REDUCING CHLORINATED ORGANIC-COMPOUNDS FROM BLEACHED KRAFT MILLS THROUGH FIRST-STAGE SUBSTITUTION OF CHLORINE DIOXIDE FOR CHLORINE

Concern about the chlorinated organic compounds in kraft bleach plant effluent has led the U.S. Environmental Protection Agency (EPA) to propose new regulations to limit discharge of AOX chlorinated dioxins and furans, and certain chlorinated phenolic compounds. Several mills have either eliminated the routine use of elemental chlorine by substitution of chlorine dioxide in their bleach plants or conducted trials to evaluate this technology. This paper describes impacts on chlorinated organic compounds discharged during long-term operation of low-chlorine bleaching at one James River Corp. mill. Results show that complete substitution of chlorine dioxide for chlorine in the first bleaching stage reduced chlorinated dioxins and highly chlorine-substituted chlorinated phenolic compounds to nondetectable levels in the bleach plant effluent. The AOX level in final mill effluent, while above that proposed by EPA, is greatly reduced from that observed before the bleach plant modifications.