Why is chlorine typically applied as a gas in water treatment?

Chlorine is typically applied as a gas in water treatment primarily because it is more economical to use in this form. When applied as a gas, chlorine allows for precise dosing and effective disinfection of large volumes of water. The gaseous form is less expensive, making it an attractive option for municipal water systems and large-scale applications.

In contrast, while other forms of chlorine, such as liquid sodium hypochlorite or solid calcium hypochlorite, can be utilized, they generally carry higher costs associated with storage, transportation, and handling. As a result, the use of gaseous chlorine is favored for both economic and operational efficiency in many treatment facilities.

Additionally, gaseous chlorine can dissolve rapidly in water, facilitating a swift reaction with pathogens, which enhances its efficacy as a disinfectant. Therefore, the choice to use chlorine gas is influenced significantly by cost-effectiveness alongside its proven disinfection capabilities.