Muhammed, There ahs been ...

Muhammed,

There ahs been much good discussion below on determining the chlorine dosage.  I have a few closing thoughts:

1.  The water needs to be free of suspended solids (i.e., filtered) for chlorination to work.  Bacteria can hid inside of a solid and not be impacted by the chlorine outside the solid.

2.  Add chlorine until you hold a residual and continue checking that the residual is maintained.

3.  What else is in the water?  If this is an industrial source, is there any other chemicals in the water?  Heavy metals?  Is the tank suitable for storing drinking water?

4.  After applying the chlorine, you must mix it in and hold for the proper CT time (the time (T) needed varies depending on the concentration [C]).  One to two hours is typically adequate.

These are just my opinions.  I recommend you hire a qualified water treatment engineer to design your system.

Good luck and be careful.