Technical Bulletin No. 0085: Significance, Measurement and Reduction of Color in Pulp Mill Effluents

Considerable attention has been given to the question of color in mill effluents and receiving waters, as well as its removal from effluents. A number of companies in the pulp and paper industry have cooperated with the National Council for Stream Improvement's Louisiana State University Project in connection with studies of this problem. One of the difficulties encountered in comparing results obtained with different effluents, and even with different treatments applied to the same effluent, has been color measurement, This has been due not only to the complexity of color and light effects as such, but to the fact that lignin and related substances change color with changes in pH value. The experimental work described in this bulletin represents an effort to develop an empirical but reproducible method of color measurement so that comparisons can be made, relative effectiveness of various treatments evaluated, and changes in stream color measured.