The sludge generated after sewage treatment has a particularly high water content (close to 98%) and a large volume, which has a serious impact on subsequent treatment and disposal, so it must be treated to reduce the water content of the sludge and reduce the volume of the sludge. The most effective way to reduce the amount of sludge and improve the dewatering property of sludge is to select the appropriate sludge dewatering agent according to the specific situation. The principle of its action is that by adding sludge dehydrating agent, the chemical reaction on the surface of the sludge colloidal particles, neutralizing the charge of the sludge colloidal particles, promoting the sludge particles to condense into large granular floc, and separating it from the sludge particles, so as to improve the dewatering performance of the sludge.

Commonly used sludge dehydrating agents are inorganic and organic two categories, sludge dehydrating agents are mainly on the water with opposite charge colloid neutralization, compression double electric layer, so that the colloid stability condensation, solid-liquid separation, but the dosage is large, the effect is not good. The organic polymer sludge dehydrant is mainly used to adsorb and bridge the stabilized condensed particles, so that they can quickly form large floc and be easily separated.

In sludge dewatering experiment, the interaction between sludge dehydrator and sludge can be clearly observed by digital microscope, so that sludge is easier to dehydrate. It can be seen from microscope observation that after the optimal dosage of sludge dehydrant is added, the floc shows a relatively flat and uniform flocculation shape on the whole, and there are also holes, which is because the sludge dehydrant plays the role of electric neutralization and bridging. To reduce the repulsive effect between sludge particles, through its good adsorption and bridging function, the stabilized condensed particles can be rapidly formed into large floc, so the floc shows different characteristics of aggregation forms, and the floc has an uneven chain network structure, and the formed floc is a complex shape larger than the surface, so the sludge dehydrating agent has better dewatering performance.