*2.5.5. Chemical*

Ozone is produced by applying high voltage electricity to a gap (tube) containing pure oxygen or filtered dry air (corona discharge method).

• With respect to interactions with pipe material, there are no concerns.

methanes (THM), aldehydes, ketoacidosis, and bromate).

product (DBP) is noticed [14].

water, which may not be available in the field [15].

*2.6.2. Limitations*

guaranteed.

*2.6.3. Process*

genic bacteria quickly [1].

*2.6.4. Equipment*

less in cost either than chlorine dioxide and ozone techniques.

• No by-products are formed (e.g., hemoglobin-associated acetaldehydes (HAA), trihalo-

Disinfection Methods

13

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

• By using UV light we can achieve the same log inactivation of Giardia and Cryptosporidium,

• When used in relation with chloramines, no formation of chlorinated disinfection by-

In underdeveloped countries, there are several limitations for UV disinfection. The major limitation is the energy requirement. In many systems, the electric power supply cannot be

A limitation might be that there is not even a single test available to examine the proper disinfection of the rays. It is only effective as a primary disinfectant as it does not leave any residues. It does not act as a secondary disinfectant as it does not work against reinfection in water.

A concern regarding the UV disinfection is chemical composition and the quality of microorganisms present in the influent water. Turbid, cloudy, or the water containing a large number of bacteria can be used to shield bacteria. Chemical composition is a basic problem as the water containing large amount minerals might cause coating on the lamp sleeve, thus reducing the effectiveness of the treatment. Phosphate injectors or water softeners can be used to prevent lamp coating. UV treatment is more effective on low turbid water or partially treated

UV disinfection units are used nowadays as water disinfection methods. The design is quite simple that consists of a UV light source that is enclosed in a transparent protective sleeve. The light source is mounted so that water can pass through a flow chamber so that UV rays can be both admitted and absorbed into the stream. No change in taste and color occur that is an advantage of this method. The contact time is also very short as these rays kill the patho-

UV disinfection systems should be properly shut down if the treatment is not needed for few days. The lamp needs to be warm-up for few minutes before turning on. Moreover, the plumbing system should be properly flushed when not in use. The whole plumbing system should be disinfected by a chemical (preferably chlorine) before relying on the process.

UV lights loses effectiveness with usage, the lamp should, therefore be properly cleaned on regular basis and replaced once in a year. It should be noted that a new lamp might lose its

**Figure 4.** Ozone contacting.

The high voltage electricity results in the formation of ozone by recombining oxygen. The reaction is as follows:

$$\text{\textbulletO}\_2 \rightarrow \text{\textbulletO}\_3$$

Ozone disinfects by oxidizing the cell walls of microorganisms, which then disintegrates (lyse), destroying the microorganism. This is a very different mechanism than with chlorine, which diffuses through the cell wall, making the cell susceptible to enzymatic attack [7] (**Figure 4**).
