TCF Bleaching of Sulfite Pulps to Achieve High Quality and the Potential for Effluent Closure, 1996 Pulping Conference Proceedings
Nils G. Johansson, David E. Fletcher, Jiri Basta, Eva Wackerberg & Ann-Sofie Holm
Eka Chemicals
Over the past decade, the growing concerns over the effect of Pulp & Paper Mill effluents has caused significant changes in today’s bleaching sequence designs. This has led to TCF becoming the dominant bleaching method for sulfite pulps, worldwide. Under the U.S. EPA’s proposed effluent guidelines, TCF will be required for the paper grade sulfite category. The ability of hydrogen peroxide and/or peracetic acid to effectively bleach sulfite pulps has been investigated and reported in previous work (1, 2). This paper will address the ability of MgO to replace NaOH as the alkali source in the bleach plant, so that COD discharges can be reduced through partial or full effluent closure. The results show that full effluent closure can be achieved by substituting MgO for NaOH, while maintaining high brightness levels.
TCF Bleaching of Sulfite Pulps to Achieve High Quality and the Potential for Effluent Closure, 1996