It is widely used in water treatment industry, and its flocculation and iron removal effect is irreplaceable. It is commonly used as flocculant, precipitator and reducing agent. It has the following characteristics: Flocculant: fast settling speed, large sludge particles, small and dense sludge volume, good color removal effect; Precipitating agent: it can generate sediment with sulfide, phosphate, etc., to remove sulfide, phosphate, etc; Reductant: It can reduce hexavalent chromium from chromium wastewater containing water in electroplating plant to trivalent chromium, and has the advantage of low price without producing toxic and carcinogenic irritant chlorides.