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This study analysed the spatial and temporal occurrence of 29 disinfection by-products (DBPs) formed by chlorination and chloramination. Four full-scale treatment works, and distribution system locations were sampled, and the results were compared with laboratory-based simulated distribution system (SDS) tests. The DBPs monitored incorporated 4 trihalomethanes (THMs), 9 haloacetic acids (HAAs), 7 haloacetonitriles (HANs) and 9 haloacetamides (HAcAms). For the first time, SDS tests were shown to successfully simulate the levels and speciation of HANs and HAcAms in both chlorinated and chloraminated systems. While THM and HAA concentrations generally increased with water age, HAN and HAcAm concentrations fluctuated and resulted in less pronounced overall increases. To explore the impact of switching the disinfectant in distribution, free chlorine and chloramines were applied in the SDS tests, which showed that chloramination not only reduces the yields of THMs (by 34%) and HAAs (by 49%), but also HANs (by 61%) and HAcAms (by 51%), although it shifts speciation towards more brominated HAAs, HANs and HAcAms species when compared against chlorination. Overall, the aim of the study was to demonstrate that SDS tests can be recommended for the simultaneous estimation of THM, HAA, HAN and HAcAm concentrations in distribution systems and to assess the effect of potential DBP minimisation strategies, such as switching the disinfectant in distribution.

The aim of this study was to investigate the influence of UV/H2O2 advanced oxidation process on the natural organic matter content and disinfection by-products formation potential of different water matrices. Three water matrices (two natural waters and a synthetic humic acid solution) with different natural organic matter characteristics and concentrations were analysed. The carbonaceous disinfection by-products: trihalomethanes, haloacetic acids and haloketones, as well as nitrogenous disinfection by-products: haloacetonitriles and chloropicrin were investigated after chlorination. The UV/H2O2 treatment resulted in significant trihalomethane and haloacetic acids precursors removal (up to 53% and 30%, respectively) in humic acid solution in conditions ≥ 1.0 mg H2O2/mg DOC, in combination with a dose of UV irradiation ≥ 3000 mJ/cm2. Under the same reaction conditions, in natural groundwater rich in hydrophobic natural organic matter, the advanced process was less effective in DBP precursors removal. On the other hand, the advanced process was very effective in trihalomethaneprecursors removal (up to 76%) in groundwater with hydrophyilic natural organic matter. Haloketones were formed after treatment in very low concentrations. Nitrogenous disinfection by-products were only formed in the natural water containing hydrophilic organic matter, during the advanced process at 3.0 mg H2O2/mg DOC. The UV/H2O2 process resulted in negligible organic matter mineralization, but increased the brominated disinfection by-products formation in waters with low to medium bromide contents. It was concluded that under the same advanced oxidation process reaction conditions different natural organic matter structures showed different reactivities with chlorine toward the formation of the investigated disinfection by-products.

Algal organic matter (AOM) is considered to be threatening for the consumption of disinfectants and the formation of disinfection by-products (DBPs) during the disinfection process. Incompatible parameters in the conventional pretreatment of algal-laden water will lead to counterproductive results, such as AOM release. Therefore, the generation of AOM and its conversion to DBPs during pretreatment should be observed. The characteristics of DBPs from extracellular organic matter (EOM) and intracellular organic matter (IOM) were epitomized and simulation experiments were conducted in deionized (DI) water and source water under pretreatment conditions. Differences in DBP formation between the different backgrounds during chlorination and powdered activated carbon (PAC) treatment were investigated. Instead of monotonous excitation-emission matrix (EEM) spectra, molecular weight (MW) fractionation was simultaneously applied to elucidate the mechanisms of chlorination and PAC adsorption on AOM-based DBPs. The fluorescence regional integration (FRI) EEM results showed a clear correlation between the fluorescent properties and MW distribution of AOM. A decreasing trend was observed after a rapid increase in fluorescence intensity during the chlorination and PAC treatment of water samples in the simulation experiments in deionized (DI) water and source water. The DBP formation potential (FP) in the source water was consistent with the change in AOM during chlorination and PAC adsorption. In addition, EEM showed decent predictability of AOM-based trihalomethanes (THM) FPs (R2 = 0.77–0.99) invoking a combination with MW fractionation. Macromolecular protein compounds were highly correlated with the formation of dichloroacetonitrile (DCAN) (R2 = 0.89–0.98). These post-mortems results imply that EEM spectra are a useful tool for identifying AOM-based precursors to reveal the accurate environmental fate and risk assessments of AOM.

Providing safe tap water while limiting the occurrence of disinfection by-products (DBPs) is probably one of the most challenging aspects of environmental chemical engineering within the urban water cycle. In the present work, an investigation about this challenge for the real water conditions of a full-scale drinking water treatment plant has been carried out. Five different and well-known technologies (four different aeration procedures, coagulation, hydrogen peroxide dosage, ion exchange and ultrafiltration) were studied in a real surface water matrix from an engineering point of view. A preliminary estimation of operation costs was also included. The study was focused primarily on trihalomethanes (THMs) and bromate, the DBPs currently regulated by the Spanish legislation, under the real treatment conditions of a drinking water treatment plant that distributes water to 100,000 inhabitants from a surface water reservoir. Based on the results, agitation aeration exhibited the greatest performance to remove THMs directly (86.46 % of removal). Ion exchange resin showed the best potential to inhibit their formation by 100 % bromide removal. Moreover, hydrogen peroxide dosage showed outstanding results in tests performed at full-scale for preventing the formation of bromate in the ozonation stage by 60 %. This was also the cheapest technology according to the dosage cost analysis performed, with 0.01 €·m−3. Thus, this investigation about the elimination of DBPs can be used as a reference to select the optimal treatment technology for limiting their occurrence under real working conditions for full-scale drinking water treatment plants., Proporcionar agua del grifo segura y al mismo tiempo limitar la aparición de subproductos de la desinfección (DBP) es probablemente uno de los aspectos más desafiantes de la ingeniería química ambiental dentro del ciclo urbano del agua. En el presente trabajo se ha llevado a cabo una investigación acerca de este desafío para las condiciones reales del agua de una planta de tratamiento de agua potable a gran escala. Se estudiaron cinco tecnologías diferentes y bien conocidas (cuatro procedimientos diferentes de aireación, coagulación, dosificación de peróxido de hidrógeno, intercambio iónico y ultrafiltración) en una matriz de agua superficial real desde el punto de vista de la ingeniería. También se incluyó una estimación preliminar de los costos de operación. El estudio se centró principalmente en los trihalometanos (THM) y el bromato, los SPD actualmente regulados por la legislación española, bajo las condiciones reales de tratamiento de una planta de tratamiento de agua potable que distribuye agua a 100.000 habitantes desde un depósito de agua superficial. Con base en los resultados, la aireación por agitación exhibió el mayor rendimiento para eliminar los THM directamente (86,46 % de eliminación). La resina de intercambio iónico mostró el mejor potencial para inhibir su formación mediante la eliminación del 100 % del bromuro. Además, la dosificación de peróxido de hidrógeno mostró resultados sobresalientes en pruebas realizadas a escala real para prevenir la formación de bromato en la etapa de ozonización en un 60 %. Esta fue también la tecnología más barata según el análisis de costes de dosificación realizado, con 0,01 €·m −3. Por lo tanto, esta investigación sobre la eliminación de DBP se puede utilizar como referencia para seleccionar la tecnología de tratamiento óptima para limitar su aparición en condiciones reales de trabajo para plantas de tratamiento de agua potable a gran escala.

Natural organic matter (NOM) has always been considered the main precursor of disinfection by-products (DBPs) during the chlorine disinfection of drinking water. This research focuses on investigating the correlation between the functional group (carboxyl and carbonyl groups) content of NOM and the formation of trichloromethane (TCM) and chloral hydrate (CH). The quantitative determination of carboxyl groups, carbonyl groups, TCM, and CH were conducted during the drinking water treatment processes with different coagulant dosages and with/without pre-oxidation by KMnO4 or NaClO. The most appropriate coagulant for the removal of conventional components was polyaluminum chloride (PAC), and the dosage was 110 mg/L. Up to 43.7% and 14.5% of the carboxyl and carbonyl groups, respectively, were removed through the coagulation and sedimentation processes, which can be enhanced by increasing PAC dosage. The filtration process further increased the removal rates of these two functional groups to 59.8% and 33.5%, respectively. The formation potential of the TCM and CH decreased as the PAC dosage increased. Pre-oxidation by KMnO4 (0.8–1.0 mg/L) effectively controlled the formation of DBPs while increasing the carboxyl and carbonyl group content. Pre-oxidation by NaClO decreased the formation of TCM rather than CH, and a suitable amount (0.5–1.0 mg/L) decreased the carboxyl and carbonyl groups. It was found that there was a good linear correlation between carboxyl groups and TCM and CH. The linear fit R2 values of the carboxyl groups to TCM and CH were 0.6644 and 0.7957, respectively. The linear fit R2 values of the carbonyl groups to TCM and CH were 0.5373 and 0.7595, respectively.

The objective of this study was to investigate the effects of combined low-pressure ultraviolet (UV)irradiation and chlorination on the formation of disinfection by-products (DBPs) from different dissolved organic matter (DOM) as DBP precursors. Commercially available humic acid (HA), extracellular organic matter (EOM) from green algae, cyanobacteria, and diatom, namely Scenedesmus quadricauda (SQ), Merismopedia sp. (Msp), and Phaedactylum tricornutum (PT), were used as the sources of DOM. The DBP formation increased with increasing total residual chlorine; EOM from PT presented the highest formation potential followed by HA, Msp, and SQ. The low dosage of 40 mJ/cm2 UV irradiation is insignificant to change the DBP formation from HA and SQ; however, it decreased the DBP formation from bromide-containing EOM of PT and promoted the DBP formation from EOM of Msp at various total residual chlorines. The DBP formation of each DOM correlated well with total residual chlorine. The maximum DBP formation potential (DBPFP) reduction of 42.25 and 13.75% for haloacetic acid formation potential (HAAFP) and trihalomethane formation potential (THMFP) was obtained at the UV irradiation dosage of 300 mJ/cm2 for EOM of PT. However, for the EOM derived from Msp, a maximum increase of 58.1 and 51.1% for HAAFP and THMFP was observed after UV-chlorination. HIGHLIGHTS Disinfection by-product (DBP) formation increased linearly with total residual chlorine from 0.28 to 1.02 mg/L.; Ultraviolet (UV) irradiation did not significantly alter the DBP formation from humic acid and algal organic matter (AOM) of Scenedesmus quadricauda.; The haloacetic acid formation potential (HAAFP) and trihalomethane formation potential (THMFP) decreased by 42.25 and 13.75%, respectively, under the UV irradiation dosage of 300 mJ/cm2 for AOM of Phaedactylum tricornutum, while the maximum increment of 58.1 and 51.1% for HAAFP and THMFP were observed from the AOM of Merismopedia sp.

While disinfection ensures the destruction of pathogenic microorganisms, the disinfectant substances used react with some organic and inorganic substances in water, causing the formation of disinfection by-products. Some disinfection by-products have been classified as carcinogenic by the Environmental Protection Agency (EPA). Haloacetic acids are one of the disinfection by-product groups that have been detected in drinking water and are carcinogenic. It is commonly believed that bottled water, which is being increasingly consumed worldwide, does not contain environmental pollutants. For this reason, research on bottled water is limited. In this study, the amount of 9 haloacetic acids and dalapon were investigated in 28 different branded bottled water samples collected from a market. As a result of the study, the total haloacetic acid concentrations were found to be from 2.13 to 7.56 μg/L, and the dalapon concentration was < detection limit-12.47 μg/L. At least three different haloacetic acids were detected in each sample analyzed. It was determined that the threshold values given by the EPA and the World Health Organization (WHO) were not exceeded. It has been observed that bottled waters, which are generally considered to be of higher quality than mains water, contain haloacetic acids and dalapon at low concentrations. A health risk assessment was performed for dalapon and trichloroacetic acid (TCAA). A low non-carcinogenic risk and tolerable carcinogenic risk were determined. Care should be taken to counter the negative health effects of HAAs and dalapon.

For years, gas chlorination has been the adopted disinfection technology in the treatment of Maltese potable water. Despite its strong bacterial inactivation potential, traditional chlorination generates high free chlorine residual and disinfection by-products that compromise the sensory attributes of drinking water and deter the population from consuming it. We have identified plausible alternative-to-gas-chlorination technologies for its treatment, with the aim of (a) reducing the disinfectant and/or chlorination dose used for microbial inactivation, and (b) attenuating the negative impact of putative disinfection by-products on the water’s organolepsis, while safeguarding its safe-for-consumption characteristics. We have subjected ultraviolet C (UVC) irradiation, hydrodynamic cavitation (HC), ClO2 generation, and electrochlorination (NaClO) to bacteriological and physicochemical bench-scale studies to assess their bacterial inactivation efficacy and by-product generation propensity, respectively. All the tested technologies except HC achieved a minimum of 3 Log10 microbial inactivation, with NaClO and ClO2 appearing more effective over neutral and alkaline pH conditions, respectively. In addition, we have identified synergistic effects of cavitation on UVC for Enterococcus faecalis inactivation, stemming from enhancement in oxidative stress. Moderate reductions in the total dissolved solid content and Ca2+ hardness of the tested water also emerged following prolonged cavitation. For feasibility studies, the performance of the technologies was further evaluated on the following areas: (a) implementation, (b) practicality, (c) adaptability, (d) integration, (e) environment and sustainability, and (f) cost and effect. Electrochemical generation of NaClO emerged as the most promising technology for further on-site work, followed by ClO2 and UVC.

Natural organic matter reacted with chlorine used for disinfection, and finally, trihalomethanes (THMs) are formatted. The main purpose of this study was to determine four THM concentrations and human health cancer risk and non-cancer risk assessment from exposure through oral ingestion, dermal contact, and inhalation for males and females in Abadan. Two sampling sites were selected, and five samples before and after treatment by two different water treatment systems (RO and ion exchange) were collected every week. Results showed that total THM concentrations before and after treatment by RO were 98.1 and 8.88 μg/L, and ion exchange ranged between 101.9 and 14.96 μg/L, respectively, that before treatment was upper than the maximum of 80 mg/L recommended by USEPA. Inhalation was the primary route of exposure by around 80–90% of cancer risk. Total cancer risk was higher than the USEPA acceptable limit of 10−6 via three exposure routes. Oral route has the higher hazard index values than dermal ways.

RESUMO O potencial de formação de trihalometanos (PFTHM) é uma metodologia utilizada para avaliar a possibilidade de formação de subprodutos da desinfecção (SPD) por cloração durante o processo de tratamento da água. Trihalometanos (THM) são compostos organoclorados e representam a soma de clorofórmio, diclorobromometano, dibromoclorometano e bromofórmio, sendo a principal classe de SPD formados a partir da reação entre o cloro residual livre e a matéria orgânica natural (MON) presente na água bruta de mananciais de superfície. Esta pesquisa teve como objetivo avaliar o PFTHM resultante da aplicação de cloro na água bruta da lagoa de Extremoz, cuja tecnologia de tratamento utilizada é a filtração direta, seguida de desinfecção com cloro. Os resultados obtidos indicaram presença de matéria orgânica natural hidrofílica com predominância de ácidos fúlvicos na água bruta do manancial. A concentração média de TTHM7 (4,22 mg.L-1) revelou que a água do manancial possui forte potencialidade para formação de compostos orgânicos halogenados. O clorofórmio representou cerca de 80% da concentração total de THM nos ensaios realizados. Foram observadas correlações fortes e significativas entre as variáveis dureza (R = 0,90 e p = 0,005) e cor aparente (R = -0,93 e p = 0,002) da água bruta, resultados que indicaram que íons Ca2+ e Mg2+ podem promover a formação de THM, assim como a cor aparente. ABSTRACT Trihalomethanes formation potential (THMFP) has been used to evaluate the possibility of disinfection byproduct (DBP) formation by chlorination during the water treatment process. Trihalomethanes (THM) are organochlorine compounds and represents the sum of chloroform, dichlorobromomethane, dibromochloromethane, and bromoform, and is the main class of DBP formed from the reaction between free residual chlorine and natural organic matter (NOM) present in the source waters of surface fountains. This research evaluates the THMFP on the source water from the Extremoz Pond (Natal-RN, Brazil), which is treated by direct filtration followed by chlorine disinfection. Results indicated the presence on source water of hydrophilic natural organic matter with the predominance of fulvic acids. The mean concentration of TTHM7 (4.22 mg.L-1) showed that the source water has a strong potential for halogenated organic compounds formation. Chloroform represented about 80% of the total THM concentration in the assays performed. Significant and strong correlations were observed between hardness (R = 0.90 and p = 0.005) and apparent color (R = -0.93 and p = 0.002) attesting that Ca2+ and Mg2+ ions can promote the formation of THM, as well as the apparent color.

Five-membered nitrogen-containing heterocyclic compounds (azoles) belong to potential moieties in complex structures where transformations during ozonation can occur. This study focused on the azole-ozone chemistry of pyrrole, imidazole, and pyrazole as model compounds. Reaction kinetics and ozonation products were determined by kinetic and analytical methods including NMR, LC-HRMS/MS, HPLC-UV, and IC-MS. Analyses of reactive oxygen species ( 1O 2, OH, H 2O 2), quantum chemical computations (Gibbs energies), and kinetic simulations were used to further support the proposed reaction mechanisms. The species-specific second-order rate constants for the reactions of ozone with pyrrole and imidazole were (1.4 ± 1.1) × 10 6 M -1 s -1 and (2.3 ± 0.1) × 10 5 M -1 s -1, respectively. Pyrazole reacted more slowly with ozone at pH 7 (k app = (5.6 ± 0.9) × 10 1 M -1 s -1). Maleimide was an identified product of pyrrole with a 34% yield. Together with other products, formate, formamide, and glyoxal, C and N mass balances of ∼50% were achieved. Imidazole reacted with ozone to cyanate, formamide, and formate (∼100% yields per transformed imidazole, respectively) with a closed mass balance. For pyrazole, a high ozone:pyrazole molar stoichiometry of 4.6 was found, suggesting that the transformation products contributed to the over-stoichiometric consumption of ozone (e.g., hydroxypyrazoles). Glyoxal and formate were the only identified transformation products (C mass balance of 65%). Overall, the identified major products are suspected to hydrolyze and/or be biodegraded and thereby abated by a biological post-treatment typically following ozonation. However, as substructures of more complex compounds (e.g., micropollutants), they might be more persistent during biological post-treatment.

Knowledge about human exposure and health effects associated with non-routinely monitored disinfection by-products (DBPs) in drinking water is sparse., This project has been funded by Ajuntament de Barcelona (Institut de Cultura, Pla Barcelona Ciencia 2019. #19S01446-006), and partly funded by Instituto de Salud Carlos III and co-funded by European Union (ERDF) “A way to make Europe” (PI20/00829). We acknowledge support from the Spanish Ministry of Science and Innovation and State Research Agency through the “Centro de Excelencia Severo Ochoa 2019-2023” Program (CEX2018-000806-S and CEX2018-000794-S, for ISGlobal and IDAEA-CSIC, respectively), and support from the Generalitat de Catalunya through the CERCA Program. MJF acknowledges her Ramón y Cajal fellowship (RyC-2015-17108), from the AEI-MICIU. We thank Alexandra Paraian, Eva Maria Herrera (IDAEA-CSIC), Natalia Lopo, Lourdes Arjona and Antonia Valentín (ISGlobal) for their technical assistance during the sampling, analytical measurements and data analysis. The HAAs analyses in urine were carried out in the framework of the final master’s thesis (Universitat de Barcelona) by Paula Villasante. We also thank Patricia González, Anna Gómez, Sònia Navarro, and Laia Font-Ribera (Public Health Agency of Barcelona) for providing valuable information on Barcelona’s drinking water supplies. We finally would like to acknowledge all the volunteers that participated in the project.

Around the world, coastal groundwater is increasingly subject to seawater intrusion (SWI). The quality and characteristics of such waters differ from those of surface and groundwater. In the current study, trihalomethane (THM) formation under varying levels of SWI, natural organic matter (NOM), and chloride-to-bromide (Cl/Br) ratio was evaluated. Different levels of SWI were simulated by mixing deionized water with real seawater (RSW) collected from the Indian Ocean or synthetic seawater (SSW) by varying seawater volumes from 0% to 3%. Humic acid (0 to 5 mg/L) was added to represent NOM at concentrations mimicking natural levels of dissolved organic carbon. The chlorine demand of the simulated water samples was significantly correlated to SWI levels and NOM concentrations. THM concentration in SSW increased from 12.64 µg/L to 105.34 µg/L after 24 h and to 115.8 µg/L after 48 h for an increase from 0% to 3% volume of seawater. For water samples simulated with RSW, maximum THMs after 24 h were 119.2 µg/L, and after 48 h were 126.4 µg/L. An increase in NOM concentration in seawater-intruded water samples resulted in increasing THMs, especially tribromomethane. However, the increment in THMs at higher NOM concentration was lower compared to that at low NOM concentration. Chlorine demand was positively correlated only to tribromomethane. An increase in bromide concentration resulted in lower Cl/Br ratio and a concomitant increase in brominated THMs. The bromine substitution factor corresponding to increasing SWI of 0.25–3% decreased from 2.67 to 1.81 over a reaction time of 24 to 48 h, indicating a shift from TBM dominance to chlorinated THMs.

To bolster freshwater supply, artificial groundwater recharge with recycled water has increasingly attracted research attentions and interests. However, artificial groundwater recharge has potential risks to groundwater quality, as recharge water disinfection is frequently used for pathogen inactivation and causes the concerns of disinfection by-products (DBPs). Colloid supplement is a good approach solving this problem, but its roles in mitigating DBPs remains unclear. In this study, we collected 20 groundwater and soil samples from a field-scale groundwater recharge project, and explored the impacts of silica colloids on chloroform migration and groundwater bacterial communities during the recharge process. Water physicochemical variables changed along the recharge time, and colloid supplement significantly reduced chloroform formation and slowed its migration in groundwater. Bacterial communities in groundwater, river water and recharge water were significantly different. Gammaproteobacteria in recharge water (71.7%) was more abundant than in river water (30.5%) and groundwater (33.5%), while Actinobacteria dominated groundwater (40.6%). After recharge, Gammaproteobacteria increased more with colloid supplement (75.7%) than without (52.6%), attributing to its dominance in soils (74.6%). Our results suggested more bacterial lineages released from soils into aquifer by silica colloid supplement, owing to the competitive adsorption encouraging microbial transfer, especially Gram-negative bacteria. Our findings unraveled the effects of colloid supplement on chloroform formation and migration during artificial groundwater recharge, which consequently altered groundwater bacterial communities, and offered valuable suggestions for the safety management of DBPs in aquifer recharge.

Chlorination by-products have been consistently associated with risk of bladder cancer in case-control studies, but confirmation from large-scale cohort studies is lacking. We assessed the association of drinking water tri-halomethanes (THM), a proxy for chlorination by-products, with risk of bladder cancer in 58,672 men and women. Data came from two population-based cohorts, parts of the Swedish Infrastructure for Medical Population-Based Life-Course and Environmental Research (SIMPLER). Individual exposure to THM was assessed by combining residential information with tap water monitoring data. Participants were categorized into non-exposed, low (< 15 mu g/L) or high (>= 15 mu g/L) THM exposure. Incident cases were ascertained from 1998 through 2019 via register linkage. During 16 years of follow-up (965,590 person-years), 831 bladder cancer cases were ascertained. We observed no overall association of THM with risk of bladder cancer, hazard ratio for the highest exposed compared to the non-exposed 0.90 (95% confidence interval: 0.73 - 1.11). The null association remained after restricting the analysis to long-term residents and across strata of smoking status and cancer stage. Our results indicate that chlorination by-product exposure at THM concentrations representative of chlorinated drinking waters in most European countries, is not associated with an increased risk of bladder cancer.

The application of oxidants for disinfection or micropollutant abatement during drinking water and wastewater treatment is accompanied by oxidation of matrix components such as dissolved organic matter (DOM). To improve predictions of the efficiency of oxidation processes and the formation of oxidation products, methods to determine concentrations of oxidant-reactive phenolic, olefinic or amine-type DOM moieties are critical. Here, a novel selective oxidative titration approach is presented, which is based on reaction kinetics of oxidation reactions towards certain DOM moieties. Phenolic moieties were determined by oxidative titration with ClO2 and O3 for five DOM isolates and two secondary wastewater effluent samples. The determined concentrations of phenolic moieties correlated with the electron-donating capacity (EDC) and the formation of inorganic ClO2-byproducts (HOCl, ClO2−, ClO3−). ClO2-byproduct yields from phenol and DOM isolates and changes due to the application of molecular tagging for phenols revealed a better understanding of oxidant-reactive structures within DOM. Overall, oxidative titrations with ClO2 and O3 provide a novel and promising tool to quantify oxidant-reactive moieties in complex mixtures such as DOM and can be expanded to other matrices or oxidants., Water Research, 207, ISSN:0043-1354, ISSN:1879-2448

The composition of oxidant-reactive dissolved organic nitrogen (DON) is poorly characterized, although its ozonation is likely to form a great variety of disinfection by-products containing a nitrogen-oxygen bond (N-DBPs). In this study, two chemical oxidation procedures were developed: continuous ozonation at pH 7.0 and free available chlorine (FAC) titrations at pH 9.2. The formation of two oxidation products (nitrate (NO3−) and chloramines, respectively) was used to quantify and characterize oxidant-reactive nitrogenous moieties in DON. In addition, batch experiments were conducted to study the NO3− yields of 30 selected nitrogenous model compounds upon ozonation. The NO3− yields of 12 primary and secondary amines were highly variable (17–100%, specific ozone dose of 20 molO3/molN), 7 amino acids had high NO3− yields (≥90%), and tertiary amines as well as pyrrole, acetamide and urea had low NO3− yields (≤15%). The mechanisms of NO3− formation were further examined with benzylamine and N-methylbenzylamine as model compounds. Our results show that nitroalkanes are the last intermediate products before the formation of NO3−, both for primary and secondary amines. The presence of an electron-withdrawing group in the vicinity of the N-atom facilitates the formation of NO3− from nitroalkanes. Therefore, the formation of NO3− is attributed to amino acids and activated primary and secondary amines. In contrast, all primary and secondary amines were transformed to chloramines upon chlorination, which was determined by a novel oxidative titration with chlorine. To further support the selectivity of this assay, it was demonstrated by derivatization of amine moieties that chloramine formation could be inhibited. 13–45% of the DON of 4 dissolved organic matter isolates and 2 wastewater effluents formed NO3− and 0–39% formed chloramines, indicating that the potential for N-DBP formation is high (µMN/mgC-level). From differences in the formation of NO3− and chloramines the nature of the precursors can be hypothesized (e.g., activated or non-activated primary and secondary amines, partially oxidized nitrogenous compounds). This study highlights the capacity of two novel methods to characterize the oxidant-reactive DON fraction. Our results suggest that this fraction is significant and could form a variety of potentially toxic N-DBPs., Water Research, 209, ISSN:0043-1354, ISSN:1879-2448

Haloacetic acids (HAAs) are undesirable disinfection by-products (DBPs), released into aquatic ecosystems from various anthropogenic and natural sources. The aim of this study was to examine the ecological risk of exposure to three HAAs commonly detected in water, such as monobromoacetic acid (MBA), monochloroacetic acid (MCA), and trichloroacetic acid (TCA), in in vivo acute and chronic toxicity tests using Daphnia magna as a model. Acute tests showed that MBA was the most toxic of these compounds followed by MCA and TCA as evidenced by immobilization. Aquatic organisms in natural conditions might be exposed simultaneously to numerous compounds; thus, binary mixtures of selected HAAs and a ternary mixture of these were tested. Concentration addition (CA) and independent action (IA) models were used for a predictive assessment of mixture toxicity. Data demonstrated that CA appeared to be the most reliable indicator for HAAs binary and ternary mixtures suggestive of an additive behavior. Median effective concentration (EC50) values from the mixed exposure tests were significantly lower than results obtained from single tests for all three HAAs where an increase of toxicity greater than 50%. Multigenerational chronic tests were also performed exposing daphnids to the ternary mixture of HAAs. A markedly decreased sexual maturity and number of offspring and broods per daphnid especially in the second generation were noted. This work received financial support from the European Union (FEDER funds POCI/01/0145/FEDER/007265) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) under the Partnership Agreement PT2020 UID/QUI/50006/2013. A. Melo wishes to thank the Fundação Ciência Tecnologia grant SFRH/BPD/86898/2012. info:eu-repo/semantics/publishedVersion

Copyright © 2019 Elsevier Inc. All rights reserved, Disinfection of water system is an essential strategy to protect human health from pathogens and prevent their regrowth during water distribution, but the reaction of disinfectant agents with organic matter can lead to the formation of disinfection by-products (DBPs). Given their widespread occurrence, potential human health impacts and (eco)toxicity associated with exposure to DBPs are of particular interest due to their potential carcinogenicity and vary non-carcinogenic effects, such as endocrine disruption. Understanding the public health implications of this emerging issue is crucial for societies and decision-makers, supporting more effective water safety plans. Here, we review the recent literature on the effects of DBPs presented in drinking water and treated swimming pools water, focusing particularly in unregulated compounds and the putative underlying mode of action, linking the available data with adverse health outcomes. Overall, the majority of studies highlight the limited knowledge in the understanding of the underlying mode of action of DBPs. Yet, available evidences indicate that different signaling pathways seem to be involved in the adverse outcomes associated with distinct DBPs classes. The main knowledge gaps in this field are also identified, and future research priorities discussed., This work was supported by FCT- Fundação Ciência e Tecnologia (grant PDE/BDE/122649/2016) and by project NORWATER (0725), financed by “Programa de Cooperação Interreg Portugal/Espanha”, (POCTEP) 2014-2020.

Biological activated carbon (BAC) filtration is usually considered to be able to decrease formation potentials (FPs) of disinfection by-products (DBPs) in drinking water treatment plant (DWTP). However, BAC filters with long running time may release microbial metabolites to effluents and therefore increase FPs of nitrogenous DBPs with high toxicity. To verify this hypothesis, this study continuously tracked BAC filters in a DWTP for one year, and assessed effects of old (running time 8–9 years) and new (running time 0–13 months) BAC filters on FPs of 15 regulated and unregulated DBPs. Results revealed that dissolved organic carbon (DOC) removal was slightly higher in the new BAC than the old one. All fluorescent components of dissolved organic matter evidently declined after new BAC filtration, but fulvic acid-like and soluble microbial product-like substances increased after old BAC filtration, which could be caused by microbial leakage. Correspondingly, new BAC filter generally removed more DBP FPs than the old one. 46.5% HAA7 FPs from chlorination and 44.3% THM4 FPs from chloramination were removed by new BAC filter. However, some DBP FPs, especially HAN FPs, were poorly removed or even increased by the old BAC filter. Proteobacteria could be a main contributor for DBP precursor removal in BAC filters. Herminiimonas, most abundant genera in new BAC filter, may explain its better DOC and UV254 removal performance and lower DBP FPs, while Bradyrhizobium, most abundant genera in old BAC filter, might produce more extracellular polymeric substances and therefore increased N-DBP FPs in old BAC effluent. This study provided insight into variations of DBP FPs and microbial communities in the new and old BAC filters, and will be helpful for the optimization of DWTP design and operation for public health.

Concerns have been raised regarding the potential negative effects on human health of water disinfectants used in swimming pools. Among the disinfection options, the approaches using chlorine-based products have been typically preferred. Chlorine readily reacts with natural organic matter that are introduced in the water mainly through the bathers, leading to the formation of potentially harmful chlorination by-products (CBPs). The formation of CBPs is of particular concern since some have been epidemiologically associated with the development of various clinical manifestations. The higher the concentration of volatile CBPs in the water, the higher their concentration in the air above the pool, and different routes of exposure to chemicals in swimming pools (water ingestion, skin absorption, and inhalation) contribute to the individual exposome. Some CBPs may affect the respiratory and skin health of those who stay indoor for long periods, such as swimming instructors, pool staff, and competitive swimmers. Whether those who use chlorinated pools as customers, particularly children, may also be affected has been a matter of debate. In this article, we discuss the current evidence regarding the health effects of both acute and chronic exposures in different populations (work-related exposures, intensive sports, and recreational attendance) and identify the main recommendations and unmet needs for research in this area.

Access to sufficient water, sanitation, and hygiene (WASH) services is a crucial requirement for patients during therapy and general well-being in the hospital. However, in low- and middle-income countries, these services are often inadequate, resulting in increased morbidity and mortality of patients. This study aimed at assessing the current situation of WASH services in six District Health Care Facilities (DHCFs) in rural areas of the Mekong Delta provinces, Vietnam. The results showed that these services were available with inappropriate quality, which did not compromise the stakeholders' needs. The revealed WASH infrastructures have raised concerns about the prolonged hospital stays for patients and push nosocomial infections to a high level. The safety of the water supply was doubted as the high E. coli (> 60%) and total coliform incidence (86%) was observed with very low residual chlorine concentration (

Iodine is a naturally-occurring halogen in natural waters generally present in concentrations between 0.5 and 100 mu g L-1. During oxidative drinking water treatment, iodine-containing disinfection by-products (I-DBPs) can be formed. The formation of I-DBPs was mostly associated to taste and odor issues in the produced tap water but has become a potential health problem more recently due to the generally more toxic character of I-DBPs compared to their chlorinated and brominated analogues., This paper is a systematic and critical review on the reactivity of iodide and on the most common intermediate reactive iodine species HOI. The first step of oxidation of I- to HOI is rapid for most oxidants (apparent second-order rate constant, k(app) > 10(3) M(-1)s(-1) at pH 7). The reactivity of hypoiodous acid with inorganic and organic compounds appears to be intermediate between chlorine and bromine. The life times of HOI during oxidative treatment determines the extent of the formation of I-DBPs. Based on this assessment, chloramine, chlorine dioxide and permanganate are of the highest concern when treating iodide-containing waters. The conditions for the formation of iodo-organic compounds are also critically reviewed., From an evaluation of I-DBPs in more than 650 drinking waters, it can be concluded that one third show low levels of I-THMs ( 10 mu g L-1. The most frequently detected I-THM is CHCl2I followed by CHBrClI. More polar I-DBPs, iodoacetic acid in particular, have been reviewed as well., Finally, the transformation of iodide to iodate, a safe iodine-derived end-product, has been proposed to mitigate the formation of I-DBPs in drinking water processes. For this purpose a pre-oxidation step with either ozone or ferrate(VI) to completely oxidize iodide to iodate is an efficient process. Activated carbon has also been shown to be efficient in reducing I-DBPs during drinking water oxidation.

Highlights: • Overview on oxidative treatment processes for different industrial applications • Compilation of disinfection by-product types/concentrations in marine water uses • Estimation of global DBP inputs into marine water from different industries • Comparison of anthropogenic bromoform production to emissions from natural sources Abstract: Oxidative treatment of seawater in coastal and shipboard installations is applied to control biofouling and/or minimize the input of noxious or invasive species into the marine environment. This treatment allows a safe and efficient operation of industrial installations and helps to protect human health from infectious diseases and to maintain the biodiversity in the marine environment. On the downside, the application of chemical oxidants generates undesired organic compounds, so-called disinfection by-products (DBPs), which are discharged into the marine environment. This article provides an overview on sources and quantities of DBP inputs, which could serve as basis for hazard analysis for the marine environment, human health and the atmosphere. During oxidation of marine water, mainly brominated DBPs are generated with bromoform (CHBr3) being the major DBP. CHBr3 has been used as an indicator to compare inputs from different sources. Total global annual volumes of treated seawater inputs resulting from cooling processes of coastal power stations, from desalination plants and from ballast water treatment in ships are estimated to be 470 – 800 × 109 m3, 46 × 109 m3 and 3.5 × 109 m3, respectively. Overall, the total estimated anthropogenic bromoform production and discharge adds up to 13.5 – 21.8 × 106 kg/a (kg per year) with contributions of 11.8 – 20.1 × 106 kg/a from cooling water treatment, 0.89 × 106 kg/a from desalination and 0.86 × 106 kg/a from ballast water treatment. This equals approximately 2 – 6 % of the natural bromoform emissions from marine water, which is estimated to be 385 – 870 × 106 kg/a.

Breakpoint chlorination (BC) and disinfection with chlorine-based disinfectant are widely used procedures in drinking water production. Both involve dosing chlorine into the raw water, where it can react with organic compounds, forming disinfection by-products (DBPs) of health concern. However, technological parameters (e.g., contact time, chlorine dosage, and bromide to residual free chlorine ratio) of the two chlorination procedures are different, which can lead to differences in DBP formation. To better understand this, a year-long sampling campaign was carried out at three waterworks in Hungary, where both BC and chlorine disinfection are used. To confirm the results of the field sampling, bench-scale experiments were carried out, investigating the impact of (a) bromide concentration in raw water, (b) residual free chlorine (bromide to residual chlorine ratio), and (c) contact time on DBP formation. The measured DBPs were trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and chlorate. During BC, the DBPs were formed in higher concentration, with the exception of one waterwork having elevated bromide content in the raw water. Bromine substitution factors (BSFs) were significantly higher during disinfection than BC in both field and laboratory experiments. After BC, the chlorate concentration range was 0.15–1.1 mg/L, and 96% of the samples exceeded the European Union (EU) parametric value (0.25 mg/L), whereas disinfection contributed only slightly. Granular activated carbon (GAC) filters used to remove DBPs in waterworks were exhausted after 6–8 months of use, first for those chlorinated THMs, which are generated predominantly during BC. The biological activity of the filters started to increase after 3–6 months of operation. This activity helps to remove the biodegradable compounds, such as disubstituted haloacetic acid (DHAAs) and HANs, even if the adsorption capacity of the GAC filters are low.

Brain tumours (BTs) are one of the most frequent tumour types in young people. We explored the association between tap water, exposure to trihalomethanes (THM) and nitrate and neuroepithelial BT risk in young people. Analysis of tap water consumption were based on 321 cases and 919 appendicitis controls (10–24 years old) from 6 of the 14 participating countries in the international MOBI-Kids case-control study (2010–2016). Available historical residential tap water concentrations of THMs and nitrate, available from 3 countries for 86 cases and 352 controls and 85 cases and 343 for nitrate, respectively, were modelled and combined with the study subjects’ personal consumption patterns to estimate ingestion and residential exposure levels in the study population (both pre- and postnatal). The mean age of participants was 16.6 years old and 56% were male. The highest levels and widest ranges for THMs were found in Spain (residential and ingested) and Italy and in Korea for nitrate. There was no association between BT and the amount of tap water consumed and the showering/bathing frequency. Odds Ratios (ORs) for BT in relation to both pre- and postnatal residential and ingestion levels of THMs were systematically below 1 (OR = 0.37 (0.08–1.73)) for postnatal average residential THMs higher than 66 μg/L. For nitrate, all ORs were above 1 (OR = 1.80 (0.91–3.55)) for postnatal average residential nitrate levels higher than 8.5 mg/L, with a suggestion of a trend of increased risk of neuroepithelial BTs with increasing residential nitrate levels in tap water, which appeared stronger in early in life. This, to our knowledge, is the first study on this topic in young people. Further research is required to clarify the observed associations.

The current study compared the impact of three different unit processes, coagulation, granular activated carbon (GAC), and a novel suspended ion exchange (SIX) technology, on disinfection by-product formation potential (DBPFP) from two UK lowland water sources with medium to high bromide content. Specific attention was given to the influence of the organic molecular weight (MW) fraction on DBPFP as well as the impact of bromide concentration. Whilst few studies have investigated the impact of MW fractions from Liquid Chromatography with Organic Carbon Detection (LC-OCD) analysis on dissolved organic carbon (DOC) removal by different processes, none have studied the influence of DOC MW fractions from this analysis on DBP formation. The impact of higher bromide concentration was to decrease the total trihalomethane (THM) and haloacetic acid (HAA) mass concentration, in contrast to previously reported studies. Results indicated that for a moderate bromide concentration source (135 μg/L), the THM formation potential was reduced by 22% or 64% after coagulation or SIX treatment, respectively. For a high bromide content source (210 μg/L), the THM formation potential removal was 47% or 69% following GAC or SIX treatment, respectively. The trend was the same for HAAs, albeit with greater differences between the two processes/feedwaters with reference to overall removal. A statistical analysis indicated that organic matter of MW > 350 g/mol had a significant impact on DBPFP. A multiple linear regression of the MW fractions against DBPFP showed a strong correlation (R2 between 0.90 and 0.93), indicating that LC-OCD analysis alone could be used to predict DBP formation with reasonable accuracy, and offering the potential for rapid risk assessment of water sources.

This study examined the potential of six aliphatic and aromatic amides, commonly found in natural waters or used as chemical aids in water treatment, to act as organic precursors for nine haloacetamides (HAcAms), five haloacetonitriles (HANs), regulated trihalomethanes (THMs) and haloacetic acids (HAAs) upon chlorination and chloramination. The impact of key experimental conditions, representative of drinking water, including pH (7 & 8), retention time (4 & 24 h) and bromide levels (0 & 100 μg/L), on the generation of the target DBPs was investigated. The highest aggregate DBP yields upon chlor(am)ination were reported for the aromatic and hydrophobic hydroxybenzamide; 2.7% ± 0.1% M/M (chlorination) and 1.7% M/M (chloramination). Increased reactivity was observed in aliphatic and hydrophilic compounds, acrylamide (2.5 ± 0.2% M/M) and acetamide (1.3 ± 0.2% M/M), in chlorination and chloramination, respectively. The addition of bromide increased average DBP yields by 50–70%. Relative to chlorination, the application of chloramines reduced DBP formation by 66.5% (without Br−) and by 46.4% (with Br−). However, bromine incorporation in HAAs and HAcAms was enhanced following chloramination, of concern due to the higher toxicological potency of brominated compounds.

Cytostatic drugs and their metabolites enter the aquatic environment mainly through the excretion of urine and faeces from chemotherapy patients into the public sewer system and can eventually reach tap water if they are not properly eliminated during waste and drinking water treatment processes. Chlorine is globally the most used chemical disinfectant in wastewater treatment plants as well as in the pretreatment of hospital effluents prior to their discharge into the public sewage system, mostly because of its low cost. Since aqueous chlorine is not capable of complete mineralization of many anthropogenic compounds, numerous disinfection by-products may be formed due to oxidation/substitution reactions. Such reactions can happen during wastewater treatment processes and due to the discharge of chlorinated waters (e.g., tap water) or bleach into the sewage system. Very little is also known about their potential transformation into other chemical species, which might be even more toxic than the parent drugs. In recent years, several studies have demonstrated that anticancer drugs can yield a series of by-products when they come in contact with aqueous chlorine. Understanding the chemical fate of these by-products is an important first step to understand their environmental significance. Therefore, the main aim of this chapter is to comprehensively review the existing literature on the reactivity of anticancer drugs in the presence of free chlorine and the formation of their by-products.

Membrane fouling is the principal factor that currently limits the performance of gravity-driven membrane (GDM) filtration systems in drinking water treatment. In this study, the benefits of applying a low dose (approximately 0.1 mg⋅L− 1) of environmentally benign oxidants, both H2O2 and KMnO4, as a pretreatment to GDM filtration system has been evaluated in terms of reduced membrane fouling and treated water quality. While both oxidants improved permeate flux, the effect of KMnO4 was greater than H2O2. Both oxidants reduced the size of influent organic substances and those of large molecular weight (>20 kDa), such as biopolymers, disappeared. The thickness of the fouling layers was substantially reduced after oxidation, and the KMnO4 system had a markedly different physical structure of fouling layer, with an apparent sub-layer of δ-MnO2 nanosheets below a fouling sub-layer. The formation of the δ-MnO2 nanosheets sub-layer appeared to protect the underlying membrane pores from contamination by influent organics. Oxidation pretreatment reduced the presence of proteins and polysaccharides in the fouling layers and significantly altered the bacterial community structures (p < 0.01) and decreased biodiversity. The microbial species that secreted amounts of extracellular polymeric substances (EPS), such as Xanthobacter, were not eliminated in the H2O2 fouling layer, while for the KMnO4 system, the manganese oxidizing bacteria (MOB; e.g., Pseudoxanthomonas) and metal-resistant genus Acidovorax, dominated the community.

An indole derivative umifenovir (Arbidol) is one of the most widely used antiviral drugs for the prevention and treatment of COVID-19 and some other viral infections. The purpose of the present study was to shed light on the transformation processes of umifenovir in municipal wastewater, including disinfection with active chlorine, as well as to assess the levels of the antiviral drug and its metabolites entering and accumulating in natural reservoirs under conditions of the SARS-CoV-2 pandemic. The combination of high-performance liquid chromatography with electrospray ionization high-resolution mass-spectrometry and inductively coupled plasma mass spectrometry was used for tentative identification and quantification of umifenovir and its transformation products in model reaction mixtures and real samples of wastewater, river water, biological sludge and bottom sediments taken at the wastewater treatment plant in Arkhangelsk, a large cultural and industrial center at the Russian North. Laboratory experiments allowed identifying fifteen bromine-containing transformation products, forming at the initial stages of the chlorination and fourteen classic volatile and semi volatile disinfection by-products with bromoform as the dominant one. Chlorinated derivatives are only the minor disinfection by-products forming by substitution of alkylamine group in the aromatic ring. The schemes of umifenovir transformation in reactions with dissolved oxygen and sodium hypochlorite are proposed. Two established primary transformation products formed by oxidation of the thioether group to sulfoxide and elimination of thiophenol were detected in noticeable concentrations in the wastewater together with their precursor. The level of umifenovir reached 1.3 mg kg−1 in the sludge and municipal wastewater treat contained 1 μg L−1 of that drug, while its removal during biological wastewater treatment was about 40%. Pronounced accumulation of umifenovir and its transformation products in biological sludge and bottom sediments of natural reservoirs may be a source of the future secondary pollution of the environment., Graphical abstract Unlabelled Image

This cross-sectional study aimed to examine the concentration of the by-products of chlorination in the swimming pool and estimate human health risk for the swimmers of Shiraz University of Medical Sciences. In this study, the chloroform concentrations of 16 samples were measured using Gas Chromatography (GC). All the measured concentrations were less than the allowed amount announced by the World Health Organization (WHO). The results of the cancer risk (CR) and hazard index (HI) showed that the major exposure routes were found to be dermal during swimming and the 95 percentile of estimated CR and HI for the male group were 1.38 × 10−10 and 1.82 × 10−5 respectively, which is higher than the values of 5.48 × 10−10 and 2.25 × 10−5 respectively, for the women group. Sensitivity analyses indicated that the swimming exposure time (ET), and chloroform concentration were the most relevant variables in the health risk model. Therefore, knowledge about the sources of micro-pollutants in swimming pools might help promote the health methods of the pool environment.

Over the past century chlorine has been widely used as an oxidant in water and wastewater treatment. Chlorine’s efficacy is demonstrated for microbial inactivation of a wide variety of pathogens along with oxidation of various chemical contaminants. However, the potential formation of disinfection by-products (DBPs), such as trihalomethane, is a concern [1]. DBPs, including trihalomethanes, can be formed as a consequence of the reaction of chlorine with natural organic matter (NOM) present in both surface and ground water [2]. NOM comprises of two fractions; humic substances (HS), which are composed of humic acids, fulvic acids, and non-humic substances (non-HS), which include carbohydrates, lipids, and amino acids [3]. Furthermore, humic acids constitute a major fraction of NOM, of which the soluble portion (aromatic compounds) of humic substances may react with chlorine to form trihalomethanes [4]. It has been reported that these THMs are carcinogens [5]. Epidemiologic studies in humans suggest a weak association with bladder, rectal and colon cancer [6,7] along with reproductive and developmental effects [8,9]. Due to these health concerns, many jurisdictions specify maximum allowable concentrations. The United States Environ- mental Protection Agency [10] specifies maximum levels for trihalomethanes (THMs) and haloacetic acids (HAAs) of 80 and 60 mg/L, respectively [11]. European Union regulations limit THMs to 100 mg/L. However, many national reports find frequent occurrence of THM exceedance [12]. It is important to limit THMs and THMs causing substances (humic acids) in water. Several approaches such as nanofiltration, ultrafiltration, reverse osmosis coagulation [13], activated carbon adsorption [14], Fenton treatment [15], nano-TiO2 photocatalysis [16], membrane filtration [17], biological treatment [18], and ozonation [19] have been employed to remove humic substances and THM’s. Biological processes, including the use of bio-filters may lead to the accumulation of suspended solids and release of bacteria [20]. Separation technologies such as biofilms and membrane filtration may be limited due to fouling [21]. Ozone’s efficacy for humic substance breakdown in water has been demonstrated, however the process may result in the formation of brominated by-products [22]. In addition, the use of such advanced oxidation processes (AOP) which are capable of oxidizing some of the NOM present in raw water sources require an additional step for mineralization increasing the operational cost. Therefore, there is a need to develop novel approaches to remove humic substances and THMs in energy efficient manner.

The occurrence of disinfection by-products (DBPs) in drinking water has become an issue of concern during the past decades. The DBPs pose health risks and are suspected to cause various cancer forms, be genotoxic, and have negative developmental effects. The vast chemical diversity of DBPs makes comprehensive monitoring challenging. Only few of the DBPs are regulated and included in analytical protocols. In this study, a method for simultaneous measurement of 20 DBPs from five different structural classes (both regulated and non-regulated) was investigated and further developed for 11 DBPs using solid-phase extraction and gas chromatography coupled with a halogen-specific detector (XSD). The XSD was highly selective towards halogenated DBPs, providing chromatograms with little noise. The method allowed detection down to 0.05 μg L−1 and showed promising results for the simultaneous determination of a range of neutral DBP classes. Compounds from two classes of emerging DBPs, more cytotoxic than the “traditional” regulated DBPs, were successfully determined using this method. However, haloacetic acids (HAAs) should be analyzed separately as some HAA methyl esters may degrade giving false positives of trihalomethanes (THMs). The method was tested on real water samples from two municipal waterworks where the target DBP concentrations were found below the regulatory limits of Sweden. Electronic supplementary material The online version of this article (10.1007/s11356-018-1419-2) contains supplementary material, which is available to authorized users.

Mutagenicity formation by low pressure (LP)-UV/H2O2 treatment of nitrate-rich water containing natural organic matter (NOM) was investigated. Laboratory-grade water samples spiked with either Pony Lake NOM or Suwannee River NOM (4 mg L−1 in both cases) and nitrate (50 mg L−1) were irradiated with UV fluences of 0, 1500 and 2000 mJ cm−2 and a H2O2 dose of 15 mg L−1 and tested for mutagenicity with the Ames II assay. LP-UV photolysis of nitrate in the presence of Pony Lake NOM caused a significant increase in the Ames II assay response and low concentrations of nitrite (0.08–0.09 mg NO2− L−1) and nitrophenols (0.014–0.046 μg L−1) were detected. Suwannee River NOM produced the same nitrite levels but no significant responses in the Ames II assay were observed. Additionally, samples collected from a drinking water treatment plant in the UK using LP-UV/H2O2 treatment were analysed with the Ames II assay. LC-OCD fractionation and SUVA measurements were performed to observe any changes in the properties of NOM. Significant differences in the mutagenicity response were observed between the treatment steps as well as between the two sampling periods. However, with respect to standard thresholds, none of the samples were found to be mutagenic towards the Salmonella typhimurium strain TA98 used.

Background Toxicological studies suggest that maternal exposure to disinfection by-products (DBPs) can impair fetal neurodevelopment. However, evidence from epidemiological studies is scarce and the underlying mechanisms remain unclear. Objective To explore the trimester-specific associations between maternal blood trihalomethane (THM) and urinary haloacetic acid (HAA) concentrations and neonatal neurobehavioral development, and the potential mediating role of oxidative stress (OS). Methods We included 438 pregnant Chinese women from the Xiaogan Disinfection By-Products (XGDBP) birth cohort. Biospecimens were repeatedly collected across trimesters and measured for blood THMs, urinary HAAs, and urinary OS biomarker concentrations. On the third day after birth, the Neonatal Behavioral Neurological Assessment (NBNA) test was administered to newborns. Associations of trimester-specific DBP measurements and OS biomarkers with neonatal NBNA scores were assessed using linear regression models with generalized estimating equations. The potential mediating role of maternal OS biomarkers was also investigated using mediation analyses. Results After adjusting for potential confounders, blood bromodichloromethane (BDCM) concentrations in the first trimester were inversely associated with NBNA scores [percent change comparing the extreme BDCM tertiles = –28.1% (95% CI: –55.2%, –0.88%); p for trend = 0.043]. Besides, third-trimester urinary trichloroacetic acid (TCAA) concentrations were inversely associated with NBNA scores [percent change comparing the extreme TCAA tertiles = –32.9% (95% CI: –64.7%, –1.0%); p for trend = 0.046]. These inverse associations differed across pregnancy trimesters (Type 3 p-value = 0.066 and 0.053, respectively) and were stronger in male infants and mothers aged ≥25 years. There was no evidence of mediating effect by 8-hydroxy-2-deoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA), or 8-iso-prostaglandin F2α (8-isoPGF2α). Conclusions Higher prenatal BDCM and TCAA concentrations during specific pregnancy trimesters were associated with lower NBNA scores. However, additional research is required to investigate underlying mechanisms.

UV lamps are being increasingly used in the treatment of swimming pool water, mainly due to their abilities to disinfect and effectively remove chloramines (combined chlorine). However, the application of UV lamps in a closed loop system, such as that in which swimming pool water is treated, creates conditions under which chlorinated water is then also irradiated with UV. Thus, the advanced oxidation process occurs, which affects the transformation of organic matter and its increased reactivity, and hence the higher usage of chlorine disinfectant. In addition, UV lamps require electrical power and the periodic replacement of filaments. In order to assess whether the application of a low-pressure UV lamp is justified, water quality tests and an analysis of the operating costs (including the energy consumption) of the water treatment system were carried out for two operation variants—those of the low-pressure UV lamp being turned on and off. The experiments were carried out on the real object of the AGH University of Science and Technology sports swimming pool for one year. The consumption of electricity and water treatment reagents was also measured. The following values of the selected parameters of the swimming pool water quality were observed (for without and with UV lamp, respectively): 0.68 and 0.52 mg/L combined chlorine, 3.12 and 3.02 mg/L dissolved organic carbon, 15.70 and 15.26 µg/L trihalomethanes, 7 and 6 cfu/mL mesophilic bacteria, and 6 and 20 cfu/mL psychrophilic bacteria. Generally, the statistically important differences in water quality parameters were not observed, thus the application of the low-pressure UV lamp in the swimming pool water treatment technology did not bring the expected improvement in water quality. However, the higher consumption of electric energy (by 29%) and chlorine disinfectant (by 15%), and the need to periodically replace the lamp filaments significantly increased the operating costs of the water treatment system (by 21%) and its ecological impact, thus this technology cannot be considered as profitable or ecological.

Both UV treatment and ozonation are used to reduce different types of disinfection by-products (DBPs) in swimming pools. UV treatment is the most common approach, as it is particularly efficient at removing combined chlorine. However, the UV treatment of pool water increases chlorine reactivity and the formation of chloro-organic DBPs such as trihalomethanes. Based on the similar selective reactivity of ozone and chlorine, we hypothesised that the created reactivity to chlorine, as a result of the UV treatment of dissolved organic matter in swimming pool water, might also be expressed as increased reactivity to ozone. Moreover, ozonation might saturate the chlorine reactivity created by UV treatment and mitigate increased formation of a range of volatile DBPs. We found that UV treatment makes pool water highly reactive to ozone. The subsequent reactivity to chlorine decreases with increasing ozone dosage prior to contact with chlorine. Furthermore, ozone had a half-life of 5 min in non-UV treated pool water whereas complete consumption of ozone was obtained in less than 2 min in UV treated pool water. The ozonation of UV-treated pool water induced the formation of some DBPs that are not commonly reported in this medium, in particular trichloronitromethane, which is noteworthy for its genotoxicity, though this issue was removed by UV treatment when repeated combined UV/ozone treatment interchanging with chlorination was conducted over a 24-h period. The discovered reaction could form the basis for a new treatment method for swimming pools.

3rd International Conference on Recycling and Reuse -- SEP 28-30, 2016 -- Istanbul, TURKEY, WOS: 000418866000031, Ozone and biofiltration columns were used to evaluate the removal efficiency of natural organic matter and to reduce chlorinated disinfection by-product (DBP) formation for eutrophicated water. Firstly, the effects of ozone dosage and then the column contact time and support material type together with ozonation and biofiltration processes on the control of DBPs were investigated. Porsuk river water, which is a eutrophicated water source, had been polluted by industrial, agricultural, and domestic wastewater in Eskisehir, Turkey. The empty bed contact time (EBCT) and support material type are significant parameters in both the operation and design for the biologically activated filter after ozonation. Sand, zeolite, and granular activated carbon (GAC) were used as biofilter support materials. The GAC had the best results in the using as a biofilter material for all observed parameters when it was compared with the other materials, sand, and zeolite. The eutrophicated water source extensively contained chlorophyll-a and hydrophilic NOM species that could not be easily removed by classical treatment methods. Ozonation and biofiltration are good alternatives. By increasing the ozone dosage for the eutrophicated water source, the formation potentials of THM and HAA could be reduced significantly when ozone and biofilter were applied together. At 1.1 mg O-3/mg TOC ozone dosage, UV254, DOC, the formation potential of THM and HAA removals reached 53%, 81%, 73%, and 53% at 30 min EBCT., State Planning Organization (DPT) of Turkey [2005K120110], The authors greatly appreciate the financial support from the State Planning Organization (DPT) of Turkey (DPT project no: 2005K120110).

This study investigates the potential of fluorescence excitation/emission matrices (EEM) measurement as a tool to predict N-Nitrosodimethylamine (NDMA) formation in water reuse applications. In particular, samples from a pilot-scale membrane biological reactor (MBR) followed by nanofiltration (NF) advanced water treatment plant, are used for the study. Concentrations of both, specific NDMA precursors and NDMA formation potential (FP) are correlated with different EEM peaks. The specific precursors investigated are: erythromycin, azithromycin, clarithromycin, venlafaxine, o-desmethylvenlafaxine, ranitidine and citalopram, while the NDMA FP is conventionally measured by the NDMA formation potential test. EEM peaks investigated are obtained by fluorescence regional integration as well as by the peak picking method generating I1, I2, I3, I4, and I5 peaks. Results showed that protein-like materials are correlated with the bulk NDMA FP and specific NDMA precursors. Additionally, selected fluorescence peaks such as I1, I2 and I4 are strongly correlated with NDMA precursors throughout the MBR-NF pilot plant. The removal of NDMA precursors and EEM peaks also correlated well (R2 > 0.8). This data shows that fluorescence EEM can be a promising tool to monitor the concentration of NDMA precursors and their removal in water reuse application.

This works investigates the chlorination and bromination of two rubber and polymer related chemicals, which have emerged as relevant water contaminants, i.e. 1,3-di-o-tolylguanidine (DTG) and 1,3-diphenylguanidine (DPG). Kinetic constants at different pH values were obtained and modelled, taking into account the pKa values of DTG/DPG and HClO, showing that the maximum reaction rate (kapp > 104 M−1 s−1) is obtained at pH values 8.8 for DPG and 9.1 for DTG. Bromination is also very fast, although unlike chlorination, deviation from the model was observed at neutral pH, which was attributed to formation of metastable transformation product (TP). A total of 35 TPs, corresponding to halogenation, hydroxylation, formation of monophenylguanidine derivatives and cyclization reactions, were tentatively identified. Furthermore it was found that chloroform can be formed up to a 25% molar yield, while dichloroacetonitrile was formed into less than a 3% yield. Several ecotoxicological endpoints were predicted by quantitative structure–activity relationship models (QSAR) for the TPs, some of which were predicted to be more toxic than DPG/DTG. Also a chlorinated solution investigated by a Vibrio Fisheri acute toxicity test, confirmed that toxicity increases with chlorination. This work was supported by the Water Challenges for a Changing World Joint Program Initiative (Water JPI) Pilot Call (ref. WATERJPI2013 – PROMOTE), funded by the Spanish Ministry of Economy and Competitiveness/Spanish Agencia Estatal de Investigación (refs. JPIW2013-117 and CTM2017-84763-C3-2-R) and French Office National de l’Eau et des Milieux Aquatiques (ref. PROMOTE). We also acknowledge the Galician Council of Culture, Education and Universities (ref. ED431C2017/36), Région Nouvelle Aquitaine and FEDER/EDRF funding. Benigno J. Sieira acknwledges the COST (European Cooperation in Science and Technology) Action ES1307 for suporting his research stay in Poitiers SI

Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC) which are potent animal carcinogens for the organs of the digestive system. We evaluated dietary intakes of nitrate and nitrite, as well as nitrate ingestion from drinking water (public drinking water supplies (PWS)), in relation to the incidence (1986–2014) of cancers of the esophagus (n = 36), stomach (n = 84), small intestine (n = 32), liver (n = 31), gallbladder (n = 66), and bile duct (n = 58) in the Iowa Women’s Health Study (42,000 women aged from 50 to 75 in 1986). Dietary nitrate and nitrite were estimated using a food frequency questionnaire and a database of nitrate and nitrite levels in foods. Historical nitrate measurements from PWS were linked to the enrollment address by duration. We used Cox regression to compute hazard ratios (HR) and 95% confidence intervals (CI) for exposure quartiles (Q), tertiles (T), or medians, depending on the number of cancer cases. In adjusted models, nitrite intake from processed meats was associated with an increased risk of stomach cancer (HRQ4vsQ1 = 2.2, CI: 1.2–4.3). A high intake of total dietary nitrite was inversely associated with gallbladder cancer (HRQ4vsQ1 = 0.3, CI: 0.1–0.96), driven by an inverse association with plant sources of nitrite (HRQ4vsQ1 = 0.3, CI: 0.1–0.9). Additionally, small intestine cancer was inversely associated with a high intake of animal nitrite (HRT3vsT1 = 0.2, CI: 0.1–0.7). There were no other dietary associations. Nitrate concentrations in PWS (average, years ≥ 1/2 the maximum contaminant level) were not associated with cancer incidence. Our findings for stomach cancer are consistent with prior dietary studies, and we are the first to evaluate nitrate and nitrite ingestion for certain gastrointestinal cancers.

Objectives: In the current study, an analytical technique has been optimized for the analysis of disinfection by-products (perchlorate (ClO4−), bromate (BrO3−), nitrate (NO3−), nitrite and sulfite (SO32–) in drinking water obtained from spring, well and tap water (desalinated) sources. Methods: The ultra-performance liquid chromatography-electrospray ionization mass spectrometry (UPLC-ESI/MS) conditions have been optimized for oxyhalides ClO4− (isotopes, 37ClO4− and 35ClO4−) and BrO3− (isotopes, 81BrO3− and 79BrO3−), and inorganic anions NO3−, NO2− and SO32–. Separation was achieved by BEH C18 column with methanol (75%) and water (24.99%, HCOOH 0.01%) mobile phase at flow rate 0.2 mL/min. Results: The analysis was carried out in 0.995–0.999), limit of detection (0.016–0.043 µg/L), limit of quantification (0.051–0.104 µg/L) and precision (repeatability, 1.54–2.28% and reproducibility, 3.13–4.08%) in terms of RSD%. The method was successfully applied, and the amounts of 35ClO4− (5.33–22.64 µg/L), 81BrO3− (7.52–16.73 µg/L), NO3− (5.42–12.14 mg/L), NO2− (1.08–4.37 mg/L) and SO32– (6.84–32.45 mg/L) were identified in spring water, whereas well and tap water contained 35ClO4− (4.20–21.33 µg/L), 81BrO3− (8.05–15.13 µg/L), NO3− (1.27–16.11 mg/L), NO2− (0.43–10.77 mg/L) and SO32– (7.14–36.10 mg/L), and 35ClO4− (0.89–7.37 µg/L), 81BrO3− (5.15–14.68 µg/L), NO3− (1.12–6.33 mg/L), NO2− (0.67–3.95 mg/L) and SO32– (5.40–23.26 mg/L), respectively. Conclusions: The levels of 35ClO4−, 81BrO3−, NO3−, NO2− and SO32– were found beyond the maximum contaminant levels and drinking water equivalent levels regulated by the Environmental Protection Agency, respectively. The outcomes also revealed that comparatively tap water produced lower levels of these contaminants especially in the cities with low population densities. In addition, the geographical site would be helpful to categorize the tap water samples.

Formation of disinfection byproducts (DBPs) in drinking water treatment (DWT) as a result of pathogen removal has always been an issue of special attention in the preparation of safe water. DBPs are formed by the action of oxidant-disinfectant chemicals, mainly chlorine derivatives (chlorine, hypochlorous acid, chloramines, etc.), that react with natural organic matter (NOM), mainly humic substances. DBPs are usually refractory to oxidation, mainly due to the presence of halogen compounds so that advanced oxidation processes (AOPs) are a recommended option to deal with their removal. In this work, the application of catalytic ozonation processes (with and without the simultaneous presence of radiation), moderately recent AOPs, for the removal of humic substances (NOM), also called DBPs precursors, and DBPs themselves is reviewed. First, a short history about the use of disinfectants in DWT, DBPs formation discovery and alternative oxidants used is presented. Then, sections are dedicated to conventional AOPs applied to remove DBPs and their precursors to finalize with the description of principal research achievements found in the literature about application of catalytic ozonation processes. In this sense, aspects such as operating conditions, reactors used, radiation sources applied in their case, kinetics and mechanisms are reviewed.

To reduce public health hazards, greywater reuse may involve disinfection, which is often performed through chlorination. The formation of toxic disinfection by-products is a negative side-effect of chlorine’s reaction with organic matter, of which trihalomethanes (THM) are one of the most dominant (though not most toxic) groups. Greywater treatment in vertical flow constructed wetlands leads to a decrease in dissolved organic matter. We hypothesized that these dissolved organic carbon (DOC) changes would be reflected in differences in THM formation. Greywater samples, at different treatment levels (i.e., decreasing organic matter content), were exposed to 5 mg/L of chlorine for 1 h. THM formation in raw greywater samples was significantly lower than in the more treated (recirculated) samples, despite their significantly higher DO concentrations. This trend was verified in six different systems. Furthermore, this was also shown when greywater was exposed to higher chlorine doses (25 and 50 mg/L). It is suggested that the increase in THM formation for longer recirculated water is the result of two factors: competition between a higher number of reactive sites in the raw water’s organic matter, which leads to smaller THM yields, and changes in the abundance of THM formation moieties in the recirculated water’s DOC. The latter was reflected in the SUVA increase in the treated water. Overall, THM formation, following treated greywater chlorination at the lower chlorine concentration studied, is not expected to pose an environmental health risk when the water is reused for irrigation.

Usually, water treatment plants employ chlorine or sodium hypochlorite during the disinfection process, ensuring that there are not any pathogenic microorganisms in water. However, chlorine might react with natural organic matter and lead to formation of potentially carcinogenic by-products regarding human health, such as haloacetic acids (HAAs). Several countries regulate the levels of these acids in drinking water. Therefore, their concentrations must be monitored with the greatest accuracy as possible. In order to achieve this goal, a method through gas chromatography coupled with mass spectrometry (GC-MS) was validated and applied to the determination of HAAs in samples of water destined to the public water service provision from the city of Maring?, Paran? State, Brazil. Measurements between two periods have close recovery values, indicating that the method has good accuracy during the same day. The limits of detection (LOD) and quantification (LOQ) were satisfactory, with LOD 0.42 ?g L-1 and LOQ 1.40 ?g L-1 for dichloro-acetic acid (DCAA) analysis. Recovery values obtained for the nine haloace-tics acids (HAA9) corresponded to 69.9-107.3 % for samples. The repeatability performed for two periods presented close relative standard deviation (RSD) values, indicating that the method has good accuracy during the same day.

The occurrence of disinfection by-products (DBPs) was investigated in 48 drinking water systems across Croatia. Eleven DBPs were studied: chlorite (ClO2−), chlorate (ClO3−), four trihalomethanes (THMs), and five haloacetic acids (HAAs). Furthermore, an intensive sampling program was conducted in the distribution system in the city of Zagreb where, aside from DBP analyses, natural organic matter (NOM) was characterized using fluorescence spectroscopy. In the drinking waters examined across Croatia, DBP values were found in the range from 0.7 μg/L to 32.8 μg/L for THMs, below LOQ to 17.2 μg/L for HAAs (primarily di- and trichloroacetic acids), below LOQ to 720 μg/L for ClO2− and below LOQ to 431 μg/L for ClO3−. The results obtained showed higher chlorite concentrations in the systems treated with hypochlorite compared to systems treated with chlorine dioxide. DBPs in the Zagreb distribution network were generally low (the average values were below 6 μg/L and 2 μg/L for total THM and total HAA respectively). In contrast to our observations throughout Croatia, dibromoacetic acid (DBAA) was found to be the predominant HAA within Zagreb, most likely due to the degradation of chlorinated carboxylates (di-/tri-chloroacetic) in the network. Characterization of NOM by Parallel Factor Analysis (PARAFAC) fluorescence spectroscopy across the Zagreb network showed distinct temporal variations arising from groundwater inputs, as evident from variable humic-, tyrosine-, and tryptophan-like peaks. Statistical correlations between fluorescence data and DBPs highlight its potential for monitoring the presence of DBPs in distribution networks.

This study assessed the feasibility of electrochemical oxidation (EO) for the removal of organic compounds in cold climate regions. A two-level full factorial design was used to test the effect of three factors, temperature (6/20 °C), anode material (Pt/BDD) and pH (7/10) on the degradation of Bisphenol A. Due to the use of a chloride electrolyte, the formation of the disinfection by-products, perchlorate and trichloromethane was assessed too. The 90 % removal of the initial Bisphenol A concentration took up to 71 % (30 min) longer and up to 46 % more power input was required at 6 °C than at 20 °C. At pH 10, degradation and formation kinetics of Bisphenol A and trichloromethane were faster due to the higher oxidation power of OCl− than HOCl (pKa = 7.5) and the formation of bisphenolate ions (pKa = 9.6), which are more prone to electrophilic attack than Bisphenol A. Temperature and anode material were the two factors that significantly affect the trichloromethane formation. Trichloromethane was formed up to 45 % faster at 20 °C than at 6 °C and up to 23 % faster on Pt than on BDD anodes. However, higher trichloromethane concentration were reached on BDD anodes, but were formed at slower rates. The anode material was the only factor, which had a statistically significant influence on for the formation of perchlorate. On BDD anode up to 89 % more perchlorate was formed than on Pt anode. The present study shows that the application of EO for organic pollutant removal in regions with low average temperatures is a feasible treatment step although it is associated with higher energy demand and consequently higher costs. The formation of unwanted disinfection by-products in chloride containing waters could not be avoided, but it was shown in this study, that it can be limited by an adequate choice of treatment time, pH and anode material.

A new analytical method was optimized to determine 18 disinfection by-products (DBPs) in drinking water, including four different chemical groups. For this purpose, spiral-shaped hollow-fibre liquid phase microextraction with 1-octanol as the acceptor solvent assisted by effervescence was applied using a homemade supporting device that was specifically designed for this application. The device was printed in a 3D printer and allows for an increased fibre surface even with a low sample volume, which significantly facilitates the extraction. The samples were analysed by gas chromatography coupled to both an electron capture detector and a mass spectrometer for the quantification and unequivocal identification of the analytes, respectively. Effervescence was generated using citric acid and bicarbonate at a molar ratio 1:2, which significantly improves the extraction efficiency and reduces mechanical operations, since stirring and modifiers are not required. The results showed enrichment factors ranging from 13.1 to 140.1. Satisfactory recoveries (80-113 %) were obtained, with relative standard deviations from 3 to 15 % and good linearity. The detection limits (ng L-1) ranged from 10 to 35 (trihalomethanes), 12 to 220 (halonitromethanes), 17 to 79 (haloacetonitriles) and 10 to 16 (haloketones). The applicability of the method was assessed in 6 local water distribution systems. The authors acknowledge the plant managers of GIAHSA and their employees for their valuable help in the water collection. This work has been supported by the projects PGC2018-16 096608-B-C21 from the Spanish Ministry of Economy and Competitiveness and Projects UHU 1256905 and P12-FQM-0442 from the Regional Department of Economy, Innovation, Science and Employment (Andalusian Government, Spain). The authors also acknowledge FEDER Funds (European Community), grants numbers UNHU13-1E-1611 and UNHU15-CE-3140.