What is the main reason chlorine dioxide is used for pre-chlorination?

Chlorine dioxide is primarily utilized for pre-chlorination due to its effectiveness in minimizing the formation of trihalomethanes (THMs), which are harmful disinfection by-products commonly associated with the chlorination process. When chlorine is used for disinfection, it can react with organic matter in water, leading to the production of THMs. Chlorine dioxide, on the other hand, reacts differently, significantly reducing the potential for THM formation.

This makes it an appealing choice for water treatment processes, particularly in systems where organic loads are high or where THMs are a concern due to regulatory standards. By using chlorine dioxide for pre-chlorination, water treatment facilities can enhance the safety and acceptability of drinking water while still effectively controlling pathogens.