Which type of chemical is used primarily for short-term disinfection of drinking water?

Calcium hypochlorite is widely used for short-term disinfection of drinking water due to its ability to effectively kill bacteria, viruses, and other pathogens. It is a strong oxidizing agent and releases chlorine when dissolved in water, making it highly efficient in sanitizing water supplies quickly. This type of chemical is particularly advantageous in emergency situations or during short-term events, such as responding to water contamination or during natural disasters, because it is easily transportable and has a relatively long shelf life.

The other options, while they have their uses in water treatment, are not primarily known for short-term disinfection in drinking water. Sodium bisulfite is primarily used as a dechlorinating agent rather than a disinfectant. Chlorine dioxide, while effective as a disinfectant, is not as commonly used for short-term applications due to its handling requirements and the need for precise dosing. Bromine is generally used in pool sanitation and in some specific applications, but it is less effective than chlorine compounds for immediate drinking water disinfection.