Total Haloacetic Acids Research Articles

Comparison of chlorine and chlorine dioxide disinfection in drinking water: Evaluation of disinfection byproduct formation under equal disinfection efficiency

Disinfection efficiency and disinfection byproduct (DBP) formation are two important aspects deserving careful consideration when evaluating different disinfection protocols. However, most of the previous studies on the selection of disinfection methods by comparing DBP formation were carried out under the same initial/residual dose and contact time of different disinfectants, and such a practice may cause overdose or underdose of a certain disinfectant, leading to the inaccurate evaluation of disinfection. In this study, a comprehensive and quantitative comparison of chlorine (Cl2) and chlorine dioxide (ClO2) disinfection was conducted with regard to their DBP formation under equal disinfection efficiency. The microbial inactivation models as well as the Cl2 and ClO2 demand models were developed. On such basis, the integral CT (ICT) values were determined and used as a bridge to connect disinfection efficiency and DBP formation. For 3-log10 and 4-log10 reductions of Pseudomonas aeruginosa, ClO2 had 1.5 and 5.8 times higher inactivation ability than Cl2, respectively. In the premise of equal disinfection efficiency (i.e., the ICT ratios of Cl2 to ClO2 = 1.5 and 5.8), the levels of total organic chlorine, total organic bromine, and total organic halogen formed in the Cl2 disinfection were significantly higher than those formed in the ClO2 disinfection. Among the 35 target aliphatic DBPs, trihalomethanes (THMs) and haloacetic acids (HAAs) were the dominant species formed in both Cl2 and ClO2 disinfection. The total THM levels formed in Cl2 disinfection were 14.6 and 30.3 times higher than those in ClO2 disinfection, respectively. The total HAA levels formed in Cl2 disinfection were 3.5 and 5.4 times higher than those in ClO2 disinfection, respectively. Formation of the target 48 aromatic DBPs was much favored in Cl2 disinfection than that in ClO2 disinfection, and the formation levels was dominated by contact time. This study demonstrated that ClO2 had significant advantages over Cl2, especially at higher microorganism inactivation and lower DBP formation requirements.

Leaching of organic matter from microplastics and its role in disinfection by-product formation

Natural organic matter (NOM) is the primary precursor of disinfection by-products (DBPs). However, as emerging environmental contaminants continue to increase in natural waters, there is a possibility of new precursors of DBPs. We investigated the potential of microplastics (MPs), a growing environmental concern, for leaching organic matter (OM) and subsequent DBP formation. Two experimental setups were used, including chlorinated water containing MPs (Cl2-MP), and non-chlorinated water containing MPs (Non-Cl2-MP), using polyethylene (PE), polyethylene tetrahydrate (PET), polypropylene (PP), and polyvinyl chloride (PVC) as MP materials. The UV absorbance spectra of Cl2-PET/PP/PVC showed peaks at 218 nm, which were significantly correlated with dissolved organic carbon (DOC), indicating lower aromaticity of the leached OM. The DOC concentrations in Cl2-MP samples were several times higher than those in Non-Cl2-MP samples. The leached OM from MPs formed trihalomethanes (THMs) and haloacetic acids (HAAs) in Cl2-MP samples. Among the MPs tested, PVC showed the highest total THM formation after 7 days, followed by PET, PE, and PP. Brominated THMs were predominant, while HAAs were highly chlorinated. THM formation increased with contact time for PE, PET, and PVC, and decreased for PP. Compared to THMs, the concentration of HAAs was low (highest total THM = 185.5 μg/L per g-MP and highest total HAA = 120.7 μg/L per g-MP). Further, the total THM concentration decreased and the total HAA concentration increased over the reaction period, indicating the leaching of different types of OM with increasing contact time. Additionally, the differences in the pattern of DOC leaching and DBP formation among different MPs suggested changes in the leached OM.

Temporal and spatial variations of disinfection by-products in South Taihu's drinking water, Zhejiang Province, China.

Some disinfection by-products (DBPs) in drinking water present a potential safety concern. This study focuses on the elements influencing DBPs formation. A total of 120 water samples were collected from 10 different drinking water facilities spanning 5 counties within Huzhou, Zhejiang Province, China. Concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs) were observed to be 14.5 and 27.4 μg/L, respectively, constituting 34 and 64% of the total DBPs. Seasonal fluctuations demonstrated that HAAs, THMs, halonitromethanes (HNMs), and haloacetonitriles (HANs) followed a similar pattern with higher levels in summer or autumn compared to spring. Importantly, the concentrations of HAAs and THMs were markedly higher in Taihu-sourced water compared to other sources. Geographically, Nanxun exhibited the highest levels of total DBPs, HAAs, and THMs, while Deqing and Changxing demonstrated significantly lower levels. Correlation studies between water quality parameters and DBPs revealed that factors such as chloride content, temperature, and residual chlorine positively influenced DBPs formation, whereas turbidity negatively affected it. Principal component analysis suggested similar formation processes for HANs, haloketones (HKs), HNMs, and THMs. Factors such as temperature, chemical oxygen demand (COD), and residual chlorine were identified as significant contributors to the prevalence of HAAs.

An overlooked crystallization effect during the O3 participated coagulation improves the performance of dual-membrane process

Till now, the transformation of amorphous flocs formed during the hydrolysis stage of coagulation has not been fully addressed. In this work, by using a conventional coagulant (alum), the transformation process was explored by observing the interactions between O3 and the amorphous alum flocs formed during flocculation at neutral pH. It was found that O3 promoted the transition of the in-situ formed alum flocs from tetrahedral Al (Al(O)4) to octahedral Al (Al(O)6) structures, through an accelerated dehydroxylation process, and therefore facilitated the crystallization process to form boehmite. During this process, the surface functional groups of amorphous Al flocs (Al–H2O and Al–OH) were observed to take part in the O3 catalytic oxidation with the generation of hydroxyl radicals (OH). This synergistic effect significantly favored the performance of the subsequent dual-membrane (UF-NF) process in terms of both fouling alleviation (1.78 and 1.60 times higher flux of UF and NF, respectively) and final effluent quality improvement, including the reduction in disinfection byproduct (DBP) formation potential (48.1% and 22.4% lower generation of total trihalomethanes and total haloacetic acid, respectively) and the corresponding calculated toxicity. The results obtained here provide a greater understanding of the transformation of amorphous Al flocs formed during flocculation with O3, and valuable information regarding its practical application in membrane filtration process with greater treatment performance.

The Occurrence of Haloacetic Acids and Dalapon in Bottled Waters and an Assessment of Their Health Risk

While disinfection ensures the destruction of pathogenic microorganisms, the disinfectant substances used react with some organic and inorganic substances in water, causing the formation of disinfection by-products. Some disinfection by-products have been classified as carcinogenic by the Environmental Protection Agency (EPA). Haloacetic acids are one of the disinfection by-product groups that have been detected in drinking water and are carcinogenic. It is commonly believed that bottled water, which is being increasingly consumed worldwide, does not contain environmental pollutants. For this reason, research on bottled water is limited. In this study, the amount of 9 haloacetic acids and dalapon were investigated in 28 different branded bottled water samples collected from a market. As a result of the study, the total haloacetic acid concentrations were found to be from 2.13 to 7.56 μg/L, and the dalapon concentration was < detection limit-12.47 μg/L. At least three different haloacetic acids were detected in each sample analyzed. It was determined that the threshold values given by the EPA and the World Health Organization (WHO) were not exceeded. It has been observed that bottled waters, which are generally considered to be of higher quality than mains water, contain haloacetic acids and dalapon at low concentrations. A health risk assessment was performed for dalapon and trichloroacetic acid (TCAA). A low non-carcinogenic risk and tolerable carcinogenic risk were determined. Care should be taken to counter the negative health effects of HAAs and dalapon.

Impacts of water hardness on coagulation-UF-NF process using aluminum salts

Surface water supplemented with reclaimed water can effectively alleviate water shortage. In this study, an integrated coagulation ultrafiltration-nanofiltration (CUF-NF) process was explored to treat reclaimed water. The effects of water hardness and different aluminum salts on the CUF-NF process were specifically investigated focusing the flocs size, membrane fouling, removal of organic matter, and disinfection by-product formation potential (DBPs-FP). Moreover, the treatment performance of two coagulants (i.e., AlCl3 and PACl25) were also compared. Results showed that the increased water hardness remarkably improved the UF membrane flux in CUF process (i.e., 51.4% to 188.3%), however, a slightly reduced flux (up to 29.5%) was noticed for NF membrane. In addition, parallel factor (PARAFAC) analysis showed that higher water hardness contributed to higher removal efficiencies of humic- (up to 40.6%) and protein-like substances (up to 60.6%), together with the reduction of total DBPs-FP (i.e., total trihalomethanes; 52.6% and total haloacetic acids; 20.4%). Furthermore, 2D-COS-FTIR also revealed the correlation between water hardness and the functional groups in UF/NF fouling layers. Overall, this work not only provides insight into the impacts of water hardness and different aluminum salts on CUF-NF processes treating surface water, but also provides new insights into the formulation of hardness standards for reclaimed water.

Exploring impacts of water-extractable organic matter on pre-ozonation followed by nanofiltration process: Insights from pH variations on DBPs formation

This study investigated the influence of pH (4–10) on the treatment of water-extractable organic matter (WEOM), and the associated disinfection by-products (DBPs) formation potential (FP), during the pre-ozonation/nanofiltration treatment process. At alkaline pH (9–10), a rapid decline in water flux (> 50 %) and higher membrane rejection was observed, as a consequence of the increased electrostatic repulsion forces between the membrane surface and organic species. Parallel factor analysis (PARAFAC) modeling and size exclusion chromatography (SEC) provides detailed insights into the WEOM compositional behavior at different pH levels. Ozonation at higher pH significantly reduced the apparent molecular weight (MW) of WEOM in the 4000–7000 Da range by transforming the large MW (humic-like) substances into small hydrophilic fractions. Fluorescence components C1 (humic-like) and C2 (fulvic-like) exhibited a predominant increase/decrease in concentration for all pH conditions during pre-ozonation and nanofiltration treatment process, however, the C3 (protein-like) component was found highly associated with the reversible and irreversible membrane foulants. The ratio C1/C2 provided a strong correlation with the formation of total trihalomethanes (THMs) (R2 = 0.9277) and total haloacetic acids (HAAs) (R2 = 0.5796). The formation potential of THMs increased, and HAAs decreased, with the increase of feed water pH. Ozonation markedly reduced the formation of THMs by up to 40 % at higher pH levels, but increased the formation of brominated-HAAs by shifting the formation potential of DBPs towards brominated precursors.

Characteristic and Relative Environmental Risk of Disinfection by Products Associated with Simple Glucose or Naturally Occurring Algal Organic Matter as Tested in Ballast Water Treatment System

To prevent the invasion of alien species, the International Maritime Organization and the United States Costal Guard require that a ballast water management system (BWMS) be installed on ships to treat the ballast water before discharging it. BWMS technologies use active substances, which create disinfection by-products (DBPs) during ballast water treatment. This study compared the characteristics of DBPs generated in the treatment of commercial glucose with those of algal organic matter (AOM) derived from field-collected phytoplankton using NaOCl as the active substance. During the treatment of AOM, a greater variety and higher concentrations of DBPs were generated than for glucose. For AOM in freshwater, bromoform and dibromoacetic acid were dominant because of the bromine ions present in the phytoplankton. During the treatment of glucose, the ratio of the predicted environmental concentration to the predicted no-effect concentration of dibromoacetonitrile and chloropicrin exceeded 1, indicating a potential environmental risk. Whole effluent toxicity (WET) testing showed that the chronic toxicity of phytoplankton and the total DBP concentration were highest in marine water with AOM. In addition, the results of WET testing suggested that the concentrations of haloacetic acids (HAAs) and haloacetonitriles (HANs) were important indicators for the evaluation of environmental risk. Therefore, to evaluate the risk of DBPs in international ports where phytoplankton outbreaks frequently occur, it is important to monitor not only the total DBP concentration but also the total HAA and HAN concentrations.

Disability-Adjusted Life Year Frameworks for Comparing Health Impacts Associated with Mycobacterium avium, Trihalomethanes, and Haloacetic Acids in a Building Plumbing System

To address trade-offs, prioritize, and manage the risks between microbial and chemical risks, the disability-adjusted life year (DALY) approach was utilized. The sampling data from cold and hot water building plumbing in Philadelphia, PA, revealed three classes of health stressors, nontuberculous mycobacteria, total trihalomethanes (THMs), and total haloacetic acids (HAAs). The concentration data specific to the water system were then used to estimate the annual risk due to the Mycobacterium avium complex (MAC), THMs, and HAAs. The results from this study suggest that efforts to reduce the potential health risks from disinfection byproducts should still be given due consideration as the annual DALY of bladder cancer (7.61*10–7) was estimated to be greater than the annual DALY of MAC pulmonary disease (4.74*10–12) by 5 orders of magnitude. The DALYs of both THMs (2.62*10–6) and HAAs (2.60*10–6) in buildings via the ingestion exposure route were higher than the reported threshold of 1 μDALY. Relative to the feed water, water quality changes in the building plumbing substantially increased the DALY impacts for microbial risks but modestly decreased the DALY impacts for chemical risks. While the results are specific to the system considered (e.g., chloramine disinfectant, no detectable Legionella), the study presents a framework for prioritizing among building plumbing microbial and chemical risks.

Application of convolutional neural networks for prediction of disinfection by-products

Fluorescence spectroscopy can provide high-level chemical characterization and quantification that is suitable for use in online process monitoring and control. However, the high-dimensionality of excitation–emission matrices and superposition of underlying signals is a major challenge to implementation. Herein the use of Convolutional Neural Networks (CNNs) is investigated to interpret fluorescence spectra and predict the formation of disinfection by-products during drinking water treatment. Using deep CNNs, mean absolute prediction error on a test set of data for total trihalomethanes, total haloacetic acids, and the major individual species were all < 6 µg/L and represent a significant difference improved by 39–62% compared to multi-layer perceptron type networks. Heat maps that identify spectral areas of importance for prediction showed unique humic-like and protein-like regions for individual disinfection by-product species that can be used to validate models and provide insight into precursor characteristics. The use of fluorescence spectroscopy coupled with deep CNNs shows promise to be used for rapid estimation of DBP formation potentials without the need for extensive data pre-processing or dimensionality reduction. Knowledge of DBP formation potentials in near real-time can enable tighter treatment controls and management efforts to minimize the exposure of the public to DBPs.

Wildfires can increase regulated nitrate, arsenic, and disinfection byproduct violations and concentrations in public drinking water supplies

Wildfires are a concern for water quality in the United States, particularly in the wildland-urban interface of populous areas. Wildfires combust vegetation and surface soil organic matter, reduce plant nutrient uptake, and can alter the composition of runoff and receiving waters. At the wildland-urban interface, fires can also introduce contaminants from the combustion of man-made structures. We examine post-wildfire effects on drinking water quality by evaluating concentrations and maximum contaminant level (MCL) violations of selected contaminants regulated in the U.S. at public drinking water systems (PWSs) located downstream from wildfire events. Among contaminants regulated under the U.S. Safe Drinking Water Act, nitrate, arsenic, disinfection byproducts, and volatile organic compounds (VOCs) were analyzed in watersheds that experienced major wildfires. Surface water sourced drinking water (SWDW) nitrate violations increased by an average of 0.56 violations per PWS and concentrations increased by 0.044 mg-N/L post-wildfire. Groundwater sourced drinking water (GWDW) nitrate violations increased by 0.069 violations per PWS and concentrations increased by 0.12 mg-N/L post-wildfire. SWDW total trihalomethane (TTHM) violations increased by 0.58 violations per PWS and concentrations increased by 10.4 μg/L. SWDW total haloacetic acid (HAA5) violations increased by 0.82 violations per PWS and concentrations increased by 8.5 μg/L. Arsenic violations increased by 1.08 violations per PWS and concentrations increased by 0.92 μg/L. There was no significant effect of wildfires on average VOC violations. Nitrate violations increased in 75% of SWDW sites and 34% of GWDW sites post-wildfire, while about 71% and 50% of SWDW sites showed an increase in TTHM and HAA5 violations. Violations also increased for 35% of arsenic and 44% of VOC sites post-wildfire. These findings support the need for increased awareness about the impact of wildfires on drinking water treatment to help PWS operators adapt to the consequences of wildfires on source water quality, particularly in wildfire-prone regions.

Evaluation of multiple disinfection by-products in tap, filtered and bottled water in Barcelona, Spain

BACKGROUND AND AIM: The formation of disinfection by-products (DBPs) as an unintended consequence of drinking water potabilization is a current global concern due to their potential relation to chronic diseases. With the aim of assessing human exposure to DBPs in drinking water, we quantified 4 trihalomethanes (THMs), 11 haloacetic acids (HAAs), 4 haloacetonitriles (HANs), chlorate, chlorite, 1,1-dichloropropanone (DCP), 1,1,1-trichloropropanone (TCP) and chloropicrin, in different drinking water types in Barcelona, Spain. METHODS: DBPs and physicochemical parameters such as conductivity and total organic carbon (TOC), were measured in tap water samples collected at 42 households, and in tap water filtered with activated carbon (AC) (N=6) and reverse osmosis (RO) (N=5). Selected DBPs were also analyzed in 10 popular bottled water brands. RESULTS:All tap water samples contained THMs and HANs, and 98% contained HAAs and chlorate above the limit of quantification (LOQ). Chlorite and TCP were found in 62 and 36% of the tap water samples, respectively, while DCP and chloropicrin were not detected. The median and interquartile range of total THMs, HAAs, HANs, and chlorate in tap water, calculated using values LOQ, were 42.0 (37.5-48.5), 18.0 (10.5-30.3), 3.2 (2.6-3.9), and 214 (159-296) µg/L, respectively. Conductivity was negatively correlated with bromodichloromethane (R=-0.91), TOC (R=-0.83), total HAAs (R=-0.82), dichloroacetonitrile (R=-0.78), TCP (R=-0.75), chlorite (R=-0.70), and positively correlated with the bromine incorporation factor (BIF) of THMs (R=0.82), DXAA (R=0.66), and TXAA (R=0.65) (X=Br/Cl). Both AC and RO filters reduced DBPs in tap water and none of the analyzed DBPs were detected in bottled water. CONCLUSIONS:THMs and HAAs were below the EU regulatory limits (Drinking Water Directive 2020/2184). A clear geographical pattern for most DBPs and for the conductivity was found, driven by the water source. With the generated data, we will develop predictive models based on routine monitoring parameters that could be applied in epidemiological research. KEYWORDS: Water quality, Chemical exposures, Exposure assessment, Multi-pollutant

Effects of changing supply water quality on drinking water distribution networks: Changes in NOM optical properties, disinfection byproduct formation, and Mn deposition and release

Field studies were conducted in a Croatian city supplied by two distinct groundwater sources (referred to as A and B) to investigate both the effects of changing water source on the water quality in the drinking water supply system, as well as to further understand discoloration events that occurred in city locations that switched water from source A to B. The water treatment processes at site A were found to alter organic matter (OM) characteristics, removing humic substances while enhancing protein-derived (tryptophan) content. Although the humic-like component predominated in raw waters, microbially/protein-derived components were found to increase throughout the distribution networks of both systems. Disinfection byproducts (DBPs) such as total trihalomethane (TTHM) and total haloacetic acid (THAA) were prevalent in water distribution system (WDS)-A, which correlated with elevated OM content as well as re-chlorination with hypochlorite (NaOCl). Our field study revealed that THMs were more readily formed than HAAs during ClO2 treatment. Unsurprisingly, chlorite concentrations were generally higher than chlorate concentrations during ClO2 treatment, whereas (secondary) NaOCl disinfection contributed to higher chlorate production. Principal component analysis indicated that variable pH values and humic-like OM could affect Mn, As and Al concentrations at the consumer's tap. Our results suggested that although Mn concentrations complied with regulations at WDS-B and were below 50 μg/L after disinfection, Mn was oxidized and formed particulate Mn oxides capable of causing discoloration events depending on prevailing network physico-chemical and hydraulic conditions. Aluminium also appears to be released during hydraulic disturbances from extensive deposits within the network. Thermodynamic calculations showed that Mn-oxidation was strongly dependent upon the ORP, and to lesser extent the pH value. Collectively, our results confirm that ensuring the provision of safe drinking waters to consumers requires an understanding of water quality across entire distribution networks in addition to any routine post-treatment monitoring.

Rapid removal of trace haloacetic acids from drinking water by a continuous adsorption process using graphene oxide

ABSTRACT Significant health risks are caused by trace levels of haloacetic acids (HAAs) in drinking water. We used graphene oxide (GO), a high-performance absorbent, to remove monochloroacetic acid (MCAA), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA). 31.6%, 27.1% and 30.2% of MCAA, DCAA and TCAA in drinking water could be rapidly removed within 2 min by the interaction of intermolecular hydrogen bonds between GO and HAAs. On the other hand, as a type of weak interaction, intermolecular hydrogen bonds are easy to fracture, which leads to the recovery of GO. The removal efficiency of MCAA, DCAA and TCAA monotonously decreased with increasing pH from 3 to 11. Temperature was not an important influence on the removal efficiency of HAAs, and only affected the interaction of intermolecular hydrogen bonds between GO and HAAs. A continuous adsorption process was used for further improving the removal efficiency of HAAs, and the concentration of total HAAs decreased from 436 to 52.5 μg L−1 after five adsorption processes. The total contact time was just 2.25 min, which was faster than other reported adsorbents, and total HAAs could be decreased by 88%. The innovative process in this study provides an effective method for application of GO to rapidly remove HAAs in drinking water.

Disinfection by-products in Croatian drinking water supplies with special emphasis on the water supply network in the city of Zagreb

The occurrence of disinfection by-products (DBPs) was investigated in 48 drinking water systems across Croatia. Eleven DBPs were studied: chlorite (ClO2−), chlorate (ClO3−), four trihalomethanes (THMs), and five haloacetic acids (HAAs). Furthermore, an intensive sampling program was conducted in the distribution system in the city of Zagreb where, aside from DBP analyses, natural organic matter (NOM) was characterized using fluorescence spectroscopy. In the drinking waters examined across Croatia, DBP values were found in the range from 0.7 μg/L to 32.8 μg/L for THMs, below LOQ to 17.2 μg/L for HAAs (primarily di- and trichloroacetic acids), below LOQ to 720 μg/L for ClO2− and below LOQ to 431 μg/L for ClO3−. The results obtained showed higher chlorite concentrations in the systems treated with hypochlorite compared to systems treated with chlorine dioxide. DBPs in the Zagreb distribution network were generally low (the average values were below 6 μg/L and 2 μg/L for total THM and total HAA respectively). In contrast to our observations throughout Croatia, dibromoacetic acid (DBAA) was found to be the predominant HAA within Zagreb, most likely due to the degradation of chlorinated carboxylates (di-/tri-chloroacetic) in the network. Characterization of NOM by Parallel Factor Analysis (PARAFAC) fluorescence spectroscopy across the Zagreb network showed distinct temporal variations arising from groundwater inputs, as evident from variable humic-, tyrosine-, and tryptophan-like peaks. Statistical correlations between fluorescence data and DBPs highlight its potential for monitoring the presence of DBPs in distribution networks.

Formation of disinfection by-products from coexisting organic matter during vacuum ultraviolet (VUV) or ultraviolet (UV) treatment following pre-chlorination and their fates after post-chlorination

Vacuum ultraviolet (VUV) treatment is a promising advanced oxidation process for the removal of organic contaminants during water treatment. Here, we investigated the formation of disinfection by-products from coexisting organic matter during VUV or ultraviolet (UV) treatment following pre-chlorination, and their fates after post-chlorination, in a standard Suwannee River humic acid water and a natural lake water. VUV treatment after pre-chlorination decreased the total trihalomethane (THM) concentration but increased total aldehyde and chloral hydrate concentrations; total haloacetic acid (HAA) and haloacetonitrile (HAN) concentrations did not change. UV treatment after pre-chlorination produced similar changes in the by-products as those observed for VUV treatment, with the exception that the total THM concentration was not changed, and the total HAN concentration was increased. The final concentrations of by-products after post-chlorination were increased by VUV or UV treatment, except for the total HAA concentration, which remained unchanged after UV treatment. The increases were greater after VUV treatment than after UV treatment, probably because the larger amount of hydroxyl radicals generated during VUV treatment compared with during UV treatment transformed coexisting organic matter into precursors of by-products that were then converted to by-products during post-chlorination.

Formation of haloacetic acids from different organic precursors in swimming pool water during chlorination

Haloacetic acids (HAAs) were reported to be the most abundant category of DBPs in swimming pool water. In this study, the formation of HAAs from different organic precursors in swimming pool water, including UV filters, human body fluids, and natural organic matter (NOM), during chlorination was examined, and the effects of chlorine dose and halide concentrations on the formation of HAAs were evaluated. The results show that the total HAA yields from benzophenone-3 (BP-3) and Suwannee River humic acid (SRHA) were the highest among the nine organic precursors, and the yields of dichloroacetic acid and bromochloroacetic acid were higher than that of the other HAA species. In all the chlorinated samples of different organic precursors, longer chlorination time enhanced HAA formation. Both chlorine dose and bromide concentration significantly affected the formation of HAAs from BP-3 and SRHA during chlorination. With the increasing chlorine dose, the total HAA yields from SRHA and BP-3 significantly increased. Besides, the proportion of trihaloacetic acids (THAAs) rose while that of dihaloacetic acids (DHAAs) and monohaloacetic acids (MHAAs) declined with the increasing chlorine dose. With the increasing bromide concentration, HAA formation from SRHA increased while that of BP-3 decreased. The bromine incorporation factor (BIF) of the formed MHAAs, DHAAs and THAAs from SRHA and BP-3 both increased with the increasing bromide concentration in the following order: BIFDHAAs > BIFTHAAs > BIFMHAAs, indicating that bromine was easier to be incorporated into DHAAs rather than MHAAs or THAAs. Moreover, bromide promoted the formation of Br-HAAs.

Comparative analysis of charcoal grilling, infrared grilling and superheated steam roasting on the colour, textural quality and heterocyclic aromatic amines of lamb patties

SummaryThe colour, textural profile and heterocyclic aromatic amines content of lamb patties cooked by charcoal grilling, infrared grilling and superheated steam roasting were investigated. The results of colour showed that lightness and yellowness values were highest in the superheated steam and lowest in charcoal grilled patties. The texture characteristics observed in the superheated steam, and infrared patties were much better. Water loss was highest in charcoal grilled meat. Charcoal grilling produced a significantly (P &lt; 0.05) much higher amount of total HAAs, ranging from 171.26 ng g−1 to 555.29 ng g−1 (polar) and from 200.77 ng g−1 to 426.07 ng g−1 (non‐polar) HAAs, than infrared (39.21 ng g−1 −181.37 ng g−1) and (52.84 ng g−1 −148.59 ng g−1) and superheated steam roasting (from 8.67 ng g−1 to 30.66 ng g−1 and from 23.61 ng g−1 to 89.66 ng g−1) for both types of HAAs in lamb patties. Colour, texture and HAAs were significantly influenced by time and by the temperature used for each cooking method.

A multiple‐site field study of stabilized hydrogen peroxide for drinking water disinfection

AbstractThis study examined the impact of changing the secondary disinfectant from chlorine to a stabilized hydrogen peroxide (SHP) in three full‐scale drinking water treatment plants serving small communities in the provinces of Ontario and Newfoundland, Canada. In all three communities, the SHP residuals were maintained within the limits specified by local regulators, with the exception of one of the sites in Newfoundland, where residuals were outside these limits on several occasions during the study. Following the transition to the SHP system, total coliforms and Escherichia coli consistently tested negative (nondetected) in all cases. Switching to the SHP system reduced concentrations of total trihalomethanes to 22–44 μg/L and total haloacetic acids to 47–70 μg/L, corresponding to 72 ± 9 and 67 ± 11% reductions, respectively. The present study indicated that changing the secondary disinfectant to SHP did not negatively affect the polyvinyl chloride and ductileiron pipes in the distribution systems studied.

Variability of TOC and DBPs (THMs and HAA5) in drinking water sources and distribution system in drought season: the North Iran case study

ABSTRACT The aim of this study is tracing seasonal variability of total organic carbon (TOC), trihalomethanes (THMs) and haloacetic acids (HAA5) as disinfection by-products (DBPs) in drinking water sources and the distribution system in the north of Iran. The results showed that the concentrations of TOC were within the range of 0.013–1.42 mg/L. In addition, the results showed that most of the water sources had nearly the same concentration level (i.e. <1 mg/L), with the exception of one peak for groundwater source and middle drinking water distribution system in the city of Sari (1.42 mg/L) and Babol (1.37 mg/L). It was demonstrated that brominated HAA (MBAA) presented the highest concentration in the Sari City (17.3 µg/L) followed by the City of Behshahr (8.9–11.19 µg/L). The Babol City showed the highest concentration of chlorinated HAA (22.403 and 22.503 µg/L for DCAA and TCAA, respectively). Among the different compounds of THMs, the concentration of CHBr3 was nearly in the same order of magnitude in the cities of Sari, Babol and Behshahr for both spring and summer seasons. The brominated THM (BDCM) concentrations were also high (14.7 µg/L) in the Behshahr City. The results of independent t-test indicated that the seasonal (spring and summer) difference was statistically significant in the case of temperature and TTHM (p < 0.05). Furthermore, total HAA5 ≤ 60 µg/L and THM ≤100 µg/L in all the considered cities over the period of the study. The TTHMs concentration was 56 µg/L in treating surface water (TSW) source in the summer season at the Sari city.