Fermentation bagasse pulp
The main composition of paper is plant fiber. Bagasse is rich in hemicellulose, cellulose, lignin, etc. It is an excellent raw material for papermaking, but if bagasse is directly mechanically pulped, the effect of lignin will cause grinding. Pulp energy consumption is too large and the pulping cost is high, so try to eliminate lignin.
Bagasse has a complex structure, but its main components are cellulose, hemicellulose, and lignin. Among them, about 20.6% of hemicellulose and 18.6% of lignin. The content of cellulose in bagasse is about 35.4%, which is composed of β-1, 4-glycosidic bonds linked to glucosides, and is a two-phase coexistence system (coexistence of crystallized region and amorphous region). The crystallized region contains hydroxyl groups that easily form hydrogen bonds with surface water molecules, and it is difficult to use the crystallized portion of cellulose to be decomposed. Hemicellulose is chemically similar to cellulose and is a heterogeneous glycan with different pentose and glycosyl groups linked by β-14 oxygen bridges. Its degree of polymerization is relatively small, and the hemicellulose of bagasse is relatively small. It contains about 70% cellulose and 30% arabinose. Lignin is an important component of bagasse, with a molecular weight of about 10000-50000 accounting for about 95%. The lignin in the bagasse is mainly distributed in the epidermis. It binds with hemicellulose to form a strong protective layer, which hinders the contact of microorganisms or enzymes with cellulose, making the hydrolysis of bagasse difficult. Long-term studies have found that white rot fungi, soft rot fungi and other fungi have the effect of selectively degrading lignin and have a good effect on softening bagasse.
The bagasse starter contains a variety of fungi, bacteria, actinomycetes and other substances, can effectively decompose the lignin in bagasse and relax the structure of the bagasse, and plays the role of softening and aging of bagasse, thereby achieving fiber during refining. Easy to separate effect. At the same time, the pretreatment of bagasse by biological fermentation can significantly improve the strength properties of the bagasse pulp (improved tensile strength and tear strength). Its operation is as follows.
First, pay attention to start.
Functional strains in bagasse starter cultures grow fastest at temperatures above 10-15°C. Below this temperature range, they are inactive or semi-dormant. Below 5°C, they are dormant, below 0°C. The functional microbial species will be in a completely dormant state and will not work properly. Therefore, in the temperature range below the most active state (less than 10-15 °C), artificial warming can generally be taken to try to make the ambient temperature reach 10-15 °C or more, which will help the microbes break the dormant state and enter the rapid breeding period. This artificial warming is called "starting." After the start of fermentation, the strains will undergo a short period of adaptation and then rapidly reproduce in geometric progression (ideally, up to 272 in 24 hours!!). During the process of fermentation, a large amount of heat and metabolites will be released. The ambient temperature continues to rise. Microbial strains can use their own heat to speed up reproduction, so that a virtuous circle can be formed and the startup can be completed.
How to get materials to start quickly? Summer temperatures are high and there is definitely no problem. In winter, you can choose to use according to the actual situation:
1, warm water. When the moisture content of the material is insufficient, hot water (30-40°C) should be added to it, which can speed up the start-up speed.
2, stove heater. In the material house, a stove or a heating system is used, and conditions can also be used for heating the air conditioner. After starting, the heater can be removed.
3, greenhouse heating. The temperature inside the greenhouse is relatively high. It can meet the starting conditions of the materials and transport the materials into the greenhouse.
4, steam warming. The purpose of warming can also be achieved by boiling water and using the diffuseness of water vapor in a room or a greenhouse.
In practical applications, many unexpected problems may arise. The following are the actual problems encountered in the two applications and solutions for reference:
1. The material is frozen and there is ice. In the winter in the south, from late autumn to early spring in the north, the material is frozen because of snow and frozen, and it contains a lot of ice. This kind of material is not startable because of the low temperature. Or even if it starts, because the material absorbs heat during the gradual melting process, the temperature of the material rises slowly or the temperature is too low, generally it can only maintain at about 40 degrees, and the fermentation speed is slow. Should: first transport the material into the room, allow it to gradually melt, and then use the above method to start.
2, impure material, impurities. Some users' materials contain inorganic impurities such as stones, slag, and sediment. If the content is small, there is no problem. If the content is too high, it will affect the fermentation temperature and speed. Should: minimize the impurity content and increase the material purity.
Second, the material ratio.
Bagasse starter can play a role in fermentation, relying on the functional bacteria. These babies are suitable for living in a "carbon-nitrogen ratio" (C/N ratio) of 20 to 30:1. At this time, the nutritional structure is optimal. We must try our best to meet this proportion in the material ratio. Too low a carbon-nitrogen ratio can lead to "malnutrition." The carbon-nitrogen ratio in bagasse is relatively suitable, and it belongs to a material that can be completed without any configuration.
One kilogram of bagasse fermentation can ferment 3-5 tons of bagasse.
Third, the dilution method
Diluted bagasse fermentation auxiliaries are generally preferred to rice bran with good quality (ratio 1:5). Rice bran has good nutrition and air permeability. In the case of non-rice bran, the powdery material such as cornmeal, bran, etc. can be used as a substitute, and the bacteria can be used first. The mixture of agent and rice bran spray a small amount of water and evenly wet (but the water can not be too much, otherwise it will become "cluster", but not conducive to spread), and then evenly spread into the heap. Sugarcane bagasse and other materials are fermented, because their nutrition is better, and the diluted material requirements are not high.
Fourth, moisture control
The moisture of the fermentation material should be maintained at 60 to 65%, so that the functional bacteria can normally reproduce. A simple way to judge is: grab a handful of material by hand, and see that the water is not dripping on the finger-tap is a generally appropriate standard. If you do not see the watermark, it is too dry. If you drip down, it is too wet. Too much or too little moisture is not conducive to fermentation: too little water, slow fermentation of microorganisms, just as people in the "dehydration" state can not work as normal. Too much moisture rises slowly, and poor ventilation creates a local anaerobic environment, prompting another very unfavorable microorganism - spoilage strains are unsolicited, spoilage bacteria become troubled, and the most obvious sign is odor production. .
When fermenting, users should pay attention to the way of water regulation. 1, add water. It is necessary to grasp the principles of a few more and more gradually added. If conditions permit, hot water should be added so that it starts quickly. 2, reduce water. If, due to various reasons, excessive moisture is generated in the material, affecting the speed of fermentation and increasing the temperature, measures should be taken to reduce the moisture. The methods include spreading and drying and adding straw powder, sawdust and the like to the material.
Fifth, pay attention to ventilation
The function microbial strains in the bagasse fermentation agent belong to the good (consumed) oxygen-based microorganisms and must participate in oxygen fermentation. This requires the material to be breathable and to prevent microorganisms from failing due to lack of oxygen. Here are some common methods of ventilation:
1. Turn over. Turn over with a tipping machine. When tipping over, it should be as detailed as possible to achieve ventilation and ventilation.
2, punch. It is practicable to drill holes in the material heap with a pointed stick of about 10 cm. The number should be as large as possible.
3, cover. Covering material fermentation should use straw, sacks and other ventilation materials. If covered with plastic sheeting, it should be padded with bricks and wooden sticks, 10-20 cm from the surface of the material. And should leave a proper gap to facilitate the entry of oxygen.
4, blower. The bottom layer of the material can be placed in a perforated pipe and blown with a blower to speed up oxygen supply.
Six, regulate pH.
Any microorganism has a pH suitable for its own growth, and the functional microorganisms in the bagasse starter are suitable for a pH of 6-8. Normal materials generally do not need to adjust the fermentation, the material can be adjusted with lime and lime, excessive alkali can be added acetic acid and other adjustments. Especially when the pH value is 10 or more or 5 or less, it must be adjusted.
Seven, rhythm control
Fermentation auxiliaries are used to ferment the material. The fermentation rhythm can be controlled within a certain range. To speed up the fermentation, it can be used separately or in combination: to increase the starting temperature, improve the nutrition structure, improve ventilation, and increase the number of turnovers (less than 30 degrees). Turn over) and other measures. It is also possible to add a suitable amount of already fermented material to it, which can achieve the purpose of “feeding material, using new material, and promoting fermentationâ€. To slow or stop the fermentation, the opposite can be used.
After a week or so, the temperature is gradually reduced to 40-50 degrees or below. The fermentation has been carried out to 78%, and the color is darker, without any original odor or faint. Ammonia odor, aroma, and earthy taste. At this time, the temperature of the material pile can be spread and the temperature can be reduced to the next process. If more than ten days later, the temperature has been above 60 degrees, should consider the suspension of fermentation, because excessive fermentation is not good, easy to consume too much cellulose and hemicellulose, can take artificial cooling measures to enter the next process, such as the material pile Quickly dilute to 10-20 cm, then dry or directly mechanically grind the pulp.
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