Water Supplies Disinfection with Chlorination

Chlorine is a supplement and not a substitute to sand filtration
-It kills pathogenic bacteria
-But has no effect on spores and certain viruses (e.g. polio, viral hepatitis) except in high doses
In addition to being germicidal, it has other properties
-Oxidizes iron, manganese and hydrogen sulphide
-It destroys some taste and odour producing constituents
-It controls algae and slime organisms and aids coagulation
How does chlorine act as disinfectant?
When chlorine is added to water, it forms:
-Hydrochloric acid (HCl) and
-Hypochlorous acid (HOCl)
-HCL neutralizes the alkalinity of the water.
-The Hypochlorous acid ionizes to form hydrogen ions and hypochlorite ions (H^+, 〖OCl〗^-)
The disinfecting action is due to:
-hypochlorous acid and
-to some extent, due to hypochlorite ions
Chlorine disinfects best when the pH of water is around 7
-When the pH value exceeds 8.5, it is unreliable as a disinfectant (as 90% of the hypochlorous acid gets ionized to hypochlorite ions)
Fortunately, most waters have a pH value of 6 – 7.5

OT and OTA test: Orthotolidine (OT) test and Orthotolidine – Arsenite (OTA) test

Membrane processes in water purification: Membrane Processes in Treatment of Drinking Water

Super Chlorination and Break Point Chlorination: Super Chlorination and Break Point Chlorination (Disinfecting Polluted Water)

Slow sand filter: Slow Sand Filter (Biological Filter)

Rapid sand filter: RAPID Sand Filter (Mechanical Filter)

Purification of water at a large scale: Water Purification at a LARGE SCALE (for water supply)

Criteria for a Chemical to be Suitable as Water Disinfectant in Water Supplies: Criteria for a Chemical to be Suitable as Water Disinfectant in Water Supplies

Water Supplies Disinfection with Chlorination: Water Supplies Disinfection with Chlorination

Principles of Chlorination: 5 Principles of Chlorination

Methods of Chlorination in Water Supplies: Methods of Chlorination in Water Supplies

Horrock's Apparatus: Horrock’s Apparatus

Disinfection of well during emergency: Disinfection of Wells during an Emergency – The Double Pot Method

Double Pot method: Disinfection of Wells during an Emergency – The Double Pot Method

Disinfection of Wells: Disinfection of Wells

OT and OTA test: OT and OTA test

Domestic or Household Purification of Water: Domestic or Household Purification of Water