to promote anaerobic fermentation by changing the physical characteristics of the substrate. The main methods are chopping, grinding, soaking, freezing, microwave, ultrasonic, steam explosion, pulse and so on.

2. Chemical pretreatment method Chemical pretreatment method can promote complex organic matter into glucose, acetic acid and other small molecules, so as to improve the efficiency of gas production. Usually acid and alkali methods.

The acid solution can destroy the crystal structure of cellulose in the straw and make the straw loose. The mechanism of alkali method is to use alkali to destroy ether bonds, saponify hemicellulose and lignin to weaken the hydrogen bonding between cellulose and hemicellulose, and expose the hydrolysis and crystallization of cellulose. The reduction and dissolution of hemicellulose under the action of alkali is beneficial to the enzymatic hydrolysis of biomass straw.

3. Biological pretreatment method The biological pretreatment method mainly uses microorganisms to produce extracellular enzymes and other substances. The conditions of the specific reaction system are mild, and the degradation of wood quality has the advantages of low reaction process and low environmental pollution. In the dry oxygen fermentation process, due to the high solid concentration, adding enough microorganisms as an inoculum is very important, even related to the success or failure of the dry process. Inoculation source, bacterial culture method and addition ratio have great influence on anaerobic fermentation. In general, the ratio of strains to raw materials during anaerobic dry fermentation is about 1:5. If it can reach more than 3:10, the gas production rate and the percentage of CH4 in biogas can be increased.

4. Organic loading determination of anaerobic and digestive biotransformation under organic loading. If the organic load is too large, it will cause the accumulation of volatile organic acids and form the phenomenon of "acidosis", which is not conducive to the growth and reproduction of CH4 microorganisms. Studies have shown that when the TS concentration is 20% to 50%, CH4 can be produced normally. With the increase of TS concentration, the amount of CH4 production decreased gradually: the concentration of TS decreased in the range of 20% ~ 40%; when the concentration of TS was 50%, the amount of CH4 was greatly reduced.

The pH value and temperature anaerobic fermentation system can grow well in the range of 5.5~8.5. Methanobacteria production is very sensitive to changes in pH, 5.5 will be completely suppressed. The suitable pH range for dry anaerobic fermentation is 6.8-7.4, less than 6.4 or greater than 7.6. Therefore, the pH value of the fermentation system should be kept in the range of 6.5~7.8, and the fermentation temperature is also an important factor affecting the dry fermentation of biogas. Temperature is closely related to the decomposition of organic matter. In a certain temperature range, the higher the temperature, the faster the decomposition of raw materials. 30 ~ 35C (medium temperature) and 50 ~ 55C (high temperature) are two suitable temperature ranges for anaerobic fermentation. The research shows that the medium temperature anaerobic fermentation process requires large scale, stable operation and convenient management, which is more suitable for dry and anaerobic fermentation technology.

6. Communication in the case of improper ingredients or raw materials is too high, the pH value of the launch phase to reduce the phenolic drama, that is, "acidosis". Stirring can avoid the accumulation of local acidic acid in the device, make the fermentation raw materials uniform, increase the contact and reaction between microorganisms and raw materials, expand the active layer, and prevent the floating surface of raw materials, the reduction of raw materials, and the release of biogas.