Evaluation of chloroform formation at an ECF bleaching pulp mill and its original compound

摘要

Elementary chlorine-free (ECF) bleaching non-intentionally forms a very small amount of chloroform, which is only about several % of that formed in the chlorine bleaching. In addition, the original organic compound of chloroform is not identified yet. Chloroform formation, balance, and discharge were estimated during 1997-2005 at an ECF bleaching hardwood kraft pulp mill that operated a complete airtight type activated sludge treatment using pure oxygen for the bleaching sewer. This was achieved by collecting and analyzing discharge water and gas samples that contained measurable levels of chloroform. During the stable operation of ECF bleaching, the average formation of chloroform was estimated to be 1.48 g/pulp adt. At the activated sludge treatment of the bleaching sewer, chloroform generated being accompanied with decomposition of organic chlorinated compounds indicated by AOX. It was suggested that the activated sludge treatment could remove or decompose the chloroform generated from ECF bleaching sewer.