Chlorine deactivates microorganisms through several mechanisms that can destroy most biological contaminants, including:
- Damaging the cell wall
- Altering the permeability of the cell (the ability to pass water in and out through the cell wall) • Altering the cell protoplasm
- Inhibiting the enzyme activity of the cell so it is unable to use its food to produce energy
- Inhibiting cell reproduction.
Chlorine is supplied as a gas, liquid and a solid / Granular / Tablet.
Chlorine as GAS LIQUID SOLID / TABLET
The gas is 100 percent elemental chlorine (Cl2), and is supplied in 150 lb. cylinders (10 inches in diameter and about 55 inches high) and in 2,000 lb. (ton) containers (30 inches in diameter and 82 inches high). The liquid is sodium hypochlorite (NaOCl) commonly used as laundry bleach. And the solid is calcium hypochlorite [Ca(OCl)2], available in granular form or as tablets.
Chlorine is available in a number of different forms: (1) as pure elemental gaseous chlorine (a greenish-yellow gas possessing a pungent and irritating odor that is heavier than air, nonflammable, and nonexplosive), which, when released to the atmosphere, is toxic and corrosive; (2) as solid calcium hypochlorite (in tablets or granules); or (3) as a liquid sodium hypochlorite solution (in various strengths). The strength of one form of chlorine compared to the others that must be used for a given water system depends on the amount of water to be treated, configuration of the water system, local availability of the chemicals, and skill of the operator. One of the major advantages of using chlorine is the effective residual that it produces. A residual indicates that disinfection is completed, and the system has an acceptable bacteriological quality. Maintaining a residual in the distribution system helps to prevent regrowth of those microorganisms that were injured but not killed during the initial disinfection stage.