Retention of humic acid by ultrafiltration with polyaluminium coagulant

Research output: Contribution to journalResearch articleContributedpeer-review


  • Vitaly Gitis - , Ben-Gurion University of the Negev (Author)
  • Rolf Gimbel - , TUD Dresden University of Technology (Author)
  • André Lerch - , Chair of Process Engineering in Hydro Systems, University of Duisburg-Essen, IWW - Rheinisch-Westfälisches Institut für Wasserforschung gGmbH (Author)


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
Journal Journal of water supply : research and technology - Aqua
Issue number4
Publication statusPublished - Jun 2005

External IDs

Scopus 23144437579
ORCID /0000-0002-6355-9122/work/142237068



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