Abstract: A system and method for converting pulp and paper mill waste water into a decolored, neutral pH effluent and a solid suitable for use as fuel in a furnace. The treatment system is used following primary and secondary treatment of pulp and paper mill waste waters typically found in the industry. After secondary biological treatment, the waste waters are pumped to a coagulation tank where the waste water is brought in contact with a polyamine coagulant which coagulates lignins, degraded sugars, and other compounds which typically discolor this water. The coagulation particles are increased in size by addition of an acrylamide polymer in a flocculation tank to improve the hydrophilic characteristics of the coagulant. The waste water is then mixed a dissolved air and water solution under pressure. Upon dissolution of the dissolved air at atmospheric pressure the air is absorbed by the flocculated matter in the aeration tank and the flocculated matter is caused to migrate towards the area of less pressure, i.e.

Abstract: A process for the decolorization of alkaline pulp such as that derived from paper waste water wherein the waste water is contacted with a strong mineral acid, contacted with a coagulated agent and then the solid coagulum is separated and neutralized to liquify the color bodies in concentrated form.