The non-metallic chain scraper is suitable for skimming floating oil, floating slag, and scraping mud and sand in rectangular tanks such as sedimentation tanks, sand settling tanks, and oil separators in refineries, water plants, or sewage treatment plants This equipment should be used in conjunction with auxiliary settings such as oil collection pipes and mud discharge valves to separate floating oil residue on the water surface and mud and sand at the bottom of the pool, completing the initial purification treatment The non-metallic chain scraper is equipped with two parallel closed traction chains It is equipped with multiple scrapers, and under the driving and traction of the driving device, the chain and scraper form a four sided circular track along the guide wheels and rails set up above and below the sedimentation tank By using a scraper to slowly move up and down, the floating oil residue on the liquid surface can be scraped and collected from the inlet end to the inlet end oil collection pipe for discharge, and the sediment settled at the bottom of the pool can be scraped and collected from the inlet end to the outlet end mud collection tank for discharge through the mud discharge valve, thus achieving the purpose of initial mechanical purification of sewage.