New Oil-Free Brownstock Washer Defoamer Can Help Mills Reduce Dioxin-Related Problems, 1990 TAPPI Conference Proceedings

Conventional brownstock washer defoamers typically contain oil(s) as a major component of their formulation. These defoamer oils may contain significant levels of dibenzofuran and/or dibenzodioxin, which could contribute to chlorinated dioxin formation under certain bleaching conditions.

A new, completely oil-free brownstock defoamer has been developed and is in use at several bleached and unbleached pulp mills. This product provides excellent brownstock foam control and enhanced washer drainage. By eliminating oil-borne dioxin precursors from the washer system, and by promoting the washout of naturally occurring precursors, the use of this product may help bleached mills reduce dioxin related problems.

Unlike most conventional brownstock defoamers, this new product contains neither oils nor fatty materials which are frequently found as components of many pulp mill pitch deposits. When used in place of conventional brownstock defoamer, this product has allowed several mills to eliminate or reduce defoamer-related pitch deposition problems. Several case studies illustrating the uses and benefits associated with this new product are provided.