AWWA JAW61920

Nitrification is a common problem faced by utilitiesusing chloramines for distribution system residual maintenance.Nitrification involves the growth of ammonia-oxidizingbacteria and the resulting production ofnitrite, which exerts a chloramine demand. This canlead to a sometimes precipitous loss of chloramine.Once nitrification becomes established, it can be difficultto bring under control. This study was undertakento help develop tools for dealing with nitrification.This article assesses the usefulness, using bothbench- and full-scale data, of a previously proposedcriterion of 0.05 mg/L nitrite-nitrogen as a criticalthreshold for confirming nitrification in chloraminateddistribution systems. In this study, the investigatorsfound that this level of nitrite-nitrogen has value indetecting nitrification, but that the 0.05 mg/L nitrite-nitrogenlevel is too high to predict nitrification beforeit becomes well established. A loss of total chlorine ormonochloramine residual, however, could give earlywarning of a potential nitrification episode.The authors conclude that, for utilities concernedabout nitrification, multiple water quality parametersshould be analyzed simultaneously, if possible, todevelop time-series trends specific to a given waterutility. If adequate resources are not available to testfor a suite of parameters, total chlorine residual datacan serve as an early warning sign of potential nitrification.Drops in total chlorine residual should then instigateadditional, targeted analyses (such as nitrite andammonia, among others). Includes 24 references, tables, figures.

Product Details

Edition:

Vol. 97 - No. 7

Published:

07/01/2005

Number of Pages:

14

File Size:

1 file , 340 KB