Fillers in PVC films generally refer to materials that are filled in other objects. In chemical engineering, the filler refers to the inert solid materials installed in the packed tower, such as Pall rings and Raschig rings, etc., whose function is to increase the gas-liquid contact surface and mix them strongly. In chemical products, fillers, also known as fillers, refer to solid materials used to improve processing performance, product mechanical properties, and/or reduce costs. In the field of sewage treatment, it is mainly used in the contact oxidation process, and microorganisms will accumulate on the surface of the filler to increase the surface contact with sewage and degrade the sewage.