What is the difference between a filter press and a centrifuge

The sludge dewatering equipment commonly used in sewage treatment plants includes decanter centrifuge and belt filter presses, both of which have their own advantages.

In the past, most of the sludge dewatering of domestic urban sewage treatment plants used belt filter presses. Centrifuges were rarely used due to their high noise, high energy consumption, and low processing capacity. However, in recent years, decanter The application of the type centrifuge is much more than that of the belt filter press.

In foreign countries, the application of decanter centrifuges is very common, while in China, the promotion of decanter centrifuges is mainly due to the successful marketing of centrifuge manufacturers. The main reason for using centrifuges abroad is that the solid content after dehydration is high, which can reach more than 30%. However, due to the low cost of sludge disposal in China, the requirement for solid content is not high. Generally, it only requires more than 20%. The material and processing accuracy of the centrifuge supplied to the country can still meet the requirements if it is reduced by one grade. Because some domestic designers are familiar with the use of centrifuges, the solid content of the centrifuge is still the same as the requirements of the belt after the centrifuge is used, so the centrifuge loses its competitive advantage.

Since the belt filter press is the mainstream of sludge dewatering in sewage treatment plants, the advantages of the centrifuge are mainly based on the comparison with the belt filter press. The centrifuge manufacturer believes that the centrifuge has the following advantages for the belt machine :

1. The decanter centrifuge uses the principle of centrifugal sedimentation to separate the solid and liquid. Due to the filter screen, it will not cause clogging. The belt machine uses the filter belt to separate the solid and liquid. In order to prevent the filter belt from clogging, high-pressure water is required to continuously wash;

2. The centrifuge is suitable for the thickening and dewatering of all kinds of sludge, and the belt machine is also suitable for all kinds of sludge, but the remaining activated sludge requires a large amount of medicine and it is difficult to dehydrate;

3. When the feed concentration of the centrifuge changes during the dehydration process, the slip and torque of the drum and screw will be automatically tracked and adjusted, so there is no need for special personnel to operate, and the belt filter will change when the feed concentration changes during the dehydration process. The belt speed, belt tension, dosage, and flushing water pressure all need to be adjusted, and the operation requirements are high;

4. The centrifuge occupies a small space and is simple to install and debug. The supporting equipment has only dosing and feeding and discharging conveyors. The whole machine is fully sealed to operate and the workshop environment is good; while the belt machine occupies a large area, and the supporting equipment except for feeding and feeding In addition to the conveyor, it is necessary to flush pumps, air compressors, sludge conditioners, etc. The whole machine has poor sealing performance, high-pressure cleaning water mist and odor pollute the environment, if the treatment is not good, it will cause mud overflow;

5. The wearing parts of the centrifuge are bearings and seals, and the maintenance cycle of the unloading screw is generally more than 3a; and the wearing parts of the belt machine in addition to the bearings and seals, the filter belt also needs to be replaced, which is expensive;

The advantage of the centrifuge is that the mud is dry and the fully enclosed operating environment is good. Without flushing water, the belt filter press has the advantages of saving power consumption and low noise. Therefore, whether to use a centrifuge or a filter press for sludge dewatering must be analyzed in detail and must not blindly follow the trend.