A basic investigation in origins of AOX-substances in paper sludges

A preliminary investigation on the contribution and origin of organic halogens (measured as AOX) in sludges out of pulp and paper production is described. Size exclusion chromatography (SEC) and indirect enzyme-tests (cellulase) have shown remarkable differences in AOX-substances between various fractions of paper sludges. In sludges from factories with 100% pulp usage (pulp sludges) chlorinated polymers from the pulp bleaching with chlorine were identified as main source. In sludges from companies with 100% waste paper usage (waste paper sludges) strong indication has been presented that the main AOX-sources are contaminations in printing inks and smaller fragments of chlorinated wood polymers, especially lignin. For the improvement of paper sludge disposal in Europe (especially Germany) it is important to decrease the AOX-contents by substitution of AOX-containing printing inks and by transforming the traditional chlorine bleaching of pulp to elemental chlorine free (ECF) or total chlorine free (TCF) processes.