Solar driven advanced oxidation processes for water decontamination and disinfection - Solar Energy Sciences and Engineering Applications - page 395

Solar driven advanced oxidation
processes for water decontamination
and disinfection
Erick R. Bandala 1 & BrianW. Raichle 2
1 Energy and Environmental Research Group., Universidad de las Américas,
Puebla. Sta., Catarina Mártir, Cholula 72820 Puebla, Mexico
2 Department of Technology and Environmental Design, Appalachian State
University, Katherine, Harper Hall, Boone, NC, USA
13.1 INTRODUCTION
The industrial revolution of the late 18th century brought about new paradigms,
including unprecedented and sustained population growth and a shift from a man-
ual labor economy towards machine-based manufacturing. As a result, generations
of industrial and domestic waste started to accumulate, resulting in new problems
related to waste management and site contamination. As industrialization increases
and populations rise, the amount of waste inevitably will surpass the natural capac-
ity of ecosystems to self-purifiy. The continued production of waste during the last
few decades has exceeded this capacity and has caused disorder, instability, harm, or
discomfort to these ecosystems.
Efforts to mitigate the negative effects of waste from anthropogenic activities fall
into two main categories. One category strives to decrease or eliminate waste gener-
ation through design and implementation of cleaner industrial processes. The second
involves site restoration using novel state-of-art technologies able to remove waste
with less impact on the surroundings. Many technological approaches for improving
water, air and soil quality have been developed over the last few decades. With an
increasing emphasis placed on sustainability, technological solutions are evaluated not
only by their cost-effectiveness but also by their ability to withdraw pollutants from the
environment without generating by-products and, preferably, by their use of renewable
sources of energy. Among the different technological approaches developed, Advanced
Oxidation Processes (AOPs) have recently emerged as very interesting alternatives for
water treatment.
AOPs were initially defined as processes involving the generation of highly reac-
tive oxidizing species able to attack and degrade organic substances (Bolton, 2001).
Nowadays, AOPs are considered physical-chemical processes with high thermody-
namic viability and the ability to produce deep changes in the chemical structure
of contaminants as a result of the participation of free radicals in Redox reactions
(Domenech et al., 2004). Free radicals, mainly hydroxyl radicals (HO), are of partic-
ular interest for environmental restoration because of their high oxidation capability.
However, other studies have suggested that, besides hydroxyl radicals, AOPs can also
generate other oxidizing species (Anipsitakis and Dionysiou, 2004). Generated radicals