Water chlorination chemistry: nonmetal redox kinetics of chloramine and nitrite ion

We carried out a kinetic study of the reaction between iodide ion and various primary N-chlorarnines and found it to be First-order in the latter Experiments also showed the rate constant f o r t h e reaction to be directly proportional to the iodide and hydrogen ion concentrations The influence of the buffer concentration reveals the presence of general acid catalysis processes 0 1996 lohn Wiley &Sons, Inc

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“…Recent studies involving iodide [ 11, bromide [2], sulphite 13). cyanide [4], and nitrite [5] revealed C1+ ion to be transferred in the process.…”

Section: Introductionmentioning

confidence: 99%

Kinetic study of the reaction between iodide and N-chloramines

Antelo

Arce

Campos

et al. 1996

Int. J. Chem. Kinet.

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“…Nitrite also has some associated health risks as it can react with secondary amines to produce carcinogenic compounds, such as nitrosamines (19). The disappearance of nitrite from distribution systems is most often attributed to chemical oxidation by chloramine (20), which in turn produces more ammonia and nitrate. However, biological oxidation of nitrite to nitrate may occur if active NOB are present (7,35), which completes the biological nitrification process.…”

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confidence: 99%

Culture-Independent Techniques for Rapid Detection of Bacteria Associated with Loss of Chloramine Residual in a Drinking Water System

Hoefel

Monis

Grooby

et al. 2005

Appl Environ Microbiol

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Chloramination is often the disinfection regimen of choice for extended drinking water systems. However, this process is prone to instability due to the growth of nitrifying bacteria. This is the first study to use alternative approaches for rapid investigation of chloraminated drinking water system instability in which flow cytometric cell sorting of bacteria with intact membranes (membrane-intact fraction) (BacLight kit) or with active esterases (esterase-active fraction) (carboxyfluorescein diacetate) was combined with 16S rRNA genedirected PCR and denaturing gradient gel electrophoresis (DGGE). No active bacteria were detected when water left the water treatment plant (WTP), but 12 km downstream the chloramine residual had diminished and the level of active bacteria in the bulk water had increased to more than 1 ؋ 10 5 bacteria ml ؊1 . The bacterial diversity in the system was represented by six major DGGE bands for the membrane-intact fraction and 10 major DGGE bands for the esterase-active fraction. PCR targeting of the 16S rRNA gene of chemolithotrophic ammonia-oxidizing bacteria (AOB) and subsequent DGGE and DNA sequence analysis revealed the presence of an active Nitrosospira-related species and Nitrosomonas cryotolerans in the system, but no AOB were detected in the associated WTP. The abundance of active AOB was then determined by quantitative real-time PCR (qPCR) targeting the amoA gene; 3.43 ؋ 10 3 active AOB ml ؊1 were detected in the membraneintact fraction, and 1.40 ؋ 10 4 active AOB ml ؊1 were detected in the esterase-active fraction. These values were several orders of magnitude greater than the 2.5 AOB ml ؊1 detected using a routine liquid most-probablenumber assay. Culture-independent techniques described here, in combination with existing chemical indicators, should allow the water industry to obtain more comprehensive data with which to make informed decisions regarding remedial action that may be required either prior to or during an instability event.For extended drinking water systems, chloramine (in particular, monochloramine) is often the preferred disinfectant. Chloramine is less reactive than free chlorine, maintains an extended disinfection residual (45), and produces lower concentrations of disinfection by-products, such as trihalomethanes and haloacetic acids (5,23,28). Despite these advantages, the use of chloramine can introduce ammonia into a distribution system, both as excess ammonia from chloramine formation and as released ammonia from chloramine decay. These factors may lead to biological instability in such systems due to biological nitrification by nitrifying bacteria, such as the chemolithotrophic ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) (34,35).Nitrification episodes in chloraminated distribution systems are common, and there is evidence that 63% of medium and large utilities in the United States have experienced episodes of nitrification (45). Cunliffe (6) studied five chloraminated distribution systems in South Australia and found that 64...

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“…The emphasis of past studies on chloraminated systems has been on AOB, as the conceptual model of the escalation of nitrification episodes has involved incomplete nitrification, with nitrite evolving from AOB activity and accumulating in the water. Subsequent nitrite disappearance has been attributed to the chemical reaction between nitrite and chloramines (21,45) in which the production of nitrate and ammonia occurs, thereby increasing the ammonia available as a growth substrate for AOB. However, it is conceivable that NOB play an important role in the ecology of nitrification and biological regrowth in these systems.…”

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confidence: 99%

Ammonia- and Nitrite-Oxidizing Bacterial Communities in a Pilot-Scale Chloraminated Drinking Water Distribution System

Regan

Harrington

Noguera

2002

Appl Environ Microbiol

205

115

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Nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. The diversity of ammonia-oxidizing bacteria (AOB) and nitriteoxidizing bacteria (NOB) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (T-RFLP) analysis and 16S rRNA gene (ribosomal DNA [rDNA]) cloning and sequencing. For ammonia oxidizers, 16S rDNA-targeted T-RFLP indicated the presence of Nitrosomonas in each of the distribution systems, with a considerably smaller peak attributable to Nitrosospira-like AOB. Sequences of AOB amplification products aligned within the Nitrosomonas oligotropha cluster and were closely related to N. oligotropha and Nitrosomonas ureae. The nitriteoxidizing communities were comprised primarily of Nitrospira, although Nitrobacter was detected in some samples. These results suggest a possible selection of AOB related to N. oligotropha and N. ureae in chloraminated systems and demonstrate the presence of NOB, indicating a biological mechanism for nitrite loss that contributes to a reduction in nitrite-associated chloramine decay.Many drinking water utilities in the United States have implemented chloramination for secondary disinfection because chloramines are less reactive than free chlorine and have been demonstrated to produce lower concentrations of disinfection by-products, such as trihalomethanes and haloacetic acids (2,23,25). However, the addition of chloramines can lead to biological instability in a drinking water distribution system by promoting the growth of nitrifying bacteria, microorganisms that oxidize ammonia to nitrite and nitrate. Chloramination introduces ammonia to the distribution system both as excess ammonia from chloramine formation and released ammonia from chloramine decay. Ammonia-oxidizing bacteria (AOB) are able to grow on the residual and released ammonia in the presence of chloramines and produce nitrite and soluble organic compounds (29, 32). The AOB cell mass and the products of AOB activity deplete the residual disinfectant concentration by exerting a chloramine demand and may sustain the growth of nitrite-oxidizing bacteria (NOB) and heterotrophs. The resulting reduction in chloramine residual and development of a microbial community in the distribution system lead to water quality deterioration and violation of drinking water regulations (49, 50).Several studies have reported on the disinfection kinetics of AOB with chloramines (4, 18, 50; P. S. Oldenburg, J. M. Regan, G. W. Harrington, and D. R. Noguera, unpublished data). In general, the results of these investigations suggest that AOB should be inactivated effectively at typical chloramine exposure times and doses. Nonetheless, nitrification episodes are common in these systems, even in the presence of high chloramine residuals (4, 36). A survey of chloraminating utilities in the United States revealed that 63% of the utilities have...

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Water chlorination chemistry: nonmetal redox kinetics of chloramine and nitrite ion

Cited by 104 publications

References 13 publications

Kinetic study of the reaction between iodide and N-chloramines

Kinetic study of the reaction between iodide and N-chloramines

Culture-Independent Techniques for Rapid Detection of Bacteria Associated with Loss of Chloramine Residual in a Drinking Water System

Ammonia- and Nitrite-Oxidizing Bacterial Communities in a Pilot-Scale Chloraminated Drinking Water Distribution System

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