Wastewater Characteristics

Abstract

Forceful measures have been taken in the past decade to reduce the pollution loads of pulp and paper mills. Besides more effective external waste water treatment, internal arrangements have been made to reduce pollution loads, e.g. by closing water systems. New processes and technically improved machines and equipment have made it possible to utilize raw materials and chemicals more efficiently. This has also reduced the pollution loads of the mills. In the 1970s, pollution loads were restricted by environmental laws and regulations in many countries, and the restrictions will become tighter during the 1980s. This will require much research and development. In this paper, characteristics of effluents (BOD, suspended solids, colour, TOC, COD, toxicity) discharged from chemical and mechanical pulping processes and from paper and board mills are presented in general terms and by mill department. Process developments and effects of these developments on pollution loads are described and future trends are discussed.