Selective purification of bleached spruce TMP process water by induced air flotation (IAF)

Dariusz Zasadowski, Anders Strand, Anna Sundberg, Håkan Edlund, Magnus Norgren

    Research output: Contribution to journalArticleScientificpeer-review

    11 Citations (Scopus)


    The environmentally benign closure of water systems in paper mills leads to the problem of accumulation of dissolved and colloidal wood substances (DCS) in process water. Notably, pitch affects the pulp and paper production negatively and increases the demand for additional treatment of the process water. In the present article, the purification of thermomechanical pulping process water from the alkaline peroxide bleaching stage has been investigated, with the induced air flotation (IAF) in focus. The following parameters were considered concerning the IAF efficiency to remove detrimental substances: concentration of cationic foaming agent, pH value, calcium concentration, and temperature. The amounts and characteristics of residual DCS were determined by gas chromatography and turbidity measurements. Residual concentrations of the foaming agent dodecyltrimetylammonium chloride were determined by electrospray ionization mass spectrometry. Up to 90% of pitch was removed, whereas hemicelluloses, which are important in preventing pitch problems, remained in the waters. Up to 70% of the pectic acids accounted for the high cationic demand of the process waters were removed by optimization of the IAF parameters. The presented separation process gives new opportunities to a selective purification of the process waters.
    Original languageUndefined/Unknown
    Pages (from-to)157–165
    Number of pages9
    Issue number2
    Publication statusPublished - 2014
    MoE publication typeA1 Journal article-refereed


    • cationic dodecyltrimetylammonium chloride (DoTAC)
    • cationic foaming agent (DoTAC)
    • colloidal wood pitch
    • induced air flotation
    • mechanical pulp
    • pectic acids
    • peroxide bleaching

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