Porous polymer(pyrrolopyrrole)was successfully prepared via domino-ring-formation reaction.The chemical-physical properties of cyanided covalent triazine frameworks(CTF-CN)were characteriazed by fourier transform infr...Porous polymer(pyrrolopyrrole)was successfully prepared via domino-ring-formation reaction.The chemical-physical properties of cyanided covalent triazine frameworks(CTF-CN)were characteriazed by fourier transform infrared spectra(FT-IR),scanning electron microscopy(SEM),nuclear magnetic resonance(NMR),specific surface area analyzer(BET)and thermogravimetric analysis(TGA),respectively.The experimental results of adsorption of chloranil(TCBQ)in aqueous solution indicated that CTF-CN exhibited distinctive adsorption capacity toward TCBQ owing to its large specific surface area.Specifically,the adsorption equilibrium of as-prepared polymer was executed within 5 h and the calculated adsorption capacity was 499.76 mg/g.Furthermore,the adsorption kinetics could be well defined with the linear pseudo-second-order model,which implies that the chemical interaction are relative important in the course of TCBQ removal.Finally,the current studies verify that CTF-CN has unique rigid and nano-porous framework structure,which can be employed for the treatment of a series of harmful aromatic substances.展开更多
Objective Since haloacetic acids (HAAs), which are nonvolatile and of high carcinogenic risk, are common species of chlorinated disinfection by-products(DBPs) in drinking water, and little has been known in China, it...Objective Since haloacetic acids (HAAs), which are nonvolatile and of high carcinogenic risk, are common species of chlorinated disinfection by-products(DBPs) in drinking water, and little has been known in China, it is necessary to make a survey about the kinds and levels of HAAs in drinking water of the nation. Method HAAs were analyzed using gas chromatography with electron capture detector(GC/ECD) and relatively complex pretreatment process of sample was applied. Five main cities in different areas of China were chosen in the survey. Results Studies showed that the main species of HAAs in drinking water in China were DCAA and TCAA, ranging from 0.4 礸/L to 12.85 礸/L and from 0.56 礸/L to 10.98 礸/L, respectively. MBAA and DBAA were also detected in one city, ranging from 2.20 礸/L to 4.95 礸/L and 1.10 礸/L to 2.81 礸/L, respectively. Therefore, the contents of HAAs varied, usually no more than 25 礸/L. Based on the acquired data to date, it is known that the concentrations of HAAs in drinking water in China were surely under the limits of Sanitary Standard for Drinking Water Quality (China, 2001). Conclusion A wider survey of HAAs in drinking water should be conducted throughout the nation to get adequate data and information, the ultimate aim of which is to control HAAs pollution and keep the balance between microbiological safety insurance and chemical risk control, minimize the formation of DBPs and ensure the safety of water supply at the same time.展开更多
Mesocyclops leukarti of zooplankton propagates excessively in eutrophic water body and it cannot be effectively inactivated by the conventional drinking water treatment process. In order to tackle this problem, a stud...Mesocyclops leukarti of zooplankton propagates excessively in eutrophic water body and it cannot be effectively inactivated by the conventional drinking water treatment process. In order to tackle this problem, a study of removal effect on Mesocylops leukarti with chlorine dioxide in a waterworks was performed. The results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide prcoxidation combined with the conventional drinking water treatment process. Higher oxidizability and molecular state of chlorine dioxide in water is the key to the inactivation of Mesocyclops leukarti. The chlorite, disinfection by-products （DBPs） of chlorine dioxide, was stable at 0.45 mg/L, which is lower than that critical value of the USEPA. GC-MS examination showed that the quantity of organic substance in the water treated by chlorine dioxide obviously decreased. Ames test further revealed that the mutagenicity was reduced by chlorine dioxide with respect to prechlorine. The propagation ofMesocyclops leukorti can be inactivated effectively and safely by chlorine dioxide pre-oxidation.展开更多
Disinfection by-products （DBPs） are regulated in drinking water in a number of countries. This critical review focuses on the issues associated with DBP regulatory compliance, including methods for DBP analysis, occ...Disinfection by-products （DBPs） are regulated in drinking water in a number of countries. This critical review focuses on the issues associated with DBP regulatory compliance, including methods for DBP analysis, occurrence levels, the regulation comparison among various countries, DBP compliance strategies, and emerging DBPs. The regulation comparison between China and the United States （US） indicated that the DBP regulations in China are more stringent based on the number of regulated compounds and maximum levels. The comparison assessment using the Information Collection Rule （ICR） database indicated that the compliance rate of 500 large US water plants under the China regulations is much lower than that under the US regulations （e.g. 62.2% versus 89.6% for total trihalomethanes）. Precursor removal and alternative disinfectants are common practices for DBP regulatory compliance. DBP removal after formation, including air stripping for trihalomethane removal and biodegradation for haloacetic acid removal, have gained more acceptance in DBP control. Formation of emerging DBPs, including iodinated DBPs and nitrogenous DBPs, is one of unintended consequences of precursor removal and alternative disinfection. At much lower levels than carbonaceous DBPs, however, emerging DBPs have posed higher health risks.展开更多
Eight typical drinking water supplies in China were selected in this study.Both source and tap water were used to investigate the occurrence of chlorinated disinfection byproducts（DBPs）,and seasonal variation in the...Eight typical drinking water supplies in China were selected in this study.Both source and tap water were used to investigate the occurrence of chlorinated disinfection byproducts（DBPs）,and seasonal variation in the concentrations of trihalomethanes（THMs） of seven water sources was compared.The results showed that the pollution level for source water in China,as shown by DBP formation potential,was low.The most encountered DBPs were chloroform,dichloroacetic acid,trichloroacetic acid,and chlorodibromoacetic acid.The concentration of every THMs and haloacetic acid（HAA） compound was under the limit of standards for drinking water quality.The highest total THMs concentrations were detected in spring.展开更多
Disinfection byproducts(DBPs)represent a ubiquitous source of chemical exposure in disinfected water.While over 700 DBPs have been identified,the drivers of toxicity remain poorly understood.Additionally,ever evolving...Disinfection byproducts(DBPs)represent a ubiquitous source of chemical exposure in disinfected water.While over 700 DBPs have been identified,the drivers of toxicity remain poorly understood.Additionally,ever evolving water treatment practices have led to a continually growing list of DBPs.Advancement of analytical technologies have enabled the identification of new classes of DBPs and the quantification of these chemically diverse sets of DBPs.Here we summarize advances in new workflows for DBP analysis,including sample preparation,chromatographic separation with mass spectrometry(MS)detection,and data processing.To aid in the selection of techniques for future studies,we discuss necessary considerations for each step in the strategy.This review focuses on how each step of a workflow can be optimized to capture diverse classes of DBPs within a single method.Additionally,we highlight new MS-based approaches that can be powerful for identifying novel DBPs of toxicological relevance.We discuss current challenges and provide perspectives on future research directions with respect to studying new DBPs of toxicological relevance.As analytical technologies continue to advance,new strategies will be increasingly used to analyze complex DBPs produced in different treatment processes with the aim to identify potential drivers of toxicity.展开更多
Swimming has become a popular exercising and recreational activity in China but little is known about the disinfection by-products （DBPs） concentration levels in the pools. This study was conducted as a survey of th...Swimming has become a popular exercising and recreational activity in China but little is known about the disinfection by-products （DBPs） concentration levels in the pools. This study was conducted as a survey of the DBPs in China swimming pools, and to establish the correlations between the DBP concentrations and the pool water quality parameters. A total of 14 public indoor and outdoor pools in Beijing were included in the survey. Results showed that the median concentrations for total tfihalomethanes （TTHM）, nine haloacetic acids （HAA9）, chloral hydrate （CH）, four haloacetonitriles （HAN4）, 1,1- dichloropropanone, 1,1,1-trichloropropanone and trichlor- onitromethane were 33.8, 109.1, 30.1, 3.2, 0.3, 0.6 pg＇L-1 and below detection limit, respectively. The TTHM and HAA9 levels were in the same magnitude of that in many regions of the world. The levels of CH and nitrogenous DBPs were greatly higher than and were comparable to that in typical drinking water, respectively. Disinfection by chlorine dioxide or trichloroisocyanuric acid could sub- stantially lower the DBP levels. The outdoor pools had higher TTHM and HAA9 levels, but lower trihaloacetic acids （THAA） levels than the indoor pools. The TTHM and HAA9 concentrations could be moderately correlated with the free chlorine and total chlorine residuals but not with the total organic carbon （TOC） contents. When the DBP concentration levels from other survey studies were also included for statistical analysis, a good correlation could be established between the TTHM levels and the TOC concentration. The influence of chlorine residual on DBP levels could also be significant.展开更多
To manage potential microbial risks and meet increasingly strict drinking water health standards,UV treatment has attracted increasing attention for use in drinking water systems in China.However,the effects of UV tre...To manage potential microbial risks and meet increasingly strict drinking water health standards,UV treatment has attracted increasing attention for use in drinking water systems in China.However,the effects of UV treatment on microbial control and disinfection byproducts(DBPs)formation in real municipal drinking water systems are poorly understood.Here,we collected water samples from three real drinking water systems in Beijing and Tianjin to investigate the impacts of UV treatment on microbial control and DBP formation.We employed heterotrophic plate count(HPC),flow cytometry(FCM),quantitative PCR analysis,and high-throughput sequencing to measure microorganisms in the samples.Different trends were observed between HPC and total cell count(measured by FCM),indicating that a single indicator could not reflect the real degree of biological re-growth in drinking water distribution systems(DWDSs).A significant increase in the 16S rRNA gene concentration was observed when the UV system was stopped.Besides,the bacterial community composition was similar at the phylum level but differed markedly at the genera level among the three DWDSs.Some chlorine-resistant bacteria,including potential pathogens(e.g.,Acinetobacter)showed a high relative abundance when the UV system was turned off.It can be concluded that UV treatment can mitigate microbial re-growth to some extent.Finally,UV treatment had a limited influence on the formation of DBPs,including trihalomethanes,haloacetic acids,and nitrogenated DBPs.The findings of this study may help to understand the performance of UV treatment in real drinking water systems.展开更多
UV/peroxymonosulfate(UV/PMS) advanced oxidation process has attracted significant attention for removal of micropollutants in water. However, during practical water treatment applications, the PMS treatment must be pe...UV/peroxymonosulfate(UV/PMS) advanced oxidation process has attracted significant attention for removal of micropollutants in water. However, during practical water treatment applications, the PMS treatment must be performed before the UV treatment to achieve full contact. In this study, sulfamethoxazole(SMX) was selected as the target micropollutant. Four different operational approaches, including UV alone, PMS alone, simultaneous UV/PMS and sequential PMS-UV, were compared for their differences in SMX removal and disinfection by-product(DBP) formation potentials during chlorine-driven disinfection. Among the four approaches, UV/PMS and PMS-UV achieved over 90% removal efficiencies for SMX without substantial differences. For raw water, the trichloronitromethane(TCNM) formation potential after treatment with PMS-UV was lower than that after UV/PMS treatment. The time interval over which the PMS-UV process was conducted had little effect on the final removal efficiency for SMX. However, a brief(5 min) pre-PMS treatment significantly reduced the TCNM formation potential and the genotoxicity from DBPs. The formation risk for TCNM during chlorination increased markedly with increasing PMS dosages, and the appropriate dosage under these experimental conditions was suggested to be 0.5–1.0 mmol/L. Under alkaline conditions, PMS-UV treatment can enhance SMX degradation as well as dramatically reduced the formation potentials for haloketones, haloacetonitriles and halonitromethanes. This study suggests that proper optimization of UV/PMS processes can remove SMX and reduce its DBP formation.展开更多
When bromide/iodide is present in source water, hypobromous acid/hypoiodous acid will be formed with addition of chlorine, chloramine, or other disinfectants. Hypobromous acid/hypoiodous acid undergoes reactions with ...When bromide/iodide is present in source water, hypobromous acid/hypoiodous acid will be formed with addition of chlorine, chloramine, or other disinfectants. Hypobromous acid/hypoiodous acid undergoes reactions with natural organic matter in source water to form numerous brominated/iodinated disinfection byproducts （DBPs）. In this study, tap water samples were collected from eight cities in China. With the aid of electrospray ionization-triple quadrupole mass spectrometry by setting precursor ion scans of m/z 35, m/z 81, and m/z 126.9, whole pictures of polar chlorinated, brominated, and iodinated DBPs in the tap water samples were revealed for the first time. Numerous polar halogenated DBPs were detected, including haloacetic acids, newly identified halogenated phenols, and many new/unknown halogenated compounds. Total organic chlorine, total organic bromine, and total organic iodine were also measured to indicate the total levels of all chlorinated, brominated, and iodinated DBPs in the tap water samples. The total organic chlorine concentrations ranged from 26.8 to 194.0 μg· L 1 as Cl, with an average of 109.2 μg·L-1 as Cl; the total organic bromine concentrations ranged from below detection limit to 113.3 μg·L-1 as Br, with an average of 34.7 μg·L-1 as Br; the total organic iodine concentrations ranged from below detection limit to 16.4 μg· L-1 as I, with an average of 9.1 μg· L-1 as I; the total organic halogen concentrations ranged from 31.3 to 220.4 μg·L-1 as Cl, with an average of 127.2 μg· L- 1 as Cl.展开更多
Introduction Natural organic matter（NOM）present in source water has significant impact on water treatment processes and on the quality of drinking water.NOM is a complex mixture of diverse groups of organic compound...Introduction Natural organic matter（NOM）present in source water has significant impact on water treatment processes and on the quality of drinking water.NOM is a complex mixture of diverse groups of organic compounds,humic and fulvic acids,proteins,peptides,carbohydrates,and heterogeneous materials展开更多
Environmental water samples can be extremely complex,with potentially thousands of molecules that can derive from natural organic matter（NOM）and thousands that derive from anthropogenic contaminants.As complex as th...Environmental water samples can be extremely complex,with potentially thousands of molecules that can derive from natural organic matter（NOM）and thousands that derive from anthropogenic contaminants.As complex as these samples are,drinking water can be even more complex.Due to disinfectants that are used to treat drinking water（e.g.,chlorine,chloramines,展开更多
Chlorine, chlorine dioxide, and ozone are widely used as disinfectants in drinking water treatments. However, the combined use of different disinfectants can result in the formation of various organic and inorganic di...Chlorine, chlorine dioxide, and ozone are widely used as disinfectants in drinking water treatments. However, the combined use of different disinfectants can result in the formation of various organic and inorganic disinfection byproducts(DBPs). The toxic interactions, including synergism, addition, and antagonism, among the complex DBPs are still unclear. In this study, we established and verified a real-time cell analysis(RTCA) method for cytotoxicity measurement on Chinese hamster ovary(CHO) cell. Using this convenient and accurate method, we assessed the cytotoxicity of a series of binary combinations consisting of one of the 3 inorganic DBPs(chlorite, chlorate, and bromate) and one of the 32 regulated and emerging organic DBPs. The combination index(CI) of each combination was calculated and evaluated by isobolographic analysis to reflect the toxic interactions. The results confirmed the synergistic effect on cytotoxicity in the binary combinations consisting of chlorite and one of the 5 organic DBPs(2 iodinated DBPs(I-DBPs) and 3 brominated DBPs(Br-DBPs)), chlorate and one of the 4 organic DBPs(3 aromatic DBPs and dibromoacetonitrile), and bromate and one of the 3 organic DBPs(2 I-DBPs and dibromoacetic acid). The possible synergism mechanism of organic DBPs on the inorganic ones may be attributed to the influence of organic DBPs on cell membrane and cell antioxidant system. This study revealed the toxic interactions among organic and inorganic DBPs, and emphasized the latent adverse outcomes in the combined use of different disinfectants.展开更多
The formation and concentration of disinfection by-products（DBPs） in pool water and the ambient air vary according to the type of water treatment process used. This exploratory study was aimed at investigating the s...The formation and concentration of disinfection by-products（DBPs） in pool water and the ambient air vary according to the type of water treatment process used. This exploratory study was aimed at investigating the short-term impact of modifications of the water treatment process on traditional DBP levels（e.g., trihalomethanes（THMs）, chloramines） and emerging DBPs（e.g., Halonitromethanes, Haloketones, NDMA） in swimming pool water and/or air. A sampling program was carried to understand the impact of the following changes made successively to the standard water treatment process： activation of ultraviolet（UV）photoreactor, halt of air stripping with continuation of air extraction from the buffer tank,halt of air stripping and suppression of air extraction from the buffer tank, suppression of the polyaluminium silicate sulfate（PASS） coagulant. UV caused a high increase of Halonitromethanes（8.4 fold）, Haloketones（2.1 fold）, and THMs in the water（1.7 fold） and, of THMs in the air（1.6 fold） and contributed to reducing the level of chloramines in the air（1.6fold） and NDMA in the water（2.1 fold）. The results highlight the positive impact of air stripping in reducing volatile contaminants. The PASS did not change the presence of DBPs, except for the THMs, which decrease slightly with the use of this coagulant. This study shows that modifications affecting the water treatment process can rapidly produce important and variable impacts on DBP levels in water and air and suggests that implementation of any water treatment process to reduce DBP levels should take into account the specific context of each swimming pool.展开更多
Dissolved black carbon(DBC)released from biochar can be one of the potential disinfection by-products(DBPs)precursors in the dissolved organic matter pool.However,the physiochemical and structural properties of DBC an...Dissolved black carbon(DBC)released from biochar can be one of the potential disinfection by-products(DBPs)precursors in the dissolved organic matter pool.However,the physiochemical and structural properties of DBC and the effects on the development of DBPs and DBP formation potential(DBPFP)during the disinfection process remain unclear.In this study,the characteristics of two kinds of DBC,namely,animal-derived DBC(poultry litter DBC,PL-DBC)and plant-derived DBC(wheat straw DBC,WS-DBC),were investigated.The effects of different kinds of DBC on the evolution of DBPs and DBPFP in chlorine and chloramine disinfection processes were compared with natural organic matter(NOM).The results showed that the total DBPs concentrations derived from PL-DBC,WS-DBC and NOM were similar during chlorination(i.e.,61.23µg/L,64.59µg/L and 64.66µg/L,respectively)and chloramination(i.e.,44.63µg/L,44.42µg/L and 45.58µg/L,respectively).The lower total DBPs and DBPFP concentrations in chloramination could be attributed to the fact that the introduction of ammonia in chloramine inhibited the breaking of the bond between the disinfectant and the active group of the precursor.Additionally,DBC presented much lower total DBPFP concentrations than NOM in both chlorination and chloramination.However,both kinds of DBC tended to form more monochloroacetic acids and haloacetamides than NOM,which could result from the higher organic strength,higher protein matter,and nitrogen-rich soluble microbial products of DBC.展开更多
A method based on regression modeling was developed to discern the contribution of component chemicals to the toxicity of highly complex, environmentally realistic mixtures of disinfection byproducts（DBPs）. Chemical...A method based on regression modeling was developed to discern the contribution of component chemicals to the toxicity of highly complex, environmentally realistic mixtures of disinfection byproducts（DBPs）. Chemical disinfection of drinking water forms DBP mixtures.Because of concerns about possible reproductive and developmental toxicity, a whole mixture（WM） of DBPs produced by chlorination of a water concentrate was administered as drinking water to Sprague–Dawley（S–D） rats in a multigenerational study. Age of puberty acquisition,i.e., preputial separation（PPS） and vaginal opening（VO）, was examined in male and female offspring, respectively. When compared to controls, a slight, but statistically significant delay in puberty acquisition was observed in females but not in males. WM-induced differences in the age at puberty acquisition were compared to those reported in S–D rats administered either a defined mixture（DM） of nine regulated DBPs or individual DBPs. Regression models were developed using individual animal data on age at PPS or VO from the DM study. Puberty acquisition data reported in the WM and individual DBP studies were then compared with the DM models. The delay in puberty acquisition observed in the WM-treated female rats could not be distinguished from delays predicted by the DM regression model, suggesting that the nine regulated DBPs in the DM might account for much of the delay observed in the WM. This method is applicable to mixtures of other types of chemicals and other endpoints.展开更多
UV/chlorine process,as an emerging advanced oxidation process(AOP),was effective for removing micro-pollutants via various reactive radicals,but it also led to the changes of natural organic matter(NOM)and formation o...UV/chlorine process,as an emerging advanced oxidation process(AOP),was effective for removing micro-pollutants via various reactive radicals,but it also led to the changes of natural organic matter(NOM)and formation of disinfection byproducts(DBPs).By using negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry(ESI FT-ICR MS),the transformation of Suwannee River NOM(SRNOM)and the formation of chlorinated DBPs(Cl-DBPs)in the UV/chlorine AOP and subsequent post-chlorination were tracked and compared with dark chlorination.In comparison to dark chlorination,the involvement of Cl O·,Cl·,and HO·in the UV/chlorine AOP promoted the transformation of NOM by removing the compounds owning higher aromaticity(AI mod)value and DBE(double-bond equivalence)/C ratio and causing the decrease in the proportion of aromatic compounds.Meanwhile,more compounds which contained only C,H,O,N atoms(CHON)were observed after the UV/chlorine AOP compared with dark chlorination via photolysis of organic chloramines or radical reactions.A total of 833 compounds contained C,H,O,Cl atoms(CHOCl)were observed after the UV/chlorine AOP,higher than 789 CHOCl compounds in dark chlorination,and one-chlorine-containing components were the dominant species.The different products from chlorine substitution reactions(SR)and addition reactions(AR)suggested that SR often occurred in the precursors owning higher H/C ratio and AR often occurred in the precursors owning higher aromaticity.Post-chlorination further caused the cleavages of NOM structures into small molecular weight compounds,removed CHON compounds and enhanced the formation of Cl-DBPs.The results provide information about NOM transformation and Cl-DBPs formation at molecular levels in the UV/chlorine AOP.展开更多
The effects of biologically active carbon(BAC)filtration on haloacetic acid(HAA)levels in plant effluents and distribution systems were investigated using the United States Environmental Protection Agency’s Informati...The effects of biologically active carbon(BAC)filtration on haloacetic acid(HAA)levels in plant effluents and distribution systems were investigated using the United States Environmental Protection Agency’s Information Collection Rule(ICR)database.The results showed that average HAA5 concentrations in all locations were 20.4μg·L^(-1)and 29.6μg·L^(-1)in ICR plants with granular activated carbon(GAC)and ICR plants without GAC process,respectively.For plants without GAC,the highest HAA levels were observed in the quarters of April to June and July to September.However,for plants with GAC,the highest HAA levels were observed in the quarters of April to June and January to March.This HAA level profile inversely correlated well with water temperature,or biologic activity.For GAC plants,simulated distribution samples matched well with distribution system equivalent samples for Cl3AA and THMs.For plants with and without GAC,simulated distribution samples overestimated readily biodegradable HAAs in distribution systems.The study indicated that through HAA biodegradation,GAC process plays an important role in lowering HAA levels in finished drinking water.展开更多
Lead contamination in the City of Flint, MI has been well documented over the past two years, with lead levels above the EPA Action Level until summer 2016. This resulted from an ill-fated decision to switch from Detr...Lead contamination in the City of Flint, MI has been well documented over the past two years, with lead levels above the EPA Action Level until summer 2016. This resulted from an ill-fated decision to switch from Detroit water（Lake Huron） with corrosion control, to Flint River water without corrosion control. Although lead levels are now closer to normal,reports of skin rashes have sparked questions surrounding tap water in some Flint homes.This study investigated the presence of contaminants, including disinfection by-products（DBPs）, in the hot tap water used for showering in the homes of residents in Flint. Extensive quantitative analysis of 61 regulated and priority unregulated DBPs was conducted in Flint hot and cold tap water, along with the analysis of 50 volatile organic compounds and a nontarget comprehensive, broadscreen analysis, to identify a possible source for the reported skin rashes. For comparison, chlorinated hot and cold waters from three other cities were also sampled, including Detroit, which also uses Lake Huron as its source water.Results showed that hot water samples generally contained elevated levels of regulated and priority unregulated DBPs compared to cold water samples, but trihalomethanes were still within regulatory limits. Overall, hot shower water from Flint was similar to waters sampled from the three other cities and did not have unusually high levels of DBPs or other organic chemicals that could be responsible for the skin rashes observed by residents. It is possible that an inorganic chemical or microbial contaminant may be responsible.展开更多
Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control.Pre-oxidation by chlorine dioxide(ClO_(2))followed by coagulation-flocculation-se...Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control.Pre-oxidation by chlorine dioxide(ClO_(2))followed by coagulation-flocculation-sedimentation and advanced oxidation processes(AOPs)is one of the promising solutions.However,the chlorite(ClO_(2)^(-))formed from the ClO_(2) preoxidation stage cannot be removed by the conventional coagulation process using aluminum sulfate.ClO_(2)^(–)negatively affects the post-UV/chlorine process due to its strong radical scavenging effect,and it also enhances the formation of chlorate(ClO_(3)^(–)).In this study,dosing micromolar-level ferrous iron(Fe(II))into aluminum-based coagulants was proposed to eliminate the ClO_(2)^(–)generated from ClO_(2) pre-oxidation and benefit the post-UV/chlorine process in radical production and ClO_(3)^(–)reduction.Results showed that the addition of 52.1-μmol/L FeSO_(4) effectively eliminated the ClO_(2)^(-)generated from the pre-oxidation using 1.0 mg/L(14.8μmol/L)of ClO 2.Reduction of ClO_(2)^(-)increased the degradation rate constant of a model micropollutant(carbamazepine)by 55.0%in the post-UV/chlorine process.The enhanced degradation was verified to be attributed to the increased steady-state concentrations of HO^(-)·and ClO_(2)·by Fe(II)addition.Moreover,Fe(II)addition also decreased the ClO_(3)^(–)formation by 53.8%in the UV/chlorine process and its impact on the formation of chloroorganic byproducts was rather minor.The findings demonstrated a promising strategy to improve the drinking water quality and safety by adding low-level Fe(II)in coagulation in an advanced drinking water treatment train.展开更多
基金the National Natural Science Foundation of China(Nos.21976069,21677062,21507155)。
文摘Porous polymer(pyrrolopyrrole)was successfully prepared via domino-ring-formation reaction.The chemical-physical properties of cyanided covalent triazine frameworks(CTF-CN)were characteriazed by fourier transform infrared spectra(FT-IR),scanning electron microscopy(SEM),nuclear magnetic resonance(NMR),specific surface area analyzer(BET)and thermogravimetric analysis(TGA),respectively.The experimental results of adsorption of chloranil(TCBQ)in aqueous solution indicated that CTF-CN exhibited distinctive adsorption capacity toward TCBQ owing to its large specific surface area.Specifically,the adsorption equilibrium of as-prepared polymer was executed within 5 h and the calculated adsorption capacity was 499.76 mg/g.Furthermore,the adsorption kinetics could be well defined with the linear pseudo-second-order model,which implies that the chemical interaction are relative important in the course of TCBQ removal.Finally,the current studies verify that CTF-CN has unique rigid and nano-porous framework structure,which can be employed for the treatment of a series of harmful aromatic substances.
文摘Objective Since haloacetic acids (HAAs), which are nonvolatile and of high carcinogenic risk, are common species of chlorinated disinfection by-products(DBPs) in drinking water, and little has been known in China, it is necessary to make a survey about the kinds and levels of HAAs in drinking water of the nation. Method HAAs were analyzed using gas chromatography with electron capture detector(GC/ECD) and relatively complex pretreatment process of sample was applied. Five main cities in different areas of China were chosen in the survey. Results Studies showed that the main species of HAAs in drinking water in China were DCAA and TCAA, ranging from 0.4 礸/L to 12.85 礸/L and from 0.56 礸/L to 10.98 礸/L, respectively. MBAA and DBAA were also detected in one city, ranging from 2.20 礸/L to 4.95 礸/L and 1.10 礸/L to 2.81 礸/L, respectively. Therefore, the contents of HAAs varied, usually no more than 25 礸/L. Based on the acquired data to date, it is known that the concentrations of HAAs in drinking water in China were surely under the limits of Sanitary Standard for Drinking Water Quality (China, 2001). Conclusion A wider survey of HAAs in drinking water should be conducted throughout the nation to get adequate data and information, the ultimate aim of which is to control HAAs pollution and keep the balance between microbiological safety insurance and chemical risk control, minimize the formation of DBPs and ensure the safety of water supply at the same time.
基金The Hi-Tech Research and Development Program (863) of China (No. 2003AA601120)
文摘Mesocyclops leukarti of zooplankton propagates excessively in eutrophic water body and it cannot be effectively inactivated by the conventional drinking water treatment process. In order to tackle this problem, a study of removal effect on Mesocylops leukarti with chlorine dioxide in a waterworks was performed. The results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide prcoxidation combined with the conventional drinking water treatment process. Higher oxidizability and molecular state of chlorine dioxide in water is the key to the inactivation of Mesocyclops leukarti. The chlorite, disinfection by-products （DBPs） of chlorine dioxide, was stable at 0.45 mg/L, which is lower than that critical value of the USEPA. GC-MS examination showed that the quantity of organic substance in the water treated by chlorine dioxide obviously decreased. Ames test further revealed that the mutagenicity was reduced by chlorine dioxide with respect to prechlorine. The propagation ofMesocyclops leukorti can be inactivated effectively and safely by chlorine dioxide pre-oxidation.
文摘Disinfection by-products （DBPs） are regulated in drinking water in a number of countries. This critical review focuses on the issues associated with DBP regulatory compliance, including methods for DBP analysis, occurrence levels, the regulation comparison among various countries, DBP compliance strategies, and emerging DBPs. The regulation comparison between China and the United States （US） indicated that the DBP regulations in China are more stringent based on the number of regulated compounds and maximum levels. The comparison assessment using the Information Collection Rule （ICR） database indicated that the compliance rate of 500 large US water plants under the China regulations is much lower than that under the US regulations （e.g. 62.2% versus 89.6% for total trihalomethanes）. Precursor removal and alternative disinfectants are common practices for DBP regulatory compliance. DBP removal after formation, including air stripping for trihalomethane removal and biodegradation for haloacetic acid removal, have gained more acceptance in DBP control. Formation of emerging DBPs, including iodinated DBPs and nitrogenous DBPs, is one of unintended consequences of precursor removal and alternative disinfection. At much lower levels than carbonaceous DBPs, however, emerging DBPs have posed higher health risks.
基金supported by the National Natural Science Foundation of China(No.51025830,50921064)the S&T Research Project of Guangdong Province(No. 2009A080303007)the Hi-Tech Research and Development Program(863) of China(No.2006AA06Z312)
文摘Eight typical drinking water supplies in China were selected in this study.Both source and tap water were used to investigate the occurrence of chlorinated disinfection byproducts（DBPs）,and seasonal variation in the concentrations of trihalomethanes（THMs） of seven water sources was compared.The results showed that the pollution level for source water in China,as shown by DBP formation potential,was low.The most encountered DBPs were chloroform,dichloroacetic acid,trichloroacetic acid,and chlorodibromoacetic acid.The concentration of every THMs and haloacetic acid（HAA） compound was under the limit of standards for drinking water quality.The highest total THMs concentrations were detected in spring.
文摘Disinfection byproducts(DBPs)represent a ubiquitous source of chemical exposure in disinfected water.While over 700 DBPs have been identified,the drivers of toxicity remain poorly understood.Additionally,ever evolving water treatment practices have led to a continually growing list of DBPs.Advancement of analytical technologies have enabled the identification of new classes of DBPs and the quantification of these chemically diverse sets of DBPs.Here we summarize advances in new workflows for DBP analysis,including sample preparation,chromatographic separation with mass spectrometry(MS)detection,and data processing.To aid in the selection of techniques for future studies,we discuss necessary considerations for each step in the strategy.This review focuses on how each step of a workflow can be optimized to capture diverse classes of DBPs within a single method.Additionally,we highlight new MS-based approaches that can be powerful for identifying novel DBPs of toxicological relevance.We discuss current challenges and provide perspectives on future research directions with respect to studying new DBPs of toxicological relevance.As analytical technologies continue to advance,new strategies will be increasingly used to analyze complex DBPs produced in different treatment processes with the aim to identify potential drivers of toxicity.
文摘Swimming has become a popular exercising and recreational activity in China but little is known about the disinfection by-products （DBPs） concentration levels in the pools. This study was conducted as a survey of the DBPs in China swimming pools, and to establish the correlations between the DBP concentrations and the pool water quality parameters. A total of 14 public indoor and outdoor pools in Beijing were included in the survey. Results showed that the median concentrations for total tfihalomethanes （TTHM）, nine haloacetic acids （HAA9）, chloral hydrate （CH）, four haloacetonitriles （HAN4）, 1,1- dichloropropanone, 1,1,1-trichloropropanone and trichlor- onitromethane were 33.8, 109.1, 30.1, 3.2, 0.3, 0.6 pg＇L-1 and below detection limit, respectively. The TTHM and HAA9 levels were in the same magnitude of that in many regions of the world. The levels of CH and nitrogenous DBPs were greatly higher than and were comparable to that in typical drinking water, respectively. Disinfection by chlorine dioxide or trichloroisocyanuric acid could sub- stantially lower the DBP levels. The outdoor pools had higher TTHM and HAA9 levels, but lower trihaloacetic acids （THAA） levels than the indoor pools. The TTHM and HAA9 concentrations could be moderately correlated with the free chlorine and total chlorine residuals but not with the total organic carbon （TOC） contents. When the DBP concentration levels from other survey studies were also included for statistical analysis, a good correlation could be established between the TTHM levels and the TOC concentration. The influence of chlorine residual on DBP levels could also be significant.
基金supported by the National Natural Science Foundation of China(Nos.51778323,51761125013 and51290284)the National Science and Technology Major Project of China(Nos.2012ZX07404-002,2017ZX07108-003 and 2017ZX07502-003)
文摘To manage potential microbial risks and meet increasingly strict drinking water health standards,UV treatment has attracted increasing attention for use in drinking water systems in China.However,the effects of UV treatment on microbial control and disinfection byproducts(DBPs)formation in real municipal drinking water systems are poorly understood.Here,we collected water samples from three real drinking water systems in Beijing and Tianjin to investigate the impacts of UV treatment on microbial control and DBP formation.We employed heterotrophic plate count(HPC),flow cytometry(FCM),quantitative PCR analysis,and high-throughput sequencing to measure microorganisms in the samples.Different trends were observed between HPC and total cell count(measured by FCM),indicating that a single indicator could not reflect the real degree of biological re-growth in drinking water distribution systems(DWDSs).A significant increase in the 16S rRNA gene concentration was observed when the UV system was stopped.Besides,the bacterial community composition was similar at the phylum level but differed markedly at the genera level among the three DWDSs.Some chlorine-resistant bacteria,including potential pathogens(e.g.,Acinetobacter)showed a high relative abundance when the UV system was turned off.It can be concluded that UV treatment can mitigate microbial re-growth to some extent.Finally,UV treatment had a limited influence on the formation of DBPs,including trihalomethanes,haloacetic acids,and nitrogenated DBPs.The findings of this study may help to understand the performance of UV treatment in real drinking water systems.
基金sponsored by the National Natural Science Foundation of China (Nos. 52070144 , 51978483 , 51808222)the National Key Research and Development Program (No. 2021YFC3201303)。
文摘UV/peroxymonosulfate(UV/PMS) advanced oxidation process has attracted significant attention for removal of micropollutants in water. However, during practical water treatment applications, the PMS treatment must be performed before the UV treatment to achieve full contact. In this study, sulfamethoxazole(SMX) was selected as the target micropollutant. Four different operational approaches, including UV alone, PMS alone, simultaneous UV/PMS and sequential PMS-UV, were compared for their differences in SMX removal and disinfection by-product(DBP) formation potentials during chlorine-driven disinfection. Among the four approaches, UV/PMS and PMS-UV achieved over 90% removal efficiencies for SMX without substantial differences. For raw water, the trichloronitromethane(TCNM) formation potential after treatment with PMS-UV was lower than that after UV/PMS treatment. The time interval over which the PMS-UV process was conducted had little effect on the final removal efficiency for SMX. However, a brief(5 min) pre-PMS treatment significantly reduced the TCNM formation potential and the genotoxicity from DBPs. The formation risk for TCNM during chlorination increased markedly with increasing PMS dosages, and the appropriate dosage under these experimental conditions was suggested to be 0.5–1.0 mmol/L. Under alkaline conditions, PMS-UV treatment can enhance SMX degradation as well as dramatically reduced the formation potentials for haloketones, haloacetonitriles and halonitromethanes. This study suggests that proper optimization of UV/PMS processes can remove SMX and reduce its DBP formation.
文摘When bromide/iodide is present in source water, hypobromous acid/hypoiodous acid will be formed with addition of chlorine, chloramine, or other disinfectants. Hypobromous acid/hypoiodous acid undergoes reactions with natural organic matter in source water to form numerous brominated/iodinated disinfection byproducts （DBPs）. In this study, tap water samples were collected from eight cities in China. With the aid of electrospray ionization-triple quadrupole mass spectrometry by setting precursor ion scans of m/z 35, m/z 81, and m/z 126.9, whole pictures of polar chlorinated, brominated, and iodinated DBPs in the tap water samples were revealed for the first time. Numerous polar halogenated DBPs were detected, including haloacetic acids, newly identified halogenated phenols, and many new/unknown halogenated compounds. Total organic chlorine, total organic bromine, and total organic iodine were also measured to indicate the total levels of all chlorinated, brominated, and iodinated DBPs in the tap water samples. The total organic chlorine concentrations ranged from 26.8 to 194.0 μg· L 1 as Cl, with an average of 109.2 μg·L-1 as Cl; the total organic bromine concentrations ranged from below detection limit to 113.3 μg·L-1 as Br, with an average of 34.7 μg·L-1 as Br; the total organic iodine concentrations ranged from below detection limit to 16.4 μg· L-1 as I, with an average of 9.1 μg· L-1 as I; the total organic halogen concentrations ranged from 31.3 to 220.4 μg·L-1 as Cl, with an average of 127.2 μg· L- 1 as Cl.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)the National Natural Science Foundation of China,Alberta Innovates,and Alberta Health
文摘Introduction Natural organic matter（NOM）present in source water has significant impact on water treatment processes and on the quality of drinking water.NOM is a complex mixture of diverse groups of organic compounds,humic and fulvic acids,proteins,peptides,carbohydrates,and heterogeneous materials
文摘Environmental water samples can be extremely complex,with potentially thousands of molecules that can derive from natural organic matter（NOM）and thousands that derive from anthropogenic contaminants.As complex as these samples are,drinking water can be even more complex.Due to disinfectants that are used to treat drinking water（e.g.,chlorine,chloramines,
基金supported by the National Natural Science Foundation of China (No. 21876210)。
文摘Chlorine, chlorine dioxide, and ozone are widely used as disinfectants in drinking water treatments. However, the combined use of different disinfectants can result in the formation of various organic and inorganic disinfection byproducts(DBPs). The toxic interactions, including synergism, addition, and antagonism, among the complex DBPs are still unclear. In this study, we established and verified a real-time cell analysis(RTCA) method for cytotoxicity measurement on Chinese hamster ovary(CHO) cell. Using this convenient and accurate method, we assessed the cytotoxicity of a series of binary combinations consisting of one of the 3 inorganic DBPs(chlorite, chlorate, and bromate) and one of the 32 regulated and emerging organic DBPs. The combination index(CI) of each combination was calculated and evaluated by isobolographic analysis to reflect the toxic interactions. The results confirmed the synergistic effect on cytotoxicity in the binary combinations consisting of chlorite and one of the 5 organic DBPs(2 iodinated DBPs(I-DBPs) and 3 brominated DBPs(Br-DBPs)), chlorate and one of the 4 organic DBPs(3 aromatic DBPs and dibromoacetonitrile), and bromate and one of the 3 organic DBPs(2 I-DBPs and dibromoacetic acid). The possible synergism mechanism of organic DBPs on the inorganic ones may be attributed to the influence of organic DBPs on cell membrane and cell antioxidant system. This study revealed the toxic interactions among organic and inorganic DBPs, and emphasized the latent adverse outcomes in the combined use of different disinfectants.
基金supported through a research fund provided by the Institut de Recherche Robert-Sauvé en Santé et Sécurité du Travail (IRSST), Québec, Canada
文摘The formation and concentration of disinfection by-products（DBPs） in pool water and the ambient air vary according to the type of water treatment process used. This exploratory study was aimed at investigating the short-term impact of modifications of the water treatment process on traditional DBP levels（e.g., trihalomethanes（THMs）, chloramines） and emerging DBPs（e.g., Halonitromethanes, Haloketones, NDMA） in swimming pool water and/or air. A sampling program was carried to understand the impact of the following changes made successively to the standard water treatment process： activation of ultraviolet（UV）photoreactor, halt of air stripping with continuation of air extraction from the buffer tank,halt of air stripping and suppression of air extraction from the buffer tank, suppression of the polyaluminium silicate sulfate（PASS） coagulant. UV caused a high increase of Halonitromethanes（8.4 fold）, Haloketones（2.1 fold）, and THMs in the water（1.7 fold） and, of THMs in the air（1.6 fold） and contributed to reducing the level of chloramines in the air（1.6fold） and NDMA in the water（2.1 fold）. The results highlight the positive impact of air stripping in reducing volatile contaminants. The PASS did not change the presence of DBPs, except for the THMs, which decrease slightly with the use of this coagulant. This study shows that modifications affecting the water treatment process can rapidly produce important and variable impacts on DBP levels in water and air and suggests that implementation of any water treatment process to reduce DBP levels should take into account the specific context of each swimming pool.
基金funding from the National Natural Science Foundation of China(Nos.52170021,42177051,and 41977317).
文摘Dissolved black carbon(DBC)released from biochar can be one of the potential disinfection by-products(DBPs)precursors in the dissolved organic matter pool.However,the physiochemical and structural properties of DBC and the effects on the development of DBPs and DBP formation potential(DBPFP)during the disinfection process remain unclear.In this study,the characteristics of two kinds of DBC,namely,animal-derived DBC(poultry litter DBC,PL-DBC)and plant-derived DBC(wheat straw DBC,WS-DBC),were investigated.The effects of different kinds of DBC on the evolution of DBPs and DBPFP in chlorine and chloramine disinfection processes were compared with natural organic matter(NOM).The results showed that the total DBPs concentrations derived from PL-DBC,WS-DBC and NOM were similar during chlorination(i.e.,61.23µg/L,64.59µg/L and 64.66µg/L,respectively)and chloramination(i.e.,44.63µg/L,44.42µg/L and 45.58µg/L,respectively).The lower total DBPs and DBPFP concentrations in chloramination could be attributed to the fact that the introduction of ammonia in chloramine inhibited the breaking of the bond between the disinfectant and the active group of the precursor.Additionally,DBC presented much lower total DBPFP concentrations than NOM in both chlorination and chloramination.However,both kinds of DBC tended to form more monochloroacetic acids and haloacetamides than NOM,which could result from the higher organic strength,higher protein matter,and nitrogen-rich soluble microbial products of DBC.
文摘A method based on regression modeling was developed to discern the contribution of component chemicals to the toxicity of highly complex, environmentally realistic mixtures of disinfection byproducts（DBPs）. Chemical disinfection of drinking water forms DBP mixtures.Because of concerns about possible reproductive and developmental toxicity, a whole mixture（WM） of DBPs produced by chlorination of a water concentrate was administered as drinking water to Sprague–Dawley（S–D） rats in a multigenerational study. Age of puberty acquisition,i.e., preputial separation（PPS） and vaginal opening（VO）, was examined in male and female offspring, respectively. When compared to controls, a slight, but statistically significant delay in puberty acquisition was observed in females but not in males. WM-induced differences in the age at puberty acquisition were compared to those reported in S–D rats administered either a defined mixture（DM） of nine regulated DBPs or individual DBPs. Regression models were developed using individual animal data on age at PPS or VO from the DM study. Puberty acquisition data reported in the WM and individual DBP studies were then compared with the DM models. The delay in puberty acquisition observed in the WM-treated female rats could not be distinguished from delays predicted by the DM regression model, suggesting that the nine regulated DBPs in the DM might account for much of the delay observed in the WM. This method is applicable to mixtures of other types of chemicals and other endpoints.
基金supported by the National Key Research and Development Program of China(No.2017YFE0133200)the National Natural Science Foundation of China(Nos.21876210 and 21806173)+1 种基金the Guangdong Provincial Science and Technology Planning Projects(No.2019A050503006)Hong Kong RGC(Nos.16206416 and T21-604/19-R)。
文摘UV/chlorine process,as an emerging advanced oxidation process(AOP),was effective for removing micro-pollutants via various reactive radicals,but it also led to the changes of natural organic matter(NOM)and formation of disinfection byproducts(DBPs).By using negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry(ESI FT-ICR MS),the transformation of Suwannee River NOM(SRNOM)and the formation of chlorinated DBPs(Cl-DBPs)in the UV/chlorine AOP and subsequent post-chlorination were tracked and compared with dark chlorination.In comparison to dark chlorination,the involvement of Cl O·,Cl·,and HO·in the UV/chlorine AOP promoted the transformation of NOM by removing the compounds owning higher aromaticity(AI mod)value and DBE(double-bond equivalence)/C ratio and causing the decrease in the proportion of aromatic compounds.Meanwhile,more compounds which contained only C,H,O,N atoms(CHON)were observed after the UV/chlorine AOP compared with dark chlorination via photolysis of organic chloramines or radical reactions.A total of 833 compounds contained C,H,O,Cl atoms(CHOCl)were observed after the UV/chlorine AOP,higher than 789 CHOCl compounds in dark chlorination,and one-chlorine-containing components were the dominant species.The different products from chlorine substitution reactions(SR)and addition reactions(AR)suggested that SR often occurred in the precursors owning higher H/C ratio and AR often occurred in the precursors owning higher aromaticity.Post-chlorination further caused the cleavages of NOM structures into small molecular weight compounds,removed CHON compounds and enhanced the formation of Cl-DBPs.The results provide information about NOM transformation and Cl-DBPs formation at molecular levels in the UV/chlorine AOP.
基金This study was supported by“Taiwan NSC”(No.96-2221-E-002-051)and“USEPA Small Public Water Technology Assistance Center”.
文摘The effects of biologically active carbon(BAC)filtration on haloacetic acid(HAA)levels in plant effluents and distribution systems were investigated using the United States Environmental Protection Agency’s Information Collection Rule(ICR)database.The results showed that average HAA5 concentrations in all locations were 20.4μg·L^(-1)and 29.6μg·L^(-1)in ICR plants with granular activated carbon(GAC)and ICR plants without GAC process,respectively.For plants without GAC,the highest HAA levels were observed in the quarters of April to June and July to September.However,for plants with GAC,the highest HAA levels were observed in the quarters of April to June and January to March.This HAA level profile inversely correlated well with water temperature,or biologic activity.For GAC plants,simulated distribution samples matched well with distribution system equivalent samples for Cl3AA and THMs.For plants with and without GAC,simulated distribution samples overestimated readily biodegradable HAAs in distribution systems.The study indicated that through HAA biodegradation,GAC process plays an important role in lowering HAA levels in finished drinking water.
基金funding from the U.S.Environmental Protection Agency, Meghan Franco for assistance with XAD resin extractions, Shealy Environmental, Inc.for VOC analyses
文摘Lead contamination in the City of Flint, MI has been well documented over the past two years, with lead levels above the EPA Action Level until summer 2016. This resulted from an ill-fated decision to switch from Detroit water（Lake Huron） with corrosion control, to Flint River water without corrosion control. Although lead levels are now closer to normal,reports of skin rashes have sparked questions surrounding tap water in some Flint homes.This study investigated the presence of contaminants, including disinfection by-products（DBPs）, in the hot tap water used for showering in the homes of residents in Flint. Extensive quantitative analysis of 61 regulated and priority unregulated DBPs was conducted in Flint hot and cold tap water, along with the analysis of 50 volatile organic compounds and a nontarget comprehensive, broadscreen analysis, to identify a possible source for the reported skin rashes. For comparison, chlorinated hot and cold waters from three other cities were also sampled, including Detroit, which also uses Lake Huron as its source water.Results showed that hot water samples generally contained elevated levels of regulated and priority unregulated DBPs compared to cold water samples, but trihalomethanes were still within regulatory limits. Overall, hot shower water from Flint was similar to waters sampled from the three other cities and did not have unusually high levels of DBPs or other organic chemicals that could be responsible for the skin rashes observed by residents. It is possible that an inorganic chemical or microbial contaminant may be responsible.
基金supported by the Hong Kong Innovation and Technology Fund (No. GHP/010/18GD)the National Natural Science Foundation of China (No. 21876210)+1 种基金the Hong Kong Research Grants Council (No. T21-604/19-R)partially supported by a fellowship award from the Research Grants Council of the Hong Kong Special Administrative Region, China (No. HKUST PDFS2021-6S05)。
文摘Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control.Pre-oxidation by chlorine dioxide(ClO_(2))followed by coagulation-flocculation-sedimentation and advanced oxidation processes(AOPs)is one of the promising solutions.However,the chlorite(ClO_(2)^(-))formed from the ClO_(2) preoxidation stage cannot be removed by the conventional coagulation process using aluminum sulfate.ClO_(2)^(–)negatively affects the post-UV/chlorine process due to its strong radical scavenging effect,and it also enhances the formation of chlorate(ClO_(3)^(–)).In this study,dosing micromolar-level ferrous iron(Fe(II))into aluminum-based coagulants was proposed to eliminate the ClO_(2)^(–)generated from ClO_(2) pre-oxidation and benefit the post-UV/chlorine process in radical production and ClO_(3)^(–)reduction.Results showed that the addition of 52.1-μmol/L FeSO_(4) effectively eliminated the ClO_(2)^(-)generated from the pre-oxidation using 1.0 mg/L(14.8μmol/L)of ClO 2.Reduction of ClO_(2)^(-)increased the degradation rate constant of a model micropollutant(carbamazepine)by 55.0%in the post-UV/chlorine process.The enhanced degradation was verified to be attributed to the increased steady-state concentrations of HO^(-)·and ClO_(2)·by Fe(II)addition.Moreover,Fe(II)addition also decreased the ClO_(3)^(–)formation by 53.8%in the UV/chlorine process and its impact on the formation of chloroorganic byproducts was rather minor.The findings demonstrated a promising strategy to improve the drinking water quality and safety by adding low-level Fe(II)in coagulation in an advanced drinking water treatment train.
