Sewage from the water system initially removes large objects through the coarse grid cleaning machine. In the sand tank system, the fine grid drum cleaning machine further purifies the fine particles in the sewage and filter the fine sand particles in the sewage into the oxidation ditch reaction tank. In the oxidation ditch system, carrying out the biochemical treatment is to decompose the harmful substances in the sewage. This process uses a number of chemicals to enhance the treatment effect, such as compound alkali, chlorine, oil flocculants, in order to remove the oil, disinfection, adjust pH value.