Correlations between differential absorbance and the formation of individual DBPs (original) (raw)
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Water Research, 2008
Effects of chlorine dose, reaction time and temperature on the formation of disinfection byproducts (DBPs) and corresponding changes in the absorbance of natural organic matter (NOM) in chlorinated water were examined in this study. Although variations of chlorination parameters, notably those of temperature that was varied from 3 to 35 1C, influenced the kinetics of chlorine consumption and DBP release, correlations between chlorine consumption, concentrations of trihalomethanes (THMs), haloacetonitriles (HANs), other DBP species and, on the other hand, intensity of differential absorbance at 272 nm remained unaffected. THM and HAN speciation was correlated with the differential absorbance, indicating preferential incorporation of bromine at the initial phases of halogenation that correspond to low DA 272 values. Because the DA 272 parameter is a strong indicator of the formation of DBP species and chlorine decay, optimization of chlorination operations and DBPs control based on this parameter can be beneficial for many water utilities, especially those with pronounced variability of water temperature and residence times. 0.5 nd , position of wavelength corresponding to 50% of the normalized differential absorbance spectra.
Water Science & Technology, 2011
Among known but unregulated disinfection by-products (DBPs), several nitrogenous species (N-DBPs) have been found in drinking waters. While concentrations of N-DBP are much lower than those of trihalomethanes (THMs) and haloacetic acids (HAAs), their potential toxicity is higher. In this study the relationships between the formation of N-DBPs and the changes in NOM caused by the chlorination of raw Ancipa water quantified by the use of differential absorbance and fluorescence indexes were investigated. Very strong relationships were found between selected N-DBPs (i.e. trichloronitromethane and dichloroacetonitrile) and the proposed spectroscopic indexes that were previously developed to quantify the changes in natural organic matter (NOM) during chlorination at varying reaction conditions (chlorine dose, reaction time and temperature) and the generation of DBPs. Obtained results clearly indicate that the changes in NOM absorbance and fluorescence are fundamental descriptors of the formation of both commonly controlled halogenated DBPs and N-DBPs. This approach may be suitable for real time monitoring of emerging N-DBPs and for studying their formation pathways.
Comparison of disinfection byproduct formation from chlorine and alternative disinfectants
Water Research, 2007
Please cite this article as: Bougeard, C.M.M., Goslan, E.H., Jefferson, B., Parsons, S.A. Comparison of the disinfection by-product formation potential of treated waters exposed to chlorine and monochloramine, Water Research (2009),
Environmental Science & Technology, 2010
The U.S. Environmental Protection Agency's "Four Lab Study" involved participation of researchers from four national Laboratories and Centers of the Office of Research and Development along with collaborators from the water industry and academia. The study evaluated toxicological effects of complex disinfection byproduct (DBP) mixtures, with an emphasis on reproductive and developmental effects that have been associated with DBP exposures in some human epidemiologic studies. This paper describes a new procedure for producing chlorinated drinking water concentrate for animal toxicology experiments, comprehensive identification of >100 DBPs, and quantification of 75 priority and regulated DBPs. In the research reported herein, complex mixtures of DBPs were produced by concentrating a natural source water with reverse osmosis membranes, followed by addition of bromide and treatment with chlorine. By concentrating natural organic matter in the source water first and disinfecting with chlorine afterward, DBPs (including volatiles and semivolatiles) were formed and maintained in a water matrix suitable for animal studies. DBP levels in the chlorinated concentrate compared well to those from EPA's Information Collection Rule (ICR) and a nationwide study of priority unregulated DBPs when normalized by total organic carbon (TOC). DBPs were relatively stable over the course of the animal studies (125 days) with multiple chlorination events (every 5-14 days), and a significant portion of total organic halogen was accounted for through a comprehensive identification approach. DBPs quantified included regulated DBPs, priority unregulated DBPs, and additional DBPs targeted by the ICR. Many DBPs are reported for the first time, including previously undetected and unreported haloacids and haloamides. The new concentration procedure not only produced a concentrated drinking water suitable for animal experiments, but also provided a greater TOC concentration factor (136×), enhancing the detection of trace DBPs that are often below detection using conventional approaches.
Desalination, 2005
Formation of disinfection by-products (DBPs) in chlorinated coastal (CS) and deep ocean (sampled at a 1500-m depth) seawater (DO) was explored using conventional chromatographic methods and differential absorbance spectroscopy. It was determined that trihalomethanes (THMs) predominated by bromoform, haloacetonitriles and haloacetic acids (HAA) form in chlorinated seawater. The yield of identified DBPs, especially THMs, was higher in CS, while in DO seawater the relative contribution of HAAs was almost four times higher than that of THMs. The fraction of consumed chlorine incorporated into the identified DBPs in DO natural organic matter (NOM) was much lower than that for coastal marine NOM, which was also more active in forming brominated DBPs. The kinetics of seawater chlorination was relatively rapid, and high levels of DBPs were released within the first 20-30 min of reaction. The kinetics of THMs and HAAs release could be approximated using a logarithmic function of reaction time. Absorbance measurements showed that chlorination caused the absorbance of DO and CS to decrease at wavelengths >250 nm. The features of the differential absorbance spectra of chlorinated seawater were close to those reported for drinking water, but their intensity was lower. The concentrations of CHBr 3 , CHBr 2 Cl and CHBrCl 2 formed in CS and DO chlorinated at varying chlorine doses and reaction times were well correlated with the corresponding !)A 272 and/or !)A 405 values. (The differential absorbance at 405 nm can be measured in the presence of residual chlorine). These results show that differential absorbance provides a number of sensitive surrogate parameters that can be used to monitor and quantify the formation of halogen-containing DBPs in seawater.
A comparative study on the control of disinfection by-products (DBPs) and toxicity in drinking water
Desalination and Water Treatment, 2011
In this work, ozone oxidation combined with ferric chloride and aluminum sulfate (Alum) coagulations was employed to investigate the optimum conditions for the control of the toxicity to Daphnia magna and Pseudokirchneriella subcapitata and disinfection by-products (DBPs) formation potential of Buyukcekmece (BC) lake water in Istanbul, Turkey. The effi ciency of the treatment was determined by means of UV absorption at 254 nm (UV 254 ) and dissolved organic carbon (DOC) parameters. Four species of trihalomethanes (THMs) and eight species of haloacetic acids (HAAs) were identifi ed and quantifi ed for the evaluation of treatment methods on the formation of DBPs. It was observed that pre-ozonation enhanced DOC removal effi ciency of alum and ferric chloride coagulations. 40 mg/l optimal alum and ferric chloride doses respectively exhibited 51% and 56% DOC reduction after 5 min pre-ozonation. As a result, THMs formation potential (THMFP) decreased approximately 43% after ozone enhanced alum and ferric chloride coagulations. Haloacetic acids formation potential (HAAFP) of water was reduced by 61% using preozonation alone but a fl uctuating increase and also decrease were reported after coagulations. Chlorinated raw and treated samples displayed acute toxicity in different pattern.
Although disinfection by-products (DBPs) occur in complex mixtures, studies evaluating health risks have been focused in few chemicals. In the framework of an epidemiological study on cancer in 11 Spanish provinces, we describe the concentration of four trihalomethanes (THMs), nine haloacetic acids (HAA), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), four haloacetonitries, two halo-ketones, chloropicrin and chloral hydrate and estimate correlations. A total of 233 tap water samples were collected in 2010. Principal component analyses were conducted to reduce dimensionality of DBPs. Overall median (range) level of THMs and HAAs was 26.4 (0.8–98.1) and 26.4 (0.9–86.9) mg/l, respectively (N¼ 217). MX analysed in a subset (N ¼36) showed a median (range) concentration of 16.7 (0.8–54.1) ng/l. Haloacetonitries, haloketones, chloropicrin and chloral hydrate were analysed in a subset (N¼ 16), showing levels from unquantifiable (o1 mg/l) to 5.5 mg/l (dibromoacetonitrile). Spearman rank correlation coefficients between DBPs varied between species and across areas, being
Environmental Research, 2012
Although disinfection by-products (DBPs) occur in complex mixtures, studies evaluating health risks have been focused in few chemicals. In the framework of an epidemiological study on cancer in 11 Spanish provinces, we describe the concentration of four trihalomethanes (THMs), nine haloacetic acids (HAA), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), four haloacetonitries, two haloketones, chloropicrin and chloral hydrate and estimate correlations. A total of 233 tap water samples were collected in 2010. Principal component analyses were conducted to reduce dimensionality of DBPs. Overall median (range) level of THMs and HAAs was 26.4 (0.8-98.1) and 26.4 (0.9-86.9) mg/l, respectively (N¼ 217). MX analysed in a subset (N ¼36) showed a median (range) concentration of 16.7 (0.8-54.1) ng/l. Haloacetonitries, haloketones, chloropicrin and chloral hydrate were analysed in a subset (N¼ 16), showing levels from unquantifiable (o1 mg/l) to 5.5 mg/l (dibromoacetonitrile). Spearman rank correlation coefficients between DBPs varied between species and across areas, being Contents lists available at SciVerse ScienceDirect