Dose delivery monitoring is the only assurance that an installed ultraviolet (UV) reactor is meeting
drinking water disinfection requirements. However, dose delivery monitoring approaches vary
significantly with UV vendors. In this paper, CFD-based dose monitoring and UV intensity
sensor modeling are used to understand the relationship between dose delivery and dose
monitoring. Plots of MS2 reduction equivalent dose (RED) versus measured UV intensity are
used to describe two approaches for dose monitoring. In the first approach, the target dose
delivery is assured at a given flowrate when the measured intensity is above a setpoint value.
This approach is shown to be most effective when the UV intensity sensor is placed at an
optimum location where dose is proportional to intensity regardless of lamp power and water UV
transmittance. In the second approach, the target dose delivery is assured at a given flowrate
when the measured intensity and UV transmittance are both above respective setpoints. This
approach works if the UV intensity sensor is relatively close to the lamp. Test conditions
required to validate the first approach are shown to differ from those required to validate the
second. Plots of MS2 RED versus measured UV intensity are also used to explore dose-
monitoring issues with medium-pressure reactors. Large bias errors are shown to occur if the UV
absorber used during validation does not mimic the absorbance spectra at a water treatment
plant, and if the spectral response of the UV intensity sensor is not restricted to the germicidal
region. Monte Carlo simulations are used to explore the impact of random uncertainty in UV
reactor validation and on-line monitoring on dose monitoring. Includes 15 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 410 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 17 |
| Published : | 11/01/2002 |
