Volume 3, Number 2
May 1990

Dioxin Update

Reprinted with permission from Friends of the Dard Hunter Paper Museum Newsletter 9(l), March l990, p.10. The author is president of Integrated Paper Services, Inc., 101 Edison Ave., Suite 250, Appleton, WI 54912 (414/749-3040).

In 1986, a five-mill study was conducted to determine the amount of dioxins in pulp and paper mill environments. This study has blown into a 104-mill coverage, spearheaded by NCASI - National Council for Air and Stream Improvement for the Pulp and Paper Industry, Inc. - headquartered in New York. Work has also been conduct in other countries such as Sweden and Canada. According to one Swedish scientist, Dr. Kringstadt, "We think the problem of dioxin has been solved."

Some of the findings so far:

• Dioxins are found in sludges, effluents and bleached pulps.
• Fines contain the most dioxins. Large amounts have been found with pitch particles.
• In the bleaching of pulp, chlorine multiples (active chlorine divided by kappa number) of less than 0.17 give very low or no dioxins.
• Higher pH values lead to lower dioxins.
• Lower consistencies give lower dioxins.
• Higher temperatures gave somewhat lower dioxins but the differences, in many cases, were not significant.

Ways to reduce dioxins:

• Replace chlorine with more chlorine dioxide.
• Oxygen delignification.
• Extended delignification.
• Efficient brown stock
• Chemical flocculation.
• Efficient Wastewater treatment.