An ultraviolet fluid treatment system having feedback control using a
kinetic model and a reactor model that interact with one another. The
kinetic model uses readily measured fluid properties upstream and
downstream of a radiation zone to calculate the conversion of a target
contaminant as it passes through the fluid treatment system. This
obviates the need to measure the contaminant concentration directly,
which generally is too slow to permit real-time control. A reactor model
relates system operating cost to system operating parameters, such as
electrical power consumption and/or rate of oxidant addition, where
applicable. The reactor model is linked to the kinetic model and is used
to optimize operating cost by adjusting system operating parameters based
on a comparison between the conversion obtained from the kinetic model
and the overall treatment objectives. A control center, an ultraviolet
fluid treatment apparatus, and a method of treating a fluid are also
disclosed.