Fluid treatment system and method of treating fluid

Abstract

It is often desirable to operate ultraviolet (UV) water treatment systems at high fluid velocities; such as, when low UV doses are required, the UV transmittance of the water being treated is high, or when a high intensity radiation source is used. The operation of an open channel UV fluid treatment system at high fluid velocity causes a disproportionate amount of water to pass through the relatively low intensity region above the top lamp. This results in non-uniform UV dose delivery and poor reactor performance. In one embodiment of the invention, by elevating the inlet to the irradiation zone of the fluid treatment system with respect to the outlet, the amount of water that passes above the top lamp can be minimized, improving overall system performance. The means of elevation can consist of a step or slope in the channel, or a combination of both. Depending on the magnitude of elevation, an increase in maximum velocity of approximately two times can be obtained. In practice, a means must be provided to prevent damage to the radiation sources of the elevated banks that become exposed during periods of low flow. This can consist of either a mechanism for switching off the affected lamp when low water level or high temperature is detected, or a means of lamp cooling.