Water Nuggets Practice Exam 2025 - Free Practice Questions and Study Guide

As the level of ammonia decreases in raw water, the formation of chloramines becomes a significant consideration. Chloramines are formed when chlorine reacts with ammonia, and their presence indicates that some amount of disinfection is occurring without reaching the breakpoint chlorination stage, where chlorine demand is satisfied and free chlorine remains.

When ammonia levels drop, it results in a decreased demand for chlorine. Consequently, this means less chlorine (Cl2) will need to be added to the water to achieve the breakpoint. This is important for ensuring effective disinfection while managing the potential formation of unwanted byproducts. The proper balance of chlorine and ammonia concentrations is crucial in water treatment to optimize both disinfection efficiency and the minimization of harmful compounds.

The other options presented do not accurately reflect the chemical dynamics that occur when ammonia levels change in raw water. For instance, the suggestion that THMs would fall to zero does not account for the fact that THMs, or trihalomethanes, can still form from other organic materials present in the water. Similarly, indicating that nothing measurable occurs or that the DPD (N,N-diethyl-p-phenylenediamine) would turn red does not capture the nuanced relationship between ammonia and chlorine during the disinfection process. Thus,