Programme OS1m Water quality 1
Nanofiltration as a sustainable Water Defluoridation operation
dedicated to large scale pilot plants in the world
Author(s): Maxime Pontie, Hanane Dach, Jérôme Leparc
Keyword(s): desalination, water defluoridation, nanofiltration, fresh water
Session: OS1m Water quality 1
This investigation concerns the use of nanofiltration (NF) to remove excess fluoride from drinking
water. The regular ingestion of water with fluoride ions concentration higher than 2mg.L-1 causes serious health
diseases like dental and bone fluorosis all over the world .
The nanofiltration (NF) membrane is a type of
pressure-driven membrane which properties is situated between reverse osmosis (RO) and ultrafiltration (UF)
membranes. NF offers several advantages such as low operational pressure, high flux, high retention of multivalent
anion salts and organics compounds with molecular weight above 300 Da, relatively low investment and low
operation and maintenance costs. Because of these advantages, the applications of NF worldwide have increase.
The history of NF dates back to the 1970s when RO membranes with a reasonable water flux operating at relatively
low pressures were developed. Hence, the high pressures traditionally used in RO resulted in a considerable energy
cost. Thus, membranes with lower rejections of dissolved components, but with higher water permeability, would be
a great improvement for separation technology. Such low-pressure RO membranes became known as NF
membranes. By the second half of the 1980s, NF had become established, and the first applications were reported
as detailed in a recent review . Today 10% of brackish waters market in the world is dedicated to nanofiltration
(NF) membranes . While nanofiltration is a relatively new membrane process, it is already widely used for water
treatment in different parts of Europe, Israel and the US. Striving towards improved quality, efficiency and
applicability, research is continuing in an attempt to understand and model the varying parameters involved during
NF. A technique that is often used for the evaluation of membranes is the flux and rejection behaviour of uncharged
and charged solutes .
In this work many commercialized RO and NF membranes have been screened in
order to find a suitable membrane for water defluoridation in the future, as illustrated in the Fig. 1. Our work shows
that the more efficient NF membrane for water defluorination are those presenting solution-diffusion mass
References :  Fluoride SERIE Vol.2, Fluoride and Environment, Elsevier, in press (2006);  N.
Hilal, H. Al-Zoubi, N. A. Darwish, A. W. Mohammad, M. Abu Arabi, Desalination, 170 (2004) 281;  J.M.
Rovel, State and behaviour of seawater desalination in the future, Proceedings of CHEMRAWNXV, 21-23 june
2004, Paris, 22-28;  H.M. Krieg, S.J. Modise, K. Keizer, H.W.J.P Neomagus, Desalination, 171 (2004)