Brominated Disinfection Byproducts Research Articles

Oxidation and volatilization of bromide by electrolysis in drinking water

To reduce the concentrations of brominated disinfection by-products, a process is presented here which removes bromide from a widely used surface water source, the California State Water Project (SWP). The process consists of oxidizing bromide to bromine and volatilizing the bromine. SWP water was passed through this unit under various conditions and the bromide was oxidized and volatilized under a variety of conditions. Five different reactor bodies with seventeen different configurations were tested. The reactors differed in the depth of the anode, in the distance between the anodes and, in the surface area of the anodes. Each reactor had SWP water pumped through the reactor at three or more different flows and at four or more different currents, producing 267 experimental conditions. Both reaction rates and removal efficiency increased with increasing current and were generally higher in the shallower reactors. The highest reaction rates were observed in the shallowest reactors and highest flow rates but the greatest efficiency was achieved is in a slightly deeper reactor at lower flows. This appears to have been the effect of the shallowest reactor having the smallest surface area that was easily saturated and but being closest to atmosphere, allowing the most rapid volatilization of bromine.

Formation and Decomposition of New and Unknown Polar Brominated Disinfection Byproducts during Chlorination

Brominated disinfection byproducts (Br-DBPs) are generally more cytotoxic and genotoxic than their chlorinated analogues. A great portion of total organic bromine in chlorinated drinking water is still unknown and may be ascribed to polar Br-DBPs. In this work, a novel approach, precursor ion scan using ultra-performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, was adopted and further developed for selective detection and identification of polar Br-DBPs, which made it possible to reveal the whole picture of the formation and decomposition of polar Br-DBPs during chlorination. Simulated drinking water samples with chlorine contact times from 1 min to 7 d were analyzed. Many new polar aromatic and unsaturated aliphatic Br-DBPs were detected and tentatively proposed with chemical structures, of which 2,4,6-tribromophenol, 3,5-dibromo-4-hydroxybenzoic acid, 2,6-dibromo-1,4-hydroquinone, and 3,3-dibromopropenoic acid were confirmed or identified with authentic standards. It was found that various polar Br-DBPs formed and reached the maximum levels at different chlorine contact times; high molecular weight Br-DBPs might undergo decomposition to relatively low molecular weight Br-DBPs or even finally to haloacetic acids and trihalomethanes. The decomposition of newly detected intermediate Br-DBPs (including molecular ion cluster m/z 345/347/349/351, 2,4,6-tribromophenol, and 3,5-dibromo-4-hydroxybenzoic acid) during chlorination was investigated in detail. The "black box" from the input of "humic substances + bromide + chlorine" through the output of "haloacetic acids + trihalomethanes" was opened to a significant extent.

Simultaneous degradation of disinfection byproducts and earthy-musty odorants by the UV/H 2O 2 advanced oxidation process

Advanced treatment technologies that control multiple contaminants are beneficial to drinking water treatment. This research applied UV/H 2O 2 for the simultaneous degradation of geosmin, 2-methylisoborneol, four trihalomethanes and six haloacetic acids. Experiments were conducted in de-ionized water at 24 ± 1.0 °C with ng/L amounts of odorants and μg/L amounts of disinfection byproducts. UV was applied with and without 6 mg/L H 2O 2. The results demonstrated that brominated trihalomethanes and brominated haloacetic acids were degraded to a greater extent than geosmin and 2-methylisoborneol. Tribromomethane and dibromochloromethane were degraded by 99% and 80% respectively at the UV dose of 1200 mJ/cm 2 with 6 mg/L H 2O 2, whereas 90% of the geosmin and 60% of the 2-methylisoborneol were removed. Tribromoacetic acid and dibromoacetic acid were degraded by 99% and 80% respectively under the same conditions. Concentrations of trichloromethane and chlorinated haloacetic acids were not substantially reduced under these conditions and were not effectively removed at doses designed to remove geosmin and 2-methylisoborneol. Brominated compounds were degraded primarily by direct photolysis and cleavage of the C–Br bond with pseudo first order rate constants ranging from 10 −3 to 10 −2 s −1. Geosmin and 2-methylisoborneol were primarily degraded by reaction with hydroxyl radical with direct photolysis as a minor factor. Perchlorinated disinfection byproducts were degraded by reaction with hydroxyl radicals. These results indicate that the UV/H 2O 2 can be applied to effectively control both odorants and brominated disinfection byproducts.

Formation and changes of regulated trihalomethanes and haloacetic acids in raw water of Yangtze River, Huangpu River and different treatment processes and pipelines network

To investigate the pollutant levels of regulated disinfection by-products trihalomethanes (THMs) and haloacetic acids (HAAs) in raw water from the Huangpu River, the Yangtze River and different treatment processes and finished water, and to explore the changes tendency in transmission and distribution pipeline network. A total of 65 ml water samples with two replicates were collected from different raw water, corresponding treatment processes, finished water and six national surveillance points in main network of transmission and distribution, water source for A water plant and B, C water plant was the Huangpu River and the Yangtze River, respectively. Regulated THMs and HAAs above water samples were detected by gas chromatography. The total trihalomethanes (THM(4)) concentration in different treatment processes of A water plant was ND-9.64 µg/L, dichlorobromomethane was the highest (6.43 µg/L). The THM(4) concentration in B and C water plant was ND to 38.06 µg/L, dibromochloromethane (12.24 µg/L) and bromoform (14.07 µg/L) were the highest in the B and the C water plant respectively. In addition to trichloroacetic acid in A water plant from the raw water, the other HAAs came from different treatment processes. The total haloacetic acids (HAA(6)) concentration of different treated processes in A water plant was 3.21 - 22.97 µg/L, mobromoacetic acid (10.40 µg/L) was the highest. Dibromoacetic acid was the highest both in B (8.25 µg/L) and C (8.84 µg/L) water plant, HAA(6) concentration was ND to 27.18 µg/L. The highest and the lowest concentration of THM(4) were found from the main distribution network of C and A water plant respectively, but the concentration of HAA(6) in the main water pipes network of A water plant was the highest, and the lowest in C water plant. The THMs concentration was 21.11 - 31.18 µg/L in C water plant and 6.72 - 8.51 µg/L in A water plant. The concentration of HAA(6) was 25.02 - 37.31 µg/L in A water plant and 18.69 - 23.32 µg/L in C water plant. The highest concentrations of brominated disinfection by-products in B and C water plant were 54.57 µg/L and 45.38 µg/L respectively, those were higher than A water plant (18.98 µg/L), and higher than the chlorinated disinfection by-products in B and C water plants (30.23 µg/L and 30.60 µg/L). The THM(4) concentrations of finished water treated from Huangpu River was lower than finished water from the Yangtze River, while the HAAs concentrations in finish water from Huangpu River was higher than the two water plants of Yangtze River. The fluctuations of THMs and HAAs concentration in distribution network were low during transmission and distribution process.

小笠原諸島の水道原水の水質 −消毒副生成物生成能を中心として−

The formation potentials of 24 disinfection by-products, six indicators of organic matter and the number of algae were measured in raw water once a month for one year from October 2006 to September 2007 in order to investigate the quality of water in the two water purification plants on the Ogasawara Islands. It was estimated that the main source of organic matter in raw water on the Ogasawara Islands was not autochthonous organic matter but allochthonous organic matter that flows from streams into reservoirs, as determined from the correlations between the parameters of water quality, the relationship between rainfall and water quality, UV absorbance: TOC ratio and other factors. The mean annual formation potentials of disinfection by-products in filtered raw water on Chichijima Island and Hahajima Island were as follows: total haloacetic acid: 286, 194 μg·L-1, total trihalomethane: 227, 190 μg·L-1, total haloacetonitrile: 13 μg·L-1, and chloral hydrate: 13, 9 μg·L-1, respectively. The total trihalomethane formation potentials were at the maximum levels in our country and the formation potentials of other disinfection by-products were also presumed to be their maximum levels. The formation potentials of the brominated disinfection by-products in most months were higher than those of the nonbrominated disinfection by-products. The correlations of total trihalomethane formation potential (mole concentration) with color, TOC, KMnO4 consumption and UV absorbance were lower than those of the formation potentials of total haloacetic acid, total haloacetonitrile and chloral hydrate in raw water. KMnO4 consumption and UV absorbance were effective indicators of disinfection by-product formation potential for these high correlations (P<0.01).

A new method for differentiating adducts of common drinking water DBPs from higher molecular weight DBPs in electrospray ionization-mass spectrometry analysis

With the presence of bromide in source waters, numerous brominated disinfection byproducts (DBPs) are formed during chlorination. Many of them are polar/highly polar DBPs and thus hard to be detected by gas chromatography mass spectrometry. Electrospray ionization triple quadrupole mass spectrometry (ESI-MS/MS) is reported to be an effective method in finding polar brominated DBPs by setting precursor ion scans of m/ z 79 and 81. But as a soft ionization technique, ESI could form adducts of common DBPs, which may complicate ESI-MS/MS spectra and hinder the efforts in finding new brominated DBPs. In this paper, a new method was developed for differentiating adducts of common DBPs from higher molecular weight DBPs. This method was based on the ESI-MS/MS precursor ion scans of the fragments that correspond to the molecular ions of common DBPs. Adducts of common DBPs were selectively detected in the ESI-MS/MS spectra of a simulated drinking water sample. Moreover, the structures of several new brominated DBPs in the sample were tentatively proposed.

Fast Selective Detection of Polar Brominated Disinfection Byproducts in Drinking Water Using Precursor Ion Scans

Brominated disinfection byproducts (DBPs), formed from the reaction of disinfectant(s) with natural organic matter and bromide in raw water, are generally more cytotoxic and genotoxic than their chlorinated analogues. Brominated DBPs have been intensively studied over the past 35 years, yet only a fraction of the total organic bromine formed during disinfection has been identified. A significant portion of the unaccounted total organic bromine may be attributed to polar/highly polar brominated DBPs. In this work, a method for fast selective detection of polar/ highly polar brominated DBPs in drinking water was developed using negative ion electrospray ionization-triple quadrupole mass spectrometry (ESI-tqMS) by setting precursor ion scans of m/z 79 and 81. This method was conducted without liquid chromatography separation. The results demonstrate that the ESI-tqMS precursor ion scan is an effective tool for the selective detection of electrospray ionizable bromine-containing compounds in a complex mixture. Many polar/ highly polar bromine-containing DBPs were tentatively found in two drinking water samples, and some of them may be new brominated DBPs that have not been previously reported. This method was also extended for the selective detection of polar bromine-containing compounds/contaminants in groundwater, surface water and wastewater.

Risk of Birth Defects in Australian Communities with High Levels of Brominated Disinfection By-products

BackgroundBy international standards, water supplies in Perth, Western Australia, contain high trihalomethane (THM) levels, particularly the brominated forms. Geographic variability in these levels provided an opportunity to examine cross-city spatial relationships between THM exposure and rates of birth defects (BDs).ObjectivesOur goal was to examine BD rates by exposure to THMs with a highly brominated fraction in metropolitan locations in Perth, Western Australia.MethodsWe collected water samples from 47 separate locations and analyzed them for total and individual THM concentrations (micrograms per liter), including separation into brominated forms. We classified collection areas by total THM (TTHM) concentration: low (< 60 μg/L), medium (> 60 to < 130 μg/L), and high (≥ 130 μg/L). We also obtained deidentified registry-based data on total births and BDs (2000–2004 inclusive) from post codes corresponding to water sample collection sites and used binomial logistic regression to compare the frequency of BDs aggregately and separately for the TTHM exposure groups, adjusting for maternal age and socioeconomic status.ResultsTotal THMs ranged from 36 to 190 μg/L. A high proportion of the THMs were brominated (on average, 92%). Women living in high-TTHM areas showed an increased risk of any BD [odds ratio (OR) = 1.22; 95% confidence interval (CI), 1.01–1.48] and for the major category of any cardiovascular BD (OR = 1.62; 95% CI, 1.04–2.51), compared with women living in low-TTHM areas.ConclusionsBrominated forms constituted the significant fraction of THMs in all areas. Small but statistically significant increases in risks of BDs were associated with residence in areas with high THMs.

Bromide removal by hydrotalcite-like compounds in a continuous system

Bromide ion removal from a real water matrix by hydrortalcite-like compounds (HTCs) was attempted in a column reactor to control the formation of brominated disinfection by-products in drinking water treatment process. The performance of HTCs was found to be comparable to a commercially available ion exchange resin for relatively low alkalinity water. Also, it was deduced that HTCs are better than ion exchange resins for high sulfate water because of their unique ion selectivity. In addition, the ion exchange reactions by HTCs were faster than a commercially available resin. Thus, HTCs are expected to provide similar performance to organic resins without the concern about secondary contamination (i.e., elution of organic compounds from resins).

DBPs formation and toxicity monitoring in different origin water treated by ozone and alum/PAC coagulation

In this study, aluminium sulphate (alum) and polyaluminum chloride (PAC) coagulation were used for coagulation of different origin water (Buyukcekmece, BC and Omerli, OM in Istanbul, Turkey and Carmine, CR in Salerno, Italy) treatment. The effect of pre-ozonation alone and combined with coagulation on NOM removal which was characterized by TOC, UV254 was investigated. DBPs formation and acute toxicity on Daphnia magna of chlorinated raw and treated samples were defined in parallel. Moreover, bromide spiking was evaluated for DBPs speciation. Optimum alum dose for TOC removal was found to be 40 mg/L for OM while 80 mg/L of alum exhibited the lowest total trihalomethane formation potential (TTHMFP). Pre-ozonation enhanced the removal of TOC and reduction of TTHMFP when it was used in combination with both coagulants. In contrast, total haloacetic acid formation potential (THAAFP) increased after each coagulation, ozonation and their combination. 300 µg/L bromide spiking (around the same level with BC) in raw sample collected from CR increased the formation of brominated disinfection byproducts. Raw and treated samples displayed acute toxicity on Daphnia magna in different pattern and practically “no dose-response behavior” was observed.

Chemometrics in monitoring spatial and temporal variations in drinking water quality

This case study reports multivariate techniques applied for the evaluation of temporal/spatial variations and interpretation of monitoring data obtained by the determination of chloro/bromo disinfection by-products in drinking water at 12 locations in the Gdańsk area (Poland), over the period 1993–2000. The complex data matrix (1756 observations) was treated with various multivariate techniques. Cluster analysis (CA) was successful, yielding two different groups of similarity reflecting different types of drinking water supplied (surface and groundwater). The locations supplied in general with groundwater could be further classified into two subgroups, depending on whether the groundwater was mixed with surface water or not. Analysis of variance (ANOVA) was used to classify and thus confirm the groups found by means of cluster analysis and proved the existence of statistically significant differences between the concentration levels of CHCl 3, CHBrCl 2+C 2HCl 3, CHBr 2Cl, and CH 2Cl 2 in the samples collected. Of all the variables evaluated, only three were characterized by statistically significant correlations (CHCl 3, CHBrCl 2+C 2HCl 3, CHBr 2Cl). The analysis of correlation coefficients revealed that chloroform formed as the main chlorinated disinfection by-product and, furthermore, the natural presence of bromide in water (both ground and surface) results in the formation of brominated disinfection by-products (DBPs). Temporal variations of volatile organic chlorinated compounds (VOCls) were also evaluated by multidimensional ANOVA. Observation of temporal changes in the concentration of VOCls at the location supplied with both surface and groundwater reveals a steady improvement in drinking water quality. In general, the study shows the importance of drinking water monitoring in connection with simple but powerful statistical tools to better understand spatial and temporal variations in water quality.

Contribution of brominated organic disinfection by-products to the mutagenicity of drinking water

The activity inducing chromosomal aberrations of the mixture of brominated disinfection by-products (DBPs) was approximately three times higher than that of the chlorinated counterparts for the same hypohalous acid dose. With the combination of chromosomal aberration test and a new analytical technique to differentiate total organic chlorine (TOCl) and total organic bromine (TOBr), it was found that TOBr was correlated to the mutagenicity of chlorinated waters. It was also implied that for a bromide-to-TOC ratio of 0.1 (mg/mg C), brominated DBPs could account for at least 29% of the total toxicity of DBPs formed during chlorination. On the other hand, bromate ion, a major ozonation DBP, was not a major contributor to the activity inducing chromosomal aberrations of the water treated with an ozone/chlorine sequential process. Therefore, ozonation is one possible option to reduce the health risk caused by DBPs even in the presence of bromide.

Application of back-propagation neural network modeling for free residual chlorine, total trihalomethanes and trihalomethanes speciation

The application of back-propagation neural networks (BPNNs) was assessed for modeling residual chlorine decay, total THM concentrations (TTHMs), and three individual THM species (CHCl3, CHBrCl2, and CHBr2Cl) in water that was chlorinated under laboratory-scale conditions. Data for modeling chlorine decay and TTHM were generated in chlorination experiments carried out with water collected in water utilities of the Quebec City region, whereas data for THM species were provided by the US Geological Survey for the Mississippi River and its tributaries. The BPNN models were compared with conventional models developed with exactly the same data. Results showed that the ability of BPNN to model residual chlorine decay is, in general terms, comparable to the ability of kinetic first- and second-order models. For TTHMs and THM speciation, however, the ability of BPNN was clearly higher in comparison with multivariate regression models, in particular when brominated disinfection by-products (DBPs) (CHBrCl2 and CHBr2Cl) were modeled. The successful application of BPNN presented in this study opens the door to other potential applications of BPNN for field-scale data concerning THMs as well as for other relevant disinfection by-products. Key words: back-propagation neural networks, drinking water, chlorination, residual chlorine decay, trihalomethanes, prediction.

MODELING DISSOLVED OZONE AND BROMATE ION FORMATION IN OZONE CONTACTORS

Many drinking water utilities that use source waters with significant bromide ion levels are currently seeking disinfection regimes that will minimize the formation of brominated disinfection byproducts while providing adequate disinfection. While ozonation appears to be a promising option for achieving these goals, the uncertainty of future drinking water regulations has developed a need for predicting actual disinfection byproduct formation prior to the costly investment for upgrading existing treatment facilities. The models developed in this paper provide comparisons of ozonation application methods, providing a basis for minimizing bromate and aiding in future design considerations. Theoretical and empirical models for the determination of ozone transferred, dissolved ozone concentrations, and bromate formation have been derived and compared with pilot-scale and full-scale data; a good agreement has been observed between the actual data and the predicted data, showing the validity of these models. True-batch bromate formation more closely simulated pilot-scale and full-scale data. Bromate formation in one stage vs two stage ozone contactors and different reactor configurations have been compared. Ozone gas phase concentration appears to have an effect on bromate formation as well.

The Effect of Bromide Ion on the Formation of Organohalogen Disinfection By-products During Ozonation

Abstract Ozonation of water containing bromide ion (Br−) leads to the formation of brominated disinfection byproducts (DBPs). The purpose of this study was to examine the influence of bromide ion upon the distribution and variation of organohalogen DBPs. Bromide ion concentration had a negative effect on chloroform formation as opposed to increased formation of brominated trihalomethanes (THMs). The results of factor analysis lead clearly to the interpretation that the bromide ion was strongly correlated with brominated THMs and less strongly with brominated HANs (haloacetonitriles). Compared to THMs and HANs, brominated HAAs (haloacetic acids) demonstrated a relatively weak correlation to bromide ion concentration. The addition of alkalinity enhanced the formation of chloroform when ozonation time was 10 to 30 minutes, while concentrations of other bromide ion-containing THMs decreased with increasing alkalinity.