Environmental Engineering Reference
In-Depth Information
toxic than the original substance. Thorough evaluation of transformation products and their potential toxicity is therefore
essential, together with correct process control, to ensure a sufficient degree of mineralization and transformation to innocuous
by-products.
The design of the photocatalytic reactor is critical to providing high light intensity and a large surface area of the catalyst
coating [112, 113]. Small-scale laboratory studies have shown the effectiveness of a stirred tank reactor, using nanoparticle TiO
2
films immobilized on glass sheets, in degrading atrazine [114] and inactivating
E. coli
[115]. The feasibility of the use of pho-
tocatalytic degradation for the treatment of water contaminated with the pesticides diuron, imidaclopriad, formetanate, and
methomyl was demonstrated at the pilot scale with a solar plant employing specially designed compound parabolic collectors
to intensify the radiation [116]. Several alternative types of solar reactor design have been proposed such as the parabolic trough
reactor, thin-film fixed bed reactor, and double-skin sheet reactor [117]. Use of immobilized photocatalysts avoids the difficulty
of separating the nanoparticles after treatment. Not all the potential applications of photocatalysis involve large-scale installa-
tions; a miniaturized photocatalytic reactor for purification of drinking water has been designed by applying microfluidic tech-
nology [118]. Interest in photocatalytic water treatment has so far has been relatively limited, despite a number of successful
field trials on contaminated groundwater and industrial wastewater. However, the development of more efficient, visible light
photocatalysts can be expected to increase its competitiveness with conventional water treatment systems.
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