1, pre-treatment stage. The solids content of the raw slurry is generally low, gravity settling or other means must be used to increase the slurry concentration to reduce processing costs. Commonly used pretreatment method is: the concentrated sludge and polymer flocculant mixed material under the action of flocculant, fine particles agglomeration and initial precipitation, which is the preparation of sludge on the machine dehydration conditions.
2, gravity dehydration stage. The flocculation pretreatment sludge is added to the filter belt, under the action of gravity, the free water outside the floc is filtered through the filter belt, reducing the water content of the sludge.
3, Wedge pre-dehydration stage. Sludge begins to enter the wedge pressing section after gravity dehydration, and the gap of the filter belt is gradually reduced, and the squeezing and shearing of the sludge are started to make the sludge dehydrate again. After this stage, the fluidity of the sludge is almost completely lost, which ensures that under normal conditions, the sludge will not be squeezed out during the squeezing and dewatering stages.
4, squeezing dehydration stage. The sludge is squeezed and sheared repeatedly by the carefully designed press roll system to remove a large amount of capillarity water and gradually reduce the sludge moisture to form a sludge filter cake. When the filter belt is separated and the filter cake is discharged Scraping scraper. Discharge the cloth after cleaning into the next cycle.