Effectiveness of re-chloramination to control nitrification in chloraminated bulk waters

Abstract

AbstractManaging chloramine residuals in water distribution systems after the onset of nitrification is a major challenge for water utilities that employ chloramine as a disinfectant. One of the strategies adopted by utilities is re-chloramination, but its effectiveness may vary depending on the stage (immediately after the onset or later) at which re-chloramination is practiced. Therefore, a systematic study of the effectiveness of re-chloramination was conducted by collecting bulk water samples from full-scale and laboratory-scale water distribution systems. The findings of this study revealed that in addition to initial dose of chloramine residuals, effectiveness of re-chloramination largely depend on the stage at which re-chloramination is practiced. Comparatively slow chloramine decay rates were observed when re-chloramination was carried out just after the onset of nitrification or after chloramine residuals dropped close to zero. However, the recurrence of nitrification is inevitable if only single...