Environmental Engineering Reference
In-Depth Information
with a UV lamp mounted over the water surface parallel to the axis of the low channel.
The UV lamp has a highly relective cylindrical mirror mounted on top of it to relect all
UV radiation toward the water. This is illustrated in Figure 22.5. The inlet of the low zone
is designed with low distributor and equalizer so that the low velocities across the low
channel are very uniform. The combination of uniform low and relective optics imparts
a very high degree of exposure to UV light. Conventional tube-in-tube UV disinfection
devices commonly in use in water treatment system design provide the minimum 45 J/
cm
2
required by ANSI/NSF 55. Compared with the commercial devices, UV Waterworks
provides UV dosage of >120 J/cm
2
.
UV Waterworks has been designed to circumvent other challenges commonly faced by
conventional UV devices. The tube-in-tube design of commercial devices requires that
the UV lamp be encased in a quartz cylindrical tube housed inside an external stainless-
steel tube. The low channel in these devices is provided by the annular space between
the stainless-steel tube and the quartz sleeve. Occasionally, the quartz sleeve gets covered
with a scale from the minerals present in water and the intensity of UV light transmitted
through the quartz sleeve drops. The UV device has to be periodically dismantled to clean
the quartz sleeve using chemicals and assembled again. During the assembly process, if
the operator is not careful, the quartz sleeve can break easily and will then need replace-
ment with a new sleeve.
The problems of scaling, requirement of cleaning chemicals, and the added expense of
replacing the quartz sleeve have been eliminated in UV Waterworks.
UV Waterworks has been validated at independent laboratories in a number of countries.
It was one of the irst such devices to receive certiication from the State of California as a
Class A device, capable of disinfecting water that was not previously pretreated through
another disinfection step. It also has been validated by laboratories in India, Mexico, the
Philippines, and South Africa.
WaterHealth believes that everyone deserves both great-tasting and quality drink-
ing water regardless of their geographical location or economic situation. As a result,
WaterHealth incorporates, where relevant, reverse osmosis technology into its puriica-
tion systems to improve the taste of the water, and provides WHO-quality potable water
without relying on chlorine. We also use UF and arsenic, iron, manganese, and luoride
Biologically
contaminated
water enters
Polished
reflector
Germicidal
UV lamp
Contoured
flow channel
Disinfected
water out
FIGURE 22.5
UV Waterworks and its working concept.
