Chlorine Disinfection Process Lab Report

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Chlorine and its Function in the Disinfection Process

Chlorine is one of the most widely used disinfectant. It is very effective for the deactivation of pathogenic microorganisms. Chlorine can be easily applied, measured and controlled. It is also relatively inexpensive.
Chlorine destroys pathogens such as bacteria and viruses by breaking the chemical bonds in their molecules. The chlorine compounds exchange atoms with other compounds, such as enzymes in bacteria and other cells. When enzymes come in contact with chlorine, one or more of the hydrogen atoms in the molecule are replaced by chlorine. This causes the entire molecule to change shape or fall apart. The then enzymes function improperly, causing the cell or bacterium will die.
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Since hypeochlorous acid is neutral it is able to penetrate the cell wall, rather than the negatively charged hypochlorite ion. Which results in the destruction of the pathogens. This cause the microorganisms to either die or suffer from reproductive failure.

The efficiency of disinfection is determined by the pH of the water. Disinfection with chlorine will take place optimally when the pH is between 5,5 and 7,5 (Lenntech, 2016).

Chlorine reacts with ammonia to for a series of chlorinate ammonia compounds called chlorimines. This includes monochlorimine (NH2Cl), dichlorimine (NHCl2) and trichloramine/ nitrogen trichloride (NCl3). The products of the reaction varies with the pH, ratio of Cl2 added to ammonia present, and contact time (Viljoen, 1996).
In recent years many water treatment facilities have switched to the use of chloramine in the disinfectant process due to the main reason that it is more stable then chlorine and therefor has a longer retention time which means it is more economical to
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