TY - JOUR
T1 - Fouling control mechanisms of demineralized water backwash: Reduction of charge screening and calcium bridging effects
AU - Li, Sheng
AU - Heijman, Bas G J
AU - Verberk, J. Q J C
AU - Le-Clech, Pierre
AU - Lu, Jie
AU - Kemperman, Antoine J B
AU - Amy, Gary L.
AU - Van Dijk, Johannis C.
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This research was funded by Senter Novem in the framework of the Innowator grants. Norit X-Flow By., the membrane manufacturer, the Netherlands, is gratefully acknowledged for providing UFC MS 0.8 membrane fibers. Evides. BV and Hatenboer-water. BV are appreciated for the cooperation in the DEMIFLUSH project.
PY - 2011/12
Y1 - 2011/12
N2 - This paper investigates the impact of the ionic environment on the charge of colloidal natural organic matter (NOM) and ultrafiltration (UF) membranes (charge screening effect) and the calcium adsorption/bridging on new and fouled membranes (calcium bridging effect) by measuring the zeta potentials of membranes and colloidal NOM. Fouling experiments were conducted with natural water to determine whether the reduction of the charge screening effect and/or calcium bridging effect by backwashing with demineralized water can explain the observed reduction in fouling. Results show that the charge of both membranes and NOM, as measured by the zeta potential, became more negative at a lower pH and a lower concentration of electrolytes, in particular, divalent electrolytes. In addition, calcium also adsorbed onto the membranes, and consequently bridged colloidal NOM and membranes via binding with functional groups. The charge screening effect could be eliminated by flushing NOM and membranes with demineralized water, since a cation-free environment was established. However, only a limited amount of the calcium bridging connection was removed with demineralized water backwashes, so the calcium bridging effect mostly could not be eliminated. As demineralized water backwash was found to be effective in fouling control, it can be concluded that the reduction of the charge screening is the dominant mechanism for this. © 2011 Elsevier Ltd.
AB - This paper investigates the impact of the ionic environment on the charge of colloidal natural organic matter (NOM) and ultrafiltration (UF) membranes (charge screening effect) and the calcium adsorption/bridging on new and fouled membranes (calcium bridging effect) by measuring the zeta potentials of membranes and colloidal NOM. Fouling experiments were conducted with natural water to determine whether the reduction of the charge screening effect and/or calcium bridging effect by backwashing with demineralized water can explain the observed reduction in fouling. Results show that the charge of both membranes and NOM, as measured by the zeta potential, became more negative at a lower pH and a lower concentration of electrolytes, in particular, divalent electrolytes. In addition, calcium also adsorbed onto the membranes, and consequently bridged colloidal NOM and membranes via binding with functional groups. The charge screening effect could be eliminated by flushing NOM and membranes with demineralized water, since a cation-free environment was established. However, only a limited amount of the calcium bridging connection was removed with demineralized water backwashes, so the calcium bridging effect mostly could not be eliminated. As demineralized water backwash was found to be effective in fouling control, it can be concluded that the reduction of the charge screening is the dominant mechanism for this. © 2011 Elsevier Ltd.
UR - http://hdl.handle.net/10754/561941
UR - https://linkinghub.elsevier.com/retrieve/pii/S0043135411004404
UR - http://www.scopus.com/inward/record.url?scp=80555122837&partnerID=8YFLogxK
U2 - 10.1016/j.watres.2011.08.004
DO - 10.1016/j.watres.2011.08.004
M3 - Article
C2 - 22014561
SN - 0043-1354
VL - 45
SP - 6289
EP - 6300
JO - Water Research
JF - Water Research
IS - 19
ER -