|dc.identifier.citation||Semião, A.J.C. ; Schäfer, A.I. (2010) Xenobiotics removal by membrane technology: An overview, Xenobiotics in the Urban Water Cycle: Mass Flows, Environmental Processes and Mitigation Strategies, Bester, K. ; Kümmerer, K. ; Fatta-Kassinos, D. (Eds) (Springer Environmental Book Series, Environmental Pollution, Vol. 16), Springer, Hardcover, ISBN: 978-90-481-3508-0, 480 pp.||en
|dc.description.abstract||Small molecular weight xenobiotics are compounds of extreme concern in potable water
applications due to their adverse human health and environmental effects. However, conventional
water treatment processes cannot fully and systematically remove them due to their low
concentrations in natural waters and wastewaters. Biological limitation to degrade such compounds
is another cause for inefficient removal.
Physical barriers like membranes possessing pore sizes smaller than the compounds to be
removed emerged as a good solution. Nanofiltration and reverse osmosis proved to be quite
effective for xenobiotics removal in potable water production in the Paris purification plant of
Méry-sur-Oise. However, even these very narrow pore membrane processes may result in
incomplete removal: xenobiotics retention is high but factors such as adsorption, size exclusion and
charge repulsion affect unpredictably their retention. The water solutions complexity to be treated
renders xenobiotics removal predictions even more difficult due to interactions between xenobiotics
and compounds in water.
Removal of xenobiotics by microfiltration and ultrafiltration is very low because adsorption
on the membrane is the main retention mechanism. Combining those with other processes (e.g.
activated carbon) can considerably improve xenobiotics removal.
The least studied processes in xenobiotics removal are electrodialysis, membrane distillation
and pervaporation. Electrodialysis removal of organic xenobiotics shows a breakthrough through
the membrane possibly due to adsorption followed by diffusion. Membrane distillation presents
high removal rates of xenobiotics due to the compounds low vapour pressure. For volatile organic
xenobiotics or solutions of trace amounts both membrane distillation and pervaporation can be used,
xenobiotics interaction with the membrane being the key factor.
In this book chapter a thorough synopsis of current knowledge on xenobiotics removal is
presented and balanced with recent fundamental studies of underlying mechanisms, informing both
the practitioner regarding membrane capabilities for xenobiotics removal and the researcher with
the current state-of-art.||en