Contacts
Clifford K. Ho
Principal Investigator
ckho@sandia.gov
(505) 844-2384
Harold Wright
Co-Principal Investigator
HWright@carollo.com
(208) 376-2288
Siri S. Khalsa
CFD Modeling
sskhals@sandia.gov
(505) 844-1229
Ed Wicklein
CFD Modeling
EWicklein@carollo.com
(206) 684-6532
|
UV Disinfection |
The objectives of this work are to:
-
assess the effectiveness of computational fluid dynamics (CFD) modeling for evaluating UV disinfection processes,
- determine sensitivity of UV disinfection performance (UV dose response) to parameters, hydraulic configurations, and
operational conditions, and
- provide guidance and protocols regarding CFD modeling that will facilitate
potential future regulatory acceptance within the context of the USEPA’s
UV Disinfection Guidance Manual (UVDGM).
Background
The use of ultraviolet (UV) disinfection for drinking water treatment
is expected to increase as a result of the Long-Term 2 Enhanced Surface
Water Treatment Rule (LT2ESWTR) (US EPA, 2006a) and Stage 2 Disinfection/Disinfection
Byproducts Rule (US EPA, 2006b).
In order for utilities to receive inactivation credits for UV under
the LT2ESWTR, systems must first be validated under the specific
design configuration and operating conditions planned for full-scale
treatment. Such validation uses costly biodosimetry methods
and must be re-done if a utility desires to change their configuration
or operation of the UV system.
CFD is a modeling tool that has been shown to successfully determine
relative differences in UV reactor performance. A CFD model
provides detailed information on flow-field characteristics that
can aid in identifying hydraulic-based reasons for variations in
reactor performance. CFD thus holds promise as an alternative
for expensive biodosimetry validation methods and a potential substitute
for revalidation.
CFD simulations of UV radiation field with three lamps on (left) and
particle tracks colored by dose with one lamp on (right) in a UV
reactor for water disinfection.
Reactor design courtesty of Calgon Carbon Corporation.
|
Top of page
Research Approach
The proposed research consists of the following major activities:
- Compilation of data from UV-reactor validation studies that
are suitable for CFD modeling, validation, and assessment
- Development of alternative CFD models and associated models
of dose distribution, microbial inactivation, and reduction equivalent
dose (RED)
- Conducting sensitivity analyses to identify important features,
parameters, and processes that impact performance metrics
- Development of guidance and protocol, consistent with the UVDGM,
to use CFD in assessing performance of UV disinfection systems
for regulatory acceptance
Flow Chart of Project Activities
Top of page
Applications Potential
In many cases, utilities will be retrofitting UV systems into existing
treatment processes, so they will be limited in their available inlet/outlet
configurations and may not be able to achieve optimal configurations. Thus,
utilities need a tool to assess hydraulic impacts on UV disinfection performance
and evaluate alternative configurations early in the design process. Moreover,
a better understanding of the effects of inlet/outlet hydraulic configurations
on UV disinfection performance will result in more pragmatic design recommendations,
with potential to significantly reduce capital costs in future UV installations.
CFD holds promise as an alternative for expensive biodosimetry validation
methods and a potential substitute for revalidation. However, CFD has
not yet achieved regulatory acceptance, and the numerous options
and approaches for CFD modeling make it nearly impossible to prescribe
a universally applicable model and approach for any given site. Therefore,
the goal of this project is not to develop a universal CFD model
that will be broadly applicable to UV disinfection systems. Rather,
the objective of this project is to evaluate the effectiveness of
CFD as a tool to assess the impact of design and operational changes
on desired performance objectives such as UV dose distribution and
the resulting reduction equivalent dose.
Top
of page
Tutorial and Tools
- Tutorial to implement discrete ordinates
radiation model in FLUENT
(Word file, 64 KB)
- Presentation on implementing discrete ordinates
radiation model in FLUENT
(PDF file, 750 KB)
- FLUENT UDF to calculate particle dose
(Windows, Serial processor, ZIP file, 64 KB)
- FLUENT UDF to calculate particle dose
(Windows, Parallel processor, ZIP file, 120 KB)
- FLUENT UDF to calculate particle dose
(Unix, Serial processor, tar file, 72 KB)
- FLUENT UDF to calculate particle dose
(Unix, Parallel processor, tar file, 113 KB)
- Pre-processor to generate injection points for Fluent
(Windows, ZIP file, 143 KB)
- Post-processor and spreadsheet to calculate RED from
Fluent output file
(Windows, ZIP file, 1 MB)
Top
of page
References
|
|
