In the large-scale sewage treatment project, centrifugal dewatering with horizontal snails is a crucial step. Today, let's talk about what's going on with it.
1, What is the principle of centrifugal dehydration for horizontal snails
The horizontal screw centrifugal dewatering machine mainly relies on centrifugal force to work. Imagine that when we use a washing machine to spin clothes, the water is thrown out of the high-speed rotating bucket. The principle of a horizontal screw centrifugal dehydrator is similar to this, but more complex.
It has a drum and a screw conveyor, both of which are on the same shaft, but at different speeds, with a speed difference. The sludge and water in the sewage are mixed together and fed into the drum, which begins to rotate at high speed, reaching several thousand revolutions per minute. Under such a strong centrifugal force, the sludge is thrown onto the inner wall of the drum due to its high specific gravity, while the water is relatively light and remains in the middle near the rotating shaft.
At this point, the screw conveyor begins to take effect. It is like a diligent worker, slowly pushing the sludge stuck on the inner wall of the drum to one end of the drum, and then discharging it out of the machine. This is the dehydrated mud cake; And the water in the middle flows out from the other end, so that the sludge and water are separated, achieving the purpose of dehydration.
2, Which sludge is suitable for processing
The application range of the horizontal screw centrifugal dewatering machine is quite wide. For example, the residual sludge generated by urban domestic sewage treatment plants is mainly composed of various organic matter, microorganisms, and solid impurities in the sewage. It is suitable to treat it with a horizontal screw centrifugal dewatering machine. There is also sludge generated during industrial wastewater treatment processes, such as sludge produced by printing and dyeing factories, paper mills, electroplating factories, and other industrial enterprises. Although the composition is relatively complex, some contain heavy metals and some contain a large amount of organic matter, the horizontal screw centrifugal dewatering machine can also be used. In addition, some of the sludge generated from river dredging can also be used for dewatering treatment to remove the water from the sludge, facilitating subsequent disposal.
3, The mud removal effect is not good, what's the reason for the appearance of thin mud
Sometimes, the snail centrifugal dewatering machine can also have a little temper, resulting in poor sludge removal effect and the production of thin mud. This is a headache, what is the reason behind it?
(1) Equipment related reasons
1. Wear and tear of the drum and screw: Over time, the equipment will experience wear and tear on the drum and screw conveyor. It's like a kitchen knife at home, the blade becomes less sharp after prolonged use. After the drum and spiral wear, the friction between them and the sludge will change, and the movement of the sludge in the machine will also be affected, making it difficult to shake the water out well and prone to thin sludge.
2. Inappropriate speed difference: As we mentioned earlier, there is a speed difference between the drum and the screw. If this speed difference is not adjusted properly, the dehydration effect will not be effective. The speed difference is too large, and the sludge stays in the machine for too short a time to fully shake off the water; The speed difference is too small, and it cannot effectively push the sludge towards the discharge port, which can also lead to insufficient dewatering and the release of thin sludge.
3. Excessive vibration of the device: If the device vibrates greatly during operation, it indicates that there is a problem. It may be due to unstable equipment installation, severe bearing wear, or the presence of some hard impurities in the drum. Excessive vibration not only affects the service life of the equipment, but also causes uneven distribution of sludge in the drum, affecting the dewatering effect and resulting in thin sludge.
(2) Reasons for the nature of sludge
1. The concentration of sludge is too low: if the concentration of sludge entering the dehydrator is too low, it will be like a bowl of too thin Congee. There is too much water and too little solid matter in it. Under the action of centrifugal force, it is difficult to form an effective mud layer, and water is not easily separated, so it is easy to produce thin mud.
2. Changes in the composition of sludge: The composition of sludge is not constant. If some special substances are mixed into the sewage, which changes the properties of the sludge, it will also affect the dewatering effect. For example, if a large amount of surfactants suddenly increase in sewage, these surfactants will form a protective film on the surface of sludge particles, preventing aggregation and precipitation between sludge particles, making dehydration difficult and resulting in thin sludge.
(3) Reasons related to pharmaceuticals
1. Improper selection of coagulants: During the dewatering process, we usually add coagulants to make the sludge particles aggregate together, becoming larger and heavier, making it easier to dewater. However, if the type of flocculant is selected incorrectly and its compatibility with sludge is poor, it will not be able to effectively exert its flocculation effect. The sludge particles will still be small, making it difficult to separate water and resulting in thin sludge.
2. Inappropriate dosage of flocculant: The dosage is too small, the flocculation effect is not enough, and the sludge particles are still dispersed; Excessive dosage can lead to excessive flocculation, which is not conducive to dehydration and may result in the formation of thin mud.
4, How to deal with the appearance of mud
(1) Equipment maintenance aspect
1. Check and replace worn parts: Regularly inspect the wear of the drum and screw conveyor, and if the wear is severe, replace new parts in a timely manner. It's like changing a tire for a car. If the old tire wears out severely, it needs to be replaced with a new one so that the car can run steadily. After replacing the new components, the friction between the equipment and the sludge returned to normal, and the dewatering effect was also improved.
2. Adjust the speed difference: Carefully adjust the speed difference between the drum and the screw according to the nature of the sludge and the dewatering effect. You can first conduct some small experiments and try different speed differences to see which one works best, and then make adjustments in actual operation. By adjusting the appropriate speed difference, the sludge can be fully dehydrated in the machine and smoothly pushed to the discharge port.
3. Solve the problem of equipment vibration: First, check whether the installation of the equipment is firm and whether the anchor bolts are loose. If it is an installation issue, reinstall the equipment smoothly and tighten the foundation bolts. If the vibration is caused by bearing wear, the bearing needs to be replaced. If there are hard impurities in the drum, the machine must be stopped to clean them out. Once the vibration issue is resolved, the equipment can operate normally and the dehydration effect can be restored.
(2) In terms of sludge pretreatment
1. Increase sludge concentration: If the sludge concentration is too low, some methods can be used to increase the concentration. For example, before the sludge enters the dewatering machine, adding a sludge concentration tank allows the sludge to settle in the tank for a period of time, removing some excess water and increasing the concentration of the sludge. This way, when the sludge enters the dewatering machine for dewatering, the effect will be much better.
2. Dealing with changes in sludge composition: When changes in sludge composition are found, the reasons should be analyzed in a timely manner. If special substances are mixed into the sewage, try to find the source and take measures to reduce the entry of these substances. At the same time, the dewatering process and the use of chemicals can be adjusted according to the new sludge composition to adapt to changes in sludge properties.
(3) Regarding medication adjustment
1. Choose a new flocculant: If you suspect that the flocculant selection is inappropriate, you can take some sludge samples and conduct screening tests for different coagulants. Add various types of flocculants to the sludge sample separately, and see which flocculant can form the largest and strongest flocs in the sludge, with the best sedimentation effect. Then choose which flocculant.
2. Optimize the dosage of flocculant: Determine the optimal dosage through small-scale experiments. Starting from a lower dosage, gradually increase the dosage, observe the dewatering effect of the sludge, and find the dosage with the best dewatering effect and the lowest cost. In actual operation, the flocculant is added according to this optimal dosage to ensure the dehydration effect.
Centrifugal dewatering by snail is very important in sewage treatment, but when there is poor sludge removal effect such as thin mud, we only need to analyze the reasons from the aspects of equipment, sludge properties, and chemicals, and then adopt corresponding treatment methods to restore the normal operation of the equipment, treat the sludge properly, and ensure the smooth progress of sewage treatment work.
