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NOMENCLATURE
A and B
constants in the logarithm microbial inactivation rate function
[-]
[Inline Formula Omitted. See PDF]
CCUV reactor chamber diameter
[m]
dt
pathogens residing time
[s]
[Inline Formula Omitted. See PDF]
drag force
[N]
I
intensity of UV radiation
[W/m2]
K
inactivation rate constant
[m2/mJ]
Kinlet
turbulent kinetic energy
[m2/s2]
N
pathogen influent
[-]
N0
pathogens effluent
[-]
N/N0
log inactivation
[-]
P
lamp power
[W]
[Inline Formula Omitted. See PDF]
reflectivities of the media
[-]
[Inline Formula Omitted. See PDF]
transmissivities of quartz and water
[-]
t
time
[s]
uinlet
velocity at inlet
[m/s2]
[Inline Formula Omitted. See PDF]
turbulent dissipation at inlet
[m2/s3]
[Inline Formula Omitted. See PDF]
density
[kg/m3]
Subscripts
i, j
position of a cell
inlet
inlet
INTRODUCTION
A water-disinfection UV reactor consists of a reaction vessel that contains a number of UV lamps. The UV lamps are protected from the water by the quartz sleeves surrounding them. The water enters the reactor and flows around the quartz sleeves. The pathogens present in the water travel through the reactor and are irradiated by the UV light. Microbial transport is simulated using the Lagrangian particle tracking method (Munoz et al. 2007). UV intensity (fluence rate) depends on the relative positions of the particle and the UV lamps. The UV dose received by the pathogens depends on two factors: the trajectories through the reactor and the fluence rate.
The fluence rate is dependent on the positions of the UV lamps within the UV reactor. The lamp arrangement simultaneously affects the fluence rate distribution and the flow of the water within the UV reactor. Two lamp arrangements are commonly used: parallel to the reactor axis and perpendicular to the reactor axis. The parallel arrangement results in greater fluence rate, but the UV fluence rate is much lower at the two reactor ends and near the reactor outer wall. The perpendicular arrangement provides a more uniform UV fluence rate distribution within the radiation zone, but there is almost no UV radiation outside the radiation zone. Taghipour (2004) examined six lamp arrangements in the UV reactor and found the performance is greatly dependent on the arrangement. In addition, Taghipour & Sozzi (2005) compared the degradation of the organic material for two lamp arrangements and...