Sludge dewatering machine is a key equipment used to reduce the moisture content of sludge in sewage treatment. Its working principle varies according to different types. The following are the working principles and characteristics of the main types:
1. Screw stack sludge dewatering machine
Working principle: Combining the dual effects of gravity concentration and mechanical extrusion. The sludge is first dehydrated by gravity through the gap between the stacking plates in the concentration section, and then enters the dehydration section. When the spiral shaft pushes the sludge forward, the pitch gradually decreases, the gap between the rings becomes narrower, and high-pressure extrusion is formed under the action of the back pressure plate, and the water is discharged from the gap between the stacking plates.
Features:
Continuous operation, high degree of automation;
Made of 304 stainless steel, corrosion-resistant and low maintenance cost;
Suitable for sludge with a moisture content of 70%~85%, but hard particles should be avoided.
2. Belt type sludge dewatering machine
Working principle: After mixing with flocculants, the sludge undergoes gravity dewatering, wedge pre-pressing dewatering and "S" type roller pressing dewatering on the filter belt in turn, and the shear force further squeezes out the water.
Features:
The processing capacity is large, but the equipment is large;
The filter cloth needs to be replaced frequently, and the operating cost is high.
3. Centrifugal sludge dewatering machine
Working principle: The centrifugal force is used to separate the solid and liquid. The sludge forms a solid ring layer in the high-speed rotating drum. The screw conveyor pushes the dry sludge to the slag discharge port, and the clear liquid is discharged from the other end.
Features:
It has strong adaptability and can handle high-concentration sludge;
The energy consumption is high, but the dewatering efficiency is stable.
4. General technical principle
All types need to destroy the sludge colloidal structure through physical action (such as extrusion, centrifugation or gravity), and combine flocculants (such as PAM) to improve the dewatering effect.
Summary: When choosing a dewatering machine, it is necessary to comprehensively consider the properties of the sludge (such as sand content, viscosity), processing scale and cost. The screw stack is suitable for small and medium-sized projects, while the centrifuge and belt machine are more suitable for large-scale processing.