J Water SRT - Aqua 54 (2005) 213-223
Retention of humic acid by ultrafiltration with polyaluminium coagulant
Vitaly Gitis, Rolf Gimbel and André Lerch
Department of Biotechnology and Environmental Engineering, Ben Gurion University of the Negev, PO Box 653, Beer-Sheva, IL-84105, Israel, gitis@bgumail.bgu.ac.il
IWW - Rheinisch-Westfälisches Institut für Wasserforschung gGmbH, Moritzstr, . 26, 45476, Muelheim an der Ruhr, Germany
Water Supply Engineering, Institute for Urban Water Management, Technische Universität Dresden, 01062, Dresden, Germany
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 [AlT]/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.
Full article (PDF Format)
PAY-PER-VIEW: Buy this article for £20.00 (IWA MEMBER PRICE: £15.00)
|
