Environmental Engineering Reference
In-Depth Information
DID YoU KNoW?
Organic matter, including microorganisms, reacts with chlorine to pro-
duce chloroorganic compounds, which show as residual chlorine and
can cause taste and odor problems.
Disinfection Methods
Although chlorination is the best known and the most common disinfection
method, other methods are available and can be used in various situations.
The three general types of disinfection are
Heat treatment —Probably one of the first methods employed to disin-
fect water was to boil it. For small quantities of water, boiling water
is still a good emergency procedure to use.
Radiation treatment —Uses ultraviolet radiation to disinfect water.
Chemical treatment —Employs the use of chemicals to disinfect water.
Examples of chemical disinfectants include oxidizing agents such
as chlorine, ozone, bromine, iodine, and potassium permanganate;
metal ions such as silver, copper, and mercury; and acids and alkalis.
Obviously, several different disinfectants are available for use in treating
water, and we'll discuss several of these in detail in subsequent sections.
For now, it is important to understand that, even though several choices are
available, whichever disinfectant is chosen must meet certain criteria—more
specifically, the disinfectant chosen must be effective for disinfecting water
(and wastewater) and must possess certain desirable characteristics.
Desirable Characteristics of a Disinfectant
1. It must act in a reasonable time.
2. It must act as temperature or pH changes.
3. It must be nontoxic.
4. It must not add unpleasant taste or odor.
5. It must be readily available.
6. It must be safe and easy to handle and apply.
7. It must be easy to determine the concentration of.
8. It must be able to provide residual protection.
9. Pathogenic organisms must be more sensitive to the disinfectant
than are nonpathogens.
10. It must be capable of being applied continually.
11. The amount applied must be sufficient to produce a safe water.
 
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