Which disinfectant has the longest lasting residual?

Which disinfectant has the longest lasting residual?

• A. Chloramine
• B. Free chlorine
• C. Ozone
• D. UV

Answer: (A)

Chloramine is recognized for having the longest lasting residual among common disinfectants used in water treatment. This characteristic is particularly beneficial for ensuring that water remains disinfected throughout the distribution system, which can be miles long and may have varying conditions that affect disinfection efficacy. Chloramine is a compound formed by combining chlorine and ammonia. This modification allows it to persist longer in the water supply compared to free chlorine, which has a relatively shorter residual time due to its reactivity and tendency to dissipate more quickly. While ozone is an effective disinfectant known for its powerful oxidation capabilities, it does not provide a residual effect in the same way as chloramine and is generally used for point-of-use treatments rather than for maintaining long-term disinfection in distribution systems. Likewise, ultraviolet (UV) light is also highly effective for disinfection but does not produce a residual that can continue to provide protection once the treatment has ended. In summary, chloramine's stability and persistence in a water distribution system make it the preferred choice for maintaining long-lasting residual disinfection, which is crucial for safeguarding public health.

Chloramine is recognized for having the longest lasting residual among common disinfectants used in water treatment. This characteristic is particularly beneficial for ensuring that water remains disinfected throughout the distribution system, which can be miles long and may have varying conditions that affect disinfection efficacy.

Chloramine is a compound formed by combining chlorine and ammonia. This modification allows it to persist longer in the water supply compared to free chlorine, which has a relatively shorter residual time due to its reactivity and tendency to dissipate more quickly. While ozone is an effective disinfectant known for its powerful oxidation capabilities, it does not provide a residual effect in the same way as chloramine and is generally used for point-of-use treatments rather than for maintaining long-term disinfection in distribution systems. Likewise, ultraviolet (UV) light is also highly effective for disinfection but does not produce a residual that can continue to provide protection once the treatment has ended.

In summary, chloramine's stability and persistence in a water distribution system make it the preferred choice for maintaining long-lasting residual disinfection, which is crucial for safeguarding public health.