Production Application of Sludge Dewatering System

In current cities, water treatment plants should provide high-quality water for residents. But many water resources have been polluted, so it is necessary to take some filteration and disinfection.

In the process of filteration and disinfection, there will be a lot of wastewater, which contains a large amount of sediments and waste materials. If the wastewater is directly discharged, it will pollute the water resources again, so water treatment plants should effectively treat it.

Sludge dewatering system plays a significant role in the process of water treatment, effectively solves the problem of wastewater discharge.

1. Working principle of sludge dewatering centrifuge

Sludge treatment is a complex system, includes a series of physical, chemical and other treatment processes.

In the entire processing steps, the most important is centrifuge. Sludge dewatering centrifuge is a type of equipment that operates at full speed, continuously feeding, separating, discharging. It is composed of frame, drum, screw, differential mechanism, motor, control system, etc.

During working process, the drum and screw rotate at high speed and the same direction. The drum rotates under the drive of the main motor, while the screw is driven by the main motor and auxiliary motor through the differential mechanism. Because of the differential mechanism, the rotating speed of the drum is lower than screw, there is a rotating speed difference between drum and screw, which can be adjusted by the differential mechanism.

In the process of sludge dewatering treatment, it is necessary to add flocculant into it. Only after the sludge and flocculant are mixed, they can be fed to the drum. During the full speed operation of the centrifuge, there is a very close relation between the sludge solid content and the drum rotating speed, the higher the drum rotating speed, the higher the sludge solid content.

2. Factors affecting the quality of sludge dewatering

There are two main factors affecting the quality of sludge dewatering: process factors and mechanical factors.

2.1 Process factors

Due to the density difference between the solid and liquid phase, they can be separated by the centrifuge at the high-speed rotation. The larger the gravity of solid phase, the easier to be separated. In order to improve the performance of sludge dewatering, an appropriate amount of organic polymer flocculant, such as polyacrylamide (PAM), should be uniformly added to the sludge, so as to reduce the specific resistance of the sludge. The type of the flocculant should be selected based on the characteristics of the sludge and the type of the sludge dewatering equipment.

2.2 Mechanical factors

2.2.1 Drum rotating speed

The drum rotating speed is adjusted by a frequency converter. The higher the rotating speed, the larger the centrifugal force, the better the dewatering effect. However, excessive rotating speed will damage the sludge flocs, and reduce the dewatering effect. At the same time, higher rotating speed requires better manufacturing materials, and it will increase machine wear, increase power consumption, vibration and noise level.

2.2.2 Differential speed

Differential speed directly affects the slag discharge capacity, dryness of the mud cake, the quality of the liquid phase, it is one of the most important parameters needed to be adjusted.

Increasing the differential speed will increase the slag discharge capacity, but the dewatering time of the sediment will be shortened, the moisture content of the mud cake will be higher, the quality of the liquid phase will be worse.

Decreasing the differential speed will prolonged the dewatering time of the sediment, so the moisture content of the mud cake will be lower, the quality of the liquid phase will be better. However, in this mode, attention should be paid to the amount of slag discharge, so as to prevent centrifuge blockage.

Therefore, the relation between processing capacity, processing effect and differential speed is not absolute. It depends on the adjustment of the on-site operators, who have rich work experience.

2.2.3 Thickness of liquid layer

The thickness of liquid layer is also an important factor affecting sludge dewatering quality. Changing and adjusting the thickness of liquid layer will change the sedimentation volume and the drying zone length, thereby changing the sludge dewatering quality.

Normally, changing the thickness of liquid layer should be executed when the centrifuge is stopped, it is changed by adjusting the liquid level plate. During the adjustment process, it is necessary to ensure that all liquid level plates are at the same height, otherwise there will be strong vibration in the centrifuge.

3. Conclusion

Sludge is an inevitable product of water treatment plants. Untreated sludge without treatment will bring secondary pollution to water and atmosphere, and damage the ecological environment. So it is imperative for water treatment plants to set up a effective sludge dewatering system.