Chemical and biological 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin equivalents in fly ash from combustion of bleached kraft pulp mill sludge

Abstract

AbstractFly ash was collected from five large‐scale or pilot tests in which burning of bleached kraft pulp mill sludge was studied. The content of dioxin‐like compounds in this fly ash was estimated both chemically and biologically. Fly ash was analyzed chemically for 17 PCDD and PCDF congeners by high‐resolution GC‐MS, and the data were transformed to Nordic TCDD equivalents. The biological analyses were based on the induction of several enzymes (aryl hydrocarbon hydroxylase [AHH], 7‐ethoxyresorufin O‐deethylase [EROD], aldehyde dehydrogenase‐3 [ALDG3]) by the fly ash extracts in a mouse hepatoma cell line, Hepa‐1. The inducing potencies were expressed as biological TCDD equivalents. There was a good correlation between the Nordic and the biological TCDD equivalents. Differences in the amounts of dioxin‐like compounds among the combustions were attributed mainly to the boiler types and not to fuel characteristics or combustion parameters.