Trihalomethanes formation in point of use surface water disinfection with chlorine or chlorine dioxide tablets

Werner, David; Valdivia-Garcia, Maria; Weir, Paul; Haffey, Mark

doi:10.1111/wej.12209

Cited by 18 publications

(12 citation statements)

References 13 publications

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“…However, surprisingly, the mean level of tTHMs decreased between 5 and 10 min reaction time, at free chlorine concentrations 3 and 5 mg L −1 . This is contradictory to other published studies which demonstrate an increase in tTHM formation in reaction times in excess of 10 min (i.e., hours, days) (Brown et al, 2010;Ghebremichael et al, 2011;Saidan et al, 2013;Werner et al, 2016). It is postulated that this observed decline could be due to the hydrolysis, or dehalogenation of already formed tTHMs present in solution (Mabey and Mill, 1978;Rahman, 2015;Abusallout et al, 2017), although, it is unknown the extent to which these reactions can occur over such a short contact time (i.e., 10 min).The decline in tTHMs was not observed with either HOCl or ECAS, probably due to a combination of the low tTHM concentrations formed, the rapid reaction kinetics of these agents, and the lower pH of the disinfectant solutions (Robinson et al, 2011;Liao et al, 2017).…”

Section: Resultscontrasting

confidence: 57%

“…Chlorine is the most widely used disinfectant in drinking water treatment due to its availability, low cost, and broad spectrum antimicrobial efficacy (Rodriguez and Serodes, 2001;Farghaly et al, 2013;Kumari and Gupta, 2015). Decentralized point-of-use (POU) drinking water treatment systems typically utilize alternative disinfectant solutions (Mbilinyi et al, 2005;Peter-Varbanets et al, 2009;Domènech, 2011;Attisani, 2016;Carratalà et al, 2016;Pooi and Ng, 2018) or chlorine release tablets (Jain et al, 2010;Werner et al, 2016), rather than conventional chlorination solutions (i.e., NaOCl) for the production of biologically safe water. Alternatives to conventional chlorination are adopted due to quicker disinfection times, ease of transport and storage (Clasen and Edmondson, 2006;Jain et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Trihalomethane Formation Using Chlorine-Based Disinfectants Within a Model System; Applications Within Point-of-Use Drinking Water Treatment

Clayton

Thorn

Reynolds

2019

Front. Environ. Sci.

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Point-of-use (POU) drinking water treatment systems provide solutions for communities where centralized facilities are unavailable. Effective POU systems treat and reduce the number of pathogens in POU water supplies often employing disinfection. Chlorine disinfection results in the formation of disinfection by-products (DBPs), such as trihalomethanes (THMs), through the reaction of chlorine with natural organic matter (NOM) over time. Although THMs are known to be harmful to human health, little is known about their production within POU systems. This study compares the disinfectants; Electrochemically Activated Solutions (ECAS), hypochlorous acid (HOCl), and sodium hypochlorite (NaOCl), with respect to their potential to produce THMs within POU drinking water systems. Headspace solid-phase microextraction (HS-SPME) gas chromatography mass spectrometry (GC-MS) was utilized to quantify THMs in treated water samples containing NOM (Suwannee River humic acid, 4 mg L −1). All disinfection treatments were matched to free chlorine concentrations of 1, 3, and 5 mg L −1 , using reaction times of 1, 5, and 10 min. THMs were produced at free chlorine concentrations of 5 mg L −1 and at reaction times of 5 and 10 min for all disinfectants. ECAS or HOCl, resulted in the formation of significantly lower total THM concentrations across all reaction times and free chlorine concentrations, compared to NaOCl. ECAS can be generated at the POU requiring only water, salt and energy for production, and this study demonstrates that its use results in reduced formation of THMs, compared with NaOCl. Further work is required to replicate these findings within scaled-up POU water treatment systems.

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Section: Resultscontrasting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Comparison of Trihalomethane Formation Using Chlorine-Based Disinfectants Within a Model System; Applications Within Point-of-Use Drinking Water Treatment

Clayton

Thorn

Reynolds

2019

Front. Environ. Sci.

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“…Samples were collected after 0,6,19,26,34,43, 56 days of operation and directly analysed for anions (ion exchange chromatograph Dionex ICS-1000, Sunnyvale, CA), dissolved organic and inorganic carbon (Shimadzu 5050A, Japan) and ammonium (NH 4 þ ) on a Spectroquant ® Pharo 300 spectrophotometer (Merck, USA) using Spectroquant ® test kits (Merck,USA). (Werner et al, 2016) after 1, 6 and 23 h of contact time following a protocol of the University of Massachusetts (Reckhow, 2006). The amount of THMs formed was normalised by the amount of DOC initially present in the water.…”

Section: Sampling and Chemical Analysesmentioning

confidence: 99%

Medium shapes the microbial community of water filters with implications for effluent quality

et al. 2018

Self Cite

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a b s t r a c tLittle is known about the forces that determine the assembly of diverse bacterial communities inhabiting drinking water treatment filters and how this affects drinking water quality. Two contrasting ecological theories can help to understand how natural microbial communities assemble; niche theory and neutral theory, where environmental deterministic factors or stochastic factors predominate respectively. This study investigates the development of the microbial community on two common contrasting filter materials (quartz sand and granular activated carbon-GAC), to elucidate the main factors governing their assembly, through the evaluation of environmental (i.e. filter medium type) and stochastic forces (random deaths, births and immigration). Laboratory-scale filter columns were used to mimic a rapid gravity filter; the microbiome of the filter materials, and of the filter influent and effluent, was characterised using next generation 16S rRNA gene amplicon sequencing and flow-cytometry. Chemical parameters (i.e. dissolved organic carbon, trihalomethanes formation) were also monitored to assess the final effluent quality. The filter communities seemed to be strongly assembled by selection rather than neutral processes, with only 28% of those OTUs shared with the source water detected on the filter medium following predictions using a neutral community model. GAC hosted a phylogenetically more diverse community than sand. The two filter media communities seeded the effluent water, triggering differences in both water quality and community composition of the effluents. Overall, GAC proved to be better than sand in controlling microbial growth, by promoting higher bacterial decay rates and hosting less bacterial cells, and showed better performance for putative pathogen control by leaking less Legionella cells into the effluent water.

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“…Finally, when chlorinated during potable water treatment, high concentrations of DOC can lead to the formation of harmful disinfection by-products, including trihalomethanes (THMs; Chow, Kanji, & Gao, 2003). THM concentrations in potable water are strictly regulated; for example, the European Union limit is 100 μg L −1 for total THMs, whereas the World Health Organisation recommends concentration limits for individual THMs of between 60 and 300 μg L −1 (Werner, Valdivia-Garcia, Weir, & Haffey, 2016). Increased DOC concentrations therefore present a problem to water companies due to the cost associated with its removal and penalties for exceeding regulatory limits (Brooks, Freeman, Gough, & Holliman, 2015).…”

Section: Introductionmentioning

confidence: 99%

Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

Peacock

Jones

Futter

et al. 2018

Hydrological Processes

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The globally widespread drainage of peatlands has often been shown to lead to increased concentrations and fluxes of dissolved organic carbon (DOC) in streams and rivers. Elevated DOC concentrations have implications for carbon cycling, ecosystem functioning, and potable water treatment. Peatland rewetting, principally through ditch blocking, is often carried out with the expectation that this will reduce DOC concentrations. Uncertainty still remains as to whether drainage, or its reversal via ditch blocking, will also lead to changes in the molecular composition of DOC/dissolved organic matter (DOM), which have the potential to affect downstream processing and treatability of U.K. drinking water supplies. To investigate this question, we used a replicated experiment consisting of 12 parallel ditches on an upland bog and took samples of ditch water, pore water, and overland flow water for 4 years. After a brief preblocking baseline period, eight ditches were blocked using two methods. A complementary suite of optical metrics, chemical measurements, and analytical techniques revealed that ditch blocking had no consistent effect on DOM quality, up to 4 years after blocking. Where significant differences were found, effect size calculations demonstrated that these differences were small and would therefore have minimal impact upon water treatability. Furthermore, some differences between ditches were evident before blocking took place, highlighting the need for robust baseline monitoring before intervention. Based on our results from a hillslope‐scale experiment, we were unable to identify clear evidence that peatland ditch blocking will deliver benefits in terms of DOM treatability in potable water supplies, although we also did not find any evidence of short‐term deterioration in water quality during the restoration period. We conclude that, although peatland restoration can be expected to deliver other benefits such as reduced carbon loss and enhanced biodiversity, it is doubtful whether it will lead to improvements in drinking water treatability.

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Trihalomethanes formation in point of use surface water disinfection with chlorine or chlorine dioxide tablets

Cited by 18 publications

References 13 publications

Comparison of Trihalomethane Formation Using Chlorine-Based Disinfectants Within a Model System; Applications Within Point-of-Use Drinking Water Treatment

Comparison of Trihalomethane Formation Using Chlorine-Based Disinfectants Within a Model System; Applications Within Point-of-Use Drinking Water Treatment

Medium shapes the microbial community of water filters with implications for effluent quality

Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

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