A Calgon 36-in Sentinel® ultraviolet (UV) reactor was selected to provide disinfection at the Rossdale Water
Treatment Plant (WTP) in Edmonton, Alberta. Nine Sentinel® reactors were designed to fit in the
existing filter gallery, one after each filter. Each reactor has three
10 kW Medium Pressure UV lamps. Due to the very restricted space, there was need for the
reactors to be mounted in a unique vertical arrangement with limited straight piping upstream or
downstream of the reactors.
The reactors were designed to achieve 3-log Cryptosporidium reduction under the Tier 2
guidelines of the June 2003 Draft of the U.S. Environmental Protection Agency (USEPA) Ultra Violet Disinfection Guidance Manual
(UVDGM) at maximum design flow of the filters, 92% UV transmittance and a 70% End of
Lamp Life/Fouling factor. A number of issues such as maintaining steady state conditions, achieving adequate mixing with
the limited head available, piping alterations for discharging the effluent, etc. made on-site
validation difficult and expensive. Therefore, reactor performance was validated at the largescale
UV validation facility in Portland, Oregon with a piping configuration simulating that of the
WTP. A test protocol was developed in accordance with the UVDGM that allowed interpolation
of dose delivery and monitoring as a function of flow, UVT, and lamp output for measured
reduction equivalent doses (RED) ranging from 17 to 69 mJ/cm<aup>2</sup>.
Because the unique piping at the Rossdale WTP was anticipated to create an undesirable flow
distribution into the installed reactors, Calgon Carbon Corporation conducted a Computational
Fluid Dynamics (CFD) analysis of the proposed reactors to simulate their performance in all the
various piping configurations at the plant. The CFD analysis performed with CFX software by
ANSYS, Inc. studied the influence that the various piping scenarios had on flow dynamics and,
thus, reactor performance. Because performance was threatened, possible flow correction
solutions were also studied. The effects of different flow-correcting baffle arrangements and
their locations were assessed to maximize dose delivery.
Based on the CFD analysis of flow correction, it was determined that two 9" baffles upstream of
the reactors provided the highest degree of optimization. Further, the reactor treating Filter 5
effluent was determined to administer a lower UV dose compared to the other reactors installed
at the plant. Therefore, Calgon recommended that Rossdale WTP validate the Filter 5 piping in
Portland with a dual 9" baffle plate as the most conservative case. Includes 3 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 2.2 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 06/17/2005 |
