Technical Bulletin No. 0186: Neutralization of Acid Bleach Effluents
The attached Technical Bulletin was first prepared in 1965 and presented the results of a study of calcium carbonate neutralization of acid bleach plant effluents. It was noted then that as the reduction in alkali losses in kraft pulping continued to make headway as a result of recovery system improvements, and as additional acid bleaching stages were added to the bleaching process, there would be an increasing tendency toward acidic mill effluents. This would call for application of neutralization techniques for protection of effluent treatment equipment, collection sewers, biological treatment processes and receiving water quality. In anticipation of these developments an investigation was undertaken involving use of calcium carbonate as the neutralization agent, in the forms in which it is commonly employed as raw material in the causticizing process, namely as limestone and clam shells.