Multi-stage sewage treatment device

The utility model discloses a multistage sewage treatment device, which belongs to the technical field of sewage treatment equipment, and comprises a shell, a water inlet arranged below the shell and a water outlet arranged above the shell, the interior of the shell is sequentially divided into a primary settling chamber, a secondary settling chamber, a sterilization and disinfection chamber and a water purification chamber from bottom to top, the water inlet is connected with the primary settling chamber, the water outlet is connected with the water purification chamber, a first filter layer is arranged between the primary settling chamber and the secondary settling chamber, a second filter layer is arranged between the secondary settling chamber and the sterilization and disinfection chamber, a third filter layer is arranged between the sterilization and disinfection chamber and the water purification chamber, and a third filter layer is arranged between the sterilization and disinfection chamber and the wa