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Blatchley ER, Cui H. Quantitative Microbial Risk Assessment for Quantification of the Effects of Ultraviolet Germicidal Irradiation on COVID-19 Transmission. Environ Sci Technol 2023; 57:17393-17403. [PMID: 37922235 DOI: 10.1021/acs.est.3c03026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2023]
Abstract
Quantitative microbial risk assessment (QMRA) is presented as a tool for evaluation of the effectiveness of ultraviolet germicidal irradiation (UVGI) systems for the disinfection of indoor air. The QMRA is developed in the context of UVGI system implementation for control of SARS-CoV-2 infection and comprises submodels to address problem formulation, exposure assessment, and health effects assessment, all of which provide input to a risk characterization submodel. The model simulations indicate that UVGI systems can effectively control the risk of infection associated with SARS-CoV-2 for low to moderate virus emission rates. The risk of disease transmission is strongly influenced by the rate of pathogen emission by an infected individual, the output power of UVGI fixtures and their configuration, the source of UV-C radiation implemented in the UVGI fixtures, and the characteristics of the heating, ventilation, and air conditioning (HVAC) system. The QMRA framework provides a quantitative link between UVGI/HVAC system characteristics and changes in the risk of disease transmission. The framework can be adapted to other airborne pathogens and provides a rational basis for the design, testing, and validation of UVGI systems.
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Affiliation(s)
- Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907-2051, United States
- Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Haiying Cui
- Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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2
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Sangwan N, Ahmed YM, Blatchley ER. Dose Distribution Scaling and Validation of Ultraviolet Photoreactors Using Dimensional Analysis. Environ Sci Technol 2023; 57:16707-16717. [PMID: 37846972 DOI: 10.1021/acs.est.3c06816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Ultraviolet (UV) disinfection is commonly applied in the treatment of drinking water and wastewater. The performance of UV disinfection systems is governed by the UV dose distribution delivered to the fluid, which is an intrinsic characteristic of the reactor under a given operating condition. Current design and validation approaches are based on empirical methods that are expensive to apply and provide limited information about the UV photoreactor behavior. To address this issue, a dose distribution scaling method was developed based on dimensional analysis (i.e., application of the Buckingham-π theorem). Three dimensionless groups representing UV dose, reactor geometry, and UV absorption behavior were defined. Using these groups, the approach was applied for the analysis of 15 operating conditions, defined by process variables of volumetric flow rate, UV transmittance, and lamp power. The approach was demonstrated to allow scaling of the dose distribution with these critical, dimensionless variables and yielded close agreement between predictions of disinfection efficacy against MS2 and E. coli based on the scaling approach with conventional CFD-E' modeling results. The approach thus provides a low-cost, rapid method for predicting the performance of UV disinfection systems across a wide range of operating conditions and against essentially any microbial challenge agent.
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Affiliation(s)
- Nikhil Sangwan
- Prairie Research Institute, University of Illinois at Urbana-Champaign, 2204 Griffith Drive, Champaign, Illinois 61820, United States
| | - Yousra M Ahmed
- Thebes Higher Institute of Engineering, Thebes Integrated Academy, Maadi, Cairo 11434, Egypt
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907-2051, United States
- Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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3
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Zhao J, Payne EM, Liu B, Shang C, Blatchley ER, Mitch WA, Yin R. Making waves: Opportunities and challenges of applying far-UVC radiation in controlling micropollutants in water. Water Res 2023; 241:120169. [PMID: 37290191 DOI: 10.1016/j.watres.2023.120169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 05/27/2023] [Accepted: 06/02/2023] [Indexed: 06/10/2023]
Abstract
Concerns over human health risks associated with chemical contaminants (micropollutants) in drinking waters are rising due to the increased use of reclaimed water or water supplies impacted by upstream wastewater discharges. Ultraviolet (UV)-driven advanced oxidation processes (UV-AOPs) using radiation sources that emit at 254 nm have been developed as advanced treatments to degrade contaminants, while those UV-AOPs can be improved towards higher radical yields and lower byproduct formation. Several previous studies have suggested that Far-UVC radiation (200-230 nm) is a promising radiance source to drive UV-AOPs because the direct photolysis of micropollutants and production of reactive species from oxidant precursors can both be improved. In this study, we summarize from the literature the photodecay rate constants of five micropollutants by direct UV photolysis, which are higher at 222 than 254 nm. We experimentally determine the molar absorption coefficients at 222 and 254 nm of eight oxidants commonly used in water treatment and present the quantum yields of the oxidant photodecay. Our experimental results also show that the concentrations of HO·, Cl·, and ClO· generated in the UV/chlorine AOP can be increased by 5.15-, 15.76-, and 2.86-fold, respectively, by switching the UV wavelength from 254 to 222 nm. We also point out the challenges of applying Far-UVC for micropollutant abatement in water treatment, including the strong light screening effect of matrix components (e.g., carbonate, nitrate, bromide, and dissolved organic matter), the formation of byproducts via new reaction pathways, and the needs to improve the energy efficiency of the Far-UVC radiation sources.
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Affiliation(s)
- Jing Zhao
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Emma M Payne
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, 4001 Discovery Drive, Boulder, CO 80303, United States
| | - Bryan Liu
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, 4001 Discovery Drive, Boulder, CO 80303, United States
| | - Chii Shang
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong; Hong Kong Branch of Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, United States; Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, IN 47907, United States
| | - William A Mitch
- Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Stanford, CA 94305, United States
| | - Ran Yin
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
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Busse MM, Hawes JK, Blatchley ER. Comparative Life Cycle Assessment of Water Disinfection Processes Applicable in Low-Income Settings. Environ Sci Technol 2022; 56:16336-16346. [PMID: 36215720 DOI: 10.1021/acs.est.2c02393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Access to safe, sufficient water for health and sanitation is a human right, and the reliable disinfection of water plays a critical role in addressing this need. The environmental impact and sustainability of water disinfection methods will also play a role in overall public health. This study presents an investigation of the environmental life cycle impacts of four ultraviolet disinfection systems utilizing ambient solar radiation directly and indirectly for water disinfection in comparison to chlorination and water delivery for application in low-income settings. Product inspection and existing literature were used to define a life cycle functional unit of 1 m3 of water for each system, which allowed quantification of material use, infrastructure requirements, and life cycle of the original components of each system and those needed to keep them operational for the studied lifespans (1, 5, 10, and 20 years) and scales (30, 100, 500, and 1000 L per day). For all studied cases, chlorine had the lowest impact in all impact categories, but end-user acceptance of chlorine in some settings is low, driving interest in low-impact alternatives. Disinfection based on low-pressure mercury lamps had the next lowest normalized impact in most categories and may represent a viable alternative, particularly for long-term (10+ years), high production (500+ liters per day) scenarios.
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Affiliation(s)
- Margaret M Busse
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jason K Hawes
- School for Environment and Sustainability, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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5
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Schuit MA, Larason TC, Krause ML, Green BM, Holland BP, Wood SP, Grantham S, Zong Y, Zarobila CJ, Freeburger DL, Miller DM, Bohannon JK, Ratnesar-Shumate SA, Blatchley ER, Li X, Dabisch PA, Miller CC. SARS-CoV-2 inactivation by ultraviolet radiation and visible light is dependent on wavelength and sample matrix. Journal of Photochemistry and Photobiology B: Biology 2022; 233:112503. [PMID: 35779426 PMCID: PMC9221687 DOI: 10.1016/j.jphotobiol.2022.112503] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 05/19/2022] [Accepted: 06/18/2022] [Indexed: 11/11/2022]
Abstract
Numerous studies have demonstrated that SARS-CoV-2 can be inactivated by ultraviolet (UV) radiation. However, there are few data available on the relative efficacy of different wavelengths of UV radiation and visible light, which complicates assessments of UV decontamination interventions. The present study evaluated the effects of monochromatic radiation at 16 wavelengths from 222 nm through 488 nm on SARS-CoV-2 in liquid aliquots and dried droplets of water and simulated saliva. The data were used to generate a set of action spectra which quantify the susceptibility of SARS-CoV-2 to genome damage and inactivation across the tested wavelengths. UVC wavelengths (≤280 nm) were most effective for inactivating SARS-CoV-2, although inactivation rates were dependent on sample type. Results from this study suggest that UV radiation can effectively inactivate SARS-CoV-2 in liquids and dried droplets, and provide a foundation for understanding the factors which affect the efficacy of different wavelengths in real-world settings.
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Tow EW, Hartman AL, Jaworowski A, Zucker I, Kum S, AzadiAghdam M, Blatchley ER, Achilli A, Gu H, Urper GM, Warsinger DM. Modeling the energy consumption of potable water reuse schemes. Water Res X 2021; 13:100126. [PMID: 34901816 PMCID: PMC8640112 DOI: 10.1016/j.wroa.2021.100126] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/30/2021] [Accepted: 11/17/2021] [Indexed: 06/14/2023]
Abstract
Potable reuse of municipal wastewater is often the lowest-energy option for increasing the availability of fresh water. However, limited data are available on the energy consumption of potable reuse facilities and schemes, and the many variables affecting energy consumption obscure the process of estimating energy requirements. By synthesizing available data and developing a simple model for the energy consumption of centralized potable reuse schemes, this study provides a framework for understanding when potable reuse is the lowest-energy option for augmenting water supply. The model is evaluated to determine a representative range for the specific electrical energy consumption of direct and indirect potable reuse schemes and compare potable reuse to other water supply augmentation options, such as seawater desalination. Finally, the model is used to identify the most promising avenues for further reducing the energy consumption of potable reuse, including encouraging direct potable reuse without additional drinking water treatment, avoiding reverse osmosis in indirect potable reuse when effluent quality allows it, updating pipe networks, or using more permeable membranes. Potable reuse already requires far less energy than seawater desalination and, with a few investments in energy efficiency, entire potable reuse schemes could operate with a specific electrical energy consumption of less than 1 kWh/m3, showing the promise of potable reuse as a low-energy option for augmenting water supply.
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Affiliation(s)
- Emily W. Tow
- Franklin W. Olin College of Engineering, 1000 Olin Way, Needham, Massachusetts, USA
| | - Anna Letcher Hartman
- Franklin W. Olin College of Engineering, 1000 Olin Way, Needham, Massachusetts, USA
| | - Aleksander Jaworowski
- Franklin W. Olin College of Engineering, 1000 Olin Way, Needham, Massachusetts, USA
- Lund University, Box 117, SE-221 00, Lund, Sweden
| | - Ines Zucker
- School of Mechanical Engineering and the Porter School of Environmental and Earth Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Soyoon Kum
- David L. Hirschfeld Dept. of Engineering, Angelo State University, 2601 W Ave N, San Angelo, TX, USA
| | - Mojtaba AzadiAghdam
- Department of Chemical & Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, Arizona, USA
| | - Ernest R. Blatchley
- Lyles School of Civil Engineering and Division of Environmental & Ecological Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana, USA
| | - Andrea Achilli
- Department of Chemical & Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, Arizona, USA
| | - Han Gu
- Research and Development Department, Orange County Water District, 18700 Ward St, Fountain Valley, California, USA
| | - Gulsum Melike Urper
- National Research Center on Membrane Technologies, Istanbul Technical University, Maslak, 34467 Saryer/Istanbul, Turkey
| | - David M. Warsinger
- School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, 610 Purdue Mall, West Lafayette, Indiana, USA
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7
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Wu T, Földes T, Lee LT, Wagner DN, Jiang J, Tasoglou A, Boor BE, Blatchley ER. Real-Time Measurements of Gas-Phase Trichloramine (NCl 3) in an Indoor Aquatic Center. Environ Sci Technol 2021; 55:8097-8107. [PMID: 34033479 DOI: 10.1021/acs.est.0c07413] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
NCl3 is formed as a disinfection byproduct in chlorinated swimming pools and can partition between the liquid and gas phases. Exposure to gas-phase NCl3 has been linked to asthma and can irritate the eyes and respiratory airways, thereby affecting the health and athletic performance of swimmers. This study involved an investigation of the spatiotemporal dynamics of gas-phase NCl3 in an aquatic center during a collegiate swim meet. Real-time (up to 1 Hz) measurements of gas-phase NCl3 were made via a novel on-line derivatization cavity ring-down spectrometer and a proton transfer reaction time-of-flight mass spectrometer. Significant temporal variations in gas-phase NCl3 and CO2 concentrations were observed across varying time scales, from seconds to hours. Gas-phase NCl3 concentrations increased with the number of active swimmers due to swimming-enhanced liquid-to-gas transfer of NCl3, with peak concentrations between 116 and 226 ppb. Strong correlations between concentrations of gas-phase NCl3 with concentrations of CO2 and water (relative humidity) were found and attributed to similar features in their physical transport processes in pool air. A vertical gradient in gas-phase NCl3 concentrations was periodically observed above the water surface, demonstrating that swimmers can be exposed to elevated levels of NCl3 beyond those measured in the bulk air.
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Affiliation(s)
- Tianren Wu
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Ray W. Herrick Laboratories, Center for High Performance Buildings, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tomas Földes
- Aquality Technologies Srl, 1050 Brussels, Belgium
- Spectroscopy, Quantum Chemistry, and Atmospheric Remote Sensing, Université libre de Bruxelles (ULB), 1050 Brussels, Belgium
| | - Lester T Lee
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Danielle N Wagner
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Ray W. Herrick Laboratories, Center for High Performance Buildings, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jinglin Jiang
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Ray W. Herrick Laboratories, Center for High Performance Buildings, Purdue University, West Lafayette, Indiana 47907, United States
| | | | - Brandon E Boor
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Ray W. Herrick Laboratories, Center for High Performance Buildings, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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8
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Yang Q, Guo Y, Xu J, Wu X, He B, Blatchley ER, Li J. Photolysis of N-chlorourea and its effect on urea removal in a combined pre-chlorination and UV 254 process. J Hazard Mater 2021; 411:125111. [PMID: 33485223 DOI: 10.1016/j.jhazmat.2021.125111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/27/2020] [Accepted: 01/10/2021] [Indexed: 06/12/2023]
Abstract
Urea is one of the most important nitrogenous organic pollutants in water, and its removal attracts attention because of a growing concern related to water eutrophication. Urea has previously been considered to be largely unaffected by the UV-chlorine process. However, N-chlorourea, an intermediate of urea chlorination, has been shown to absorb ultraviolet radiation, and as such its photolysis is possible. Experiments were conducted to quantify the kinetics of N-chlorourea degradation under UV254 irradiation. The results showed that about 92% of N-chlorourea was degraded under UV254 irradiation. Ammonia and nitrate were detected as the primary nitrogen containing products of the photolysis of N-chlorourea. Solution pH ranging from 3.0 to 7.5 influenced the distribution of these products but not on the degradation rate. Based on these data, a possible pathway of photodegradation of N-chlorourea under UV254 is proposed. The degradation of urea was also achieved by the photolysis of N-chlorourea during the combined pre-chlorination and UV254 process. Insights gained in this study may be useful for exploring the potential of combined pre-chlorination and UV254 process on urea removal in water treatment.
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Affiliation(s)
- Qian Yang
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Yang Guo
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Jie Xu
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Xingyi Wu
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Bingying He
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, 550 Stadium Mall Drive, Purdue University, West Lafayette, IN 47907, USA; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Jing Li
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
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9
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Sun Q, Wu S, Yin R, Bai X, Bhunia AK, Liu C, Zheng Y, Wang F, Blatchley ER. Effects of fulvic acid size on microcystin-LR photodegradation and detoxification in the chlorine/UV process. Water Res 2021; 193:116893. [PMID: 33582494 DOI: 10.1016/j.watres.2021.116893] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 01/29/2021] [Accepted: 01/31/2021] [Indexed: 06/12/2023]
Abstract
Microcystin-LR (MC-LR), a polypeptide toxin generated by cyanobacteria, threatens the safety of drinking water supplies. In this study, fulvic acid (FA) was separated into two molecular weight (MW) ranges to evaluate the effects of FA size on MC-LR degradation in the chlorine/UV process. The rates of MC-LR degradation were significantly reduced in FA-containing water (3.7 × 10-3 s-1 for small MW FA; 4.3 × 10-3 s-1 for large MW FA) as compared with FA free water (4.9 × 10-3 s-1). The contributions of ClO• to MC-LR degradation were dramatically lower in small MW FA water (0.4%) than large MW FA (13.9%) and FA free water (17.4%), suggesting inhibition by lignin-like substances in FA in the transformation of Cl• to ClO• and scavenging ClO•. Monochlorination and hydroxylation occurred in the first step of the MC-LR degradation process. The accumulation of intermediate products in the chlorine/UV process indicated that small MW FA inhibited further degradation of MC-LR. Small MW FA, rather than MC-LR degradation, was the dominant factor in minimizing MC-LR cytotoxicity toward a human intestinal epithelial cell line.
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Affiliation(s)
- Qiyuan Sun
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, Fujian, 350007, China; Lyles School of Civil Engineering, Purdue University, West Lafayette, IN, 47907, United States; Fujian Key Laboratory of Pollution Control & Resource Reuse, Fuzhou, Fujian, 350007, China
| | - Shanbin Wu
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, Fujian, 350007, China
| | - Ran Yin
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Xingjian Bai
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, 47907, United States
| | - Arun K Bhunia
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, 47907, United States
| | - Changqing Liu
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, Fujian, 350007, China; Fujian Key Laboratory of Pollution Control & Resource Reuse, Fuzhou, Fujian, 350007, China
| | - Yuyi Zheng
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, Fujian, 350007, China; Fujian Key Laboratory of Pollution Control & Resource Reuse, Fuzhou, Fujian, 350007, China
| | - Feifeng Wang
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, Fujian, 350007, China; Fujian Key Laboratory of Pollution Control & Resource Reuse, Fuzhou, Fujian, 350007, China.
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, West Lafayette, IN, 47907, United States; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN, 47907, United States.
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10
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Sun Z, Fu J, Li X, Blatchley ER, Zhou Z. Using Algal Virus Paramecium bursaria Chlorella Virus as a Human Adenovirus Surrogate for Validation of UV Treatment Systems. Environ Sci Technol 2020; 54:15507-15515. [PMID: 33166135 DOI: 10.1021/acs.est.0c06354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Adenovirus is among the most UV-resistant waterborne human pathogens. There is a need to identify nonpathogenic surrogates for adenovirus for the water treatment industry. In this study, the feasibility of using the algal virus Paramecium bursaria chlorella virus (PBCV-1) as an adenovirus surrogate for validation of UV reactors was evaluated. The UV dose-response behavior of PBCV-1 to monochromatic UV radiation at 254 nm and action spectrum for wavelengths ranging from 214 to 289 nm were measured. A culture-based infectivity assay was used to evaluate viral inactivation, and a quantitative PCR assay was used to quantify DNA damage. A UV254 dose of 150 mJ/cm2 resulted in roughly 5-log10 units of reduction of PBCV-1, which is similar to that of adenovirus. Furthermore, the inactivation action spectrum of PBCV-1 was similar to that of adenovirus between 214 and 289 nm. A simplified and inexpensive prepurification method was also developed to prepare PBCV-1 viral suspensions with similar inactivation behavior to purified PBCV-1. Overall, PBCV-1 appears to represent an appropriate adenovirus surrogate for UV system performance evaluation and illustrates the potential of using algal viruses as nonpathogenic, easy to culture, and readily available surrogates for human pathogens.
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Affiliation(s)
- Zhe Sun
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jianing Fu
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Xing Li
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Zhi Zhou
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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11
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Yin R, Blatchley ER, Shang C. UV Photolysis of Mono- and Dichloramine Using UV-LEDs as Radiation Sources: Photodecay Rates and Radical Concentrations. Environ Sci Technol 2020; 54:8420-8429. [PMID: 32501682 DOI: 10.1021/acs.est.0c01639] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
UV-LEDs with four characteristic wavelengths (255, 265, 285, and 300 nm) were used to investigate the wavelength-dependence of the photolysis of two inorganic chloramines (NH2Cl and NHCl2) and their subsequent radical formation. The fluence-based photodecay rates of NH2Cl decreased with increasing wavelength from 255 to 300 nm, while NHCl2 photodecay rates exhibited the opposite wavelength-dependence. The fluence-based photodecay rate of NH2Cl was comparable to that of NHCl2 at 255 nm, but was lower than NHCl2 at other tested wavelengths. The wavelength-dependence was more influenced by the molar absorption coefficient than the apparent/innate quantum yield and the lower photosensitivity was mainly attributed to the higher bond (N-Cl) dissociation energy (BDE) of NH2Cl than NHCl2. The steady-state concentrations of HO• and reactive chlorine species (e.g., Cl2•-, ClO•, and Cl•) that were generated from the photolysis of NH2Cl and NHCl2 at different wavelengths were determined experimentally and compared with the simulated results by a kinetic model. UV photolysis of NHCl2 at 265, 285, and 300 nm generated higher concentrations of radicals (e.g., HO•, ClO•, Cl•, and Cl2-•) than NH2Cl, while UV photolysis of NH2Cl at 255 nm generated higher concentrations of HO•, ClO•, and Cl• but not Cl2-• than NHCl2. The findings of this study provide fundamental information to be used in selecting specific wavelengths of UV radiation for enhancing/optimizing NH2Cl/NHCl2 photodecay in swimming pools and radical generation for micropollutant abatement in drinking water treatment or potable water reuse.
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Affiliation(s)
- Ran Yin
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
- Lyles School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
- Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
- Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Chii Shang
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
- Hong Kong Branch of Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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Hu Y, Yang Q, Guo Y, Xu J, Zhou W, Li J, Blatchley ER. Volatile organic chloramines formation during ClO 2 treatment. J Environ Sci (China) 2020; 92:256-263. [PMID: 32430128 DOI: 10.1016/j.jes.2020.02.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/18/2020] [Accepted: 02/18/2020] [Indexed: 06/11/2023]
Abstract
Volatile organic chloramines are reported as the disinfection byproducts during chlorination or chloramination. However, ClO2, as an important alternative disinfectant for chlorine, was not considered to produce halogenated amines. In the present work, volatile organic chloramines including (CH3)2NCl and CH3NCl2 were found to be generated during the reaction of ClO2 and the dye pollutants. (CH3)2NCl was the dominant volatile DBP to result from ClO2 treated all four dye pollutants including Methyl Orange, Methyl Red, Methylene Blue and Malachite Green, with molar yields ranging from 2.6% to 38.5% at a ClO2 to precursor (ClO2/P) molar ratio of 10. HOCl was identified and proved to be the reactive species for the formation of (CH3)2NCl, which implied (CH3)2NCl was transformed by a combined oxidation of ClO2 and hypochlorous acid. (CH3)2NCl concentrations in the ppb range were observed when real water samples were treated by ClO2 in the presence of the dye pollutants. The results suggest that these azo dyes are one of the significant precursors for the formation of HOCl during ClO2 treatment and that organic chloramines should be considered in ClO2 disinfection chemistry and water treatment.
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Affiliation(s)
- Yuanzhi Hu
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, China
| | - Qian Yang
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, China
| | - Yang Guo
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, China
| | - Jie Xu
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, China
| | - Wenfeng Zhou
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, China
| | - Jing Li
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, China.
| | - Ernest R Blatchley
- School of Civil Engineering, 550 Stadium Mall Drive, Purdue University, West Lafayette, IN 47907-2051, USA; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN 47907, USA
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13
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Yang Q, Guo Y, E Y, Zhang S, Blatchley ER, Li J. Methyl chloride produced during UV 254 irradiation of saline water. J Hazard Mater 2020; 384:121263. [PMID: 31605974 DOI: 10.1016/j.jhazmat.2019.121263] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 06/10/2023]
Abstract
Ultraviolet (UV) irradiation is widely used for water treatment due to its effectiveness against a wide range of waterborne pathogens with minimal production of regulated disinfection byproducts. However, in this study, the formation of methyl chloride (CH3Cl) from guaiacol and chloride was observed during UV254 irradiation. The results indicated that direct photolysis of guaiacol produced an arenium ion, and the reactive methoxy group was further transformed to CH3Cl in the presence of chloride. O-quinone was detected as the primary product of the degradation of guaiacol resulting from UV254 irradiation. Other organic compounds containing methoxy, ethoxy, or methylamino groups with structures that are similar to guaiacol were also demonstrated to generate halocarbons in aqueous chloride or bromide solution under UV254 irradiation. Scavenging experiments and removal of oxygen demonstrated that neither oxygen nor chlorine radicals were involved in CH3Cl formation. In seawater samples, CH3Cl was also detected in the presence or absence of added organic matter. These results demonstrate that CH3Cl can be formed during UV254 irradiation in saline water and that attention should be paid to this compound and structurally-related compounds in the application of UV254 processes.
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Affiliation(s)
- Qian Yang
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Yang Guo
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Yue E
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Sanbing Zhang
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, 550 Stadium Mall Drive, Purdue University, West Lafayette, IN, 47907, USA; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Jing Li
- Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
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14
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Abstract
Carbamate insecticides, which are common micropollutants in surface waters, were found to generate dichloromethlyamine (DCMA) during chlorination. DCMA formation from other precursors has been reported previously; it is part of the emerging class of nitrogen-based disinfection byproducts (N-DBPs) of health concern in chlorinated water. However, there is a limited understanding about its formation, stability, and toxicity. Four carbamate insecticides (methomyl, carbofuran, carbaryl, and thiodicarb) were examined as DCMA precursors over a range of reaction conditions, based on variables of chlorine/precursor (Cl/P) molar ratio, pH, time, and temperature. DCMA was found to be the dominant volatile DBP to result from chlorination of all four carbamate insecticides, with molar yields ranging from 12% to 150% at a Cl/P molar ratio of 20. Further experiments indicated CH3NCl2 to be relatively stable, with a half-life of up to 35 h in water. The toxicity of CH3NCl2 was investigated using a bacterial bioluminescence inhibition test and survival of human lung tumor cells. The results of these toxicity assays indicated that CH3NCl2 is about 3 orders of magnitude more toxic than CHCl3. CH3NCl2 concentrations in the ppb range were observed to result from chlorination of surface water or tap water samples collected from several different locations in China. The results suggest that precursors to CH3NCl2 formation are ubiquitous and that CH3NCl2 poses a hazard to public health and the environment and should be considered in disinfection chemistry and water treatment.
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Affiliation(s)
- Yue E
- Department of Applied Chemistry , China Agricultural University , Beijing 100193 , China
| | - Qian Yang
- Department of Applied Chemistry , China Agricultural University , Beijing 100193 , China
| | - Yang Guo
- Department of Applied Chemistry , China Agricultural University , Beijing 100193 , China
| | - Lushi Lian
- Department of Applied Chemistry , China Agricultural University , Beijing 100193 , China
| | - Jing Li
- Department of Applied Chemistry , China Agricultural University , Beijing 100193 , China
| | - Ernest R Blatchley
- Lyles School of Civil Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
- Division of Environmental & Ecological Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
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15
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Clair RP, Rastogi R, Lee S, Clawson RA, Blatchley ER, Erdmann C. A Dialectical and Dialogical Approach to Health Policies and Programs: The Case of Open Defecation in India. Health Commun 2019; 34:1231-1241. [PMID: 29764196 DOI: 10.1080/10410236.2018.1473705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A multi-pronged approach to health policy and programs related to open defecation (OD) is proposed via a qualitative study conducted in rural India. A dialogic and dialectic perspective is employed to interpret the key findings from nine focus groups, highlighting the dialectical views toward OD and latrines. Findings indicate that current policy may be too narrow as it does not fully deal with the multiple reasons, including social communication as well as gender, cultural, health and work identity issues, for OD. The results suggest that OD is more complicated than it appears and a multi-pronged, poly-vocal approach to health communication campaigns and policy should be considered.
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Affiliation(s)
| | - Rahul Rastogi
- Department of Communication and Media, State University of New York, College at Oneonta
| | - Seungyoon Lee
- Brian Lamb School of Communication, Purdue University
| | | | - Ernest R Blatchley
- Lyles School of Civil Engineering and Division of Environmental and Ecological Engineering, Purdue University
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16
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Li M, Li W, Wen D, Bolton JR, Blatchley ER, Qiang Z. Micropollutant Degradation by the UV/H 2O 2 Process: Kinetic Comparison among Various Radiation Sources. Environ Sci Technol 2019; 53:5241-5248. [PMID: 30920806 DOI: 10.1021/acs.est.8b06557] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Kinetic comparisons of micropollutant degradation by ultraviolet (UV) based advanced oxidation processes among various radiation sources are an important issue, yet this is still a challenge at present. This study investigated comparatively the kinetics of sulfamethazine (SMN) degradation by the UV/H2O2 process among three representative radiation sources, including low-pressure mercury UV (LPUV, monochromatic), medium-pressure mercury UV (MPUV, polychromatic), and vacuum UV(VUV)/UV (dual wavelengths causing different reaction mechanisms) lamps. Experiments were conducted with a newly developed mini-fluidic MPUV photoreaction system and a previously developed mini-fluidic VUV/UV photoreaction system. Measured and modeled results both indicate that the photon fluence-based SMN degradation rate constant ( kp') followed a descending order of VUV/UV/H2O2 > MPUV/H2O2 (200-300 nm) > LPUV/H2O2, and the kp' of the MPUV lamp was dependent on the wavelength range selected for photon fluence calculation. Analysis of potential errors revealed that a shorter effective path-length could have a lower error, and the maximum errors for the MPUV/H2O2 and LPUV/H2O2 processes in this study were 7.7% and 18.2%, respectively. This study has developed a new method for kinetic comparisons of micropollutant degradation by UV-AOPs among various radiation sources at bench-scale, which provides useful reference to practical applications.
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Affiliation(s)
- Mengkai Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
- Lyles School of Civil Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Wentao Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
| | - Dong Wen
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
| | - James R Bolton
- Department of Civil and Environmental Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Ernest R Blatchley
- Lyles School of Civil Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
- Division of Environmental & Ecological Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
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17
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Zhang X, Ren P, Li W, Lei Y, Yang X, Blatchley ER. Synergistic removal of ammonium by monochloramine photolysis. Water Res 2019; 152:226-233. [PMID: 30677633 DOI: 10.1016/j.watres.2018.12.065] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 12/07/2018] [Accepted: 12/25/2018] [Indexed: 06/09/2023]
Abstract
The presence of ammonium (NH4+) in drinking water treatment results in inhibition of disinfection efficiency and formation of nitrogenous disinfection by-products. Our previous study found monochloramine (NH2Cl) photolysis under 254 nm UV irradiation can be effective for removal of NH4+; however, the mechanisms of NH4+ degradation in this process were unknown. The kinetics and fundamental radical chemistry responsible for NH4+ removal in the UV/NH2Cl process were investigated in this study. The results showed that the pseudo first-order rate constant for NH4+ degradation in the UV/NH2Cl process ranged between 3.6 × 10-4 to 1.8 × 10-3 s-1. Solution pH affected radical conversion and a higher NH4+ degradation efficiency was achieved under acidic conditions. The effects of chloride were limited; however, the presence of either bicarbonate or natural organic matter scavenged radicals and inhibited NH4+ removal. NH2Cl photolysis generated an aminyl radical (NH2•) and a chlorine radical (Cl•) that further transformed to a chlorine dimer (Cl2•-) and a hydroxyl radical (HO•). The second-order rate constants for Cl• and Cl2•- reacting with NH4+ were estimated as 2.59 × 108 M-1s-1 and 3.45 × 105 M-1s-1 at pH 3.9, respectively. Cl•, Cl2•-, and HO• contributed 95.2%, 3.5%, and 1.3% to NH4+ removal, respectively, at the condition of 3 mM NH2Cl and pH 7.5. Major products included nitrite and nitrate, possibly accompanied by nitrogen-containing gases. This investigation provides insight into the photochemistry of NH4+ degradation in the UV/NH2Cl process and offers an alternative method for drinking water production.
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Affiliation(s)
- Xinran Zhang
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China.
| | - Pengfei Ren
- Guangzhou Municipal Engineering Design & Research Institute, Guangzhou, 510060, China
| | - Weiguang Li
- School of Municipal and Environmental Engineering, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, PR China
| | - Yu Lei
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Xin Yang
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN, 47907-2051, USA; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN, 47907-2051, USA
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18
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Li M, Li W, Bolton JR, Blatchley ER, Qiang Z. Organic Pollutant Degradation in Water by the Vacuum-Ultraviolet/Ultraviolet/H 2O 2 Process: Inhibition and Enhancement Roles of H 2O 2. Environ Sci Technol 2019; 53:912-918. [PMID: 30548062 DOI: 10.1021/acs.est.8b05831] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A vacuum-ultraviolet/ultraviolet (VUV/UV) mercury lamp was found to be a highly efficient radiation source for UV-based advanced oxidation processes (AOPs). If this lamp could enhance the UV/H2O2 process, it would be very attractive. Hence, we have investigated sulfamethazine (SMN) degradation by the VUV/UV/H2O2 process based on a bench-scale mini-fluidic VUV/UV photoreaction system (MVPS), a pilot reactor, and a model analysis. At high [SMN]0 in the MVPS, the apparent SMN degradation rate constant ( k'app) increased with increasing H2O2 dose, while at low [SMN]0, k'app decreased with increasing H2O2 dose; this behavior was unexpected. Meanwhile, at low [SMN]0 in a pilot reactor, H2O2 induced just a slight enhancement in the VUV/UV/H2O process. A numerical simulation of the process suggested that for an integrated AOP (i.e., VUV/UV/H2O2) consisting of various component AOPs, H2O2 could inhibit the component AOPs with HO* that did not originate from H2O2 (e.g., VUV photolysis of water). The apparent H2O2 role in the integrated AOPs was dependent on the contribution comparison between component AOPs that involved HO* that did or did not originate from H2O2. These results revealed important information regarding the application of the VUV/UV/H2O2 process in water treatment.
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Affiliation(s)
- Mengkai Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences , Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
| | - Wentao Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences , Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
| | - James R Bolton
- Department of Civil and Environmental Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | | | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences , Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
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19
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Mbonimpa EG, Blatchley ER, Applegate B, Harper WF. Ultraviolet A and B wavelength-dependent inactivation of viruses and bacteria in the water. J Water Health 2018; 16:796-806. [PMID: 30285960 DOI: 10.2166/wh.2018.071] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
UVA and UVB can be applied to solar disinfection of water. In this study, the inactivation and photoreactivation of viruses and bacteria in the UVA-B range were analyzed. MS2 and T4 bacteriophages, and Escherichia coli were used as surrogates to quantify dose-response behaviors. Inactivation in UVC was used to validate the methodology and to expand the inactivation action spectra. The results showed log-linear inactivation for MS2 and T4 in the 254-320 nm wavelength range. T4 inactivation was consistently faster than MS2 (except at 320 nm), and for both phages, inactivation decreased with increasing wavelength. The dose-response of bacteria exhibited a lag at low doses, possibly because the photons must strike a discrete number of critical targets before growth stops. A tail was present at high doses for some wavelengths, perhaps due to clumping or the presence of subgroups with higher resistance. The inactivation action spectra for bacteria exhibited a reduction in inactivation as wavelength increased. No bacterial inactivation was observed beyond 320 nm at doses applied. After inactivation at 297 nm (UVA), bacteria regained viability through photoreactivation, and repair increased with increase in photoreactivating light exposure time. This implies additional doses above inactivation thresholds are required to cause irreversible damage. These results are useful for designing solar disinfection systems.
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Affiliation(s)
- E G Mbonimpa
- Department of Systems Engineering and Management, Air Force Institute of Technology, WPAFB, Ohio, USA E-mail:
| | - E R Blatchley
- School of Civil Engineering, Purdue University, West Lafayette, Indiana, USA
| | - B Applegate
- Department of Food Science, Purdue University, West Lafayette, Indiana, USA
| | - W F Harper
- Department of Systems Engineering and Management, Air Force Institute of Technology, WPAFB, Ohio, USA E-mail:
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20
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Li M, Hao M, Yang L, Yao H, Bolton JR, Blatchley ER, Qiang Z. Trace Organic Pollutant Removal by VUV/UV/chlorine Process: Feasibility Investigation for Drinking Water Treatment on a Mini-Fluidic VUV/UV Photoreaction System and a Pilot Photoreactor. Environ Sci Technol 2018; 52:7426-7433. [PMID: 29792423 DOI: 10.1021/acs.est.8b00611] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The vacuum-ultraviolet/ultraviolet/chlorine (VUV/UV/chlorine) process, with a VUV/UV mercury lamp used as the light source, was found to be a highly efficient advanced oxidation process (AOP) in a previous study. Hence, its application feasibility for trace organic pollutant removal from drinking water becomes attractive. In this work, a bench-scale mini-fluidic VUV/UV photoreaction system was used to determine the degradation kinetics of sulfamethazine (SMN), a model sulfonamide antibiotic frequently detected with trace levels in aquatic environments. Results indicated that SMN (0.1 mg L-1) could be degraded rapidly by VUV/UV/chlorine, and a synergism was observed between the VUV/UV and UV/chlorine processes. Photon-fluence based rate constants of SMN degradation were determined to be 6.76 × 103 and 8.51 × 103 m2 einstein-1 at chlorine doses of 0.05 and 0.5 mg L-1, respectively. The presence of natural organic matter in real waters significantly inhibited SMN degradation. In addition, pilot tests were conducted to explore the practical performance of the VUV/UV/chlorine process, thereby allowing electrical energy per order to be calculated for cost evaluation. The effect of flow pattern on photoreactor efficiency was also analyzed by computational fluid dynamics simulations. Both bench- and pilot-scale tests have demonstrated that the VUV/UV/chlorine process, as a new AOP, has potential applications to trace organic pollutant removal in small-scale water treatment.
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Affiliation(s)
- Mengkai Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
- Lyles School of Civil Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Mengyu Hao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
- Department of Municipal and Environmental Engineering , Beijing Jiaotong University , Beijing 100044 , China
| | - Laxiang Yang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
| | - Hong Yao
- Department of Municipal and Environmental Engineering , Beijing Jiaotong University , Beijing 100044 , China
| | - James R Bolton
- Department of Civil and Environmental Engineering , University of Alberta , Edmonton , AB T6G 1H9 , Canada
| | - Ernest R Blatchley
- Lyles School of Civil Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
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Abstract
The performance of photochemical reactors is governed by the spatial distribution of radiant energy within the irradiated region of the reactor. Ray tracing has been widely used for simulation of lighting systems. The central hypothesis of this work was that ray tracing can provide accurate simulations of fluence rate fields within ultraviolet (UV) photoreactors by accounting for the physical and optical phenomena that will govern fluence rate fields in UV photoreactors. Ray tracing works by simulating the behavior of a large population of rays emanating from a radiation source to describe the spatial distribution of radiant energy (i.e., fluence rate) within a system. In this study, fluence rate calculations were performed using commercial ray tracing software for three basic UV reactors, each with a single low-pressure Hg lamp. Fluence rate calculations in the ray tracing program were based on the formal definition of fluence rate, calculated as the incident radiant power from all directions on a small spherical receptor, divided by the cross-sectional area of that sphere. The results of this study demonstrate that ray tracing can provide predictions of fluence rate in UV radiative systems that are close to experimental measurements and the predictions of other numerical methods.
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Affiliation(s)
- Yousra M Ahmed
- Lyles School of Civil Engineering , Purdue University , 550 Stadium Mall Drive , West Lafayette , Indiana 47907 , United States
| | - Mark Jongewaard
- LTI Optics, LLC , Westminster , Colorado 80021 , United States
| | - Mengkai Li
- Lyles School of Civil Engineering , Purdue University , 550 Stadium Mall Drive , West Lafayette , Indiana 47907 , United States
- Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , 18 Shuang-qing Road , Beijing 100085 , China
| | - Ernest R Blatchley
- Lyles School of Civil Engineering , Purdue University , 550 Stadium Mall Drive , West Lafayette , Indiana 47907 , United States
- Division of Environmental & Ecological Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
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22
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Weng S, Yang JY, Li YH, Blatchley ER. UV-induced effects on toxicity of model disinfection byproducts. Sci Total Environ 2017; 599-600:94-97. [PMID: 28467913 DOI: 10.1016/j.scitotenv.2017.04.198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/13/2017] [Accepted: 04/26/2017] [Indexed: 06/07/2023]
Abstract
UV (Ultraviolet)-based treatment has been demonstrated to be effective for removal of some disinfection byproducts (DBPs) and to be beneficial for reduction of genotoxicity and cytotoxicity in chlorinated water. However, to a large extent, UV-induced effects on chemistry and toxicology have been treated as a black box, in the sense that little or no UV dose-dependent behavior has been reported. To address this issue, the effects of UV254 irradiation on 1,4-dibenzoquinone (BQ), 2,6-dichloro-1,4-benzoquinone (DCBQ), and chlorocreatinine (Cl-Cre) as model DBPs were examined, both in terms of photodegradation and cytotoxicity. These compounds have been identified as DBPs that are relevant in swimming pool settings; however, these compounds will be relevant in other water treatment settings, including drinking water production and wastewater reuse. UV254 irradiation was shown to promote photodecay of all three compounds. However, for BQ and DCBQ, the corresponding cytotoxicity of the UV-irradiated samples remained essentially unchanged, even when the compound was completely photodegraded. These results indicate that the photodegradation products of BQ and DCBQ carry similar cytotoxicity as their respective parent compounds. On the other hand, UV254-irradiation of Cl-Cre yielded a decrease in cytotoxicity that correlated with photodechlorination of Cl-Cre. These experiments also demonstrated a reduction in cytotoxicity in connection with photodechlorination of an N-chlorinated organic compound. Overall, the results of these experiments indicate the importance of defining products of UV photodecay processes, both in terms of chemistry and toxicity; these attributes are expected to be important in many UV-based applications, including potable water production, water reuse, and recreational water settings.
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Affiliation(s)
- ShihChi Weng
- JHU/MWH Alliance, 615 N. Wolfe St., Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jer-Yen Yang
- Department of Basic Medical Sciences, Purdue University, IN 47907, USA; Center for Cancer Research, Purdue University, IN 47907, USA
| | - Yen-Hsing Li
- Department of Basic Medical Sciences, Purdue University, IN 47907, USA
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, IN 47907, USA; Division of Environmental and Ecological Engineering, Purdue University, IN 47907, USA.
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23
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Li M, Li W, Wen D, Qiang Z, Blatchley ER. Experimental Evaluation of Turbidity Impact on the Fluence Rate Distribution in a UV Reactor Using a Microfluorescent Silica Detector. Environ Sci Technol 2017; 51:13241-13247. [PMID: 29068223 DOI: 10.1021/acs.est.7b02730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Turbidity is a common parameter used to assess particle concentration in water using visible light. However, the fact that particles play multiple roles (e.g., scattering, refraction, and reflection) in influencing the optical properties of aqueous suspensions complicates examinations of their effects on ultraviolet (UV) photoreactor performance. To address this issue, UV fluence rate (FR) distributions in a photoreactor containing various particle suspensions (SiO2, MgO, and TiO2) were measured using a microfluorescent silica detector (MFSD). Reflectance of solid particles, as well as transmittance and scattering properties of the suspensions were characterized at UV, visible, and infrared (IR) wavelengths. The results of these measurements indicated that the optical properties of all three particle types were similar at visible and IR wavelengths, but obvious differences were evident in the UV range. The FR results indicated that for turbidity associated with SiO2 and MgO suspensions, the weighted average FR (WAFR) increased relative to deionized water. These increases were attributed to low particle photon absorption and strong scattering. In contrast, the WAFR values decreased with increasing turbidity for TiO2 suspensions because of their high particle photon absorption and low scattering potential. The findings also indicate that measurements of scattering and transmittance at UV wavelengths can be used to quantify the effects of turbidity on UV FR distributions.
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Affiliation(s)
- Mengkai Li
- Lyles School of Civil Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Wentao Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Dong Wen
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Division of Environmental & Ecological Engineering, Purdue University , West Lafayette, Indiana 47907, United States
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24
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Sun Z, Blatchley ER. Tetraselmis as a challenge organism for validation of ballast water UV systems. Water Res 2017; 121:311-319. [PMID: 28570870 DOI: 10.1016/j.watres.2017.05.052] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 05/20/2017] [Accepted: 05/24/2017] [Indexed: 06/07/2023]
Abstract
Transport and release of waterborne organisms as a result of ballasting and de-ballasting operations is widely acknowledged to represent an important mechanism for invasions by non-indigenous species. Regulatory requirements have been implemented globally to require treatment of ballast water before its release to the environment as a means of minimizing risks of invasion. UV-based processes represent an option for ballast water treatment; however, their use will require development of appropriate methods for reactor validation. To address this need, Tetraselmis was examined as challenge organism using a most probable number (MPN) assay for quantification of the concentration of viable (reproductively active) cells in suspension. A low pressure collimated-beam reactor was used to investigate UV254 dose-response behavior of Tetraselmis. Based on the experimental conditions applied, Tetraselmis indicated 4.5-5 log10 units of inactivation for UV254 doses of approximately 120 mJ/cm2, with no apparent change of resistance resulting from repeated exposure. A medium pressure UV collimated-beam reactor equipped with a series of narrow bandpass optical filters was used to investigate the action spectrum of Tetraselmis for wavelengths ranging from 228 nm-297 nm. Radiation with wavelengths in the range 254-280 nm was observed to be most efficient for inactivation of Tetraselmis. Additionally, DNA was extracted from Tetraselmis to allow measurement of its absorption spectrum. These results indicated strong absorbance from 254 nm to 280 nm, thereby suggesting that damage to DNA plays an important role in the inactivation of Tetraselmis sp. However, deviations of the action spectrum shape from the shape of the DNA absorption spectrum suggest that UV-induced damage to biomolecules other than DNA may contribute to Tetraselmis inactivation at some wavelengths in the UVC range.
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Affiliation(s)
- Zhe Sun
- Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN 47907, USA.
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25
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Li M, Qiang Z, Wang C, Bolton JR, Blatchley ER. Experimental Assessment of Photon Fluence Rate Distributions in a Medium-Pressure UV Photoreactor. Environ Sci Technol 2017; 51:3453-3460. [PMID: 28221779 DOI: 10.1021/acs.est.6b06298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The performance of a medium-pressure (MP) mercury lamp photoreactor is strongly influenced by the spatial photon fluence rate (PFR) distributions which are wavelength-dependent. To address this issue, PFR distributions in an MP lamp photoreactor were measured using a 360-degree response microfluorescent silica detector (MFSD). To accurately express the optical behavior in an MP photoreactor, PFR, MFSD response PFR (PFRMFSD), and effective germicidal PFR (PFRGER) were defined and compared. The measured axial and radial PFRMFSD values agreed well with the corresponding results from a simulation model (UVCalc). The PFR and PFRGER were obtained from the measured PFRMFSD by using correction factors calculated by the UVCalc. Under identical UV transmittance (254 nm) conditions (75% and 85%), the weighted average PFRGER values were 13.3-18.7% lower than the corresponding PFR values, indicating that PFRGER, rather than PFR should be used in MP photoreactor design to meet disinfection standards. Based on measured lamp output, medium absorption spectrum, MFSD response, and microbial DNA response spectrum, the detailed relationships between the PFR, PFRMFSD, and PFRGER were elucidated. This work proposes a new method for the accurate description of wavelength-dependent PFR distributions in MP photoreactors, thus providing an important tool for the optimal design of these systems.
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Affiliation(s)
- Mengkai Li
- Lyles School of Civil Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Chen Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - James R Bolton
- Department of Civil and Environmental Engineering, University of Alberta , Edmonton, AB T6G 2W2, Canada
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Division of Environmental & Ecological Engineering, Purdue University , West Lafayette, Indiana 47907, United States
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26
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E Y, Bai H, Lian L, Li J, Blatchley ER. Effect of chloride on the formation of volatile disinfection byproducts in chlorinated swimming pools. Water Res 2016; 105:413-420. [PMID: 27664542 DOI: 10.1016/j.watres.2016.09.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 08/17/2016] [Accepted: 09/11/2016] [Indexed: 06/06/2023]
Abstract
Chloride can accumulate in chlorinated swimming pool water. Although substantial efforts have been made to examine the effects of halide ions on the formation of volatile disinfection byproducts (DBPs), most have focused on bromide. The effects of chloride ion concentration on the formation of volatile DBPs in swimming pools remain largely unstudied. In this study, chlorination of typical precursors and body fluid analogue (BFA) were investigated with variable chloride concentration and pH. The formation of three volatile DBPs (NCl3, CHCl3 and CNCHCl2) was observed to be linearly correlated with chloride concentration, both in bench experiments and in actual swimming pool water samples. Free chlorine consumption was also observed to increase with chloride concentration. These behaviors appear to be attributable to shifts in speciation of free chlorine, with higher chloride resulting in higher concentration of molecular chlorine (Cl2), which is much more reactive than HOCl. The results of this work suggest that changes in pool management strategies to promote low chloride concentration could be important for control of volatile DBPs in pools and to economize free chlorine usage.
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Affiliation(s)
- Yue E
- Department of Applied Chemistry, China Agricultural University, Beijing, 100193, China
| | - Hui Bai
- Department of Applied Chemistry, China Agricultural University, Beijing, 100193, China
| | - Lushi Lian
- Department of Applied Chemistry, China Agricultural University, Beijing, 100193, China
| | - Jing Li
- Department of Applied Chemistry, China Agricultural University, Beijing, 100193, China.
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, 550 Stadium Mall Drive, Purdue University, West Lafayette, IN, 47907, USA; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN, 47907, USA
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27
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Zare Afifi M, Blatchley ER. Effects of UV-based treatment on volatile disinfection byproducts in a chlorinated, indoor swimming pool. Water Res 2016; 105:167-177. [PMID: 27614037 DOI: 10.1016/j.watres.2016.08.064] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/26/2016] [Accepted: 08/29/2016] [Indexed: 06/06/2023]
Abstract
Ultraviolet (UV) irradiation and chlorination are commonly used together in treatment of swimming pool water because they function as complementary disinfectants and because UV-based processes have been shown to promote photodecay of chloramines. However, UV-based treatment also has the potential to promote formation of some disinfection byproducts (DBPs). As a result, the overall effects of UV irradiation with chlorination on swimming pool chemistry remain unclear. To address this issue, a three-year study was conducted in a chlorinated, indoor swimming pool under three different operating conditions: conventional chlorination (1st year) which served as a control, chlorination augmented by MP UV irradiation (2nd year), and chlorination augmented by LP UV irradiation (3rd year). Water samples were collected from the pool for measurement of pH, temperature, total alkalinity, free and combined chlorine, eleven volatile DBPs, and urea concentration. After installation of MP UV, the concentrations of most volatile DBPs decreased; similar effects were observed after inclusion of LP UV. Collectively, these results imply an overall improvement in water quality as a result of the inclusion of the both UV systems. In general, MP UV was more efficient than LP UV for reducing the concentrations of most of the volatile DBPs measured in this pool. However, a need exists to standardize the application of UV systems in recreational water settings.
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Affiliation(s)
- Mehrnaz Zare Afifi
- Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN 47907, USA.
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28
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Daiber EJ, DeMarini DM, Ravuri SA, Liberatore HK, Cuthbertson AA, Thompson-Klemish A, Byer JD, Schmid JE, Afifi MZ, Blatchley ER, Richardson SD. Progressive Increase in Disinfection Byproducts and Mutagenicity from Source to Tap to Swimming Pool and Spa Water: Impact of Human Inputs. Environ Sci Technol 2016; 50:6652-62. [PMID: 27124361 DOI: 10.1021/acs.est.6b00808] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Pools and spas are enjoyed throughout the world for exercise and relaxation. However, there are no previous studies on mutagenicity of disinfected spa (hot tub) waters or comprehensive identification of disinfection byproducts (DBPs) formed in spas. Using 28 water samples from seven sites, we report the first integrated mutagenicity and comprehensive analytical chemistry of spas treated with chlorine, bromine, or ozone, along with pools treated with these same disinfectants. Gas chromatography (GC) with high-resolution mass spectrometry, membrane-introduction mass spectrometry, and GC-electron capture detection were used to comprehensively identify and quantify DBPs and other contaminants. Mutagenicity was assessed by the Salmonella mutagenicity assay. More than 100 DBPs were identified, including a new class of DBPs, bromoimidazoles. Organic extracts of brominated pool/spa waters were 1.8× more mutagenic than chlorinated ones; spa waters were 1.7× more mutagenic than pools. Pool and spa samples were 2.4 and 4.1× more mutagenic, respectively, than corresponding tap waters. The concentration of the sum of 21 DBPs measured quantitatively increased from finished to tap to pool to spa; and mutagenic potency increased from finished/tap to pools to spas. Mutagenic potencies of samples from a chlorinated site correlated best with brominated haloacetic acid concentrations (Br-HAAs) (r = 0.98) and nitrogen-containing DBPs (N-DBPs) (r = 0.97) and the least with Br-trihalomethanes (r = 0.29) and Br-N-DBPs (r = 0.04). The mutagenic potencies of samples from a brominated site correlated best (r = 0.82) with the concentrations of the nine HAAs, Br-HAAs, and Br-DBPs. Human use increased significantly the DBP concentrations and mutagenic potencies for most pools and spas. These data provide evidence that human precursors can increase mutagenic potencies of pools and spas and that this increase is associated with increased DBP concentrations.
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Affiliation(s)
- Eric J Daiber
- Student Services Authority, U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, Georgia 30605, United States
| | - David M DeMarini
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Sridevi A Ravuri
- Student Services Authority, U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, Georgia 30605, United States
| | - Hannah K Liberatore
- Department of Chemistry and Biochemistry, University of South Carolina , 631 Sumter St., Columbia, South Carolina 29208, United States
| | - Amy A Cuthbertson
- Department of Chemistry and Biochemistry, University of South Carolina , 631 Sumter St., Columbia, South Carolina 29208, United States
| | - Alexis Thompson-Klemish
- Department of Chemistry and Biochemistry, University of South Carolina , 631 Sumter St., Columbia, South Carolina 29208, United States
| | - Jonathan D Byer
- LECO Corp., 3000 Lakeview Ave., St. Joseph, Michigan 49085, United States
| | - Judith E Schmid
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Mehrnaz Z Afifi
- Lyles School of Civil Engineering, Purdue University , 550 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University , 550 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
- Division of Environmental & Ecological Engineering, Purdue University , 500 Central Drive, West Lafayette, Indiana 47907, United States
| | - Susan D Richardson
- Department of Chemistry and Biochemistry, University of South Carolina , 631 Sumter St., Columbia, South Carolina 29208, United States
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29
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Grady CA, Kipkorir EC, Nguyen K, Blatchley ER. Microbial quality of improved drinking water sources: evidence from western Kenya and southern Vietnam. J Water Health 2015; 13:607-612. [PMID: 26042991 DOI: 10.2166/wh.2014.206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In recent decades, more than 2 billion people have gained access to improved drinking water sources thanks to extensive effort from governments, and public and private sector entities. Despite this progress, many water sector development interventions do not provide access to safe water or fail to be sustained for long-term use. The authors examined drinking water quality of previously implemented water improvement projects in three communities in western Kenya and three communities in southern Vietnam. The cross-sectional study of 219 households included measurements of viable Escherichia coli. High rates of E. coli prevalence in these improved water sources were found in many of the samples. These findings suggest that measures above and beyond the traditional 'improved source' definition may be necessary to ensure truly safe water throughout these regions.
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Affiliation(s)
- Caitlin A Grady
- Ecological Sciences and Engineering Program, Purdue University, 550 Stadium Mall, West Lafayette, IN 47907-2051, USA E-mail: ; School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Emmanuel C Kipkorir
- School of Engineering, Department of Civil and Structural Engineering, University of Eldoret, Eldoret, Kenya
| | - Kien Nguyen
- Research Center for Rural Development, An Giang University, Long Xuyen, Vietnam
| | - E R Blatchley
- School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA; Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, IN 47907, USA
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30
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Zhang X, Li W, Blatchley ER, Wang X, Ren P. UV/chlorine process for ammonia removal and disinfection by-product reduction: comparison with chlorination. Water Res 2015; 68:804-811. [PMID: 25466638 DOI: 10.1016/j.watres.2014.10.044] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 10/14/2014] [Accepted: 10/20/2014] [Indexed: 06/04/2023]
Abstract
The combined application of UV irradiation at 254 nm and chlorination (UV/chlorine process) was investigated for ammonia removal in water treatment. The UV/chlorine process led to higher ammonia removal with less chlorine demand, as compared to breakpoint chlorination. Chlorination of NH₃ led to NH₂Cl formation in the first step. The photolysis of NH₂Cl and radical- mediated oxidation of ammonia appeared to represent the main pathways for ammonia removal. The trivalent nitrogen of ammonia was oxidized, presumably by reactions with aminyl radicals and chlorine radicals. Measured products included NO₃⁻and NO₂⁻; it is likely that N₂ and N₂O were also generated. In addition, UV irradiation appeared to have altered the reactivity of NOM toward free chlorine. The UV/chlorine process had lower chlorine demand, less C-DBPs (THMs and HAAs), but more HANs than chlorination. These results indicate that the UV/chlorine process could represent an alternative to conventional breakpoint chlorination for ammonia-containing water, with several advantages in terms of simplicity, short reaction time, and reduced chemical dosage.
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Affiliation(s)
- Xinran Zhang
- School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, PR China
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31
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Zare Afifi M, Blatchley ER. Seasonal dynamics of water and air chemistry in an indoor chlorinated swimming pool. Water Res 2015; 68:771-783. [PMID: 25462781 DOI: 10.1016/j.watres.2014.10.037] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 10/15/2014] [Accepted: 10/20/2014] [Indexed: 06/04/2023]
Abstract
Although swimming is known to be beneficial in terms of cardiovascular health, as well as for some forms of rehabilitation, swimming is also known to present risks to human health, largely in the form of exposure to microbial pathogens and disinfection byproducts (DBPs). Relatively little information is available in the literature to characterize the seasonal dynamics of air and water chemistry in indoor chlorinated swimming pools. To address this issue, water samples were collected five days per week from an indoor chlorinated swimming pool facility at a high school during the academic year and once per week during summer over a fourteen-month period. The samples were analyzed for free and combined chlorine, urea, volatile DBPs, pH, temperature and total alkalinity. Membrane Introduction Mass Spectrometry (MIMS) was used to identify and measure the concentrations of eleven aqueous-phase volatile DBPs. Variability in the concentrations of these DBPs was observed. Factors that influenced variability included bather loading and mixing by swimmers. These compounds have the ability to adversely affect water and air quality and human health. A large fraction of the existing literature regarding swimming pool air quality has focused on trichloramine (NCl₃). For this work, gas-phase NCl₃ was analyzed by an air sparging-DPD/KI method. The results showed that gas-phase NCl₃ concentration is influenced by bather loading and liquid-phase NCl₃ concentration. Urea is the dominant organic-N compound in human urine and sweat, and is known to be an important precursor for producing NCl₃ in swimming pools. Results of daily measurements of urea indicated a link between bather load and urea concentration in the pool.
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Affiliation(s)
- Mehrnaz Zare Afifi
- Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA
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32
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Lian L, E Y, Li J, Blatchley ER. Volatile disinfection byproducts resulting from chlorination of uric acid: implications for swimming pools. Environ Sci Technol 2014; 48:3210-3217. [PMID: 24568660 DOI: 10.1021/es405402r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Cyanogen chloride (CNCl) and trichloramine (NCl3) are important disinfection byproducts in chlorinated swimming pools. However, some unknowns exist regarding the precursors of their formation. In this study, uric acid is shown to be an efficient precursor to formation of CNCl and NCl3. The molar yields of CNCl and NCl3 were observed to be as high as 44% (pH = 6.0, chlorine/precursor molar ratio [Cl/P] = 6.4) and 108% (pH = 7.0, Cl/P = 30), respectively, both being strong functions of Cl/P, pH, and temperature. Analysis of swimming pool water samples, combined with the results of experiments involving chlorination of uric acid, and chlorination of body fluid analog mixtures, indicated that uric acid chlorination may account for a large fraction of CNCl formation in swimming pools. Moreover, given that uric acid introduction to pools is attributable to urination, a voluntary action for most swimmers, these findings indicate important benefits to pool water and air chemistry that could result from improved hygiene habits on the part of swimmers.
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Affiliation(s)
- Lushi Lian
- Department of Applied Chemistry, China Agricultural University , Beijing 100193, People's Republic of China
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33
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Weng SC, Li J, Wood KV, Kenttämaa HI, Williams PE, Amundson LM, Blatchley ER. UV-induced effects on chlorination of creatinine. Water Res 2013; 47:4948-4956. [PMID: 23863372 DOI: 10.1016/j.watres.2013.05.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 04/26/2013] [Accepted: 05/20/2013] [Indexed: 06/02/2023]
Abstract
Ultraviolet (UV) irradiation is commonly employed for water treatment in swimming pools to complement conventional chlorination, and to reduce the concentration of inorganic chloramine compounds. The approach of combining UV irradiation and chlorination has the potential to improve water quality, as defined by microbial composition. However, relatively little is known about the effects of this process on water chemistry. To address this issue, experiments were conducted to examine the effects of sequential UV254 irradiation/chlorination, as will occur in recirculating system of swimming pools, on disinfection byproduct (DBP) formation. Creatinine, which is present in human sweat and urine, was selected as the target precursor for these experiments. Enhanced formation of dichloromethylamine (CH3NCl2) and inorganic chloramines was observed to result from post-chlorination of UV-irradiated samples. Chlorocreatinine was found to be more sensitive to UV254 irradiation than creatinine; UV254 irradiation of chlorocreatinine resulted in opening of the ring structure, thereby yielding a series of intermediates that were more susceptible to free chlorine attack than their parent compound. The quantum yields for photodegradation of creatinine and chlorocreatinine at 254 nm were estimated at 0.011 ± 0.002 mol/E and 0.144 ± 0.011 mol/E, respectively. The N-Cl bond was found to be common to UV-sensitive chlorinated compounds (e.g., inorganic chloramines, CH3NCl2, and chlorocreatinine); compounds that were less susceptible to UV-based attack generally lacked the N-Cl bond. This suggested that the N-Cl bond is susceptible to UV254 irradiation, and cleavage of the N-Cl bond appears to open or promote reaction pathways that involve free chlorine, thereby enhancing formation of some DBPs and promoting loss of free chlorine. Proposed reaction mechanisms to describe this behavior based on creatinine as a precursor are presented.
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Affiliation(s)
- Shih Chi Weng
- School of Civil Engineering, Purdue University, West Lafayette, IN 47906, USA
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34
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Weng S, Blatchley ER. Ultraviolet-induced effects on chloramine and cyanogen chloride formation from chlorination of amino acids. Environ Sci Technol 2013; 47:4269-4276. [PMID: 23560482 DOI: 10.1021/es400273w] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ultraviolet (UV)-based treatment is commonly used to augment chlorination in swimming pools. However, the effects of combined application of UV254/chlorine on disinfection byproduct (DBP) formation are incompletely defined. To examine this issue, experiments were conducted with amino acids (l-arginine, l-histidine, and glycine) that are representative of those introduced to swimming pools via human body fluids. For each precursor, stepwise experiments were conducted with chlorination and UV254 exposure, with/without post-chlorination. Net formation and decomposition of chloramines and cyanogen chloride (CNCl) were measured for a range of chlorine/precursor (Cl/P) molar ratios and UV254 doses. Substantial production of NH2Cl from l-arginine and l-histidine was observed at Cl/P = 1.0 and 2.0 when post-chlorination was applied to UV254-irradiated samples. These results suggested a mechanism of rapid N-chlorination, followed by cleavage of NH3 by UV254 irradiation. CNCl formation was observed from UV254-irradiated samples of l-arginine and l-histidine when Cl/P = 2.0 and 3.0, as well as from glycine for Cl/P ≤ 1. Structurally related precursor compounds were examined for CNCl formation potential in chlorination/UV experiments. CNCl formation was promoted by UV254 exposure of chlorinated imidazole and guanidine compounds, which suggested that these groups contributed to CNCl formation. The results have implications with respect to the application of chlorine and UV for water treatment in swimming pools and other settings, such as water reuse and advanced oxidation processes.
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Affiliation(s)
- ShihChi Weng
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, USA
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35
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Blatchley ER, Weng S, Afifi MZ, Chiu HH, Reichlin DB, Jousset S, Erhardt RS. Ozone and UV254 radiation for municipal wastewater disinfection. Water Environ Res 2012; 84:2017-2027. [PMID: 23356017 DOI: 10.2175/106143012x13373550426634] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Bench-scale experiments were conducted with municipal wastewater effluent samples to examine the feasibility of combined application of ozone and ultraviolet (UV) radiation for disinfection. Effluent samples displayed rapid initial ozone demand, which promotes ozone transfer but diminishes disinfection efficacy. Ozone doses up to 10 mg/L yielded only trace quantities of residual ozone; despite the fact that initial ozone demand was never exceeded, quantifiable (though variable) inactivation of E. coli was observed, along with modest improvements of UV transmittance. Results from collimated beam experiments demonstrated that compliance with effluent discharge permit limitations could be achieved consistently with a UV254 dose of 12.4 mJ/cm2 at a pre-ozonation dose of 2 to 3 mg/L. In the absence of pre-ozonation, consistent compliance was observed at a UV dose of 16.5 mJ/cm2. No evidence of synergism between ozone and UV254 radiation was found in the measured inactivation responses of E. coli.
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Affiliation(s)
- Ernest R Blatchley
- School of Civil Engineering and Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN 47907-2051, USA.
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36
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Weng S, Li J, Blatchley ER. Effects of UV 254 irradiation on residual chlorine and DBPs in chlorination of model organic-N precursors in swimming pools. Water Res 2012; 46:2674-2682. [PMID: 22425148 DOI: 10.1016/j.watres.2012.02.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 02/11/2012] [Accepted: 02/11/2012] [Indexed: 05/31/2023]
Abstract
Ultraviolet (UV) irradiation is commonly applied as a secondary disinfection process in chlorinated pools. UV-based systems have been reported to yield improvements in swimming pool water and air chemistry, but to date these observations have been largely anecdotal. The objectives of this investigation were to evaluate the effects of UV irradiation on chlorination of important organic-N precursors in swimming pools. Creatinine, L-arginine, L-histidine, glycine, and urea, which comprise the majority of the organic-N in human sweat and urine, were selected as precursors for use in conducting batch experiments to examine the time-course behavior of several DBPs and residual chlorine, with and without UV(254) irradiation. In addition, water samples from two natatoria were subjected to monochromatic UV irradiation at wavelengths of 222 nm and 254 nm to evaluate changes of liquid-phase chemistry. UV(254) irradiation promoted formation and/or decay of several chlorinated N-DBPs and also increased the rate of free chlorine consumption. UV exposure resulted in loss of inorganic chloramines (e.g., NCl(3)) from solution. Dichloromethylamine (CH(3)NCl(2)) formation from creatinine was promoted by UV exposure, when free chlorine was present in solution; however, when free chlorine was depleted, CH(3)NCl(2) photodecay was observed. Dichloroacetonitrile (CNCHCl(2)) formation (from L-histidine and L-arginine) was promoted by UV(254) irradiation, as long as free chlorine was present in solution. Likewise, UV exposure was observed to amplify cyanogen chloride (CNCl) formation from chlorination of L-histidine, L-arginine, and glycine, up to the point of free chlorine depletion. The results from experiments involving UV irradiation of chlorinated swimming pool water were qualitatively consistent with the results of model experiments involving UV/chlorination of precursors in terms of the behavior of residual chlorine and DBPs measured in this study. The results indicate that UV(254) irradiation promotes several reactions that are involved in the formation and/or destruction of chlorinated N-DBPs in pool settings. Enhancement of DBP formation was consistent with a mechanism whereby a rate-limiting step in DBP formation was promoted by UV exposure. Promotion of these reactions also resulted in increases of free chlorine consumption rates.
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Affiliation(s)
- ShihChi Weng
- School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, USA
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37
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Mbonimpa EG, Vadheim B, Blatchley ER. Continuous-flow solar UVB disinfection reactor for drinking water. Water Res 2012; 46:2344-2354. [PMID: 22386084 DOI: 10.1016/j.watres.2012.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 01/31/2012] [Accepted: 02/01/2012] [Indexed: 05/26/2023]
Abstract
Access to safe, reliable sources of drinking water is a long-standing problem among people in developing countries. Sustainable solutions to these problems often involve point-of-use or community-scale water treatment systems that rely on locally-available resources and expertise. This philosophy was used in the development of a continuous-flow, solar UVB disinfection system. Numerical modeling of solar UVB spectral irradiance was used to define temporal variations in spectral irradiance at several geographically-distinct locations. The results of these simulations indicated that a solar UVB system would benefit from incorporation of a device to amplify ambient UVB fluence rate. A compound parabolic collector (CPC) was selected for this purpose. Design of the CPC was based on numerical simulations that accounted for the shape of the collector and reflectance. Based on these simulations, a prototype CPC was constructed using materials that would be available and inexpensive in many developing countries. A UVB-transparent pipe was positioned in the focal area of the CPC; water was pumped through the pipe to allow exposure of waterborne microbes to germicidal solar UVB radiation. The system was demonstrated to be effective for inactivation of Escherichia coli, and DNA-weighted UV dose was shown to govern reactor performance. The design of the reactor is expected to scale linearly, and improvements in process performance (relative to results from the prototype) can be expected by use of larger CPC geometry, inclusion of better reflective materials, and application in areas with greater ambient solar UV spectral irradiance than the location of the prototype tests. The system is expected to have application for water treatment among communities in (developing) countries in near-equatorial and tropical locations. It may also have application for disaster relief or military field operations, as well as in water treatment in areas of developed countries that receive relatively intense solar UVB radiation.
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Affiliation(s)
- Eric Gentil Mbonimpa
- School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, USA
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38
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Weng S, Blatchley ER. Disinfection by-product dynamics in a chlorinated, indoor swimming pool under conditions of heavy use: national swimming competition. Water Res 2011; 45:5241-5248. [PMID: 21864880 DOI: 10.1016/j.watres.2011.07.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 06/03/2011] [Accepted: 07/24/2011] [Indexed: 05/31/2023]
Abstract
Anecdotal evidence suggests that water quality in chlorinated, indoor pools deteriorates under conditions of heavy use. However, data to define these dynamics have not been reported. To address this issue, a study was performed in which water chemistry was monitored in a chlorinated, indoor pool before and during a national swimming competition, a period of heavy, intense use. NCl3 concentration was observed to double after the first day, and increased by a factor of 3-4 over the 4 days of competition. CNCHCl2 and CH3NCl2 concentrations both increased by a factor of 2-3 during the course of the meet, while CHCl3 concentration showed only a modest increase during this same period. Diurnal patterns of NCl3, CH3NCl2 and CHCl3 concentrations were observed, and these patterns appeared to depend on the Henry's law constant of the compound. Urea concentration showed a diurnal pattern, superimposed on a trend of steady increase during each day of the competition; however, the diurnal pattern of urea behavior could not be explained by reactions with chlorine, as the urea-free chlorine reaction is relatively slow. It is more likely that the overnight decrease in urea concentration was attributable to mixing of surface water with water in the deeper parts of the pool. The findings of this study provide an indication of the changes in pool water chemistry that take place in a chlorinated, indoor pool under heavy use conditions.
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Affiliation(s)
- ShihChi Weng
- School of Civil Engineering and Division of Environmental & Ecological Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, USA.
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39
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Weng SC, Weaver WA, Afifi MZ, Blatchley TN, Cramer JS, Chen J, Blatchley ER. Dynamics of gas-phase trichloramine (NCl3) in chlorinated, indoor swimming pool facilities. Indoor Air 2011; 21:391-399. [PMID: 21251074 DOI: 10.1111/j.1600-0668.2011.00710.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
UNLABELLED Trichloramine (NCl(3)) is recognized as an irritant of the human respiratory system and other tissues. Processes that lead to volatilization from the liquid phase allow for human exposure to gas-phase NCl(3) in swimming pool settings. The dynamics of these processes are not well defined. A N,N-diethyl-p-phenylenediamine/potassium iodide (DPD/KI)-based wet-chemistry method for measuring gas-phase NCl(3) concentration was verified and applied in chlorinated, indoor swimming pool facilities. Other gas-phase oxidants in the air of indoor pools provided interference of 15% or less. The DPD/KI method was applied for the measurement of gas-phase NCl(3) in four chlorinated, indoor swimming pool facilities. All results showed a correlation between bather loading and gas-phase NCl(3) concentration. The nature of swimmer activities also influenced air quality, presumably because of the effects of these activities on mixing near the gas-liquid interface. PRACTICAL IMPLICATIONS The activities of swimmers promote transfer of volatile compounds from water to the surrounding air. For chlorinated, indoor pool facilities, this can lead to exposure to gas-phase chemicals that can cause irritation of the respiratory system and other tissues. The focus of this study was on NCl(3), a common disinfection by-product (DBP) in chlorinated pools. However, the conditions that promote NCl(3) transfer are likely to promote transfer of other volatile chemicals from water to air. As such, it is possible that other DBPs formed in pools may also contribute to diminished air quality.
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Affiliation(s)
- S-C Weng
- School of Civil Engineering, Purdue University, West Lafayette, IN, USA
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40
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Abstract
Experiments were conducted to elucidate the mechanism of the reaction between free chlorine and urea. In combination with findings of previous investigations, the results of these experiments indicate a process by which urea undergoes multiple N-chlorination steps. The first of these steps results in the formation of N-chlorourea; this step appears to require Cl₂ to proceed and is the overall rate-limiting step in the reaction for conditions that correspond to most swimming pools. N-Chlorourea then appears to undergo further chlorine substitution; the fully N-chlorinated urea molecule is hypothesized to undergo hydrolysis and additional chlorination to yield NCl₃ as an intermediate. NCl₃ is hydrolyzed to yield NH₂Cl and NHCl₂, with subsequent decay to stable end products, including N₂ and NO₃⁻. Conversion of urea-N to nitrate is pH-dependent. The pattern of nitrate yield is believed to be attributable to the fact that when urea serves as the source of reduced-N, entry into the reactions that describe chlorination of ammoniacal nitrogen is through NCl₃, whereas when NH₃ is the source of reduced-N, entry to these reactions is through NH₂Cl.
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Affiliation(s)
- Ernest R Blatchley
- School of Civil Engineering and Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, Indiana 47907-2051, USA.
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Abstract
The efficacy of UV disinfection of water depends on the ability of radiation to pass from UV lamps through the quartz sleeves that encase them; the accumulation of metal-containing foulants on sleeve surfaces inhibits disinfection by absorbing radiation that would otherwise be available for inactivation. In a series of experiments, the composition and quantity of sleeve foulants were studied relative to water chemistry and sleeve transmittance. Findings indicate that iron and calcium dominate fouling, with elevated fouling activity by iron, aluminum, manganese, and zinc. A regression-based modeling approach was used to characterize and quantify the effects of foulant metals on UV absorbance. The molar extinction coefficient for iron was found to be more than 3 times greater than that of calcium. Iron's relatively high activity in fouling reactions, elevated capacity to absorb UV, and reduced solubility under oxidizing conditions makes it a fouling precursor of particular concern, with respect to potential for sleeve fouling in UV reactors.
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Affiliation(s)
- Isaac W Wait
- College of Information Technology and Engineering, Marshall University, One John Marshall Dr., Huntington, WV 25705, USA.
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42
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Weaver WA, Li J, Wen Y, Johnston J, Blatchley MR, Blatchley ER. Volatile disinfection by-product analysis from chlorinated indoor swimming pools. Water Res 2009; 43:3308-18. [PMID: 19501873 DOI: 10.1016/j.watres.2009.04.035] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 04/15/2009] [Accepted: 04/21/2009] [Indexed: 05/11/2023]
Abstract
Chlorination of indoor swimming pools is practiced for disinfection and oxidation of reduced compounds that are introduced to water by swimmers. However, there is growing concern associated with formation for chlorinated disinfection by-products (DBPs) in these settings. Volatile DBPs are of particular concern because they may promote respiratory ailments and other adverse health effects among swimmers and patrons of indoor pool facilities. To examine the scope of this issue, water samples were collected from 11 pools over a 6month period and analyzed for free chlorine and their volatile DBP content. Eleven volatile DBPs were identified: monochloramine (NH(2)Cl), dichloramine (NHCl(2)), trichloramine (NCl(3)), chloroform (CHCl(3)), bromoform (CHBr(3)), dichlorobromomethane (CHBrCl(2)), dibromochloromethane (CHBr(2)Cl), cyanogen chloride (CNCl), cyanogen bromide (CNBr), dichloroacetonitrile (CNCHCl(2)), and dichloromethylamine (CH(3)NCl(2)). Of these 11 DBPs, 10 were identified as regularly occurring, with CHBrCl(2) only appearing sporadically. Pool water samples were analyzed for residual chlorine compounds using the DPD colorimetric method and by membrane introduction mass spectrometry (MIMS). These two methods were chosen as complementary measures of residual chlorine, and to allow for comparisons between the methods. The DPD method was demonstrated to consistently overestimate inorganic chloramine content in swimming pools. Pairwise correlations among the measured volatile DBPs allowed identification of dichloromethylamine and dichloroacetonitrile as potential swimming pool water quality indicator compounds.
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Affiliation(s)
- William A Weaver
- School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, USA
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43
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Weisel CP, Richardson SD, Nemery B, Aggazzotti G, Baraldi E, Blatchley ER, Blount BC, Carlsen KH, Eggleston PA, Frimmel FH, Goodman M, Gordon G, Grinshpun SA, Heederik D, Kogevinas M, LaKind JS, Nieuwenhuijsen MJ, Piper FC, Sattar SA. Childhood asthma and environmental exposures at swimming pools: state of the science and research recommendations. Environ Health Perspect 2009; 117:500-7. [PMID: 19440486 PMCID: PMC2679591 DOI: 10.1289/ehp.11513] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Accepted: 09/30/2008] [Indexed: 05/03/2023]
Abstract
OBJECTIVES Recent studies have explored the potential for swimming pool disinfection by-products (DBPs), which are respiratory irritants, to cause asthma in young children. Here we describe the state of the science on methods for understanding children's exposure to DBPs and biologics at swimming pools and associations with new-onset childhood asthma and recommend a research agenda to improve our understanding of this issue. DATA SOURCES A workshop was held in Leuven, Belgium, 21-23 August 2007, to evaluate the literature and to develop a research agenda to better understand children's exposures in the swimming pool environment and their potential associations with new-onset asthma. Participants, including clinicians, epidemiologists, exposure scientists, pool operations experts, and chemists, reviewed the literature, prepared background summaries, and held extensive discussions on the relevant published studies, knowledge of asthma characterization and exposures at swimming pools, and epidemiologic study designs. SYNTHESIS Childhood swimming and new-onset childhood asthma have clear implications for public health. If attendance at indoor pools increases risk of childhood asthma, then concerns are warranted and action is necessary. If there is no such relationship, these concerns could unnecessarily deter children from indoor swimming and/or compromise water disinfection. CONCLUSIONS Current evidence of an association between childhood swimming and new-onset asthma is suggestive but not conclusive. Important data gaps need to be filled, particularly in exposure assessment and characterization of asthma in the very young. Participants recommended that additional evaluations using a multidisciplinary approach are needed to determine whether a clear association exists.
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Affiliation(s)
- Clifford P Weisel
- Environmental and Occupational Health Sciences Institute, Robert Wood Johnson Medical School/University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854, USA.
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44
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Shen C, Scheible OK, Chan P, Mofidi A, Yun TI, Lee CC, Blatchley ER. Validation of medium-pressure UV disinfection reactors by Lagrangian actinometry using dyed microspheres. Water Res 2009; 43:1370-1380. [PMID: 19138781 DOI: 10.1016/j.watres.2008.12.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 11/05/2008] [Accepted: 12/09/2008] [Indexed: 05/27/2023]
Abstract
Lagrangian actinometry (LA) has been demonstrated to represent an alternative to conventional biodosimetry for validation of ultraviolet (UV) disinfection systems used in drinking water treatment. However, previous applications of LA for this purpose have all involved monochromatic (lambda = 254 nm) UV reactor systems. To address this issue, dyed microspheres (DMS) were applied for quantification of dose distribution delivery by field-scale UV reactor systems based on medium-pressure Hg lamp (MP) technology. These MP reactor systems are characterized by polychromatic output. Dose distribution estimates developed by LA for these reactors were reported as equivalent 254 nm distributions. When combined with the UV(254) dose-response behavior for challenge organisms used in simultaneous or parallel biodosimetry experiments, the dose distribution estimates developed from the microspheres yielded estimates of challenge organism inactivation that were in agreement with measured values. For one of the reactors tested, biodosimetry tests were conducted with two challenge organisms that had different UV dose-response behavior; UV dose distribution estimates from LA yielded predictions of microbial inactivation that were in agreement with measured inactivation responses for both challenge organisms for all test conditions. It is likely that the agreement between LA results and biodosimetry data was related, in part, to the agreement between the action spectra of the microspheres and the challenge organisms. Because LA yields a measure of the UV dose distribution delivered by a reactor, the information from LA assays will eliminate many sources of uncertainty in the design and operation of UV systems, thereby allowing for implementation of UV reactor systems that are less expensive than their predecessors, yet more reliable.
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Affiliation(s)
- C Shen
- HydroQual, Inc., 1200 MacArthur Blvd., Mahwah, NJ 07430, USA
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45
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Abstract
The ultraviolet (UV) photolysis of monochloramine (NH2Cl), dichloramine (NHCl2), and trichloramine (NCl3) in aqueous solution was investigated at wavelengths of 222, 254, and 282 nm. All three chloramines can be degraded by UV irradiation, and the quantum yields for these processes are wavelength-dependent. Stable photoproducts include nitrite, nitrate, nitrous oxide, and ammonium. Solution pH was observed to have little effect on the rate of photodecay; however, the product distribution showed strong pH dependence. Nitrate formation was favored at low pH, while nitrite formation was favored at high pH. The effects of pH on formation of N2O and NH4+ were less clear. On the basis of the results, a mechanism of photodecay of monochloramine is proposed.
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Affiliation(s)
- Jing Li
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, USA
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46
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Naunovic Z, Lim S, Blatchley ER. Investigation of microbial inactivation efficiency of a UV disinfection system employing an excimer lamp. Water Res 2008; 42:4838-4846. [PMID: 18848711 DOI: 10.1016/j.watres.2008.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 08/27/2008] [Accepted: 09/02/2008] [Indexed: 05/26/2023]
Abstract
An ultraviolet (UV) disinfection reactor based on excimer lamp technology was designed by integration of the results of numerical simulations based on computational fluid dynamics and a fluence rate (E') distribution model for cylindrical excimer lamps. The E' distribution model was developed based on a point source approach that accounts for absorption, dissipation, reflection, and refraction within the reactor system. A prototype reactor was constructed with a xenon-bromide excimer lamp and an internal spiral baffle. Experiments were conducted on the reactor to test its effectiveness for disinfection of drinking water in situations where the use of mercury-based UV sources is restricted or undesirable; a similar design approach could be used to develop an excimer UV reactor for disinfection of other fluid media, including wastewater or air.
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47
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Naunovic Z, Pennell KG, Blatchley ER. Development and performance of a fluence rate distribution model for a cylindrical excimer lamp. Environ Sci Technol 2008; 42:1605-1614. [PMID: 18441810 DOI: 10.1021/es070968w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ultraviolet disinfection systems employing excimer lamp technology represent a suitable choice in situations where lamp mercury content is restricted, or otherwise undesirable. The XeBr* excimer lamp emits nearly monochromatic radiation at 282 nm, and dose-response experiments with Bacillus subtilis spores have shown that it is germicidally effective. A numerical model was developed to describe the fluence rate (E') distribution emanating from a cylindrical XeBr* excimer lamp, based on liquid water or air as the surrounding medium. The E' distribution model is based on physical phenomena that are known to govern excimer lamps; the model also accounts for refraction, reflection, and absorbance effects of the quartz lamp envelope and the media surrounding the lamp. Measurements of the E' distribution by local actinometry supported the validity of the numerical model. This model can be used as a component (submodel) of a more general model to simulate the behavior of photochemical reactors that employ excimer lamps as their source of electromagnetic radiation.
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Affiliation(s)
- Zorana Naunovic
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, USA
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48
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Fang S, Guan Y, Blatchley ER, Shen C, Bergstrom DE. Conjugation of (E)-5-[2-(Methoxycarbonyl)ethenyl]cytidine to Hydrophilic Microspheres: Development of a Mobile Microscale UV Light Actinometer. Bioconjug Chem 2008; 19:592-7. [PMID: 18266312 DOI: 10.1021/bc700336x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shiyue Fang
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, Birck Nanotechnology Center, Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907, and The Walther Cancer Institute, Indianapolis, Indiana 46208
| | - Yousheng Guan
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, Birck Nanotechnology Center, Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907, and The Walther Cancer Institute, Indianapolis, Indiana 46208
| | - Ernest R. Blatchley
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, Birck Nanotechnology Center, Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907, and The Walther Cancer Institute, Indianapolis, Indiana 46208
| | - Chengyue Shen
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, Birck Nanotechnology Center, Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907, and The Walther Cancer Institute, Indianapolis, Indiana 46208
| | - Donald E. Bergstrom
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, Birck Nanotechnology Center, Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907, and The Walther Cancer Institute, Indianapolis, Indiana 46208
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49
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Blatchley ER, Shen C, Scheible OK, Robinson JP, Ragheb K, Bergstrom DE, Rokjer D. Validation of large-scale, monochromatic UV disinfection systems for drinking water using dyed microspheres. Water Res 2008; 42:677-88. [PMID: 17888484 DOI: 10.1016/j.watres.2007.08.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Revised: 08/20/2007] [Accepted: 08/21/2007] [Indexed: 05/17/2023]
Abstract
Dyed microspheres have been developed as a new method for validation of ultraviolet (UV) reactor systems. When properly applied, dyed microspheres allow measurement of the UV dose distribution delivered by a photochemical reactor for a given operating condition. Prior to this research, dyed microspheres had only been applied to a bench-scale UV reactor. The goal of this research was to extend the application of dyed microspheres to large-scale reactors. Dyed microsphere tests were conducted on two prototype large-scale UV reactors at the UV Validation and Research Center of New York (UV Center) in Johnstown, NY. All microsphere tests were conducted under conditions that had been used previously in biodosimetry experiments involving two challenge bacteriophage: MS2 and Qbeta. Numerical simulations based on computational fluid dynamics and irradiance field modeling were also performed for the same set of operating conditions used in the microspheres assays. Microsphere tests on the first reactor illustrated difficulties in sample collection and discrimination of microspheres against ambient particles. Changes in sample collection and work-up were implemented in tests conducted on the second reactor that allowed for improvements in microsphere capture and discrimination against the background. Under these conditions, estimates of the UV dose distribution from the microspheres assay were consistent with numerical simulations and the results of biodosimetry, using both challenge organisms. The combined application of dyed microspheres, biodosimetry, and numerical simulation offers the potential to provide a more in-depth description of reactor performance than any of these methods individually, or in combination. This approach also has the potential to substantially reduce uncertainties in reactor validation, thereby leading to better understanding of reactor performance, improvements in reactor design, and decreases in reactor capital and operating costs.
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Affiliation(s)
- E R Blatchley
- School of Civil Engineering, Purdue University, West Lafayette, IN 47907-2051, USA.
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50
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Li J, Blatchley ER. Volatile disinfection byproduct formation resulting from chlorination of organic-nitrogen precursors in swimming pools. Environ Sci Technol 2007; 41:6732-6739. [PMID: 17969688 DOI: 10.1021/es070871+] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Clinical studies have documented the promotion of respiratory ailments (e.g., asthma) among swimmers, especially in indoor swimming pools. Most studies of this behavior have identified trichloramine (NCl3) as the causative agent for these respiratory ailments; however, the analytical methods employed in these studies were not suited for identification or quantification of other volatile disinfection byproducts (DPBs) that could also contribute to this process. To address this issue, volatile DBP formation resulting from the chlorination of four model compounds (creatinine, urea, L-histidine, and L-arginine) was investigated over a range of chlorine/precursor (Cl/P) molar ratios. Trichloramine was observed to result from chlorination of all four model organic-nitrogen compounds. In addition to trichloramine, dichloromethylamine (CH3NCl2) was detected in the chlorination of creatinine, while cyanogen chloride (CNCl) and dichoroacetonitrile (CNCHCl2) were identified in the chlorination of L-histidine. Roughly 0.1 mg/L (as Cl2) NCl3, 0.01 mg/L CNCHCl2, and 0.01 mg/L CH3NCl2 were also observed in actual swimming pool water samples. DPD/FAS titration and MIMS (membrane introduction mass spectrometry) were both employed to measure residual chlorine and DBPs. The combined application of these methods allowed for identification of sources of interference in the conventional method (DPD/FAS), as well as structural information about the volatile DBPs that formed. The analysis by MIMS clearly indicates that volatile DBP formation in swimming pools is not limited to inorganic chloramines and haloforms. Additional experimentation allowed for the identification of possible reaction pathways to describe the formation of these DBPs from the precursor compounds used in this study.
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Affiliation(s)
- Jing Li
- School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, USA
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