Which of the following reasons are responsible for adoption of post chlorination of water?
1. chlorine demand is reduced
2. possibility of taste and odour formation is reduced
3. possibility of carcinogenic compounds is reduced
4. chloramines are formed
Post-chlorination is the practice of adding chlorine to water at the very end of the treatment process, right before it
enters the distribution system.
By this final stage, most of the organic matter, algae, and impurities have already been removed through sedimentation
and filtration.Because these organic materials are gone, adding chlorine at this point drastically minimizes the formation
of foul tastes, medicinal odours, and dangerouscarcinogenic compounds like Trihalomethanes (THMs). Furthermore,
the chlorine reacts with any remaining ammonia in the clean water to form chloramines, which are highly stable and
provide lasting disinfection as the water travels through the pipe network to consumers.In contrast, statement 1 is
incorrect because delaying chlorination to the final stage does not change or reduce the water's chemical chlorine
demand; it simply ensures that the chlorine applied is used efficiently for disinfection rather than reacting with raw
organic pollutants
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