Page 293 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

water. The degree of inactivation by ultraviolet radiation is directly related to the UV dose applied to the water. The
dosage, a product of UV light intensity and exposure time, is measured in microwatt second per square centimeter
(µws/cm2 ). The accompanying table lists dosage requirements to destroy common microorganisms. Most UV units
are designed to provide a dosage greater than 30,000 µws/cm2 after one year of continuous operation. Notice
that UV does not effectively disinfect some organisms (most molds, protozoa, and cysts of Giardia lamblia and
Cryptosporidium) since they require a higher dose
Advantages:

1 It helps in the destruction of 99.99% of microorganisms.
2 It is eco-friendly because it does not leave any by-products after the treatment.
3 It is cost-effective and user-friendly since the only lamp and sleeve have to be replaced annually. Apart from
it, hardly any maintenance is required by the UV water purifiers.

4 It is chemical-free, and there is no change in the taste and color of the water.
5 Water purification through UV rays is a quick process since the water flows through the system without a holding
tank or reaction times.

Disadvantages:
1 It does not help in the removal of contaminants. UV deactivates only the living microorganisms. Therefore, a
prefiltration of particles is necessary.
2 The UV lamps heat the water if the cleaner is not in use.

3 A UV system requires the power supply;y to run. Hence, an undisrupted power supply is necessary for the
functioning of a UV water purifier.
Different Types of Water Purifiers

1 Activated carbon water purifier:
Pesticides and other potentially harmful organic compounds are removed from water by activated carbon in water
purifiers. Chemicals that give water a foul taste are also removed by activated carbon in water filters. Consequently,
having an activated carbon water filter purifier is an excellent idea for drinking water.
However, it cannot remove pollutants such as fluorides, nitrates, sodium, and microscopic organisms like parasites
and bacteria.
2 Sediment filter water purifier:
The more advanced water purifiers use sediment cartridge filters as the first in a series of several filters. A sediment
filter’s main function is to remove bigger solid particles from water, such as mud, dirt, sludge, and other similar
solid particles.
3 Gravity-based water purifiers:
Gravity-based water purifiers use many filtration techniques to produce clean water. Many people in India utilize
cheap gravity water filters. The primary benefits of gravity water purifiers are their low cost and ability to operate
without electricity.

As the name suggests, gravity water purifiers use gravitational forces to drive water through various filter cartridge
parts. However, gravity filters have a very slow flow rate—almost drop by drop into the storage tank below—
through their filters.
4 UV purifier:
A UV water purifier is a water filter that employs UV or Ultraviolet light to kill germs, bacteria, protozoa, cysts, and
other organisms in the water.
By projecting powerful UV or ultraviolet rays on the bacteria in the water, UV water purifiers kill them. The UV
Ultraviolet rays penetrate bacteria, viruses, and cyst cells and stop them from reproducing. Without it, these
organisms can’t reproduce and eventually die.
The UV water purifier light kills up to 99.99% of bacteria in water, making it a relatively simple but effective method.
In the kitchen, a typical UV water filter will consume around the same amount of electricity as a 40-watt light bulb.

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CITS : E & H - Electronics Mechanic - Lesson 160 - 179