In the process of sewage treatment, a large amount of sludge is often accompanied with a relatively high moisture content in the sludge, which requires further treatment, ie, sludge thickening and dewatering. In the process of sludge thickening and dehydration, different methods can be used for processing, including mechanical dehydration.
Next, we will briefly introduce the main work flow of the sludge thickening and dewatering-mechanical dehydration method. The first step is to pretreat the sludge to improve its dewatering performance before dewatering. The most common pretreatment method is to add inorganic salts or high-molecular coagulants. In addition, panning and heat treatment can also be used.
In sludge thickening and dehydration, the so-called mechanical dehydration method mainly includes two methods, one is filtration, and the other is centrifugal method in the field. Filtration is to filter the wet sludge layer (porous material such as filter cloth, metal mesh) so that moisture (filtrate) permeates the filter layer, and the dewatered sludge (filter cake) is trapped on the filter layer. The centrifugation method is based on the different centrifugal tendencies produced by differences in the solid and liquid specific gravity of the sludge to achieve the separation of the slurry.
At present, sludge thickening and dewatering of sludge is performed using a filtration method. Commonly used equipment includes a vacuum filter, a frame filter press, and a belt filter. Among them, the vacuum filter continuously enters the mud, and mud is continuously discharged. The operation is stable, but there are many ancillary facilities. The plate and frame filter press is commonly used in the chemical industry. It has a large driving force for filtration, and the mud cake has a low moisture content. The inflow of mud and mud is intermittent and the productivity is low. The belt filter is a new type of filter with a variety of designs.
In comparison, the sludge thickening dewatering method is mainly used horizontal high-speed sedimentation centrifugal dewatering machine. The continuous production and automatic control of the centrifugal dewatering machine has better sanitation conditions and small footprint. It not only can quickly achieve sludge thickening and dehydration, but also can achieve a higher dehydration rate.