Effects of bromide and iodide ions on the formation of disinfection by-products during ozonation and subsequent chlorination of water containing biological source matters

This study aims to investigate the influence of the coexistence of halogen ions (bromide/iodide) and biological source matters on the speciation and yield of trihalomethanes (THMs), haloacetic acids (HAAs), and N-nitrosodimethylamine (NDMA) during the ozonation and subsequent chlorination of water. The results show that the concentrations of brominated THMs and iodinated THMs increased with increasing bromide and iodide concentration. These results may be attributed to the higher reactivity of hypobromous acid and hypoiodous acid generated from the ozonation and subsequent chlorination in the presence of bromide or iodide ions. The presence of bromide increased the species of brominated HAAs. There was a shift from chlorinated HAAs to brominated HAAs after increasing the concentration of bromide. The effect of iodide on HAA formation was more complex than bromide. For most samples, the concentration of total HAAs (T-HAAs) increased to the maximum and then decreased with increasing iodide concentration. The components of the organic precursors also significantly influenced the formation of brominated and iodinated disinfection by-products (Br-DBPs and I-DBPs). Humic acids produced more CHBr₃ (596.60 μg/L) than other organic materials. Microcystis aeruginosa cells produced the most tribromoacetic acid (TBAA, 84.16 μg/L). Furthermore, the yield of NDMA decreased with increasing bromide concentration, indicating that the formation of NDMA was inhibited by the high concentration of bromide.     

Modeling the formation of chlorination by-products in river waters with different quality

Water chlorination results in formation of a variety of organic compounds, known as chlorination by-products (CBPs), mainly trihalomethanes (THMs) and haloacetic acids (HAAs). Factors affecting their concentrations have been found to be organic matter content of water, pH, temperature, chlorine dose, contact time and bromide concentration, but the mechanisms of their formation are still under investigation. Within this scope, chlorination experiments have been conducted with river waters from Lesvos island, Greece, with different water quality regarding bromide concentration and organic matter content. The factors studied were pH, time and chlorine dose. The determination of CBPs was carried out by gas chromatography techniques. Statistical analysis of the results was focused on the development of multiple regression models for predicting the concentrations of total trihalomethanes and total HAAs based on the use of pH, reaction time and chlorine dose. The developed models, although providing satisfactory estimations of the concentrations of the CBPs, showed lower correlation coefficients than the multiple regression models developed for THMs only during previous study. It seems that the different water quality characteristics of the two river waters in the present study is responsible for this phenomenon. The results indicate that under these conditions the formation of THMs and HAAs in water has a more stochastic character, which is difficult to be described by the conventional regression techniques.     

Occurrence of THMs and HAAs in experimental chlorinated waters of the Quebec City area (Canada)

Haloacetic acids (HAAs) and trihalomethanes (THMs) were generated in bench-scale chlorination experiments using treated waters (prior to final chlorination) of the three major drinking water utilities of the Quebec City area. The purpose was to investigate the formation and occurrence of these chlorination by-products (CBPs) on a seasonal basis. Data for HAAs, THMs and other physico-chemical parameters were produced through a six-month sampling program with variable conditions of water quality, water temperature, applied chlorine dose and reaction time. In waters from the three utilities, chloroform (THM specie), dichloroacetic and trichloroacetic acid (HAA species) were the most prevalent compounds due to the low concentrations of bromide in the utilities' raw waters. Significant differences in CBP occurrence were noted between the three utilities' chlorinated waters, mainly due to the type of disinfectant applied to raw water. The use of pre-ozonation, as opposed to pre-chlorination (or direct chlorination) in one of the utilities appears to be the major factor contributing to that utility's potential for compliance with current THM and future HAA standards. Seasonal variations in THMs and HAAs were mainly associated with variations in organic precursors and to changes in water temperature (two parameters which vary widely on a seasonal basis in surface waters of southern Quebec), with CBP occurrence at its highest in spring. Statistical correlations between HAAs and THMs were moderate and only temperature appeared to affect the preponderance of one CBP or the other. Finally, a regression analysis was carried out aimed at associating each CBP to water quality and the experimental parameters. Thanks to their predictive ability, multivariate models seem to be the tools with the best potential for decision-making purposes.     

Fate of disinfection by-products in groundwater during aquifer storage and recovery with reclaimed water

Knowledge on the behaviour of disinfection by-products (DBPs) during aquifer storage and recovery (ASR) is limited even though this can be an important consideration where recovered waters are used for potable purposes. A reclaimed water ASR trial in an anoxic aquifer in South Australia has provided some of the first quantitative information at field-scale on the fate and transport of trihalomethanes (THMs) and haloacetic acids (HAAs). The results revealed that THM half-lives varied from <1 to 65 days, with persistence of chloroform being highest and bromoform lowest. HAA attenuation was rapid (<1 day). Rates of THM attenuation were shown to be highly dependent on the geochemical environment as evidenced by the 2-5 fold reduction in half-lives at the ASR well which became methanogenic during the storage phase of the trial, as compared to an observation well situated 4 m away, which remained nitrate-reducing. These findings agree with previous laboratory-based studies which also show persistence declining with increased bromination of THMs and reducing redox conditions. Modelling suggests that the chlorinated injectant has sufficient residual chlorine and natural organic matter for substantial increases in THMs to occur within the aquifer, however this is masked in some of the field observations due to concurrent attenuation, particularly for the more rapidly attenuated brominated compounds. The model is based on data taken from water distribution systems and may not be representative for ASR since bromide and ammonia concentrations in the injected water and the possible role of organic carbon in the aquifer were not taken into consideration. During the storage phase DBP formation potentials were reduced as a result of the removal of precursor material despite an increase in the THM formation potential per unit weight of total organic carbon. This suggests that water quality improvements with respect to THMs and HAAs can be achieved through ASR in anoxic aquifers.     

Fate of disinfection by-products in groundwater during aquifer storage and recovery with reclaimed water

Knowledge on the behaviour of disinfection by-products (DBPs) during aquifer storage and recovery (ASR) is limited even though this can be an important consideration where recovered waters are used for potable purposes. A reclaimed water ASR trial in an anoxic aquifer in South Australia has provided some of the first quantitative information at field-scale on the fate and transport of trihalomethanes (THMs) and haloacetic acids (HAAs). The results revealed that THM half-lives varied from <1 to 65 days, with persistence of chloroform being highest and bromoform lowest. HAA attenuation was rapid (<1 day). Rates of THM attenuation were shown to be highly dependent on the geochemical environment as evidenced by the 2-5 fold reduction in half-lives at the ASR well which became methanogenic during the storage phase of the trial, as compared to an observation well situated 4 m away, which remained nitrate-reducing. These findings agree with previous laboratory-based studies which also show persistence declining with increased bromination of THMs and reducing redox conditions. Modelling suggests that the chlorinated injectant has sufficient residual chlorine and natural organic matter for substantial increases in THMs to occur within the aquifer, however this is masked in some of the field observations due to concurrent attenuation, particularly for the more rapidly attenuated brominated compounds. The model is based on data taken from water distribution systems and may not be representative for ASR since bromide and ammonia concentrations in the injected water and the possible role of organic carbon in the aquifer were not taken into consideration. During the storage phase DBP formation potentials were reduced as a result of the removal of precursor material despite an increase in the THM formation potential per unit weight of total organic carbon. This suggests that water quality improvements with respect to THMs and HAAs can be achieved through ASR in anoxic aquifers.     

Formation of halogenated acetaldehydes, and occurrence in Canadian drinking water

Controlled laboratory chlorination of acetaldehyde (ACD) under typical drinking water conditions (pH 6.7, 7.6 and 8.8, and temperature 4 degrees C and 21 degrees C) revealed that the formation of chloral hydrate (CH), the most common halogenated acetaldehyde (HAs), increased with contact time (0-10 days). However, at increased pH and temperature, CH reached maximum levels and subsequently broke down partially to chloroform and other unidentified compounds. After 10 days contact time, a maximum of 63% (molar) of the initial ACD consumed were converted into CH or chloroform (TCM). Various surveys of drinking water systems indicated that ACD is not the only precursor of CH. A suite of aldehydes (including ACD), and chlorinated disinfection by-products (including TCM and CH) were found in most distribution systems. The levels of bromide in source water impacted speciation of HAs. In addition to CH, brominated and other mixed (Cl/Br) acetaldehydes were detected in most samples; the speciation of HAs and THMs followed comparable trends. Similar to chloroform for trihalomethanes, CH contributed from as low as 5% to up to 60% of the total HAs. The bromine incorporation factors (BIF) in THMs and HAs were shown to increase with increasing bromide ion concentrations in the source water. Brominated THMs are more readily formed than their HA analogues; in fact, BIF values for THMs were 2-3 times higher than for the HAs. It was found that HAs may be as high as THMs in some drinking waters. As a result, the determination of the other target HAs, in addition to CH, is necessary for a better assessment of the pool of disinfection by-products in drinking water.     

Spatial and Seasonal Variations of Disinfection Byproducts (DBPs) in Drinking Water Distribution Systems of Istanbul City,Turkey

This study presents the seasonal and spatial variations of trihalomethanes (THMs) and haloacetic acids (HAAs) in 30 sampling points within three water distribution systems of Istanbul City, Turkey. The effects of surface water quality, seasonal variation, and species differences were examined. The occurrence of chlorinated THMs and HAAs levels was considerably lower in the system in which raw water is subjected to pre-ozonation versus pre-chlorination. Seasonal analysis of the data indicated that the median concentration of four THMs (THM₄) was higher than nine HAAs (HAA₉) concentrations in all three distribution systems sampling points. For all distribution systems monitored, the highest median THM₄ and HAA₉ concentrations were observed in the spring and summer season, while the lowest concentrations of these disinfection byproduct (DBP) compounds were obtained in the fall and winter period. Due to the higher level of bromide in supplying waters of these two systems, moderate levels of brominated DBP species have been observed in the Kagithane and Buyukcekmece distribution systems districts. In fact, Spearman partial correlations (Spearman rank correlation coefficients [rs]) tend to be higher among analogues in terms of number and types of substituent, especially TCAA with TCM (rs 0.91), and DBAA with DBCM (rs 0.90). In contrast, the hydraulic (residence time and flow rate) and chemical mechanisms (hydrolysis, volatilization, and adsorption) affect the fate and transport of DBPs in distribution systems. Seasonal and spatial variations of DBPs presented in this study have important implications on regulatory issues and from an epidemiological point of view.     

Modeling and optimization of trihalomethanes formation potential of surface water (a drinking water source) using Box–Behnken design

Purpose  

The present research aims to investigate the individual and interactive effects of chlorine dose/dissolved organic carbon ratio, pH, temperature, bromide concentration, and reaction time on trihalomethanes (THMs) formation in surface water (a drinking water source) during disinfection by chlorination in a prototype laboratory-scale simulation and to develop a model for the prediction and optimization of THMs levels in chlorinated water for their effective control.     

The occurrence of disinfection by-products in the drinking water of Athens,Greece

Application of chlorination for the disinfection of drinking water results in the formation of a wide range of organic compounds, called disinfection by-products (DBPs), which occur due to the reaction of chlorine with natural organic materials. The occurrence of DBPs was studied in samples from four drinking-water treatment plants (WTPs) and from the distribution network of Athens, Greece. Twenty-four compounds, which belong to different categories of DBPs, were monitored, including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), haloketones (HAKs), chloral hydrate (CH) and chloropicrin (CP). Sampling was performed monthly for a period of two years, from three different points at each WTP and from eight points atthe distribution network. Samples were analyzed by GC-ECD methods, which included pretreatment with liquid-liquid extraction for volatile DBPs and acidic methanol esterification for HAAs. The results of the analyses have shown the presence of disinfection by-products belonging to all categories studied in all water samples collected after prechlorination. The major categories of DBPs detected were THMs and HAAs, while the other volatile DBPs occurred at lower concentrations. The concentrations of DBPs did not in any case exceed the maximum contaminant levels (MCL) set by USEPA and WHO. However, monitoring these compounds needs to be continued, because their levels could increase due to changes in the quality of water entering the water treatment plants. Reduction of the concentrations of DBPs could be achieved by optimization of the chlorination conditions, taking into account the effect of time. Moreover, research on alternative disinfection methods (e.g. ozone, chlorine dioxide, chloramines) and their by-products should be conducted to evaluate their applicability in the case of the drinking water of Greece.     

河流型水源地源水典型氯化消毒副产物及其前体物的强化去除工艺

以长三角某典型河流型水源地源水为研究对象,设计了传统工艺及基于凹凸棒土处理单元的6种强化工艺,对各工艺及其处理单元应用于典型氯化消毒副产物(三卤甲烷和卤乙酸)及其前体物控制的技术和经济可行性进行了系统分析。结果表明,预O3+凹土强化混凝+O3-GAC强化的工艺对上述2种消毒副产物及其前体物的控制效果最佳;在传统工艺中单纯增加O3处理也能在一定程度上提高其对消毒副产物前体物的去除效果;KMnO4控制消毒副产物的效果一般,但KMnO4处理可强化后续单元对消毒副产物前体物的去除效果。各工艺处理出水中三卤甲烷和卤乙酸单项指标均能达标,但传统工艺和经凹土强化混凝+GAC强化的工艺出水三卤甲烷4种化合物的实测浓度与其各自限值的比值之和均大于1.0,不能满足水质要求,必须进行强化处理。凹土强化混凝单元在6种强化工艺条件下对三卤甲烷生成潜能(THMFP)和卤乙酸生成潜能(HAAFP)的去除率较传统混凝单元平均提高15.99%和4.92%;各强化工艺对THMFP和HAAFP的去除率较传统工艺均提高20%以上(除凹土强化混凝+GAC强化的工艺外),消毒副产物产生量降低40%以上,工艺成本降低20%以上。     

The effects of pH, bromide and nitrite on halonitromethane and trihalomethane formation from amino acids and amino sugars

In this study, the effects of pH, bromide and nitrite on the formation of halonitromethanes (HNMs) and trihalomethanes (THMs) from eight amino acids (glycine, alanine, serine, cysteine, aspartic acid, glutamic acid, lysine and histidine) and four amino sugars (glucosamine, galactosamine, N-acetylglucosamine and N-acetylneuraminic acid) were examined for chlorination and ozonation followed by chlorination. During ozonation-chlorination, two amino acids, glycine and lysine, exhibited distinctly higher HNM formation than the other compounds. The formation of HNMs was higher at pH 8 than 6. Glycine and lysine also produced higher levels of THMs than the other compounds at pH 8. The presence of nitrite resulted in an increase in HNM formation. The presence of bromide increased the HNM formation, especially brominated HNM species. Bromine incorporation factors of trihalogenated HNMs were higher than those of THMs. For chlorination alone, HNM levels were about the detection limit (4 nM or 0.7 μg L⁻¹) at pH 6 and 8, and in the presence of bromide or nitrite. Amino acids and amino sugars tested, except glycine and lysine, showed relatively low levels of THM (∼15 μg L⁻¹) formation.     

Occurrence and formation of trihalomethanes in marine aquaria studied using solid-phase microextraction gas chromatography-mass spectrometry

The occurrence and formation of chlorinated and brominated trihalomethanes (THMs) were studied in artificial saltwater and natural seawater marine aquaria as well as in groundwater and surface waters. A new headspace solid-phase microextraction method was used, which included gas chromatography-mass spectrometry and provided method detection limits of less than 0.1 microg/L, with a signal-to-noise ratio of 3 to 5. The results showed that disinfection by using either chlorine or ozone caused a significant formation of THMs in situ. Speciation of the THMs was a strong function of the water matrix, with initial bromide concentrations playing a pivotal role. These results provide a tool for understanding and monitoring the formation of key disinfection byproducts in marine aquaria that may cause respiratory, eye irritation, or other health concerns.     

Particles in swimming pool filters--does pH determine the DBP formation?

The formation was investigated for different groups of disinfection byproducts (DBPs) during chlorination of filter particles from swimming pools at different pH-values and the toxicity was estimated. Specifically, the formation of the DBP group trihalomethanes (THMs), which is regulated in many countries, and the non-regulated haloacetic acids (HAAs) and haloacetonitriles (HANs) were investigated at 6.0≤pH≤8.0, under controlled chlorination conditions. The investigated particles were collected from a hot tub with a drum micro filter. In two series of experiments with either constant initial active or initial free chlorine concentrations the particles were chlorinated at different pH-values in the relevant range for swimming pools. THM and HAA formations were reduced by decreasing pH while HAN formation increased with decreasing pH. Based on the organic content the relative DBP formation from the particles was higher than previously reported for body fluid analogue and filling water. The genotoxicity and cytotoxicity estimated from formation of DBPs from the treated particle suspension increased with decreasing pH. Among the quantified DBP groups the HANs were responsible for the majority of the toxicity from the measured DBPs.     

UV-H2O2 based AOP and its integration with biological activated carbon treatment for DBP reduction in drinking water

The presence of disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs) in drinking water is of great concern due to their adverse effects on human health. Emerging regulation limiting the concentration of DBPs in drinking water has increased demands for technologies and processes which reduce the formation of DBPs in drinking water. In this study, UV-H₂O₂ based advance oxidation process (AOP) was used to treat raw surface water. Experiments were conducted using low pressure mercury vapor UV lamps in collimated beam and flow-through annular photoreactors. The effect of UV fluence (0–3500 mJ cm⁻²) and hydrogen peroxide concentration (0–23 mg l⁻¹) in reducing the concentration of THMs and HAAs was examined. The UV-H₂O₂ AOP was then coupled with a downstream biological activated carbon (BAC) treatment to assess the synergetic benefits of combining the two treatments. It was observed that UV-H₂O₂ AOP was only effective at reducing DBPs at UV fluences of more than 1000 mJ cm⁻²and initial H₂O₂ concentrations of about or greater than 23 mg l⁻¹. However, the combined AOP–BAC treatment showed significant reductions of 43%, 52%, and 59% relative to untreated raw water for DBPs, TOC, and UV₂₅₄, respectively.     

水体中卤乙酸（HAAs）的产生、测定方法与控制途径

对饮用水中普遍存在的消毒副产物形式HAAs的产生、测定方法以及控制途径进行了阐述。并对影响HAAs生成的主要因素投氯量、溴的影响以及卤乙酸副产物（HAAFP）含量等进行了分析。生物活性炭技术是一种非常有效的控制HAAs含量和减少HAAFP含量的方法，对于保障饮用水安全性具有重要意义。     

水体中卤乙酸(HAAs)的产生、测定方法与控制途径

对饮用水中普遍存在的消毒副产物形式HAAs的产生、测定方法以及控制途径进行了阐述.并对影响HAAs生成的主要因素投氯量、溴的影响以及卤乙酸副产物(HAAFP)含量等进行了分析.生物活性炭技术是一种非常有效的控制HAAs含量和减少HAAFP含量的方法,对于保障饮用水安全性具有重要意义.     

Novel insights in Al-MCM-41 precursor as adsorbent for regulated haloacetic acids and nitrate from water

High concentration of NO ₃ ^? in groundwater has raised concern over possible contamination of drinking water supplies. In addition, the formation of haloacetic acids (HAAs) as by-products during disinfection with chlorine-based agents is still a relevant issue, since HAAs pose serious health hazard. In this work, we investigated the affinity of a precursor of Al-MCM-41 (a mesostructured hexagonal aluminosilicate containing the template surfactant) towards nitrate and HAAs, for its possible application in the removal of these pollutants from natural and drinking waters. Additionally, adsorption kinetics and isotherms were studied. The adsorbent was synthesized using cetyltrimethylammonium bromide as surfactant and characterized by physico?Cchemical techniques. Simulated drinking water was spiked with the EPA-regulated HAAs (monochloroacetic (MCAA), monobromoacetic (MBAA), dichloroacetic (DCAA), dibromoacetic (DBAA), and trichloroacetic (TCAA) acids) and placed in contact with the adsorbent. The effect of matrix composition was studied. Adsorption kinetic studies were performed testing three kinetics models. For the adsorption studies, three adsorption isotherm approaches have been tested to experimental data. The pollutant recoveries were evaluated by suppressed ion chromatography. The affinity of the adsorbent was TCAA = DBAA = DCAA > MBAA > MCAA with DCAA, DBAA, and TCAA completely removed. A removal as high as 77?% was achieved for 13?mg/L nitrate. The adsorption isotherms of NO ₃ ^? and monochloroacetic acid can be modeled by the Freundlich equation, while their adsorption kinetics follow a pseudo-second-order rate mechanism. The adsorbent exhibited high affinity towards HAAs in simulated drinking water even at relevant matrix concentrations, suggesting its potential application for water remediation technologies.     

Minimization of the formation of disinfection by-products

The drinking water industry is required to minimize DBPs levels while ensuring adequate disinfection. In this study, efficient and appropriate treatment scheme for the reduction of disinfection by-product (DBPs) formation in drinking water containing natural organic matter has been established. This was carried out by the investigation of different treatment schemes consisting of enhanced coagulation, sedimentation, disinfection by using chlorine dioxide/ozone, filtration by sand filter, or granular activated carbon (GAC). Bench scale treatment schemes were applied on actual samples from different selected sites to identify the best conditions for the treatment of water. Samples were collected from effluent of each step in the treatment train in order to analyze pH, UV absorbance at 254 nm (UVA₂₅₄), specific UV absorbance at 254 nm (SUVA₂₅₄), dissolved organic carbon (DOC), haloacetic acids (HAAs) and trihalomethanes (THMs). The obtained results indicated that using pre-ozonation/enhanced coagulation/activated carbon filtration treatment train appears to be the most effective method for reducing DBPs precursors in drinking water treatment.     

Transformation of effluent organic matter during subsurface wetland treatment in the Sonoran Desert

The fate of dissolved organic matter (DOM) during subsurface wetland treatment of wastewater effluent in a hot, semi-arid environment was examined. The study objectives were to (1) discern changes in the character of dissolved organics as consequence of wetland treatment (2) establish the nature of wetland-derived organic matter, and (3) investigate the impact of wetland treatment on the formation potential of trihalomethanes (THMs). Subsurface wetland treatment produced little change in DOM polarity (hydrophobic-hydrophilic) distribution. Biodegradation of labile effluent organic matter (EfOM) and internal loading of wetland-derived natural organic matter (NOM) together produced only minor changes in the distribution of carbon moieties in hydrophobic acid (HPO-A) and transphilic acid (TPI-A) isolates of wetland effluent. Aliphatic carbon decreased as a percentage of total carbon during wetland treatment. The ratio of atomic C:N in wetland-derived NOM suggests that its character is determined by microbial activity. Formation of THMs upon chlorination of HPO-A and TPI-A isolates increased as a consequence of wetland treatment. Wetland-derived NOM was more reactive in forming THMs and less biodegradable than EfOM. For both HPO-A and TPI-A fractions, relationships between biodegradability and THM formation potential were similar among EfOM and NOM isolates; the less biodegradable isolates exhibited greater THM formation potential.     

Effects of copper(II) and copper oxides on THMs formation in copper pipe

Little is known about how the growth of trihalomethanes (THMs) in drinking water is affected in copper pipe. The formation of THMs and chlorine consumption in copper pipe under stagnant flow conditions were investigated. Experiments for the same water held in glass bottles were performed for comparison. Results showed that although THMs levels firstly increased in the presence of chlorine in copper pipe, faster decay of chlorine as compared to the glass bottle affected the rate of THMs formation. The analysis of water phase was supplemented by surface analysis of corrosion scales using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX). The results showed the scales on the pipe surface mainly consisted of Cu₂O, CuO and Cu(OH)₂ or CuCO₃. Designed experiments confirmed that the fast depletion of chlorine in copper pipe was mainly due to effect of Cu₂O, CuO in corrosion scales on copper pipe. Although copper(II) and copper oxides showed effect on THMs formation, the rapid consumption of chlorine due to copper oxide made THM levels lower than that in glass bottles after 4 h. The transformations of CF, DCBM and CDBM to BF were accelerated in the presence of copper(II), cupric oxide and cuprous oxide. The effect of pH on THMs formation was influenced by effect of pH on corrosion of copper pipe. When pH was below 7, THMs levels in copper pipe was higher as compared to glass bottle, but lower when pH was above 7.