Estimation of chloramine decay in drinking water distribution systems

Abstract

Development of a means to identify and predict factors associated with chloramine decay in drinking water distribution systems could assist in providing targeted operational strategies which ensure regulatory compliance and ultimately lead to major cost-savings. In this study, novel benchscale pipe section reactors (PSRs) were utilized to evaluate the impact of source water (surface or groundwater), pipe material, pipe age, and flow velocity on chloramine decay in a distribution system in the Greater Toronto Area, Ontario, Canada. Batch tests in amber glass bottles quantified decay in treated water which were compared to low-and high-flow PSR experiments to elucidate the impact of water velocity and pipe material on monochloramine decay. Of the factors examined, pipe material and condition (e.g., old or new) were identified as the most critical. Overall, the results of this study reinforce the importance of determining the source of residual disinfectant decay when considering chloramination. iii ACKNOWLEDGMENTS This project was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) Chair in Drinking Water Research at the University of Toronto as well as the Regional Municipality of York, Ontario. York Region was consulted in designing, planning, and coordinating this study and has authorized the publication of this work. Thank you kindly to my supervisor, Dr. Robert Andrews, as well as to Dr. Susan Andrews and Dr. Michael McKie; your counsel guided me throughout my degree, and I am incredibly grateful for your leadership.

Depletion of ARGs in antibiotic-resistance Klebsiella, Pseudomonas and Staphylococcus in hospital urines by electro and photo-electro disinfection

“…On the one hand, the formation of hazardous chloro-species as chlorates and perchlorates was avoided due to the high complexity of urine media [64]. On the other hand, chloramines show higher stability than hypochlorite, being easier to measure as they maintain an acceptable residual concentration in solution over time [65]. Herein, the evolution of the concentration of total chloramines is shown in Fig.…”

Disinfection Residual Behaviour within Drinking Water Distribution Systems

“…For this reason, chloramine is sometimes used in DWDS with high water ages, where residual maintenance at the network extremities may present a challenge. However, the biological, chemical and physical characteristics of DWDS effect residual decay, predominantly pipe-wall interactions (with corrosion deposits and biofilms), reactions with naturally occurring compounds, such as total organic carbon (TOC) and elevated water temperatures [1], [4]- [8]. As a result, residuals can become depleted and drinking water quality may deteriorate during transit from the water treatment works (WTW) to customer taps [4].…”

“…Previous research into chloramine and chlorine DWDS residual maintenance is heavily focused on reaction kinetics and decay models [13], [14], either computational or alongside bench top scale reactors [7], [8]. There seems to be limited studies considering the impact of both pipe wall and bulk water conditions on residual decay out in the field, whereby disinfection residuals are examined between two points within a DWDS [15].…”

Nitrite Production by Nitrifying Bacteria in Urban Groundwater Used in a Chlorinated Public Bath System in Japan

“…Ammonium reacts with NaClO and converts it to chloramine, a type of combined chlorine ( Vikesland et al , 2001 ). Other substances, such as ferrous iron and natural organic matter, have been shown to contribute to the decay of chloramine ( Curling et al , 2022 ). These substances may have decreased the residual chlorine concentration.…”