Method for recycling paper mill waste water

摘要

Disclosed is a method for coagulating the suspended solids in paper mill waste water so that the coagulated solids may be easily separated from the waste water and the clarified waste water reused in the paper making process. Coagulation is induced by first adding sulfuric acid to lower the pH to below 4, mixing thoroughly, and then adding calcium hydroxide to raise the pH to above 10. The coagulated solids separated from the waste water may be used as a landfill, used as a low grade pulp source, or dewatered and burned as a fuel.