Abstract

More than 55% of the paper used in the United States is recovered and recycled. Similar high recovery rates are reported for Japan and some European countries. Recovered paper that is recycled includes old newspapers and magazines, old corrugated containers, and printing and writing paper. Products produced from recovered paper include newsprint, magazine paper, tissue products, corrugated cartons, other boxes, and printing and writing paper.

Paper recycling mills are a series of unit operations designed to disintegrate paper to form pulp, detach ink and other contaminants, such as adhesives from cellulose fibers, and separate the dispersed contaminants from the cellulose fibers. The fibers are optionally bleached and then made back into paper. The type of paper, the types of contaminants present, and the recycled paper product determine the choice of unit operations and their sequence. In particular, different ink types such as toner inks affect mill design and the choice of process chemicals. Both chemical and mechanical phenomena promote contaminant detachment from cellulose fibers and separation of the dispersed contaminant particles from pulp. Important chemicals used in paper recycling include agents to provide high pH, dispersants, surfactants, chelants, and bleaching agents. More paper recycling mills are clarifying and reusing process water. As a result, water clarification has become an important part of mill operations.