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The ubiquitous occurrence of per- and polyfluoroalkyl substances (PFAS) and the detection of unexplained extractable organofluorine (EOF) in drinking water have raised growing concerns. A recent study reported the detection of inorganic fluorinated anions in German river systems, and therefore, in some samples, EOF may include some inorganic fluorinated anions. Thus, it might be more appropriate to use the term "extractable fluorine (EF) analysis" instead of the term EOF analysis. In this study, tap water samples ( n = 39) from Shanghai were collected to assess the levels of EF/EOF, 35 target PFAS, two inorganic fluorinated anions (tetrafluoroborate (BF 4 - ) and hexafluorophosphate (PF 6 ) was reported in drinking water from China, and - )), and novel PFAS through suspect screening and potential oxidizable precursors through oxidative conversion. The results showed that ultra-short PFAS were the largest contributors to target PFAS, accounting for up to 97% of ΣPFAS. To the best of our knowledge, this was the first time that bis(trifluoromethanesulfonyl)imide (NTf 2 ) was reported in drinking water from China, and p -perfluorous nonenoxybenzenesulfonate (OBS) was also identified through suspect screening. Small amounts of precursors that can be oxidatively converted to PFCAs were noted after oxidative conversion. EF mass balance analysis revealed that target PFAS could only explain less than 36% of EF. However, the amounts of unexplained extractable fluorine were greatly reduced when BF 4 - and PF 6 - were included. These compounds further explained more than 44% of the EF, indicating the role of inorganic fluorinated anions in the mass balance analysis.

Per- and polyfluoroalkyl substances (PFAS) have raised concerns due to their worldwide occurrence and adverse effects on both the environment and humans as well as posing challenges for monitoring. Further collection of information is required for a better understanding of their occurrence and the unknown fractions of the extractable organofluorine (EOF) not explained by commonly monitored target PFAS. In this study, eight pairs of raw and treated water were collected from drinking water treatment plants (DWTPs) around Taihu Lake in China and analyzed for EOF and 34 target PFAS. Mass balance analysis of organofluorine revealed that at least 68% of EOF could not be explained by target PFAS. Relatively higher total target concentrations were observed in 4 DWTPs (D1 to D4) when compared to other samples with the highest sum concentration up to 189 ng L -1 . PFOA, PFOS and PFHxS were the abundant compounds. Suspect screening analysis identified 10 emerging PFAS ( e.g. , H-PFAAs, H-PFESAs and OBS) in addition to target PFAS in raw or treated water. The ratios PFBA/PFOA and PFBS/PFOS between previous and current studies showed significant replacements of short-chain to long-chain PFAS. The ratios of the measured PFAS concentrations to the guideline values showed that some of the treated drinking water exceeds guideline values, appealing for efforts on drinking water safety guarantee.

Safe drinking water is crucial to public health. However, approximately one-third of the world's population lacks access to clean drinking water. The presence of antibiotics and antibiotic resistance genes (ARGs) in drinking water sources has become a severe problem worldwide due to its potential threat to human health. We monitored the occurrence and variations of 23 antibiotics and 9 ARGs in different treatment processes in a constructed wetland serving as drinking water source in the Yangtze River Delta, China. The studied wetland is consisted of four treatment processes: pretreatment area, pump station lifting, root-channel ecological purification area and deep purification area. Except for sulfapyridine and roxithromycin, 21 antibiotics were detected at concentrations ranging from 0.15 to 59.52 ng/L. The concentration of macrolides was the highest in this wetland, especially tylosin (42.86-59.52 ng/L). TetG, tetX and sul2 were the dominant ARGs in both water (2.41 × 10 -4 -1.87 × 10 -2 ) and sediment (6.65 × 10 -5 -4.92 × 10 -3 ). In addition, a strong correlation between ARGs in water and ARGs in sediment (Pearson, R 2  > 0.9, p < 0.05) indicated an exchange between the two phases. Moreover, the significantly positive correlation of ARGs between the inlet and outlet of each subsystem illustrated that upstream pollution was the primary source for downstream processes. In general, the wetland system could efficiently eliminate antibiotics (9.0-53.8%) and ARGs (14.5-94.1%), with the deep purification area having the highest removal efficiency. Overall, our results provide important insights into the occurrence, abundance and removal of antibiotics and ARGs in the constructed wetland serving as drinking water sources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

There is growing worry that drinking water can be affected by contaminants of emerging concern (CECs), potentially threatening human health. In this study, a wide range of CECs (n = 177), including pharmaceuticals, pesticides, perfluoroalkyl substances (PFASs) and other compounds, were analysed in raw water and in drinking water collected from drinking water treatment plants (DWTPs) in Europe and Asia (n = 13). The impact of human activities was reflected in large numbers of compounds detected (n = 115) and high variation in concentrations in the raw water (range 15-7995 ng L -1 for ∑ 177 CECs). The variation was less pronounced in drinking water, with total concentration ranging from 35 to 919 ng L -1 . Treatment efficiency was on average 65 ± 28%, with wide variation between different DWTPs. The DWTP with the highest ∑CEC concentrations in raw water had the most efficient treatment procedure (average treatment efficiency 89%), whereas the DWTP with the lowest ∑ 177 CEC concentration in the raw water had the lowest average treatment efficiency (2.3%). Suspect screening was performed for 500 compounds ranked high as chemicals of concern for drinking water, using a prioritisation tool (SusTool). Overall, 208 features of interest were discovered and three were confirmed with reference standards. There was co-variation between removal efficiency in DWTPs for the target compounds and the suspected features detected using suspect screening, implying that removal of known contaminants can be used to predict overall removal of potential CECs for drinking water production. Our results can be of high value for DWTPs around the globe in their planning for future treatment strategies to meet the increasing concern about human exposure to unknown CECs present in their drinking water., Competing Interests: Declaration of Competing Interest All author hereby declares no conflict of interest., (Copyright © 2021. Published by Elsevier Ltd.)

Dichloroacetamide (DCAcAm), a disinfection byproduct, has been detected in drinking water. Previous research showed that amino acids may be DCAcAm precursors. However, other precursors may be present. This study explored the contribution of the antibiotic chloramphenicol (CAP) and two of its analogues (thiamphenicol, TAP; florfenicol, FF) (referred to collectively as CAPs), which occur in wastewater-impacted source waters, to the formation of DCAcAm. Their formation yields were compared to free and combined amino acids, and they were investigated in filtered waters from drinking-water-treatment plants, heavily wastewater-impacted natural waters, and secondary effluents from wastewater treatment plants. CAPs had greater DCAcAm formation potential than two representative amino acid precursors. However, in drinking waters with ng/L levels of CAPs, they will not contribute as much to DCAcAm formation as the μg/L levels of amino acids. Also, the effect of advanced oxidation processes (AOPs) on DCAcAm formation from CAPs in real water samples during subsequent chlorination was evaluated. Preoxidation of CAPs with AOPs reduced the formation of DCAcAm during postchlorination. The results of this study suggest that CAPs should be considered as possible precursors of DCAcAm, especially in heavily wastewater-impacted waters.

Haloacetamides (HAcAms), an emerging class of nitrogenous disinfection by-products (N-DBPs) of health concern, have been frequently identified in drinking waters. It has long been appreciated that free amino acids (AAs), accounting for a small fraction of the dissolved organic nitrogen (DON) pool, can form dichloroacetamide (DCAcAm) during chlorination. However, the information regarding the impacts of combined AAs, which contribute to the greatest identifiable DON portion in natural waters, is limited. In this study, we compared the formation of HAcAms from free AAs (tyrosine [Tyr] and alanine [Ala]) and combined AAs (Tyr-Ala, Ala-Tyr, Tyr-Tyr-Tyr, Ala-Ala-Ala), and found that HAcAm formation from the chlorination of AAs in combined forms (oligopeptides) significantly exhibited a different pattern with HAcAm formation from free AAs. Due to the presence of peptide bonds in tripeptides, Tyr-Tyr-Tyr and Ala-Ala-Ala produced trichloroacetamide (TCAcAm) in which free AAs was unable to form TCAcAm during chlorination. Moreover, peptide bond in tripeptides formed more tri-HAcAms than di-HAcAms in the presence of bromide. Therefore, the peptide bond may be an important indicator to predict the formation of specific N-DBPs in chlorination. The increased use of algal- and wastewater-impacted water as drinking water sources will increase health concerns over exposure to HAcAms in drinking water.

The occurrence and distribution of antibiotic resistance genes (ARGs) in drinking water treatment plants (DWTPs) and finished water are not well understood, and even less is known about the contribution of each treatment process to resistance gene reduction. The prevalence of ten commonly detected sulfonamide and tetracycline resistance genes, namely, sul I, sul II, tet(C), tet(G), tet(X), tet(A), tet(B), tet(O), tet(M) and tet(W) as well as 16S-rRNA genes, were surveyed in seven DWTPs in the Yangtze River Delta, China, with SYBR Green I-based real-time quantitative polymerase chain reaction. All of the investigated ARGs were detected in the source waters of the seven DWTPs, and sul I, sul II, tet(C) and tet(G) were the four most abundant ARGs. Total concentrations of ARGs belonging to either the sulfonamide or tetracycline resistance gene class were above 10(5) copies/mL. The effects of a treatment process on ARG removal varied depending on the overall treatment scheme of the DWTP. With combinations of the treatment procedures, however, the copy numbers of resistance genes were reduced effectively, but the proportions of ARGs to bacteria numbers increased in several cases. Among the treatment processes, the biological treatment tanks might serve as reservoirs of ARGs. ARGs were found in finished water of two plants, imposing a potential risk to human health. The results presented in this study not only provide information for the management of antibiotics and ARGs but also facilitate improvement of drinking water quality., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Selenium (Se) has been recognized as one key to understanding mercury (Hg) exposure risks. To explore the effects of Se on Hg-induced immunotoxicity, female Balb/c mice were exposed to HgCl2- or MeHgCl-contaminated drinking water (0.001, 0.01, and 0.1 mM as Hg) with coexisting Na2SeO3 at different Se/Hg molar ratios (0:1, 1/3:1, 1:1 and 3:1). The potential immunotoxicity induced by Na2SeO3 exposure alone (by way of drinking water) was also determined within a wide range of concentrations. After 14 days' exposure, the effects of Hg or Se on the immune system of Balb/c mice were investigated by determining the proliferation of T and B lymphocytes and the activity of natural killer cells. Hg exposure alone induced a dose-dependent suppression effect, whereas Se provided promotion effects at low exposure level (<0.01 mM) and inhibition effects at high exposure level (>0.03 mM). Under Hg and Se coexposure condition, the effects on immunotoxicity depended on the Hg species, Se/Hg ratio, and exposure concentration. At low Hg concentration (0.001 mM), greater Se ingestion exhibited stronger protective effects on Hg-induced suppression effect mainly by way of decreasing Hg concentrations in target organs. At greater Hg concentration (0.01 and 0.1 mM), immunotoxicity induced by Se (>0.03 mM) became evident, and the protective effects appeared more significant at an Se/Hg molar ratio of 1:1. The complex antagonistic effects between Se and Hg suggested that both Se/Hg molar ratio and concentration should be considered when evaluating the potential health risk of Hg-contaminated biota.

The haloacetamides (HAcAms) are disinfection by-products (DBPs) in drinking water which are currently receiving increased scientific attention due to their elevated toxicity relative to regulated disinfection by-products. A simultaneous determination method of 13 HAcAms, combining solid-phase extraction (SPE) enrichment, liquid chromatographic (LC) separation, and triple quadrupole mass spectrometry (tqMS) detection with atmospheric pressure chemical ionization (APCI) using selective reaction monitoring in positive mode, was developed to measure HAcAms, including chlorinated, brominated, and iodinated analogs. Ammonium chloride and Oasis HLB were selected as the dechlorinating reagent and polymeric SPE sorbent of HAcAm samples. The used tqMS apparatus showed higher sensitivity for the studied HAcAms in the APCI mode than electrospray ionization. 13 HAcAms were separated by LC in 9.0 min, and the detection limits ranged from 7.6 to 19.7 ng/L. The SPE-LC/tqMS method was successfully applied to quantify 13 HAcAms in drinking water samples for the first time, and first indentified tribromoacetamide and chloroiodoacetamide as DBPs in drinking water., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The formation of regulated and emerging halogenated carbonaceous (C-) and nitrogenous disinfection by-products (N-DBPs) from the chlor(am)ination and UV irradiation of tyrosine (Tyr) was investigated. Increased chlorine contact time and/or Cl(2)/Tyr ratio increased the formation of most C-DBPs, with the exception of 4-chlorophenol, dichloroacetonitrile, and dichloroacetamideChloroform and dichloroacetic acid increased with increasing pH, dichloroacetonitrile first increased and then decreased, and other DBPs had maximum yields at pH 7 or 8. The addition of ammonia significantly reduced the formation of most C-DBPs but increased 4-chlorophenol, dichloroacetonitrile, dichloroacetamide, and trichloroacetonitrile yields for short prechlorination contact times before dosing ammonia. When UV irradiation and chlorination were performed simultaneously, the concentrations of the relatively stable C-DBPs increased, and the concentrations of dichloroacetonitrile, dichloroacetamide, and 4-chlorophenol decreased with increasing UV dose. This information was used to develop a mechanistic model for the formation of intermediate DBPs and end products from the interaction of disinfectants with tyrosine., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The formation of disinfection by-products (DBPs), including both nitrogenous DBPs (N-DBPs) and carbonaceous DBPs (C-DBPs), was investigated by analyzing chlorinated water samples following the application of three pretreatment processes: (i) powdered activated carbon (PAC) adsorption; (ii) KMnO(4) oxidation and (iii) biological contact oxidation (BCO), coupled with conventional water treatment processes. PAC adsorption can remove effectively the precursors of chloroform (42.7%), dichloroacetonitrile (28.6%), dichloroacetamide (DCAcAm) (27.2%) and trichloronitromethane (35.7%), which were higher than that pretreated by KMnO(4) oxidation and/or BCO process. The removal efficiency of dissolved organic carbon by BCO process (76.5%)--was superior to that by PAC adsorption (69.9%) and KMnO(4) oxidation (61.4%). However, BCO increased the dissolved organic nitrogen (DON) concentration which caused more N-DBPs to be formed during subsequent chlorination. Soluble microbial products including numerous DON compounds were produced in the BCO process and were observed to play an essential role in the formation of DCAcAm in particular., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Metal pollution in drinking water source has been under scrutiny as it seriously affects human health. This work examined 12 dissolved metals in the surface and overlying water of the Xiangjiang River, an important drinking water source in southern China, and characterized their distribution, identified their possible sources, assessed their toxicity load, and determined their potential ecological and health risk. No significant difference was found in the metal concentration between surface and overlying water. The average metal concentration fell in the order of Mg > Mn > Ba > Fe > Zn > As > Sb > Ni > Cd > V > Cr > Co, and all was lower than the safety threshold in the drinking water guideline of China. Anthropogenic activities were found to be the main source of metals from correlation analysis, principal component analysis (PCA), and cluster analysis (CA). According to the total heavy metal toxicity load (HMTL), 98.20%, 71.54%, 68.88%, and 7.97% of As, Cd, Sb, and Mn should be removed from the surface water to ensure safety. Most water samples from the surveyed area were found to have high ecological risk as was measured by the ecological risk index (RI). Health risk assessment showed that children are more susceptible than adults to the non-carcinogenic risk of dissolved metals, and the potential carcinogenic risk (CR) of As and Cd should be addressed. The results provide guidance for controlling the metal pollution of the Xiangjiang River and improving its quality as a drinking water source. [ABSTRACT FROM AUTHOR]

Background: Aquatic ecosystems are considered to be among the most important reservoirs of antibiotic resistance genes (ARGs). Drinking water sources could serve as critical points of ARGs transfer from environment to human. In this study, the distribution of antibiotics and ARGs across Qingcaosha Reservoir located in the Yangtze River Delta during three seasons was investigated to characterize the pollution patterns. Results: Sulfamethoxazole, sulfamonomethoxine and penicillin G potassium salt were the dominant antibiotics in this reservoir. Sulfonamide resistance genes (sul1 and sul2) were the most prevalent and predominant genes. Higher total relative abundance of the ARGs was detected in the site closest to the inflow than those in other sites. Overall, the concentrations of antibiotics in May were relatively lower than those in November and February. Correlation analysis indicated sul1, ermB and mphA had positive correlation with corresponding antibiotics in February and sul1, sul2, ermB and mphA was also positively correlated to intI1. Conclusion: In conclusion, antibiotics and ARGs were widespread in Qingcaosha Reservoir. Our results indicated that the drinking water reservoir might serve as gene reservoir for antibiotic resistance and mobile gene element intI1 can serve as a medium to contribute to the widespread of various ARGs. As the ARGs abundance was found to be higher in the inflow of the reservoir compared to the outflow, it is considered that reservoir could serve as a functional area contributing to the elimination or dilution of ARGs. [ABSTRACT FROM AUTHOR]

Background: Taste and odor problem in drinking water is one major concern for consumers and water supply. Exploring the odor characteristics and the major odor causing compounds in the source water is the base for odor control in drinking water treatment plant (WTP). In this study, focusing on a newly constructed reservoir with Huangpu River as the source water, the occurrence of typical odorants and their variations were first identified. Correspondingly, the removal behavior in an ozone/GAC advanced treatment process was investigated. Results: The results indicated that 2-methylisoborneol (2-MIB), geosmin (GSM), and bis (2-chloroisopropyl) ether (BCIE) have major contribution to the musty/earthy and chemical/septic odors in the source water, respectively. Pre-ozonation alone (1 mg L−1) showed limited removal for 2-MIB and BCIE, at less than 30% and 20%, respectively, while combining with coagulation, sedimentation, and sand filtration, the removals were improved to higher than 50%. After post-ozonation, the desired removal was achieved at a 1.5 mg L−1 dosage with all the odorants decreased below the corresponding odor threshold concentrations (OTCs) in the effluents. Furthermore, at a 1 mg L−1 post-ozone addition, by combining with subsequent GAC process, the odor problem was solved as well. Conclusion: To resolve the odor problem in the drinking water, the concentrations of the odorants at less than their OTCs need to be achieved. As 2-MIB and BCIE have low reactivity towards direct ozonation, a subsequent GAC is needed with a moderate dosage of post-ozonation (1 mg L−1). Thus, for the odor problem in the source water, the suggested operation is: 1 mg L−1 of pre-ozonation in combination with coagulation, sedimentation, and sand filtration, followed by a 1 mg L−1 dosage of post-ozonation and finished by a GAC process. [ABSTRACT FROM AUTHOR]

Domestic water purification devices (point-of-use) are important choices for people to deal with sudden drinking water contamination. Especially for sudden heavy metal and arsenic contamination, home water purification units can play a key role as a secondary line of defense. Most of the arsenic removal studies are limited to meeting the requirements of local water quality standards and few studies have been conducted on arsenic removal from household water purifiers. In this paper, the distribution characteristics of arsenic in water at the end of the pipeline network in the Shanghai water supply area have been investigated. Three types of household water purifiers, mainly with membrane separation technology, were selected to treat the simulated arsenic contamination in tap water sources. The effects of pH and inorganic salts on arsenic removal were studied in comparison to the results of coexisting ion concentrations in tap water. The results showed that the total arsenic concentrations in different tap water samples range from 0.479–1.195 µg L−1, which is lower than the limit value for arsenic concentration set by China's drinking water standard GB 5749–2006 (10 µg L−1) and by the World Health Organization (10 µg L−1). It is found that reverse osmosis and nanofiltration water purifiers were more effective in removing As(V), with removal rate above 97.7%, and less effective in removing As(III), the rate ranging from 40.1 to 56.3%. Preliminary validation was provided for the safety of household water purifiers in securing universal and sudden drinking water contamination. Domestic water purifiers are effective in reducing the risk of arsenic exposure in drinking water. [ABSTRACT FROM AUTHOR]

Highlights: [•] Formation of haloacetamides function of DON/DOC, SUVA254 and bromide. [•] DON/DOC may act as an indicator of HAcAm yields during chlorination. [•] More formation during chloramination in low-SUVA waters with no bromide. [•] More formation of dihalogenated species than tri- or mono-halogenated species. [•] Bromine incorporation increased with increasing bromide with either disinfectant. [Copyright &y& Elsevier]

Graphical abstract Highlights • Enzyme-hydrolysed BSA exhibited higher chlorine demand than un-hydrolysed BSA. • Enzymolysis enhanced TOX and CX 3 R-type DBP formation during the chlorination of BSA. • TOX formation was promoted to a greater extend by enzymolysis when bromide was present. • The removal of DBP precursors by pre-oxidation was indirectly offset by enzymolysis. Abstract It is commonly acknowledged that proteins, comprising a large portion of dissolved organic nitrogen pool, are important precursors of disinfection by-products (DBPs). Moreover, proteins can also undergo degradation (e.g. enzymolysis) in aquatic environment or during biological treatment processes. In this study, a well-characterized protein, bovine serum albumin (BSA) was used as model compound to investigate the effect of enzymolysis on the formation of four classes of CX 3 R-type DBPs (i.e. trihalomethanes, haloacetaldehydes, haloacetonitriles, and haloacetamides) during chlorination. After enzymolysis, the three-dimension structure of BSA was destroyed, increasing the accessibility of inside amino acids to chlorine, thus enzyme-hydrolysed BSA exhibited higher chlorine demand and higher formation of total organic halogen (TOX) than un-hydrolysed BSA. Generally, enzyme-hydrolysed BSA produced more CX 3 R-type DBPs, which is due to the facilitation of fragmentation of BSA by enzymolysis. In the presence of bromide, enzymolysis promoted the formation of TOX to a greater extent than in the absence of bromide. The effect of enzymolysis on pre-oxidation efficiency in the control of CX 3 R-type DBPs was also investigated. It was found that the reduction in CX 3 R-type DBP formation from chlorinated enzyme-hydrolysed BSA was more significant than that from chlorinated un-hydrolysed BSA, but the former still exhibited higher calculated cytotoxicity than the latter, indicating the removal of CX 3 R-type DBP precursors was indirectly offset by the effect of enzymolysis. This study provides insights into the effect of the structural transformation of protein during water treatment processes on CX 3 R-type DBP formation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Reduced sulfur compounds generated lower CX 3 R-type DBPs at lower disinfectant doses. • One molar reduced sulfur group consumed 4–6 M chlor(am)ine at initial reaction periods. • Increasing reaction times and disinfectant doses increased CX 3 R-type DBP yields. • Reduced sulfur group inhibited the formation of CX 3 R-type DBPs during chlor(am)ination. Abstract Previous studies have examined the effects of peptide bond and unsaturated bond on the formation of disinfection by-products (DBPs). However, limited information has been available for the impact of reduced sulfur group on the formation of DBPs. This study investigated the formation of carbonaceous and nitrogenous DBPs (C-DBPs and N-DBPs) with a similar structure of ''CX 3 R'' (X = H, Cl, Br or I, R = functional group), including trihalomethanes, haloacetaldehydes, haloketones, haloacetonitriles, haloacetamides and halonitromethanes, during chlor(am)ination of three reduced sulfur compounds (RSCs), such as N -acetylcysteine, glutathione and glutathiol. Results showed that all DBPs except dichloroacetonitrile (DCAN) continuously increased with increasing Cl 2 or NH 2 Cl doses in this study. The chlor(am)ination of three RSCs with lower disinfectant doses (the molar ratio of disinfectant to precursor ≤5) generated low DBPs compare to non-RSCs. More chloroform was observed in alkaline condition, while weak acidic condition was in favor of DCAN and dichloroacetamide formation. The results of frontier electron density calculation reported that the much higher reactivity for Cl 2 and NH 2 Cl toward reduced sulfur group in RSCs protects other groups, which account for the formation of CX 3 R-type DBPs. This phenomenon has important environmental implications. When RSCs are present in the water, Cl 2 or NH 2 Cl will reacts preferably with them rather than non-RSCs to form RSO 3 H as the major products. Hence, the trade-offs of between the products generated upon S -chlorination, which account for the formation RSO 3 H, and alkyl halogenation and N -chlorination, which account for the formation of CX 3 R-type DBPs, influence the formation of CX 3 R-type DBPs. [ABSTRACT FROM AUTHOR]

Abstract Two chlorophenylacetonitriles (CPANs) (2-chloro- and 3,4-dichlorophenylacetonitrile), representatives of an emerging class of aromatic nitrogenous disinfection byproducts, were recently identified in chlor(am)inated drinking water with liquid/liquid extraction and gas chromatography/mass spectrometry (GC/MS). Due to their high cytotoxicity, they are potentially significant drinking water contaminants. The detection limit for these two CPANs with the previous method was 100 ng L−1. To search for additional CPAN isomers, a more sensitive method for the simultaneous determination of eight CPANs was developed using solid-phase extraction (SPE)-GC/MS. GC/MS parameters and SPE pre-concentration conditions, including SPE cartridge, eluent type, eluent volume, and sample pH, were optimized. Under optimized conditions, the new method had method detection limits, method quantification limits, and precision ranging from 0.15 to 0.37 ng L−1, 0.50–0.95 ng L−1, and 5.8%–11%, respectively. The recoveries of the eight CPANs ranged from 92% to 102%. The concentrations of the eight CPANs in nine finished drinking waters were determined to be at concentrations ranging from 0.5 to 155 ng L−1. Seven CPANs were detectable in all samples. CPANs were detected at concentrations between 0.8 and 155 ng L−1 in chlorinated waters, and from 0.5 to 15 ng L−1 in chloraminated waters. Across all waters, the sum of all CPANs in chloraminated waters was 13% of that in chlorinated systems. Graphical abstract Image 1 Highlights • A new SPE-GC/MS method was developed to determine 8 chlorophenylacetonitriles (CPANs). • CPANs were identified as new aromatic N-DBPs in drinking water for the first time. • CPANs were ubiquitous in finished drinking water at levels from 0.5 to 155 ng L−1. • 2-CPAN was the most abundant CPAN species in chlorinated and chloraminated waters. • CPAN concentrations in chlorinated waters were higher than in chloraminated waters. [ABSTRACT FROM AUTHOR]

Haloacetamides (HAcAms), a class of highly toxic nitrogenous disinfection by-products (N-DBPs), have been widely detected in drinking water. The control of DBPs is an important measure to ensure the safety of drinking water. Due to the presence of residual chlorine and organic compounds that failed to be effectively removed, HAcAms could be formed in the finished drinking water distribution systems. In the study, Cu/Fe bimetal with different molar ratios of Cu to Fe was synthesized. This study reported that Cu/Fe bimetal reduced trichloroacetamide (TCAcAm) to dichloroacetamide (DCAcAm) and monoacetamide (MCAcAm), and the reduction ability of Fe was greatly improved due to the incorporation of Cu. The optimal HAcAm removal was achieved when the molar ratio of Cu to Fe was 2.0%, Cu/Fe bimetal could reach complete degradation of TCAcAm within 1 h. With the increase of Cu/Fe bimetal dose or the decrease of solution pH, the reduction ability of Cu/Fe bimetal for HAcAm removal also increased. The calculated integrated toxicity values from HAcAms, which was used to reflect the comprehensive control effect of Cu/Fe bimetal for HAcAms, were also reduced with the decrease of solution pH and the increase of bimetal dose. The release of Cu 2+ was not detected during the whole treatment process, Cu/Fe bimetal may be an excellent material for controlling DBPs as the end – control methods in tap water. [ABSTRACT FROM AUTHOR]

The use of persulfate oxidation processes is receiving increasing interest for the removal of aquatic contaminants. However, it is unknown whether its application in the presence of iodide has the potential to directly form iodinated DBPs. This study investigated formation of six chlorinated, brominated and iodinated di-haloacetamides (DHAcAms) during persulfate oxidation in the presence of bromide and iodide. Formation of the same DHAcAms during chlorination was monitored for comparison. Persulfate oxidation of natural water formed diiodoacetamide (DIAcAm), and heat-activated persulfate, at 45 °C and 55 °C, generated bromoiodoacetamide (BIAcAm) and dibromoacetamide (DBAcAm), besides DIAcAm. At an ambient iodide concentration of 0.3 μM, total DHAcAms increased slightly from 0.43 to 0.57 nM as the water temperature increased from 4 °C to 35 °C, respectively (only DIAcAm detected), then significantly increased to 1.6 nM at 55 °C (DIAcAm, BIAcAm and DBAcAm detected). Equivalent total DHAcAm concentrations in the presence of 3.0 μM iodide were 0.5, 0.91 and 2.1 nM, respectively. Total DHAcAms formed during chlorination, predominantly dichloroacetamide (DCAcAm) and bromochloroacetamide (BCAcAm), were always significantly higher than that during persulfate oxidation. However, an integrated risk assessment showed the toxicity resulting from the DHAcAms was higher during persulfate oxidation than chlorination. An increase in water temperature from 25 °C to 55 °C significantly increased the integrated toxic risk values for both persulfate oxidation and chlorination. Use of persulfate oxidation should be weighed against the formation of high-toxicity iodinated HAcAms in waters with high ambient iodide concentrations. [ABSTRACT FROM AUTHOR]

Low-molecular weight organic acids (LMWOAs) are widespread in nature, and many are recalcitrant during conventional drinking water treatment, due to their LMW and hydrophilic character. This study assessed the formation of a range of disinfection by-products (DBPs) from the chloramination of seven non-nitrogenous LMWOA precursors, with an emphasis on the contribution of N-chloramine incorporation to haloacetamide (HAcAm) formation. The other DBPs comprised chlorinated halomethanes, haloacetonitriles and haloacetic acids. Citric acid generated higher yields of trichloromethane and two chloroacetic acids than the other LMWOAs. Further, the unsaturated acids (fumaric acid and itaconic acid) formed more chloroacetic acids than saturated acids (oxalic acid, succinic acid, adipic acid). Importantly, non-nitrogenous LMWOAs formed three nitrogenous DBPs (dichloroacetamide, trichloroacetamide, and small amounts of dichloroacetonitrile) during chloramination, firstly indicating the monochloramine can supply the nitrogen in nitrogenous DBPs, and the formation of haloacetamides at least in part is independent of the hydrolysis of haloacetonitriles. To the authors’ knowledge, this is the first time formation of halogenated nitrogenous DBPs (N-DBPs) has been reported from chloramination of non-nitrogenous LMWOA precursors. This indicates that concentrations of dissolved organic nitrogen compounds in drinking water are not a reliable surrogate for formation of N-DBPs during chloramination. Bromine incorporation factor increased with increasing bromide during chloramination of citric acid, and bromine was easier to incorporate into di-HAcAms than mono- and tri-HAcAms during chloramination. [ABSTRACT FROM AUTHOR]

Dichloroacetamide (DCAcAm), a disinfection byproduct, has been detected in drinking water. Previous research showed that amino acids may be DCAcAm precursors. However, other precursors may be present. This study explored the contribution of the antibiotic chloramphenicol (CAP) and two of its analogues (thiamphenicol, TAP; florfenicol, FF) (referred to collectively as CAPs), which occur in wastewater-impacted source waters, to the formation of DCAcAm. Their formation yields were compared tofree and combined amino acids, and they were investigated in filtered waters from drinking-water-treatment plants, heavily wastewater-impacted natural waters, and secondary effluents from wastewater treatment plants. CAPs had greater DCAcAm formation potential than two representative amino acid precursors. However, in drinking waters with ng/L levels of CAPs, they will not contribute as much to DCAcAm formation as the μg/L levels of amino acids. Also, the effect of advanced oxidation processes (AOPs) on DCAcAm formation from CAPs in real water samples during subsequent chlorination was evaluated. Preoxidation of CAPs with AOPs reduced the formation of DCAcAm during postchlorination. The results of this study suggest that CAPs should be considered as possible precursors of DCAcAm, especially in heavily wastewater-impacted waters. [ABSTRACT FROM AUTHOR]

There has been a series of research work on exploring how disinfection by-products (DBPs) are formed from free amino acids (AAs) during chlorination in drinking water. Yet there is very limited information about the formation of carbonaceous DBPs (C-DBPs) and nitrogenous DBPs (N-DBPs) from the chlorination of those AAs in combined forms which are more abundant than free AAs in source waters. In this study, we compared the differences on the formation of trihalomethanes (THMs, representing C-DBPs) and haloacetonitriles (HANs, representing N-DBPs) from free AAs and combined AAs (short oligopeptides) during chlorination. And, the influence of the selected pre-oxidation processes (permanganate, persulfate, hydrogen peroxide) on THM and HAN formation during subsequent chlorination was also examined. There were significant differences in chloroform (CF), dichloroacetonitrile (DCAN) and trichloroacetonitrile (TCAN) formation between free AAs and short oligopeptides, which was probably ascribed to the presence of peptide bond. Of note, the combined tyrosine (Tyr) in tripeptides (Tyr–Tyr–Tyr) formed more TCAN compared with free Tyr and other combined Tyr in dipeptides, and a novel possible formation pathway of TCAN from Tyr–Tyr–Tyr was proposed. In addition, the effect of three pre-oxidation on DBP formation was different, and their rank order was permanganate > persulfate > hydrogen peroxide. The permanganate is a better choice than persulfate and hydrogen peroxide for controlling AA derived HANs, but this benefit should be weighed against the potential drawback of increased regulated THMs. [ABSTRACT FROM AUTHOR]

Highlights: [•] The rank order of the HAcAms concentrations: di-HAcAms>>tri-HAcAms>mono-HAcAms. [•] DCAcAm and DCM are the main species of HAcAms and HMs in chloraminated waters. [•] DCAcAm represents a more significant toxic risk than DCM in chloraminated waters. [Copyright &y& Elsevier]

The prevalence of antibiotic resistance genes (ARGs) and their relationship with antibiotics in the surface waters of the Huangpu River and the drinking water sources of Shanghai, China, were investigated. 39 ARGs, including four sulfonamide ARGs, 23 tetracycline ARGs, four chloramphenicol ARGs, five β–lactam ARGs and three penicillin ARGs were targeted in this study. Two sulfonamide ARGs (sul I and sul II), eight tetracycline ARGs (tet(A), tet(B), tet(C), tet(G), tet(M), tet(O), tet(W) and tet(X)), and one β–lactam ARG (TEM) were detected to be present in water samples by polymerase chain reaction (PCR), with the detection frequencies ranging from 42.86% to 100%. The average concentrations of the 11 ARGs ranged from 3.66×101 copy/mL (tet(B)) to 1.62×105 copy/mL (sul II), quantified by quantitative real-time PCR (QPCR). The number of detected ARGs and the ARG concentrations were generally higher in suburban sampling sites than in urban sites. Being in or near suburban rural areas, some raw drinking water sources were observed to have comparatively higher ARG contamination, drawing an urgent attention for the concern of public health. Generally consistent relations were observed between the concentrations of tet genes and the tetracycline levels and between the concentrations of sul genes and the sulfonamide levels. [ABSTRACT FROM AUTHOR]

Abstract: Bromate is recognized as an oxyhalide disinfection byproduct in drinking water. In this study, supported noble metal (Pd, Pt) catalysts with different supports of SiO2, Al2O3 and activated carbon (AC) were prepared and the catalytic hydrogenation of aqueous bromate was first investigated. Characterization results showed the isoelectric points (IEPs) of Pd/SiO2 and Pd/Al2O3 catalysts were around 2.0 and 8.0, respectively, whereas the IEP of Pd/AC was much lower than 2.0. In comparison with Pd/SiO2 and Pd/AC, Pd/Al2O3 exhibited a substantially higher catalytic activity at pH 5.6 for bromate reduction due to the electrostatic attractive interaction between the bromate ion and the catalyst. Moreover, bromate with an initial concentration of 0.39mM was removed by 80.2% over Pt/Al2O3 and nearly 100% over Pd/Al2O3 after reaction for 2h, indicative of a higher catalytic activity of Pd/Al2O3. For Pd/Al2O3, the bromate reduction followed the Langmuir–Hinshelwood model, reflecting an adsorption controlled reduction mechanism. Increasing Pd loading amount resulted in enhanced bromate reduction. In addition, the bromate reduction was found to be strongly pH-dependent and enhanced reduction rate could be achieved at low pH. In the presence of coexisting anions (Cl−, Br− and SO4 2−) the bromate reduction was suppressed, wherein SO4 2− exhibited the most marked inhibition effect, attributed to competitive adsorption for active surface sites. The present results indicate that catalytic hydrogenation can be used as a potential treatment technique for the removal of bromate in drinking water. [Copyright &y& Elsevier]

• CX 3 R-type DBP formation is compared between PMS/Cl− and NaClO disinfection. • CX 3 R-type DBP level in PMS/Cl− is lower than that in NaClO disinfection. • DBP formation pathway during PMS/Cl− disinfection is proposed. • The cytotoxicity from DBPs in PMS/Cl− is lower than that in NaClO disinfection. Peroxymonosulfate (PMS) is receiving increasing interest as an oxidant used during the disinfection of drinking water. However, it does not have continuous disinfection ability as sodium hypochlorite (NaClO) does. PMS/Cl− can produce reactive chlorine species and thus provide a persistent disinfectant residual in distribution systems. This study investigated PMS/Cl− disinfection versus NaClO disinfection in terms of the formation and estimated cytotoxicity of CX 3 R-type disinfection by-products (DBPs) under the same dose of free chorine. Results showed that free chlorine produced by PMS/Cl− reaction can react with organic compounds and the productions of CX 3 R-type DBPs were dependent on the free chlorine dose, pH and reaction time. Specifically, chloroform (CF) and chloral hydrate (CH) generally increased with increasing of free chlorine dose and reaction time. CF increased steadily with increasing pH, while CH firstly increased and then decreased with increasing pH. Haloacetonitriles and haloacetamides firstly increased and then decreased with increasing of free chlorine dose and reaction time, and decreased continuously with increasing pH. The formation pathway of CX 3 R-type DBPs during chlorination (PMS/Cl−) of tyrosine was proposed, based on the detected intermediates (i.e., Benzyl cyanide, 4-hydroxy-benzyl-cyanide, 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol). The estimated cytotoxicity of CX 3 R-type DBPs in chlorinated water firstly increased and then decreased with the increasing of reaction time, free chlorine dose and pH, which highly related to the changes of DCAN (the most toxic CX 3 R-type DBP) levels. Comparing to NaClO disinfection, PMS/Cl− disinfection can better control the formation and cytotoxicity of CX 3 R-type DBPs, which was attributed to the degradation of natural organic matter, CX 3 R-type DBPs intermediates and CX 3 R-type DBPs by the residual PMS. This study demonstrated the superiority of PMS/Cl− as an alternative disinfectant comparing to NaClO. [ABSTRACT FROM AUTHOR]

Taihu (Tai Lake) is China´s third largest freshwater lake and serves as drinking water resources for several million people. Located in a densely populated region close to Shanghai, Taihu is a drastic example of water pollution. Organic contaminants, heavy metals and the excess of nutrients from urban areas, industry and agricultural run-off not only pose a risk for the environment but also endanger a safe drinking water quality. Therefore, the SIno-German SIGN project aims to adapt proven technologies and management concepts from Germany to the conditions in China in order to improve lake management and guarantee a long-term safe drinking water supply.This study presents and discusses the results of the first project (2015-2018) with respect to occurrences of organic pollutants, their toxicity and impact on drinking water. Moreover, it presents first results of the second project (2018-2021) focusing on organic contamination of sediment as potential source of raw water pollution and on elimination rates of 200 organic contaminants during different treatment steps in drinking water plants.During the first project, multiple sampling campaigns in the Northern Taihu, artificial wetlands, drinking water and wastewater treatment plants have been conducted. More than 80 samples have been collected and analysed for pesticides, industrial chemicals, pharmaceuticals, PAHs, VOCs and THMs. Here, 70 different organic pollutants have been detected, whereas spatial patterns indicate multiple sources within the various catchment areas of the major inflowing rivers. The results further show that the artificial wetlands, which are used as pollution control for water fluxes entering Taihu, are able to substantially lower pollution loads. Also, several pollutants have been detected in the drinking water. In order to evaluate mixture effects regarding endocrine disruption and genotoxicity, in vitro bioassays have been conducted. Estrogenic activity up to 2.1 ng EEQ / L could be determined in 18 samples while no androgenic effect and no genotoxic potential were observed. Furthermore, a potential environmental and human risk was assessed, identifying spatial and temporal exceedances of 19 parameters like the analgetic Ibuprofen, the herbicide Bentazone and the x-ray contrast agent Iohexol.Based on the results of the study, several recommendations for drinking water treatment facilities have been derived. For example, the dosage of ozone for water purification should be adjusted according to online measured physico-chemical parameters in order to avoid the generation of transformation products. [ABSTRACT FROM AUTHOR]