With grass stalks and wood pulp as raw materials, the procedure of pulping and papermaking includes pulping, washing, bleaching and papermaking. Alkaline pulping, semi-chemical pulping and mechanical pulping are current methods used for pulping in the paper mill industry. Depending on different methods, ingredients, yields, paper varieties and chemical recovery, the pollutants in paper mill wastewater differ greatly, but basically include a number of suspended solids, BOD5, COD and some poisonous chemicals.

Paper mill sewage –equalization—micro drum filter—air flotation machine—biological treatment-media filters (optional)—sludge dewatering -- discharge