Meaning of CHLORINATION OF WELL
“The process of using / addition of chlorine for disinfecting well water is called chlorination of well”.
The efficiency depends on
- Quality of water
- Concentration of chlorine
- Contact Period
III. Steps in Disinfection / Chlorination of Well
1. Find the volume of water of the well
2. Find the Amount of bleaching powder required
3. Dissolve bleaching powder in water
4. Delivery of Chlorine solution into well
5. Contact period
6. Orthotoludine Test
Mnemonic
1. Measurement of the Diameter of the well (d)
2, Measure the depth of water column (h)
3. AMOUNT of water / measure the depth of water column
4. CALCULATE / find the amount of Bleaching powder required. (Substitute
‘h’ and ‘d’).
5. MIXING / dissolving Bleaching powder in water.
6. ADDITION / delivery of Chlorine solution into the well
7. CONTACT PERIOD
8. ORTHOTOLUDINE TEST
I. MEASUREMENT of Diameter of well.
First step.
Measure the diameter of the well (d) in meter. (100 cm = 1 meter)
Done with the help of rope and measuring tape.
2. AMOUNT OF WATER / Measure the Depth of water column
Second step.
Measure the depth of water column (h ) in meter.
Done with the help of rope attached with a stone
Since all units are in meters, the answer will also be in Cubic meter.
So, to convert Cu.m to volume in liter, multiply it with ‘1000’
Volume of water of the well
If diameter (d) = π d² h/4 (π d2 h/250)
If radius (r)= π r² h x1000
= 3.14 x d² x h x 1000
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3. Calculate / find the amount of Bleaching powder required.
Estimate the Chlorine demand of the well water by ‘Horrock’s Apparatus’ and calculate the amount of bleaching powder required to disinfect the well.
Roughly, ‘2.5g’ of good bleaching powder would need for disinfecting 1000 liters of water.
This will give an approximate dose of 0.7mg of applied chlorine per liter of water.
4. MIXING / Dissolving Bleaching powder in water.
The bleaching powder to be added is first placed in a bucket ( not more than 100g in one bucket in water) and
Made into a thin paste by mixing with a little quantity of water.
Then more water is added with constant stirring till bucket is nearly 3- 4 th full of water.
The contents are stirred well and
Allowed to sediment for ‘5 - 10’ minutes
During this period, the lime settle down.
The supernatant solution, which is chlorine solution, which is transferred to another bucket and the chalk / lime is thrown away / discarded.
Note:
The lime should not poured into the well as it increases the hardness
of well water.
5. ADDITION / delivery of Chlorine solution in the well
The bucket containing chlorine solution is lowered in to the well, some distance below the water surface and
Well water is agitated by moving the bucket violently both vertically and laterally i.e. lowering and drawing up the bucket several times around the well.
This should be done several times so that the chlorine solution mixes intermittently with the water inside the well.
6. CONTACT PERIOD
A contact period of minimum 60 minutes (1 hour) should be allowed after chlorination to ensure destruction of pathogens before the water is drawn for use.
VII. ORTHOTOLUDINE TEST
At the end of one hour, the Orthotoludine arsenite test is done to detect the presence of free residual chlorine.
If it is less than 0.5mg/ liter of water, the chlorination procedure to be repeated before any water is drawn.
Wells are well disinfected at night, after the days draw off.
During epidemics of cholera / Water borne diseases, well must be disinfected every day (Super chlorination) with double doses of bleaching powder).
IV. Process of disinfection of water
When chlorine comes in contact with water, hydrochloric acid and Hypochloride acid are produced (H2O + Cl2 = HCl + HOCl).
Hypochloride acid is further ionized into Hydrogen ions and Hypochlorite ions and it is reversible’.
It destroy all the pathogens present in the water