CHARACTERIZATION OF EFFLUENTS FROM TCF BLEACHING OF SOFTWOOD KRAFT PULP

Organic material dissolved during the different stages of a totally ch lorine-free (TCF) mill-scale bleaching of pine (Pinus sylvestris) kraf t pulp was characterized. The TCF bleach sequence was XZ(EOP)(AZ)(EP)S . the amount of carbohydrates, lignin, carboxylic acids, and total org anic carbon (TOC) varied in the liquor samples from each stage in the range 0.5-3.8, 0.1-2.8, <0.1-5.7, and 0.6-11.7 kg/air-dry ton of bleac hed pulp, respectively. The high content of xylose moieties in dissolv ed carbohydrates indicated that xylan fragments were the major hemicel lulose constituents present. The most abundant aliphatic carboxylic ac ids were formic, acetic, glycolic, and 3-hydroxypropanoic acids.