**2.2. Chlorination (sodium hypochlorite solution)**

Sodium hypochlorite is used as a bleaching agent, mostly to bleach papers or textiles, and as a disinfectant in solution. The solution generally contains 10–15% of the available chlorine, but rapidly loses its force in storing process. Regular controlled environment is needed as the solution is affected greatly by the pH, light, heat, and heavy metals [6].

### *2.2.1. Advantages*


Consequently, to aid in the prevention of gasification, the dosing arrangements must have a positive head on the pump suction (with pump inlet always below the minimum tank liquid level). In addition, piping system configurations which will trap sodium NaOCl between two

A calibration cylinder, a pulsation damper, a pressure relief valve, and a loading valve are the main components of a dosing system. Automatic auto-degas valves systems are also provided by some dosing pump suppliers. NaOCl is dosed either through a spreader bar submerged within an open channel or through an injection fitting (pressurized pipes). The pulsation damper and the dosing pump should be placed close to each other. Pulsation damping also helps in improving dispersion. A loading valve should also be provided in systems where the back pressure at the pump delivery side is not sufficient (<0.7–1.0 Bar), till a suction demand

For protecting the diaphragm from rupturing, a PRV (pressure relief valve) should also be provided on the delivery side of the pump. PRV's operation must be detected and alarmed: e.g., the outlet of the valve could be directed to a small "catch-pot," equipped with a float switch. All the systems or pumps which are shut down should contain methods to relieve any

As sodium hydroxide (NaOH) is used in its manufacturing, the pH of NaOCl is high. Extreme

product can lead to lower flow rates, reduced pipe diameter, reduce pump capacities, and

NaOCl solution is a corrosive liquid with a high pH, i.e., 12. So, general precautionary measures for dealing with corrosive materials should be used such as avoiding metal contact, including stainless steel. These solutions might contain chlorate. Due do product degradation, chlorate can be formed during the processes of manufacturing and storage of sodium hypochlorite. The formation of chlorate and the degradation of NaOCl are directly related to each other. By reducing the degradation of NaOCl, the formation of chlorate can be minimized by avoiding high temperatures, reducing light exposure, and through limiting storage time. Spill containment should be provided for the NaOCl storage tanks. Typical spill containment structures include no uncontrolled floor drains, containment for the entire contents of the largest tank (along with the freeboard for rainfall/

NaOCl solution (or liquid bleach) is a solution with 5–15% concentration of chlorine. It is used as bleaching and cleaning agent. It is also used extensively as water disinfectant, but it may not be the most economical solution as it is more expensive than gas. Being liquid, it can be handled easily than gas or calcium hypochlorite, but it is limited by its lack of stability and corrosive nature. It can be produced easily. Continuous supply of salt and electricity is needed for onsite generation of liquid bleach. Liquid bleach has a better POU application

fire sprinklers), and separate containment areas for each incompatible chemical [9].

because of its availability and relative manageability [1] (**Figure 2**).

present), as the highly alkaline

Disinfection Methods

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http://dx.doi.org/10.5772/intechopen.80999

closed isolation valves or check valves should be avoided.

care is needed when using hard waters (or waters with CO<sup>2</sup>

valve is installed on the suction side.

scale formation at dosing points [8].

pressure buildup.

*2.2.4. Equipment*

*2.2.5. Chemicals*

**Figure 1.** Chlorination by gas method.

