A Chemical-Physical Wastewater Renovation Process for Kraft Pulp and Paper Wastes

The nature of pulp and paper wastes makes it difficult to obtain the necessary reductions of BOD, color, and dissolved solids with a single treatment process. Proposed is an overall treatment scheme which handles the wastewater step-wise to produce a reusable process water. A four-stage process utilizing lime dosing, biological treatment, activated carbon filtration, and demineralization was used on bleached and unbleached kraft total-mill-effluent. A three-stage system without biological treatment also was tested. BOD and color removal were: 97 and 99.5 percent, respectively, for 4-stage; and 85.5 and 99.5 percent, respectively, for 3-stage. Cost comparisons are made.