Source apportionment of pulping wastewater and application of mechanical vapor recompression: Environmental and economic analyses

摘要

It is expected that low-energy and scientific zero discharge of chemical-mechanical pulping wastewater will be achieved by applying the mechanical vapor recompression (MVR) technology. In this paper, the equal-standard pollution load model was introduced into pulp and paper field to parse the pollution sources for the first time. The results from the source apportionment indicated that the screw press and concentrating were the major pollution unit operations, and their cumulative load ratio reached 92.92%. The further survey demonstrated that the dominating pollution factors in the traditional chemical-mechanical pulping process were Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD_5), and Suspended Solids (SS), whose cumulative load ratio was 92.69%. The environmental analysis demonstrated the implementation of MVR technology significantly decreased the pollution load and reduce the pressure of subsequent wastewater treatment. In addition, a further economic performance indicated that the utilization of MVR technology possessed a smaller operating cost of 2.899 S/m~3. The result of the given model provides a scientific gist and instruction for the future treatment of water pollutants in the chemical-mechanical pulping process. The MVR technology is conducive for wastewater treatment to minimize environmental effects and costs.