Which chlorination byproduct can cause a persistent odor in sewage when chlorine reacts with ammonia?

Prepare for the American Water Works Water Treatment Plant Operator Test. Study with multiple choice questions, each with hints and explanations. Get ready to excel!

When chlorine is added to wastewater that contains ammonia, it reacts to form chloramines. Under certain conditions this can produce a highly volatile chloramine called nitrogen trichloride (trichloramine), which can escape into the air and cause a persistent, strong odor in sewage. This is the odor you’re typically sensing even after chlorine demand has been met. The other substances listed aren’t formed in this particular reaction path: chlorine gas is not the byproduct here, hydrogen sulfide comes from anaerobic decay of organic matter, and nitrogen dioxide isn’t the persistent chloramine-related odor produced by chlorinating ammonia.