Papermaking wastewater has high COD and suspended solids(SS) content. Meanwhile, the chroma is serious. COD is usually composed of insoluble COD and soluble COD. Usually, insoluble COD accounts for most of the total COD composition. When SS in wastewater is removed, most of the insoluble COD is removed at the same time.
Adding polyacrylamide by air flotation or precipitation method can remove most of the SS, while removing most of the insoluble COD and partially soluble COD and BOD.