Chapter 19: Paper and Pulp

Overview

The pulp and paper making industry is very water intensive (about 60 m ³ water per ton of paper produced), and in terms of freshwater use ranks third after the primary metals and chemical industries. The major raw material used by the pulp and paper industry is wood, which is composed of cellulose fibers. The wood is broken down to separate the cellulose from the noncellulose material; the cellulose is then dissolved chemically to form a pulp. The pulp slurry is then vacuum dried on a machine to produce a paper sheet. Dyes, coating materials, and preservatives are also added at some point in the process. Lignin is a complex aromatic polymer that is an integral cell wall constituent that gives strength and rigidity to the tissues and allows vascular resist microbial attack. The presence of residual lignin affects some properties of the manufactured pulp and paper products. Therefore, lignin is selectively removed during pulping without significant degradation of the cellulose fibers. The paper industry has several sectors such as packaging board, newsprint, boxes, printing and writings, and tissues. The world production of paper and board is about 320 million tons per year (1996 data). North America produces more than half, Western Europe about 20%, and Japan about 12%. The consumption of water varies depending on the type of paper being produced. Manufacture of tissue, printing and writing paper, newsprint, and packaging material requires about 60, 35, 30, and 18 m ³ of water per ton (Thompson...