Technology Advances as Industry Reduces Environmental Impact, 1992 Engineering Conference Proceedings

In recent years universal public concern has developed regarding chlorinated organics. Governments are reacting to these environmental concerns by imposing limits on total organic chlorides (TOC1). adsorbable organic halides (AOX), and dioxin in pulp and paper mill effluents. Citizens are also concerned about the aesthetic value of waters downstream from pulp mills and, in response, states are imposing stringent standards limiting colorant discharges. One of the key elements in reducing chlorinated organics and minimizing color is to use fewer chlorinated Products to bleach the pulp. The paper industry has responded to legislative and environmental pressures to reduce pollutants (dioxin releases have already been reduced by 75%) by developing alternatives to the use of chlorine as a bleaching agent. This paper briefly explores some of these alternatives, which may be considered under the general headings of (a) delignification before bleaching and, (b) changes in the bleaching compounds and/or bleaching sequence.