Retention of humic acid by ultrafiltration with polyaluminium coagulant

Vitaly Gitis, André Lerch, Rolf Gimbel

    Research output: Contribution to journalArticlepeer-review

    14 Scopus citations

    Abstract

    The chemical and technological aspects for the retention of humic acid (HA) by combining coagulation and ultrafiltration (UF) are discussed in this paper. Coagulation was performed with polyaluminium chloride (PACl) in three operating modes: in-line 30 s coagulation, coagulation with 25 min flocculation, and coagulation/flocculation with 3 h sedimentation. UF capillaries with a molecular weight cut-off (MWCO) of about 200 kDa, made of polyethersulfone (PES), were operated in inside-out mode with constant positive pressure. The applied experimental scheme posed additional demands to the HA-PACl flocs, limiting their size and density. The optimal floc was achieved at low [Al T]/DOC mass-to-mass ratio of 0.4. The obtained flocs were big enough to provide sufficient retention of HA by UF, small enough to minimize clogging, and with moderate density to minimize fouling. The optimal floc provided a highest 70% HA retention with minimal fouling. Combining coagulation with flocculation we were able to achieve an accumulation of 5 mg HA per capillary not compromising the duration of the filter run. Alteration of pH and Al dose to achieve ultimate 'charge neutralization' or 'sweep coagulation' yielded virtually similar results in terms of HA retention.

    Original languageEnglish
    Pages (from-to)213-223
    Number of pages11
    JournalJournal of Water Supply: Research and Technology - AQUA
    Volume54
    Issue number4
    DOIs
    StatePublished - 1 Jan 2005

    Keywords

    • Fouling
    • Humic acid
    • Mass-to-mass stoichiometry
    • Natural organic matter
    • Ultrafiltration membranes

    ASJC Scopus subject areas

    • Environmental Engineering
    • Water Science and Technology
    • Health, Toxicology and Mutagenesis

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