Abstract
A procedure for characterizing mill effluent toxicity in terms of toxic equivalence based on pentachlorophenol (pep), resin acids, and fatty acids was developed. The procedure is similar to the classification of dioxin and furan congeners in terms of their 2,3,7,8 TCDD equivalence. The procedure was used to estimate the toxic equivalence of bleaching effluent from molecular-chlorine-gas-free bleaching of hardwood and softwood. Lab scale pulping and bleaching trials were conducted to simulate MCC cooking, oxygen delignification, and D100EpoDnD bleaching of hardwood and softwood to market brightness. The results obtained demonstrated a reduction in AOX, and a far greater reduction in toxic equivalence in combined acid and alkaline filtrates from the molecular-chlorine-gas-free bleaching sequence compared to data from conventional cooking and bleaching processes. Untreated mill effluent is predicted to be non acutely toxic, secondary treated mill effluent is predicted to be non chronically toxic, based on chlorophenolic, resin acid, and fatty acid toxicity equivalence. The value of AOX as a meaningful regulatory parameter for the protection of receiving waters is questioned.
Selective Production of Aromatics from 2-Octanol on Zinc Ion-Exchanged MFI Zeolite Catalysts