23-01-2012, 02:20 PM
Advanced technologies in water and wastewater treatment
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Introduction
Conventionalwater andwastewater treatment processes have
been long established in removing many chemical and microbial
contaminants of concern to public health and the environment.
However, the effectiveness of these processes has become
limited over the last two decades because of three new
challenges (Langlais et al. 1991; Mallevialle et al. 1996). First,
Received for publication in Can. J. Civ. Eng. 28 February 2000.
Revision accepted 22August 2000. Published on theNRCResearch
PressWeb site on 28 February 2001.
Reprinted from Can. J. Civ. Eng. 28(Suppl. 1): 49–66 (2001).
Published in J. Environ. Eng. Sci. on the NRC Research Press
Web site on 15 July 2002.
H. Zhou. School of Engineering, University of Guelph, Guelph,
ON N1G 2W1, Canada.
D.W. Smith. Environmental Engineering Program, Department of
Civil and Environmental Engineering, University of Alberta, Edmonton,
AB T6G 2G7, Canada.
Written discussion of this article is welcomed and will be received
by the Editor until 30 November 2002.
increased knowledge about the consequences from water pollution
and the public desire for better qualitywater have promoted
the implementation of much stricter regulations by expanding
the scope of regulated contaminants and lowering their maximum
contaminant levels (MCLs).
Membrane filtration technologies
Membrane filtration can be broadly defined as a separation
process that uses semipermeable membrane to divide the feed
stream into two portions: a permeate that contains the material
passing through the membranes, and a retentate consisting of the
species being left behind (Mallevialle et al. 1996). More specifically,
membrane filtration can be further classified in terms of
the size range of permeating species, the mechanisms of rejection,
the driving forces employed, the chemical structure and
composition of membranes, and the geometry of construction.
Membrane filtration system selection and design
The successful use of membrane processes depends on a
proper selection of membrane material. Ideally, a membrane
should have a high permeate flux, high contaminant rejection,
great durability, good chemical resistance, and low cost
