Chlorinated Tap Water Research Articles

Carbon black as a cost-effective nanomodifier for (electro)chemical-free pre-treatment thermoplastic polyurethane-based 3D printed electrodes

Here, we report the investigation of carbon black as a cost-effective nanomodifier of thermoplastic polyurethane-based 3D printed electrodes for enhancing their electrochemical performances. The sensor was produced by scratching the working electrode with sandpaper, followed by the deposition of carbon black dispersion by drop casting. The morphological characterisation was carried out, showing the presence of a homogeneous coating of carbon black with a typical rough and spongy structure. Additionally, the electrochemical characterisation using electrochemical impedance spectroscopy highlighted the advantage of using carbon black as a nanomodifier of the working electrode surface after printing by obtaining the resistance of charge transfer equal to 327 ± 43 kΩ and 1.45 ± 0.06 kΩ for bare electrode and carbon black-modified electrode, respectively. When tested in cyclic voltammetry using ferro/ferricyanide, uric acid, dopamine, ascorbic acid, and free chlorine as target electroactive compounds, we demonstrated that the presence of carbon black cast onto the working electrode surface transformed the electrode from non-responsive to responsive electroanalytical tool. The analytical features of the developed responsive sensor were assessed for the detection of free chlorine in tap water with a linearity of 0.2–20 ppm and a limit of detection equal to 0.01 ppm. The accuracy was evaluated by spiking tap water samples with free chlorine concentrations equal to 0.5, 1, and 5 ppm, obtaining recovery percentages of (103 ± 2)%, (104 ± 3)%, and (95 ± 3)%, respectively. Additionally, the sustainability (electro)chemical-free pre-treatment thermoplastic polyurethane-based 3D printed electrodes modified with carbon black were evaluated by the White Analytical Chemistry principles. The advantages of 3D printed sensors modified with carbon black by drop casting were demonstrated, in terms of both the electrochemical performances and sustainable aspect, enlarging the use of carbon black as a nanomodifier to the 3D printed electrodes, beyond the 2D printed electrodes.

Quantitation of glyphosate, glufosinate, and AMPA in drinking water and surface waters using direct injection and charged-surface ultra-high performance liquid chromatography-tandem mass spectrometry

Herbicides glyphosate (N-(phosphonomethyl)glycine) and glufosinate (2-amino-4-(hydroxymethylphosphinyl)butanoic acid) and the main transformation product of glyphosate, aminomethanephosphonic acid (AMPA), are challenging to analyze for in environmental samples. The quantitative method developed by this study adapts previously standardized dechlorination procedures coupled to a novel charged surface C18 column, ultra-high performance liquid chromatography-tandem mass spectrometry, polarity switching, and direct injection. The method was applied to chlorinated tap water, as well as river samples, collected in the City of Winnipeg and rural Manitoba, Canada. Using only syringe filtration without derivatization, the validated method resulted in good accuracies in both tap and surface water, at both 2 and 20 μg L−1. Method limits of detection (MLD) and quantification (MLQ) ranged from 0.022/0.074 to 0.11/0.36 μg L−1, with precisions of 0.46–2.2% (intraday) and 1.3–7.3% (interday). The mean (SEM) of the pesticides in μg L−1 for tap water were 0.11 (0.007) (AMPA), glufosinate and glyphosate < MLDs; and for Red River water were 0.56 (0.045) (AMPA), glufosinate < MLQ, and glyphosate 0.40 (0.072). For the smaller tributaries, glufosinate was >MLD but < MLQ once and that was for Shannon Creek at 0.2 μg L−1. For the remaining rivers, the mean concentrations ranged from 0.31 to 3.1 μg L−1 for AMPA, and 0.087–0.53 μg L−1 for glyphosate. The method will be ideal for supporting monitoring and risk assessment programs that require high throughput sampling and quantitative methods capable of producing robust results that leverages chromatographic and mass spectrometric paradigms instead of being extraction technology focused.

Cobalt-based metal-organic framework-functionalized graphene oxide modified electrode as a new electrochemical sensing platform for detection of free chlorine in aqueous solution

This work reports the profit of using a MOF compound for developing a sensitive electrochemical sensor to free chlorine detection in an aqueous solution. Co-MOF and FGO composites were synthesized and combined with the carbon paste (CP) to prepare an efficient electrochemical sensor with high sensing ability. The fabricated Co-MOF and FGO composites were characterized by SEM, EDX, FT-IR, and XRD techniques. Meanwhile, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized to assess the electrochemical performance of the Co-MOF-FGO/CP modified electrode. Under the optimized condition, the amperometric detection showed that the reduction current of free chlorine increased linearly with a coefficient determination of 0.995 during its wide concentration range of 0.1–700 ppm. Also the detection limit (LOD) (S/N = 3) was 0.01 ppm. The selectivity of the sensor was tested with possible interferences, and satisfactory results were obtained. The proposed sensor was successfully used to determine the free chlorine in tap water and swimming pool water real samples. The results suggested that this proposed sensor could pave the way for developing the electrochemical sensor of free chlorine in aqueous media with MOFs.

Combined exposure to polystyrene nanoplastics and bisphenol A induces hepato- and intestinal-toxicity and disturbs gut microbiota in channel catfish (Ictalurus punctatus)

The widespread consumption of nanoplastics (NPs) and bisphenol A (BPA) affected the aquatic ecosystem and imposed risks to the safety of aquatic organisms. This study was aimed at assessing the ecotoxicological effects of single and combined exposure to BPA and polystyrene nanoplastics (PSNPs) on the channel catfish (Ictalurus punctatus). A total of 120 channel catfish were separated into four groups with triplicate (each contains 10 fish) and exposed to chlorinated tap water (control group), PSNP single exposure (0.3 mg/L), BPA single exposure (500 μg/L) and PSNPs (0.3 mg/L) + BPA (500 μg/L) co-exposure for 7 days. Our results showed a relatively higher intestinal accumulation of PSNPs in co-exposure group, compared to PSNP single exposure group. Histopathological analysis showed that single exposure to PSNPs and BPA caused breakage of intestinal villi and swelling of hepatocytes in channel catfish, while the co-exposure exacerbated the histopathological damage. In addition, co-exposure significantly increased SOD, CAT activities and MDA contents in the intestine and liver, inducing oxidative stress. In terms of immune function, the activities of ACP and AKP were significantly decreased. The expressions of immune-related genes such as IL-1β, TLR3, TLR5, hepcidin and β-defensin were significantly up-regulated, and the expression of IL-10 was down-regulated. Additionally, the co-exposure significantly altered the composition of the intestinal microbiota, leading to an increase in the Shannon index and a decrease in the Simpson index. In summary, this study revealed that mixture exposure to PSNPs and BPA exacerbated toxic effects on histopathology, oxidative stress, immune function and intestinal microbiota in channel catfish. It emphasized the threat of NPs and BPA to the health of aquatic organisms and human food safety, with a call for effective ways to regulate the consumption of these anthropogenic chemicals.

A Review of Traditional and Emerging Residual Chlorine Quenchers on Disinfection By-Products: Impact and Mechanisms.

Disinfection by-products (DBPs) are the most common organic contaminants in tap water and are of wide concern because of their highly developmental toxic, cytotoxic, and carcinogenic properties. Typically, to control the proliferation of pathogenic microorganisms, a certain concentration of residual chlorine is retained in the factory water, which reacts with the natural organic matter and the disinfection by-products that have been formed, thus affecting the determination of DBPs. Therefore, to obtain an accurate concentration, residual chlorine in tap water needs to be quenched prior to treatment. Currently, the most commonly used quenching agents are ascorbic acid, sodium thiosulfate, ammonium chloride, sodium sulfite, and sodium arsenite, but these quenching agents can cause varying degrees of DBPs degradation. Therefore, in recent years, researchers have attempted to find emerging chlorine quenchers. However, no studies have been conducted to systematically review the effects of traditional quenchers and new ones on DBPs, as well as their advantages, disadvantages, and scope of application. For inorganic DBPs (bromate, chlorate, and chlorite), sodium sulfite has been proven to be the ideal chlorine quencher. For organic DBPs, although ascorbic acid caused the degradation of some DBPs, it remains the ideal quenching agent for most known DBPs. Among the studied emerging chlorine quenchers, n-acetylcysteine (NAC), glutathione (GSH), and 1,3,5-trimethoxybenzene are promising for their application as the ideal chlorine quencher of organic DBPs. The dehalogenation of trichloronitromethane, trichloroacetonitrile, trichloroacetamide, and bromochlorophenol by sodium sulfite is caused by nucleophilic substitution reaction. This paper takes the understanding of DBPs and traditional and emerging chlorine quenchers as a starting point to comprehensively summarize their effects on different types of DBPs, and to provide assistance in understanding and selecting the most suitable residual chlorine quenchers during DBPs research.

Insight into mixed chlorine/chloramines conversion and associated water quality variability in drinking water distribution systems

Mixed chlorine/chloramines are common in drinking water distribution systems (DWDSs); however, their transformation and impact on chemical and microbial characteristics are not well understood. We systematically investigated water quality parameters associated with mixed chlorine/chloramine species conversion in 192 samples (including raw, finished, and tap water) collected throughout the year in a city in East China. Various chlorine/chloramine species (free chlorine, monochloramine [NH2Cl], dichloramine [NHCl2], and organic chloramines [OC]) were detected in both chlorinated and chloraminated DWDSs. NHCl2 + OC increased with transport distance along the pipeline network. The maximum proportion of NHCl2 + OC in over total chlorine in tap water reached 66 % and 38 % from chlorinated and chloraminated DWDSs, respectively. Both free chlorine and NH2Cl showed a rapid decay in the water pipe systems, but NHCl2 and OC were more persistent. Correlations between chlorine/chloramine species and physicochemical parameters were established. Models for predicting the sum of chloroform/TCM, bromodichloromethane/BDCM, chlorodibromomethane/CBDM, and bromoform/TBM (THM4) (R2 = 0.56) and haloacetic acids (HAAs) (R2 = 0.65) exhibited greater accuracy based on machine learning tuned with chlorine/chloramine species, particularly NHCl2 + OC. The predominant bacterial communities in mixed chlorine/chloramine systems were those resistant to chlorine or chloramine such as proteobacteria. NH2Cl was the most significant explanatory factor (28.1 %) for the variation in microbial community assemblage in chloraminated DWDSs. Although residual free chlorine and NHCl2 + OC, accounted for a smaller proportion of chlorine species in chloraminated DWDSs, they played an essential role (12.4 % and 9.1 %, respectively) in the microbial community structure.

Aspartame-Sweetened Tap Water: Transformation Products and 2,6-Dichloro-1,4-Benzoquinone Formation.

Aspartame (APM), a dipeptide of aspartic acid (ASP) and phenylalanine (PHE), is a widely used artificial sweetener in beverages. It is unclear whether residual chlorine in tap water can react with APM to form disinfection byproducts (DBPs). Therefore, we investigated the formation of DBPs from the reaction of APM with residual chlorine in authentic tap water. APM and a commercial sweetener (CS) packet containing APM were studied under authentic and simulated tap water conditions. Eight chlorinated products of APM were detected using solid-phase extraction (SPE) and high performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS). These new chloro-products were tentatively identified based on accurate masses, isotopic patterns of 35,37Cl, and MS/MS spectra. Furthermore, we identified APM as a precursor to 2,6-dichloro-1,4-benzoquinone (DCBQ). DCBQ significantly increased to 2.3-12 ng/L with the addition of APM or CS in tap waters collected from different locations compared to 1.4-1.8 ng/L in the same tap water samples without sweetener. DCBQ and two of the chlorinated transformation products were identified in cold prepared tea containing APM. DCBQ formation was eliminated when the residual chlorine in tap water was reduced by ascorbic acid or boiling prior to the addition of APM or CS. This study found that eight new DBPs and DCBQ were produced by the reactions of residual chlorine with APM and CS. These findings show an unintended exposure source of emerging DBPs via APM sweetened beverages.

Revisiting the effect of boiling on halogenated disinfection byproducts, total organic halogen, and cytotoxicity in simulated tap water

Boiling is a widely adopted household tap water treatment method because of its ability to inactivate chlorine-resistant pathogenic bacteria, and to reduce certain groups of disinfection byproducts (DBPs). From a more comprehensive point of view, this study revisited the effect of boiling on four groups of 17 aliphatic DBPs and six groups of 44 aromatic DBPs in both simulated chlorinated and chloraminated tap water samples, with a special focus on the changes of total organic halogen (TOX) and cytotoxicity. Results showed that the concentrations of aliphatic DBPs substantially decreased during boiling via volatilization (trihalomethanes and chloral hydrate) and hydrolysis (haloacetamides) in chlorinated and chloraminated tap water samples. The concentrations of aromatic DBPs during boiling generally followed an increasing trend due to decarboxylation of polycarboxylic precursors in chlorinated tap water samples, and showed a first increasing and then decreasing trend in chloraminated tap water samples. A sharp decreasing of TOX occurred in the heating process of tap water samples from room temperature to 100 °C, and a relatively gentle decreasing was kept in the prolonged boiling process till 5 min. The most abundant DBP group in the tap water samples without boiling was trihalomethanes, and was replaced by haloacetic acids with boiling for 5 min. Continuous boiling for 5 min substantially reduced the cytotoxicity of chlorinated and chloraminated water samples by 52.6% and 21.3%, respectively. Reduction of cytotoxicity matched well with the reduction of TOCl (r = 0.907, P < 0.01), TOBr (r = 0.885, P < 0.01) and TOX (r = 0.905, P < 0.01), suggesting that the cytotoxicity reduction during boiling was mainly ascribed to the reduction of halogenated DBPs. Therefore, boiling of tap water to 100 °C was strongly recommended to reduce the potential health risks induced by tap water ingestion.

An Automated Toolchain for Camera-Enabled Sensing of Drinking Water Chlorine Residual.

Chlorine residual concentration is an important parameter to prevent pathogen growth in drinking water. Disposable color changing test strips that measure chlorine in tap water are commercially available to the public; however, the color changes are difficult to read by eye, and the data are not captured for water service providers. Here we present an automated toolchain designed to process digital images of free chlorine residual test strips taken with mobile phone cameras. The toolchain crops the image using image processing algorithms that isolate the areas relevant for analysis and automatically white balances the image to allow for use with different phones and lighting conditions. The average red, green, and blue (RGB) color values of the image are used to predict a free chlorine concentration that is classified into three concentration tiers (<0.2 mg/L, 0.2-0.5 mg/L, or >0.5 mg/L), which can be reported to water users and recorded for utility use. The proposed approach was applied to three different phone types under three different lighting conditions using a standard background. This approach can discriminate between concentrations above and below 0.5 mg/L with an accuracy of 90% and 94% for training and testing data sets, respectively. Furthermore, it can discriminate between concentrations of <0.2 mg/L, 0.2-0.5 mg/L, or >0.5 mg/L with weighted-averaged F1 scores of 79% and 88% for training and testing data sets, respectively. This tool sets the stage for tap water consumers and water utilities to gather frequent measurements and high-resolution temporal and spatial data on drinking water quality.

The Soul Is a Biophysical Reality: Review of the Experimental Evidence

Introduction: In the present report, we studied the responses of a dwarf form of the unicellular organism, Stentor coeruleus, at the life/ death interphase. Methods: Uncovered deep well slides were filled with culture media containing the large forms of Stentor coeruleus. On evaporation of the culture medium, the cell membrane of these larger forms disrupted. When rehydrated 24 hours later the micronuclei previously released from the dying cells showed the formation of numerous, mobile dwarf cells. Chlorinated tap water added to the medium was used to induce cell death. Results: The initial indication of the dying dwarf cell is “blebbing,” a signature of programmed cell death known as apoptosis. Within 8-12min, the stationary dwarf cell progressively released a morphological replicate of the dead cell before the replicate faded into the ambient environment. In other experiments, just prior to fading, the slide was exposed to a magnetic field (75 milligaus) which caused a retraction of the replicate back into the dwarf cell. Subsequently, the cells resumed their previously mobile activity. Conclusions: These findings support the hypothesis that a phenomenon analogous to the characteristics ascribed to the soul in the metaphysical literature can be demonstrated in the laboratory. We suggest that the responses shown by this unicellular organism at the life/death interphase may be conserved across the evolutionary spectrum.

Free chlorine ultra-sensitive detection in tap water via an enrichment-sensing process by an interdigitated microelectrode sensor

Electrochemical free chlorine sensor is considered to be a feasible device for on-line monitoring of free chlorine in tap water due to their reagent-free and short-response-time etc. However, the low sensitivity and the difficulty of to mass-production of the sensor always are the stubborn issues for reliable detection and application in ultra-low concentration range. In this paper, we design an interdigitated microelectrode structured electrochemical sensor chip for free chlorine sensing in tap water and fabricate by MEMS. The batch-fabricated sensor demonstrates an acceptable limit of detection (<0.05 mg/L), a desirable linearity (R2 = 0.991). What's more, a novel detection method (TSAM) is proposed/applied to improve the sensitivity for free chlorine sensing though an enrichment-sensing process. A small and positive potential (0.1 V) is applied to the interdigital electrode to form a ClO−enrichment region near WE before the operating bias voltage (-1.65 V). Fortunately, about 30 times increase (46.334 μA/mgL−1) in sensitivity of sensor by TSAM is witnessed, comparing with the amperometric method. Far greater than the sensitivity of other researches on free chlorine sensor. Beside, by employing the MEMS technique, favorable response consistency and high reproducibility (RSD<3.85%) is witnessed, offering the opportunity of mass-producing the proposed sensor in future. It is anticipated that the proposed sensor and sensing method will provide a competitive strategy to design high sensitivity, reliable and mini sensor for water contaminants detection.

A batch microfabrication of a self-cleaning, ultradurable electrochemical sensor employing a BDD film for the online monitoring of free chlorine in tap water

Free chlorine is one of the key water quality parameters in tap water. However, a free chlorine sensor with the characteristics of batch processing, durability, antibiofouling/antiorganic passivation and in situ monitoring of free chlorine in tap water continues to be a challenging issue. In this paper, a novel silicon-based electrochemical sensor for free chlorine that can self-clean and be mass produced via microfabrication technique/MEMS (Micro-Electro-Mechanical System) is proposed. A liquid-conjugated Ag/AgCl reference electrode is fabricated, and electrochemically stable BDD/Pt is employed as the working/counter electrode to verify the effectiveness of the as-fabricated sensor for free chlorine detection. The sensor demonstrates an acceptable limit of detection (0.056 mg/L) and desirable linearity (R2 = 0.998). Particularly, at a potential of +2.5 V, hydroxyl radicals are generated on the BBD electrode by electrolyzing water, which then remove the organic matter attached to the surface of the sensor though an electrochemical digestion process. The performance of the fouled sensor recovers from 50.2 to 94.1% compared with the initial state after self-cleaning for 30 min. In addition, by employing the MEMS technique, favorable response consistency and high reproducibility (RSD < 4.05%) are observed, offering the opportunity to mass produce the proposed sensor in the future. A desirable linear dependency between the pH, temperature, and flow rate and the detection of free chlorine is observed, ensuring the accuracy of the sensor with any hydrologic parameter. The interesting sensing and self-cleaning behavior of the as-proposed sensor indicate that this study of the mass production of free chlorine sensors by MEMS is successful in developing a competitive device for the online monitoring of free chlorine in tap water.

REDGIM COMO APLICATIVO DE SMARTPHONE PARA APLICAÇÕES QUIMIOMÉTRICAS POR MEIO DE ANÁLISE DE IMAGENS: UM USO EM PLS

REDGIM AS A SMARTPHONE APP FOR CHEMOMETRICS APPLICATIONS THROUGH IMAGE ANALYSIS: A USE IN PLS. The study of the spectrum of light has increased its range of action in the field of chemistry, with the help of several advanced equipment and innovative techniques that have become a strong ally of analytical chemistry. However, the simplicity of obtaining results integrated with mobile devices appears as an interesting path to be taken in the field of chemical analysis. This work addresses the dissemination of an application called REDGIM for smartphones on the Android platform capable of working with multivariate image analysis using chemometric methods through the luminous intensities of photos and R (red), G (green) and B (blue) channels. In order to show the potential of REDGIM, we propose two applications using the partial least squares (PLS) regression method: 1) quantification of free chlorine in tap water; and 2) quantification of cannabinol, (CBN, a type of cannabinoid) in marijuana and hashish samples. The free chlorine concentration obtained for two investigated samples was 0.73 and 0.74 mg L–1 and 0.74 and 0.76 mg L–1 by the spectrophotometer and by the application (container: cuvette), respectively. For the quantification of CBN in marijuana and hashish samples, the mean concentration ranged from 6.137 to 8.823 mg mL–1. The results obtained by the application are compatible with results from traditional techniques, such as UV-Vis spectrophotometry, for example. Therefore, REDGIM was proved to be a simple and accessible technological tool for the scientific community, being viable for chemical tests of a multivariate nature.

Influence of residual chlorine and pressure on the degradation of water pipes of polyethylene of raised temperature

A simple and accurate evaluation of the degradation of polymeric products, which are indispensable parts of our daily life, is important for the safe and long-term use of these products. Herein, we present a novel evaluation method for the pipes of polyethylene of raised temperature (PE-RT), a non-cross-linked polyethylene. In this method, we conducted accelerated degradation tests using a custom-designed small pressure vessel. Although it is known that residual chlorine in tap water accelerates the degradation of plastic pipes, this method reveals that the water pressure further accelerates the degradation of the pipes. We demonstrate for the first time that the results of three-dimensional fluorescence spectral studies exhibit a similar trend as those of the conventional isothermal oxidation induction time (I-OIT) measurement. This fluorescence-based method can contribute to the development of new evaluation methods to study plastic degradation, because it is very simple, does not require sample pretreatment, unlike I-OIT and other degradation evaluation methods, and the measurement can be performed directly within a few minutes.

Unraveling Membrane Fouling Induced by Chlorinated Water Versus Surface Water: Biofouling Properties and Microbiological Investigation

• Chlorinated tap water has more severe biofouling potential than surface water. • Densely compact morphology was observed for tap-water biofilm than surface-water. • Xanthobacter was the dominant taxon in tap-water biofilm. • Hydrophilicity of membrane plays a minor role in biofouling formation. Chlorine is usually applied in the urban water treatment process to deactivate pathogens and prevent waterborne diseases. As a pre-treatment, it remains unclear whether chlorinated water can effectively alleviate membrane fouling during ultrafiltration (UF). In this study, tap water was investigated for its effect on biofilm formation and biofouling in a gravity-driven membrane (GDM) filtration system. For comparison, biofilm/biofouling with untreated surface (lake) water was studied in parallel. It was found that more severe membrane fouling occurred with the filtration of tap water than lake water, and larger quantities of polysaccharide and extracellular DNA (eDNA) were present in the tap-water biofilm than in the lake-water biofilm. The tap-water biofilm had a densely compact morphology. In contrast, a porous, spider-like structure was observed for the lake-water biofilm, which was assumed to be associated with the bacteria in the biofilm. This hypothesis was verified by 16S ribosomal RNA (rRNA) sequencing, which demonstrated that Xanthobacter was the dominant taxon in the tap-water biofilm. Additionally, membrane hydrophobicity/hydrophilicity played a minor role in affecting the membrane fouling properties and microbial community. This study revealed the significant role of chlorine-resistant bacteria in biofouling formation and provides a deeper understanding of membrane fouling, which can potentially aid in searching for effective ways of controlling membrane fouling.

Assessment of carcinogenic risk from exposure to chlororganic compounds of water of systems of centralized water supply

Introduction. The problem of providing the population with drinking water with guaranteed quality, safety, and physiological usefulness is highly relevant for many regions of Russia. The use of chlorination for disinfection of the water is a potential cause of the formation of excess concentrations of organochlorine compounds in it, including trihalogenomethanes, which leads to elevated levels of carcinogenic risk. The study’s object was: data on the content in water of centralized water supply systems of carcinogenic organochlorine compounds - chloroform, dichlorobromomethane and chlorodibromomethane. Material and methods. information on the incidence of the population of malignant neoplasms; the results of an experiment to evaluate the effectiveness of the preliminary ammonization method. The paper used methods of health risk assessment, variation statistics, and mathematical modeling. Results. The use of preliminary ammonization in Taganrog prevents the formation of trihalogenomethanes and ensures the maintenance of an individual multi-route carcinogenic risk at an acceptable level (9.933 · 10-6). Systematic unreasonable hyper chlorination of river water without prior ammoniation is the main reason for the excess content of chlororganic compounds and the high level of individual carcinogenic risk in the Primorsky rural settlement of the Neklinovsky District - up to 3.234 · 10-3 in 2015. Modeling on the basis of experimental chlorination of natural water indicates the high efficiency of preliminary ammonization in the disinfection mode, which ensures the content of free total active chlorine in tap water in the range from 0.8 to 1.2 mg/l. Conclusion. The high efficiency of the application of preliminary ammonization of natural water to prevent the formation of trihalogenomethanes and reduce carcinogenic risk has been confirmed. The priority factor for the formation of excess amounts of organochlorine compounds in drinking water is its hyper chlorination. Promising measures to reduce the carcinogenic risk of trihalogenomethanes in tap water include the systematic monitoring of their content, the use of preliminary ammonization, the exact dosage of chlorine, the deep purification of the source water before chlorination, the replacement of primary chlorination with ultraviolet disinfection, and others.

Occurrence and health risk assessment of pharmaceutically active compounds in riverbank filtrated drinking water

The presence of pharmaceutically active compounds (PhACs) in drinking waters might pose a serious threat to human health worldwide. Therefore, this study sought to measure PhACs in Danube-derived tap water from the Budapest metropolitan region (Hungary), and to compare the results of those measured in the bank filtrate after which a human health risk assessment (based on human risk quotient [hRQ]) was conducted for the detected PhACs. A total of 108 samples were collected from 21 sampling sites throughout 6 sampling campaigns. Our study screened for 102 PhACs, of which 19 were detected in the persistently chlorinated tap water samples. PhAC concentrations were much lower than previously assumed based on the contamination of raw water resources. The total mean concentration of the analyzed PhACs exceeded 30 ng L−1 only at 5 sites. Moreover, the frequency of occurrence (FRO) of the 6 most common compounds (carbamazepine, lamotrigine, lidocaine, benzoylecgonine, tramadol, and cinolazepam) reached 50 % at 4 sites. The most frequent PhAC was carbamazepine (FRO = 53.7 %), the risk level of all PhACs investigated was negligible (hRQ<1) with carbamazepine having the highest hRQs (hRQMAX = 0.007; hRQMEAN = 0.001). Tap water provided lower PhAC concentrations farther from the water abstraction wells and treatment stations along the Danube. The travel time between the drinking water wells and taps with other factors, such as the varying microbiological pattern and the deposits in the supply system influence the PhAC concentrations. Based on the risk assessment, all investigated PhACs pose a negligible risk to consumers in the investigated urban area.

Identification of chloramination disinfection by-products from phenylalanine in tap drinking water

Phenylalanine (Phe) is widely present in natural water and serves as a precursor of disinfection by-products (DBPs). We reported the identification of chloramination DBPs from Phe in drinking water using ultra-high performance liquid chromatography (UHPLC) coupled with complementary high-resolution quadrupole time-of-flight (QTOF) and triple quadrupole (tQ) tandem mass spectrometry (MS/MS). In the chloraminated Phe water solution, sixteen new DBPs in a total of seventeen were identified based on their accurate mass, MS/MS spectra and 35Cl/37Cl isotopic patterns. Three of these DBPs were verified as benzamide, phenylacetamide, and p-hydroxyphenylacetamide with their standards, while the others were chlorinated derivatives of Phe, hydrazone, amidine, amide and peroxide, in which the unique structures of these DBPs were rarely reported. Their stability and formation process were investigated as well. Furthermore, a method consisting of solid phase extraction (SPE) and UHPLC-MS/MS using dynamic multiple reaction monitoring (dMRM) was developed to investigate these DBPs in authentic waters. Phe, benzamide, phenylacetamide, and N–Cl-2-phenylacetimidamide were detected in chlorinated tap water. Compared with the other identified DBPs, these three DBPs were exceptionally stable and could be formed in wide formation conditions. Our work not only provided ideas for the identification of new chloramination DBPs, but also demonstrated that some DBPs usually generated in the chloramination disinfection process could also be found in the chlorinated drinking water.

Addition of lemon before boiling chlorinated tap water: A strategy to control halogenated disinfection byproducts

Chlorine disinfection is required to inactivate pathogens in drinking water, but it inevitably generates potentially toxic halogenated disinfection byproducts (halo-DBPs). A previous study has reported that the addition of ascorbate to tap water before boiling could significantly decrease the concentration of overall halo-DBPs in the boiled water. Since the fruit lemon is rich in vitamin C (i.e., ascorbic acid), adding it to tap water followed by heating and boiling in an effort to decrease levels of halo-DBPs was investigated in this study. We examined three approaches that produce lemon water: (i) adding lemon to tap water at room temperature, termed “Lemon”; (ii) adding lemon to boiled tap water (at 100 °C) and then cooling to room temperature, termed “Boiling + Lemon”; and (iii) adding lemon to tap water then boiling and cooling to room temperature, termed “Lemon + Boiling”. The concentrations of total and individual halo-DBPs in the resultant water samples were quantified with high-performance liquid chromatography-tandem mass spectrometry and the cytotoxicity of DBP mixtures extracted from the water samples was evaluated using human epithelial colorectal adenocarcinoma Caco-2 cells and hepatoma HepG2 cells. Our results show that the “Lemon + Boiling” approach substantially decreased the concentrations of halo-DBPs and the cytotoxicity of tap water. This strategy could be applied to control halo-DBPs, as well as to lower the adverse health effects of halo-DBPs on humans through tap water ingestion.

A randomized, double-blind water taste test to evaluate the equivalence of taste between tap water and filtered water in the Taipei metropolis

High water quality and sufficient water availability are the main concerns of water users. Promoting the efficient use of tap water can contribute to sustainable drinking water management and progress towards Sustainable Development Goals. In many metropolises, water suppliers treat municipal water with appropriate treatment processes and well-maintained distribution infrastructure. Under this circumstance, it is acceptable that municipal water can be a source of drinking water. The presence of residual chlorine in tap water, connected to municipal water supply, inactivates pathogenic microorganisms and prevents recontamination. However, adding chlorine to tap water may affect the organoleptic properties of drinking water. On the other hand, the use of point-of-use (POU) water dispensers, which provides an additional treatment step on tap water, is not energy-efficient. A randomized, double-blind water taste test was conducted in the Taipei metropolis to assess whether tap water from public drinking fountains and filtered water from POU water dispensers have similar organoleptic properties. An odds ratio (OR) and the area under the receiver operating characteristic curve (AUC) were used to measure the participants’ ability to distinguish between the two water varieties. A five-region hypothesis test was conducted to test the OR, and a 95% bootstrap confidence interval of the AUC was calculated. The results of the study showed that the 95% five-region confidence interval of OR equal to (0.5, 1.49), and the 95% bootstrap confidence interval of AUC equal to (0.42, 0.56). These results implied that people in the Taipei metropolis could not distinguish between tap water and filtered water. It is recommended that more drinking fountains be installed and maintained fully functional and clean to achieve excellence in tap water access.