Which option is an alternative to free chlorine for disinfection?

Chloramine is commonly used as an alternative to free chlorine for disinfection in water treatment. It is formed by combining chlorine with ammonia and, unlike free chlorine, it provides a more stable residual that can last longer in the distribution system. This characteristic helps in maintaining disinfection over longer distances, ensuring that pathogens remain controlled by the time water reaches consumers.

Chloramine is particularly beneficial in reducing the formation of disinfection by-products (DBPs), which are often a concern with chlorine usage. Reducing DBPs is important for compliance with health regulations and for minimizing potential health risks to consumers. Additionally, chloramine is effective in controlling biofilms in the distribution system, contributing to overall water quality.

While other disinfection methods offer various advantages, chloramine is favored as a long-term residual option in many water systems transitioning away from free chlorine.