The Experts below are selected from a list of 1917 Experts worldwide ranked by ideXlab platform
Huijuan Liu - One of the best experts on this subject based on the ideXlab platform.
-
characterization of dissolved organic matter from surface waters with low to high dissolved organic carbon and the related disinfection byproduct formation potential
Journal of Hazardous Materials, 2014Co-Authors: Xu Zhao, Ran Mao, Huijuan LiuAbstract:Abstract In this study, the disinfection byproduct formation potential (DBPFP) of three surface waters with the dissolved organic carbon (DOC) content of 2.5, 5.2, and 7.9 mg/L was investigated. The formation and distribution of Trihalomethanes and haloacetic acids were evaluated. Samples collected from three surface waters in China were fractionated based on molecular weight and hydrophobicity. The raw water containing more hydrophobic (Ho) fraction exhibited higher formation potentials of haloacetic acid and Trihalomethane. The DBPFP of the surface waters did not correlate with the DOC value. The values of DBPFP per DOC were correlated with the specific ultraviolet absorbance (SUVA) for Ho and Hi fractions. The obtained results suggested that SUVA cannot reveal the ability of reactive sites to form disinfection byproducts for waters with few aromatic structures. Combined with the analysis of FTIR and nuclear magnetic resonance spectra of the raw waters and the corresponding fractions, it was concluded that the Ho fraction with phenolic hydroxyl and conjugated double bonds was responsible for the production of trichloromethanes and trichloroacetic acids. The Hi fraction with amino and carboxyl groups had the potential to form dichloroacetic acids and chlorinated Trihalomethanes.
-
characteristic transformation of humic acid during photoelectrocatalysis process and its subsequent disinfection byproduct formation potential
Water Research, 2011Co-Authors: Xu Zhao, Huijuan LiuAbstract:In this study, degradation of humic acid (HA) via photoelectrocatalysis (PEC) process and corresponding disinfection byproduct formation potential (DBPFP) were investigated. Particularly, structure variation and subsequent DBPFP of HA during PEC treatment were correlated. The PEC process was found to be effective in reducing dissolved organic carbon concentration by 75.0% and UV absorbance at 254 nm by 92.0%. Furthermore, 90.3% of haloacetic acids formation potential and 89.8% of Trihalomethanes formation potential were reduced within 180 min. Based on molecular weight and resin fraction results, it was demonstrated that HA with large aromatic, hydrophobic and long aliphatic chain organics were transformed into small and hydrophilic organics during PEC process. Combined with the fourier transform infrared spectra and (13)C nuclear magnetic resonance spectra analysis of HA fractions, it was concluded that phenolic hydroxyl and conjugated double bonds tended to be attacked by hydroxyl radicals during PEC process; these groups were reactive with chlorine to produce disinfection byproducts (DBP), especially Trihalomethane and trichloroacetic acid. By contrast, amino, carboxyl and alcoholic hydroxyl groups were relatively difficult to be oxidized during PEC process; these groups had the potential to form dichloroacetic acid during chlorination. Results of these studies confirmed that PEC process was a safe and effective technique to decrease DBP formation significantly in water treatment plant. (C) 2011 Elsevier Ltd. All rights reserved.
-
formation and distribution of disinfection by products during chlorine disinfection in the presence of bromide ion
Chinese Science Bulletin, 2008Co-Authors: Huijuan Liu, Xu ZhaoAbstract:The influences of contact time and pH value on the formation and distribution of four species of Trihalomethanes and five species of haloacetic acids during chlorination in the presence of bromine were investigated. Results showed that the distribution of molar fraction of Trihalomethanes varied with contact time due to the change of bromide ion concentration during chlorination. Most of the Trihalomethanes comprising bromine-containing species and the favored products of the haloacetic acids were chlorine-containing species after 24 h of chlorination. The extent of bromine incorporation in Trihalomethanes and haloacetic acids both decreased with time. The contact time also had influence on the formation rate of different species of haloacetic acids. The formation and distribution of Trihalomethanes and haloacetic acids strongly depended on the chlorination pH value. All of the Trihalomethanes species formation increased with the increase of pH value except the bromoform that had not been detected. The molar fraction of bromodichloromethane and dibromochloromethane containing bromine increased with pH value while chloroform without bromine decreased. Under the pH range studied in this experiment, the predominant haloacetic acids species were trichloroacetic acid and dichloroacetic acid which all decreased with the increase of pH value and the level of TCAA was higher than that of DCAA.
Xu Zhao - One of the best experts on this subject based on the ideXlab platform.
-
characterization of dissolved organic matter from surface waters with low to high dissolved organic carbon and the related disinfection byproduct formation potential
Journal of Hazardous Materials, 2014Co-Authors: Xu Zhao, Ran Mao, Huijuan LiuAbstract:Abstract In this study, the disinfection byproduct formation potential (DBPFP) of three surface waters with the dissolved organic carbon (DOC) content of 2.5, 5.2, and 7.9 mg/L was investigated. The formation and distribution of Trihalomethanes and haloacetic acids were evaluated. Samples collected from three surface waters in China were fractionated based on molecular weight and hydrophobicity. The raw water containing more hydrophobic (Ho) fraction exhibited higher formation potentials of haloacetic acid and Trihalomethane. The DBPFP of the surface waters did not correlate with the DOC value. The values of DBPFP per DOC were correlated with the specific ultraviolet absorbance (SUVA) for Ho and Hi fractions. The obtained results suggested that SUVA cannot reveal the ability of reactive sites to form disinfection byproducts for waters with few aromatic structures. Combined with the analysis of FTIR and nuclear magnetic resonance spectra of the raw waters and the corresponding fractions, it was concluded that the Ho fraction with phenolic hydroxyl and conjugated double bonds was responsible for the production of trichloromethanes and trichloroacetic acids. The Hi fraction with amino and carboxyl groups had the potential to form dichloroacetic acids and chlorinated Trihalomethanes.
-
characteristic transformation of humic acid during photoelectrocatalysis process and its subsequent disinfection byproduct formation potential
Water Research, 2011Co-Authors: Xu Zhao, Huijuan LiuAbstract:In this study, degradation of humic acid (HA) via photoelectrocatalysis (PEC) process and corresponding disinfection byproduct formation potential (DBPFP) were investigated. Particularly, structure variation and subsequent DBPFP of HA during PEC treatment were correlated. The PEC process was found to be effective in reducing dissolved organic carbon concentration by 75.0% and UV absorbance at 254 nm by 92.0%. Furthermore, 90.3% of haloacetic acids formation potential and 89.8% of Trihalomethanes formation potential were reduced within 180 min. Based on molecular weight and resin fraction results, it was demonstrated that HA with large aromatic, hydrophobic and long aliphatic chain organics were transformed into small and hydrophilic organics during PEC process. Combined with the fourier transform infrared spectra and (13)C nuclear magnetic resonance spectra analysis of HA fractions, it was concluded that phenolic hydroxyl and conjugated double bonds tended to be attacked by hydroxyl radicals during PEC process; these groups were reactive with chlorine to produce disinfection byproducts (DBP), especially Trihalomethane and trichloroacetic acid. By contrast, amino, carboxyl and alcoholic hydroxyl groups were relatively difficult to be oxidized during PEC process; these groups had the potential to form dichloroacetic acid during chlorination. Results of these studies confirmed that PEC process was a safe and effective technique to decrease DBP formation significantly in water treatment plant. (C) 2011 Elsevier Ltd. All rights reserved.
-
formation and distribution of disinfection by products during chlorine disinfection in the presence of bromide ion
Chinese Science Bulletin, 2008Co-Authors: Huijuan Liu, Xu ZhaoAbstract:The influences of contact time and pH value on the formation and distribution of four species of Trihalomethanes and five species of haloacetic acids during chlorination in the presence of bromine were investigated. Results showed that the distribution of molar fraction of Trihalomethanes varied with contact time due to the change of bromide ion concentration during chlorination. Most of the Trihalomethanes comprising bromine-containing species and the favored products of the haloacetic acids were chlorine-containing species after 24 h of chlorination. The extent of bromine incorporation in Trihalomethanes and haloacetic acids both decreased with time. The contact time also had influence on the formation rate of different species of haloacetic acids. The formation and distribution of Trihalomethanes and haloacetic acids strongly depended on the chlorination pH value. All of the Trihalomethanes species formation increased with the increase of pH value except the bromoform that had not been detected. The molar fraction of bromodichloromethane and dibromochloromethane containing bromine increased with pH value while chloroform without bromine decreased. Under the pH range studied in this experiment, the predominant haloacetic acids species were trichloroacetic acid and dichloroacetic acid which all decreased with the increase of pH value and the level of TCAA was higher than that of DCAA.
Jesús Ibarluzea - One of the best experts on this subject based on the ideXlab platform.
-
Drinking Water Disinfection By-products, Genetic Polymorphisms, and Birth Outcomes in a European Mother-Child Cohort Study.
Epidemiology, 2016Co-Authors: Manolis Kogevinas, Esther Gracia-lavedan, Nathalie Costet, Asta Danileviciute, Mariona Bustamante, Regina Grazuleviciene, Ferran Ballester, Sylvaine Cordier, Ana Espinosa, Jesús IbarluzeaAbstract:Background: We examined the association between exposure during pregnancy to Trihalomethanes, the most common water disinfection by-products, and birth outcomes in a European cohort study (Health Impacts of Long-Term Exposure to Disinfection By-Products in Drinking Water). We took into account exposure through different water uses, measures of water toxicity, and genetic susceptibility. Methods: We enrolled 14,005 mothers (2002–2010) and their children from France, Greece, Lithuania, Spain, and the UK. Information on lifestyle- and water-related activities was recorded. We ascertained residential concentrations of Trihalomethanes through regulatory records and ad hoc sampling campaigns and estimated route-specific Trihalomethane uptake by trimester and for whole pregnancy. We examined single nucleotide polymorphisms and copy number variants in disinfection by-product metabolizing genes in nested case–control studies. Results: Average levels of Trihalomethanes ranged from around 10 μg/L to above the regulatory limits in the EU of 100 μg/L between centers. There was no association between birth weight and total Trihalomethane exposure during pregnancy (β = 2.2 g in birth weight per 10 μg/L of Trihalomethane, 95% confidence interval = 3.3, 7.6). Birth weight was not associated with exposure through different routes or with specific Trihalomethane species. Exposure to Trihalomethanes was not associated with low birth weight (odds ratio [OR] per 10 μg/L = 1.02, 95% confidence interval = 0.95, 1.10), small-for-gestational age (OR = 0.99, 0.94, 1.03) and preterm births (OR = 0.98, 0.9, 1.05). We found no gene–environment interactions for mother or child polymorphisms in relation to preterm birth or small-for-gestational age. Conclusions: In this large European study, we found no association between birth outcomes and Trihalomethane exposures during pregnancy in the total population or in potentially genetically susceptible subgroups. (See video abstract at http://links.lww.com/EDE/B104.)
MarÍa Victoria Selma - One of the best experts on this subject based on the ideXlab platform.
-
suitability of aqueous chlorine dioxide versus sodium hypochlorite as an effective sanitizer for preserving quality of fresh cut lettuce while avoiding by product formation
Postharvest Biology and Technology, 2010Co-Authors: Francisco Lopezgalvez, Ascension Martinezsanchez, Pilar Truchado, Ana Allende, Juan A. Tudela, MarÍa Victoria SelmaAbstract:Abstract Aqueous chlorine dioxide (ClO 2 ) has been postulated as an alternative to sodium hypochlorite (NaClO) for fresh-cut produce sanitization with the advantage of avoiding the risks associated with chlorination by-products. However, little is known about its influence on preserving quality and the potential formation of Trihalomethanes (THMs) under typical processing conditions. The suitability of aqueous chlorine dioxide (3 mg L −1 ) as an effective sanitizer of fresh-cut iceberg lettuce stored under active modified atmosphere packaging (MAP) at refrigerated conditions was determined and compared with sodium hypochlorite (100 mg L −1 ). Fresh-cut lettuce washed with tap water was used as a control. The epiphytic microbiota were characterized by the evaluation of the major relevant microbial groups such as mesophiles, psychrophiles, Pseudomonas spp., Enterobacteriaceae , lactic acid bacteria, yeasts and moulds. Additionally, gas composition, sensory quality, vitamin C and individual and total phenolics were monitored after washing and during storage for 3 d at 4 °C followed by 7 d at 8 °C. In general, the natural microbiota of fresh-cut lettuce after washing and storage was equally affected by the different washing solutions, with the exception of yeasts which showed the highest growth after 10 d storage in samples washed with chlorine dioxide. None of the tested washings negatively affected sensory quality, which was acceptable after 10 d storage. Additionally, the content of bioactive compounds was not significantly affected either by washing solution or by storage time. The potential formation of THMs was evaluated by the analysis of lettuce washed in water with a chemical oxygen demand (COD) of 700 mg L −1 treated for 30 min with sodium hypochlorite (100 mg L −1 ) or chlorine dioxide (3.7 mg L −1 ). Trihalomethane formation was only detected in the process water in which sodium hypochlorite was applied (217 ± 38 μg L −1 ). However, THMs formation in fresh-cut lettuce was negligible despite the sanitation procedure. The formation of THMs was only detected in fresh-cut lettuce when sodium hypochlorite was used under very extreme conditions where lettuce was washed in water with a high level of organic matter (COD = 1800 mg L −1 ), high sodium hypochlorite concentration (700 mg L −1 ) and long contact time (60 min). Our data suggest that aqueous chlorine dioxide is as suitable as sodium hypochlorite for fresh-cut lettuce sanitation with the advantage of preventing the formation of THMs.
Howard S Weinberg - One of the best experts on this subject based on the ideXlab platform.
-
the effect of inorganic precursors on disinfection byproduct formation during uv chlorine chloramine drinking water treatment
Water Research, 2012Co-Authors: Bonnie A Lyon, Aaron Dotson, Karl G Linden, Howard S WeinbergAbstract:Ultraviolet (UV) disinfection is being increasingly used in drinking water treatment. It is important to understand how its application to different types of water may influence finished water quality, particularly as anthropogenic activity continues to impact the quality of source waters. The objective of this study was to evaluate the effect of inorganic precursors on the formation of regulated and unregulated disinfection byproducts (DBPs) during UV irradiation of surface waters when combined with chlorination or chloramination. Samples were collected from three drinking water utilities supplied by source waters with varying organic and inorganic precursor content. The filtered samples were treated in the laboratory with a range of UV doses delivered from low pressure (LP, UV output at 253.7 nm) and medium pressure (MP, polychromatic UV output 200-400 nm) mercury lamps followed by chlorination or chloramination, in the presence and absence of additional bromide and nitrate. The regulated Trihalomethanes and haloacetic acids were not affected by UV pretreatment at disinfection doses (40-186 mJ/cm 2). With higher doses (1000 mJ/cm 2), Trihalomethane formation was increased 30-40%. While most effects on DBPs were only observed with doses much higher than typically used for UV disinfection, there were some effects on unregulated DBPs at lower doses. In nitrate-spiked samples (1-10 mg N/L), chloropicrin formation doubled and increased three- to six-fold with 40 mJ/cm 2 MP UV followed by chloramination and chlorination, respectively. Bromopicrin formation was increased in samples containing bromide (0.5-1 mg/L) and nitrate (1-10 mg N/L) when pretreated with LP or MP UV (30-60% with 40 mJ/cm 2 LP UV and four- to ten-fold increase with 40 mJ/cm 2 MP UV, after subsequent chlorination). The formation of cyanogen chloride doubled and increased three-fold with MP UV doses of 186 and 1000 mJ/cm 2, respectively, when followed by chloramination in nitrate-spiked samples but remained below the World Health Organization guideline value of 70 μg/L in all cases. MP UV and high LP UV doses (1000 mJ/cm 2) increased chloral hydrate formation after subsequent chlorination (20-40% increase for 40 mJ/cm 2 MP UV). These results indicate the importance of bench-testing DBP implications of UV applications in combination with post-disinfectants as part of the engineering assessment of a UV-chlorine/chloramine multi-barrier disinfection design for drinking water treatment.
