Kinetics of chlorine and chloramine reactions in reverse osmosis permeate and their impact on radical formation during UV/chlorine advanced oxidation for potable reuse

Copyright © 2024. Published by Elsevier Ltd..

Knowledge of the speciation of chlorine and chloramines in reverse osmosis (RO) permeate is needed to estimate the performance (i.e., pollutant log reduction) of subsequent UV/chlorine advanced oxidation processes (AOPs). To accurately predict the speciation, a previously reported breakpoint chlorination kinetic model was experimentally validated for pH 5.5 and reaction times < 3 min and used to predict the kinetics of breakpoint chlorination in RO permeate. The predictions showed that eliminating chloramines by adding chlorine at a dose beyond the chlorine-to-nitrogen (Cl/N) breakpoint ratio is not practical due to the high breakpoint Cl/N ratio for RO permeate (∼3.0 molar ratio) and an estimated > 40 min reaction time. The conversion from monochloramine (NH2Cl) to dichloramine (NHCl2) is the major process involved, and either or both free chlorine and chloramines may be the major species present, depending on the Cl/N ratio. Model simulations showed that increasing the oxidant dose may not always enhance the performance of UV/chlor(am)ine in RO permeate, due to the need for a low free chlorine dose for optimal •OH exposure in RO permeate. Further UV/AOPs modelling showed that it is important to control the NH2Cl concentration to improve the UV/AOP performance in RO permeate, which may be achieved by extending the reaction time after chlorine is added or increasing the applied Cl/N ratio (e.g., increasing chlorine dose). However, these measures only enhance the pollutant percentage removal by about 5 % under the conditions modelled. A simulation tool was developed and is provided to predict the speciation of chlor(am)ine in RO permeate.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:254

Enthalten in:

Water research - 254(2024) vom: 01. Apr., Seite 121433

Sprache:

Englisch

Beteiligte Personen:

Chen, Tianyi [VerfasserIn]
Mackey, Erin [VerfasserIn]
Andrews, Susan [VerfasserIn]
Hofmann, Ron [VerfasserIn]

Links:

Volltext

Themen:

4R7X1O2820
Chloramine
Chloramine speciation
Chloramines
Chlorine
Journal Article
KW8K411A1P
N762921K75
Nitrogen
Reverse osmosis permeate
UV/chlorine
Water Pollutants, Chemical
Water reuse

Anmerkungen:

Date Completed 08.04.2024

Date Revised 08.04.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.watres.2024.121433

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM369513304