The use of ultraviolet-initiated (UV-initiated) advanced oxidation processes (AOP) is rapidly
becoming an attractive alternative for the degradation of harmful organic contaminants that are
not easily removed using conventional water treatment processes. Although UV-initiated AOPs
include such processes as UV/hydrogen peroxide (H2O2), UV/ozone, and UV/heterogeneous
catalyst (such as titanium dioxide), the focus of this research is the UV/H<sub>2</sub>O<sub>2</sub> process with the
goal that the methods and models developed herein can be modified for other UV-initiated AOP
processes. Design and optimization of UV/H<sub>2</sub>O<sub>2</sub> systems must incorporate both reactor design
(hydrodynamics, lamp orientation) and chemical kinetics (reaction mechanisms, kinetic rate
constants). While some numerical techniques have been developed for understanding the
performance of these systems, these techniques are limited in their applicability for analyzing
full-scale UV/AOP systems while incorporating both reactor design and chemical kinetics. As a
result, engineers and other water professionals need more appropriate numerical tools to use as
part of the design process and in optimizing UV/AOP systems.
The reaction mechanisms for the degradation of organic contaminants by UV-initiated AOPs
typically consist of a complex chain of fast chemical reactions. As such, the resulting
intermediates and products from these processes will be highly sensitive not only to the light
distribution within the reactor but also the level of turbulence and micromixing, especially in
mixing-limited conditions. In addition, the level of macromixing that is impacted by upstream
and downstream hydraulic configurations, internal reactor layout, and lamp arrangement will
influence process performance.
Researchers have previously demonstrated the importance of combining UV reactor hydraulics
with dynamic fluence rate models to predict the effectiveness of the disinfection process. A
recent AwwaRF study that successfully applied UV-initiated advanced oxidation for the
degradation of organic contaminants recognized the dependence on non-ideal reactor
characteristics (hydrodynamics and fluence rate) for the overall AOP performance (Linden, et
al., 2004). Sharpless and Linden (2003) concluded that development of a predictive UV/AOP
model that incorporates reactor hydraulics would allow design simulations that optimize lamp
placement, minimize light screening, and improve prediction of contaminant removal in different
UV reactors. The research presents the protocol for using CFD models to
simulate UV-initiated AOPs by combining reactor hydraulics, fluence rate distribution, and chemical kinetics. As oxidation pathways for emerging water contaminants are identified, a
simulation model, such as the one described, will become an important technique for the
evaluation, design, and optimization of advanced oxidation systems. Includes 39 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.1 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 40 |
| Published : | 06/01/2007 |
