1
|
Li J, Hua Z, Qin W, Chen C, Zhu B, Ruan T, Xiang Y, Fang J. Probing nitro(so) and chloro byproducts and their precursors in natural organic matter during UV/NH 2Cl treatment by FT-ICR MS with machine learning insights. WATER RESEARCH 2024; 262:122097. [PMID: 39018583 DOI: 10.1016/j.watres.2024.122097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 07/01/2024] [Accepted: 07/13/2024] [Indexed: 07/19/2024]
Abstract
The UV/monochloramine (UV/NH2Cl) process, while efficiently eliminating micropollutants, produces toxic byproducts. This study utilized Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to investigate molecular-level changes in natural organic matter (NOM) and to disclose formation pathways of nitro(so) and chloro byproducts in the UV/NH2Cl process. The UV/NH2Cl process significantly increased the saturation and oxidation levels and altered the elemental composition of NOM. Using 15N labeling and a screening workflow, nitro(so) byproducts with nitrogen originating from inorganic sources (i.e., reactive nitrogen species (RNS) and/or NH2Cl) were found to exhibit total intensities comparable to those from NOM. RNS, rather than NH2Cl, played a significant role in incorporating nitrogen into NOM. Through linkage analysis, nitro(so) addition emerged as an important reaction type among the 25 reaction types applied. By using phenol as a representative model compound, the nitro byproducts were confirmed to be mainly generated through the oxidation of nitroso byproducts instead of nitration. Machine learning and SHAP analysis further identified the major molecular indices distinguishing nitro(so) and chloro precursors from non-precursors. This study enhances our fundamental understanding of the mechanisms driving the generation of nitro(so) and chloro byproducts from their precursors in complex NOM during the UV/NH2Cl process.
Collapse
Affiliation(s)
- Junfang Li
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, PR China; College of Chemistry and Chemical Engineering, Xinjiang Agricultural University, Urumqi, 830052, PR China
| | - Zhechao Hua
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, PR China
| | - Wenlei Qin
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, PR China
| | - Chunyan Chen
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, PR China
| | - Bao Zhu
- Research Centre for Eco-Environmental Sciences, State Key Laboratory of Environmental Chemistry and Ecotoxicology, Beijing, 100085, PR China
| | - Ting Ruan
- Research Centre for Eco-Environmental Sciences, State Key Laboratory of Environmental Chemistry and Ecotoxicology, Beijing, 100085, PR China
| | - Yingying Xiang
- Nanyang Environment & Water Research Institute, Nanyang Technological University, 637141, Singapore; Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 000, Hong Kong SAR, PR China.
| | - Jingyun Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, PR China.
| |
Collapse
|
2
|
Ao J, Bu L, Wu Y, Zhu S, Zhou S. Insights into the fate and properties of organic halamines during ultraviolet irradiation: Implications for drinking water safety. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:165994. [PMID: 37536590 DOI: 10.1016/j.scitotenv.2023.165994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/24/2023] [Accepted: 07/31/2023] [Indexed: 08/05/2023]
Abstract
Organic halamines compounds present a significant threat to the safety of drinking water due to their potential toxicity and stability. While Ultraviolet (UV) disinfection is commonly used for water treatment, its specific effects on organic halamines and the underlying mechanisms remain poorly understood. In this study, we investigated eight amino acid-derived organic chlor- and bromamines as representative compounds. Our findings revealed that organic halamines have a slow hydrolysis rate (<10-3 M-1 s-1) and can persist in water for extended periods (30-2000 min). However, their disinfection efficacy against Staphylococcus aureus and their ability to degrade micropollutants like carbamazepine were found to be limited. Interestingly, under UV irradiation, the N-X bonds in organic halamines were observed to break, leading to accelerated decomposition and the generation of abundant free radicals. These free radicals synergistically facilitated the removal of micropollutants and the inactivation of pathogenic microorganisms. It is worth noting that this transformation of organic halamines during UV disinfection resulted in a slight increase in the concentrations of nitrogenous disinfection byproducts. These findings shed light on the behavior and characteristics of organic halamines during UV disinfection processes, providing crucial insights for effectively managing drinking water quality impacted by these compounds. By understanding the implications of organic halamines, we can refine water treatment strategies and ensure the safety of drinking water supplies.
Collapse
Affiliation(s)
- Jian Ao
- Hunan Engineering Research Center of Water Security Technology and Application, College of Civil Engineering, Hunan University, Changsha 410082, PR China
| | - Lingjun Bu
- Hunan Engineering Research Center of Water Security Technology and Application, College of Civil Engineering, Hunan University, Changsha 410082, PR China
| | - Yangtao Wu
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Shumin Zhu
- Hunan Engineering Research Center of Water Security Technology and Application, College of Civil Engineering, Hunan University, Changsha 410082, PR China.
| | - Shiqing Zhou
- Hunan Engineering Research Center of Water Security Technology and Application, College of Civil Engineering, Hunan University, Changsha 410082, PR China
| |
Collapse
|
3
|
Hua Z, Liang J, Wang D, Zhou Z, Fang J. Formation Mechanisms of Nitro Products from Transformation of Aliphatic Amines by UV/Chlorine Treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:18754-18764. [PMID: 37294018 DOI: 10.1021/acs.est.3c00744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Formation of nitrogenous disinfection byproducts from aliphatic amines is a widespread concern owing to the serious health risks associated with them. However, the mechanisms of transforming aliphatic amines and forming nitro products in the UV/chlorine process have rarely been discussed, which are investigated in this work. Initially, secondary amines (R1R2NH) are transformed into secondary organic chloramines (R1R2NCl) via chlorination. Subsequently, radicals, such as HO• and Cl•, are found to contribute predominantly to such transformations. The rate constants at which HO•, Cl•, and Cl2•- react with R1R2NCl are (2.4-5.1) × 109, (1.5-3.8) × 109, and (1.2-6.1) × 107 M-1 s-1, respectively. Consequently, R1R2NCl are transformed into primary amines (R1NH2/R2NH2) and chlorinated primary amines (R1NHCl/R2NHCl and R1NCl2/R2NCl2) by excess chlorine. Furthermore, primarily driven by UV photolysis, chlorinated primary amines can be transformed into nitroalkanes with conversion rates of ∼10%. Dissolved oxygen and free chlorine play crucial roles in forming nitroalkanes, and post-chlorination can further form chloronitroalkanes, such as trichloronitromethane (TCNM). Radicals are involved in forming TCNM in the UV/chlorine process. This study provides new insights into the mechanisms of transforming aliphatic amines and forming nitro products using the UV/chlorine process.
Collapse
Affiliation(s)
- Zhechao Hua
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Jieying Liang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Ding Wang
- General Institute of Water Resources and Hydropower Planning and Design, Beijing 100120, China
| | - Zhihong Zhou
- Guangzhou Ecological Environmental Monitoring Center, Guangzhou 510006, China
| | - Jingyun Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| |
Collapse
|
4
|
Chuang YH, Chen TY, Chou CS, Chu LK, Hou CY, Szczuka A. Critical Role of Trichloramine Interaction with Dichloramine for N-Nitrosamine Formation during Breakpoint Chlorination. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:15232-15242. [PMID: 37603422 DOI: 10.1021/acs.est.3c03326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Breakpoint chlorination is prevalent in drinking water and potable reuse water treatment. Breakpoint chlorination enhances the formation of N-nitrosamines through reactions that form nitrosating agents. The most recent study suggests that nitroxyl (HNO) can react with free chlorine (HOCl) to form the nitrosyl chloride (ClNO) nitrosating agent but has not experimentally verified its importance in breakpoint chlorination. This study first assessed the formation of N-nitrosamines from model N-chloro-alkylamine precursors when they were added to a mixture of HOCl and HNO-derived nitrosating agents generated by chlorinating hydroxyurea. Results demonstrated negligible N-nitrosamine formation. Instead, we observed that the interaction of NCl3 with NHCl2 (total Cl2/total N molar ratio = 2.4-3:1) produced an intermediate capable of nitrosating N-chloro-alkylamines to N-nitrosamines at yields 8-fold higher to those observed in NHCl2 treatment alone, within a very short timescale (<3 min). We examined the stoichiometry of the reaction of NCl3 with NHCl2 using a UV-spectrum-based approach. Nitrosyl chloride was proposed as the key intermediate, likely formed alongside the reformation of NHCl2. Further isotopic experiments, byproduct measurements, and kinetic modeling supported the hypotheses. Modeling indicated that the reaction of NCl3 with NHCl2 explained ∼75% of NDMA formation during breakpoint chlorination. Because NCl3 is mainly derived from the reaction of HOCl with NHCl2, controlling NHCl2 (e.g., with additional treatment) is critical for minimizing nitrosamine formation in waters where breakpoint chlorination occurs.
Collapse
Affiliation(s)
- Yi-Hsueh Chuang
- Institute of Environmental Engineering, National Yang Ming Chiao Tung University, 1001, University Rd., Hsinchu City 30010, Taiwan
| | - Ting-Yuan Chen
- Institute of Environmental Engineering, National Yang Ming Chiao Tung University, 1001, University Rd., Hsinchu City 30010, Taiwan
| | - Chia-Shun Chou
- Institute of Environmental Engineering, National Yang Ming Chiao Tung University, 1001, University Rd., Hsinchu City 30010, Taiwan
| | - Li-Kang Chu
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Chun-Yao Hou
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Aleksandra Szczuka
- Department of Civil and Environmental Engineering, University of Michigan, 1351 Beal Ave. Ann Arbor, Michigan 48109, United States
| |
Collapse
|
5
|
Peng F, Lu Y, Dong X, Wang Y, Li H, Yang Z. Advances and research needs for disinfection byproducts control strategies in swimming pools. JOURNAL OF HAZARDOUS MATERIALS 2023; 454:131533. [PMID: 37146331 DOI: 10.1016/j.jhazmat.2023.131533] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 04/16/2023] [Accepted: 04/27/2023] [Indexed: 05/07/2023]
Abstract
The control of disinfection byproducts (DBPs) in swimming pools is of great significance due to the non-negligible toxicity and widespread existence of DBPs. However, the management of DBPs remains challenging as the removal and regulation of DBPs is a multifactorial phenomenon in pools. This study summarized recent studies on the removal and regulation of DBPs, and further proposed some research needs. Specifically, the removal of DBPs was divided into the direct removal of the generated DBPs and the indirect removal by inhibiting DBP formation. Inhibiting DBP formation seems to be the more effective and economically practical strategy, which can be achieved mainly by reducing precursors, improving disinfection technology, and optimizing water quality parameters. Alternative disinfection technologies to chlorine disinfection have attracted increasing attention, while their applicability in pools requires further investigation. The regulation of DBPs was discussed in terms of improving the standards on DBPs and their preccursors. The development of online monitoring technology for DBPs is essential for implementing the standard. Overall, this study makes a significant contribution to the control of DBPs in pool water by updating the latest research advances and providing detailed perspectives.
Collapse
Affiliation(s)
- Fangyuan Peng
- Center for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China; Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Changsha 410083, PR China
| | - Yi Lu
- Center for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China; Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Changsha 410083, PR China
| | - Xuelian Dong
- Center for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China; Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Changsha 410083, PR China
| | - Yingyang Wang
- Center for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China; Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Changsha 410083, PR China
| | - Haipu Li
- Center for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China; Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Changsha 410083, PR China.
| | - Zhaoguang Yang
- Center for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China; Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Changsha 410083, PR China.
| |
Collapse
|
6
|
Kumar M, Shekhar S, Kumar R, Kumar P, Govarthanan M, Chaminda T. Drinking water treatment and associated toxic byproducts: Concurrence and urgence. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 320:121009. [PMID: 36634860 DOI: 10.1016/j.envpol.2023.121009] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 12/30/2022] [Accepted: 01/02/2023] [Indexed: 06/17/2023]
Abstract
Reclaimed water is highly required for environmental sustainability and to meet sustainable development goals (SDGs). Chemical processes are frequently associated with highly hazardous and toxic by-products, like nitrosamines, trihalomethanes, haloaldehydes, haloketones, and haloacetic acids. In this context, we aim to summarize the formation of various commonly produced disinfection by-products (DBPs) during wastewater treatment and their treatment approaches. Owing to DBPs formation, we discussed permissible limits, concentrations in various water systems reported globally, and their consequences on humans. While most reviews focus on DBPs detection methods, this review discusses factors affecting DBPs formation and critically reviews various remediation approaches, such as adsorption, reverse osmosis, nano/micro-filtration, UV treatment, ozonation, and advanced oxidation process. However, research in the detection of hazardous DBPs and their removal is quite at an early and initial stage, and therefore, numerous advancements are required prior to scale-up at commercial level. DBPs abatement in wastewater treatment approach should be considered. This review provides the baseline for optimizing DBPs formation and advancements in the remediation process, efficiently reducing their production and providing safe, clean drinking water. Future studies should focus on a more efficient and rigorous understanding of DBPs properties and degradation of hazardous pollutants using low-cost techniques in wastewater treatment.
Collapse
Affiliation(s)
- Manish Kumar
- Sustainability Cluster, University of Petroleum & Energy Studies, Dehradun, Uttarakhand, 248007, India; Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Monterey, Monterrey, 64849, Nuevo Leon, Mexico.
| | - Shashank Shekhar
- Sustainability Cluster, University of Petroleum & Energy Studies, Dehradun, Uttarakhand, 248007, India
| | - Rakesh Kumar
- School of Ecology and Environment Studies, Nalanda University, Rajgir, 803116, Bihar, India
| | - Pawan Kumar
- Sustainability Cluster, University of Petroleum & Energy Studies, Dehradun, Uttarakhand, 248007, India
| | - Muthusamy Govarthanan
- Department of Environmental Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, 41566, South Korea; Department of Biomaterials, Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Sciences, Chennai, 600 077, India
| | - Tushara Chaminda
- Department of Civil and Environmental Engineering, Faculty of Engineering, University of Ruhuna, Galle, Sri Lanka
| |
Collapse
|
7
|
Seid MG, Son A, Cho K, Byun J, Hong SW. Doped and immobilized titanium dioxide photocatalysts as a potential source of nitrosamine formation. WATER RESEARCH 2023; 230:119573. [PMID: 36621279 DOI: 10.1016/j.watres.2023.119573] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 11/27/2022] [Accepted: 01/03/2023] [Indexed: 06/17/2023]
Abstract
Immobilized and visible-light-active titanium dioxide (TiO2) is widely used for water treatment. However, the accelerated generation of degradation byproducts is a potential risk of TiO2-based photocatalysis. This study aimed to investigate the structural effect of engineered TiO2 samples on the formation of major nitrosamines during photocatalysis. The nitrogen-containing impurities and leached metal ions from doped-TiO2 samples could exacerbate nitrosamine formation potential (FP) in distilled water, secondary effluent, and chloraminated water. Doped-TiO2 with 2-ethylimidazole, trimethylamine, triethylamine, and N-carbon nanotubes could leach in the range of 47-64 ng L-1 nitrosamines (including N-nitrosomethylethylamine, N-nitrosodiethylamine, N-nitrosodimethylamine, and N-nitrosopyrrolidine) even under dark conditions. Furthermore, we investigated the role of metal dopants on nitrosamine-FP during the chloramination of precursors such as dimethylamine and microcystin-LR. Metal ions such as Cu that leached from the metal-doped catalysts may catalyze the nitrosamine-FP. Therefore, pre-purification (washing) and immobilization of doped-TiO2 samples on substrates are suggested to remove a considerable amount of nitrosamines. However, during the prolonged tryout, the selection of substrates was critical. Polymeric supports, such as polyimide and polyvinylpyrrolidone, can produce up to 85 ng L-1 nitrosamine, whereas TiO2 immobilized onto steel mesh can remove nitrosamine formation during photocatalytic oxidation followed by chloramination. This study systematically screened a diverse range of dopants, supports, and solvents in engineered TiO2 photocatalysts, in 61 samples, and provided novel insights into their effect on nitrosamine formation.
Collapse
Affiliation(s)
- Mingizem Gashaw Seid
- Center for Water Cycle Research, Korea Institute of Science and Technology, Hwarangro 14 gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Aseom Son
- Center for Water Cycle Research, Korea Institute of Science and Technology, Hwarangro 14 gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Civil, Environmental, and Architectural Engineering, Korea University, Seoul 136-701, Republic of Korea
| | - Kangwoo Cho
- Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea; Institute for Convergence Research and Education in Advanced Technology (I-CREATE), Yonsei University, Incheon 406-840, Republic of Korea
| | - Jeehye Byun
- Center for Water Cycle Research, Korea Institute of Science and Technology, Hwarangro 14 gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Division of Energy and Environment Technology, KIST-School, University of Science and Technology, Seoul 02792, Republic of Korea.
| | - Seok Won Hong
- Center for Water Cycle Research, Korea Institute of Science and Technology, Hwarangro 14 gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Division of Energy and Environment Technology, KIST-School, University of Science and Technology, Seoul 02792, Republic of Korea.
| |
Collapse
|
8
|
Huang T, Deng L, Wang T, Liao X, Hu J, Tan C, Singh RP. Effects of bromide ion on the formation and toxicity alteration of halonitromethanes from nitrate containing humic acid water during UV/chlor(am)ine disinfection. WATER RESEARCH 2022; 225:119175. [PMID: 36191529 DOI: 10.1016/j.watres.2022.119175] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 09/25/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
UV/chlor(am)ine are efficient for achieving multiple-barrier disinfection and maintaining residuals, while bromide (Br-) has notable impacts on the formation and toxicity of halonitromethanes (HNMs) during UV/chlor(am)ine disinfection. This study investigated the effects of Br- on HNMs formation and toxicity alteration during UV/chlor(am)ine disinfection of nitrate containing humic acid (HA) water. Results reveal that the maximum concentration of HNMs during UV/chlorine disinfection was 12.03 μg L-1 with 0.2 mg L-1 Br-, which was 22.5% higher than that without Br-, and the predominant species of HNMs were converted from trichloronitromethane (TCNM) to dibromonitromethane (DBNM) and tribromonitromethane (TBNM). However, the maximum concentration of HNMs during UV/chloramine disinfection was 3.69 μg L-1 with 0.2 mg L-1 Br-, which was increased by 26.0% than that without Br-, and the predominant species of HNMs were converted from dichloronitromethane (DCNM) to bromochloronitromethane (BCNM) and DBNM. Notably, the HNMs species and yields during UV/chloramine disinfection were less than those during UV/chlorine disinfection, primarily due to the higher concentrations of HO· and reactive chlorine/bromine species in UV/chlorine. Also, in the ranges of the Br-:Cl2 molar ratio from 0 to 0.32 and pH from 6.0 to 8.0, the Br-:Cl2 molar ratio of 0.16 and acidic pH contributed to the HNMs formation during UV/chlorine disinfection, and a high Br-:Cl2 molar ratio and neutral pH contributed to the HNMs formation during UV/chloramine disinfection. Note that the incorporation of Br- significantly improved the calculated cytotoxicity (CTI) and genotoxicity (GTI) of HNMs formed, and the calculated CTI and GTI of HNMs formed during UV/chloramine disinfection were 28.19 and 48.90% of those during UV/chlorine disinfection. Based on the diversity of nitrogen sources, the possible formation pathways of HNMs from nitrate containing HA water were proposed during UV/chlor(am)ine disinfection in the presence of Br-. Results of this study indicated that UV/chloramine can reduce the formation and toxicity of HNMs efficiently.
Collapse
Affiliation(s)
- Tingting Huang
- Department of Municipal Engineering, Southeast University, Nanjing 211189, China.
| | - Lin Deng
- Department of Municipal Engineering, Southeast University, Nanjing 211189, China.
| | - Tao Wang
- Department of Municipal Engineering, Southeast University, Nanjing 211189, China.
| | - Xueying Liao
- Department of Municipal Engineering, Southeast University, Nanjing 211189, China.
| | - Jun Hu
- Department of Municipal Engineering, Southeast University, Nanjing 211189, China.
| | - Chaoqun Tan
- Department of Municipal Engineering, Southeast University, Nanjing 211189, China.
| | | |
Collapse
|
9
|
Liu D, Rao L, Shi X, Du J, Chen C, Sun W, Fu ML, Yuan B. Comparison of the formation of N-nitrosodimethylamine (NDMA) from algae organic matter by chlor(am)ination and UV irradiation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156078. [PMID: 35597338 DOI: 10.1016/j.scitotenv.2022.156078] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/04/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
Microcystis aeruginosa (M. aeruginosa, blue-green algae) blooms frequently in drinking water reservoirs and subsequently causes the formation of disinfection by-products (DBPs) after disinfection, which may pose a potential health risk. In this study, the formation of N-nitrosodimethylamine (NDMA) was evaluated from algal organic matter (AOM) including extracellular organic matter (EOM) and intracellular organic matter (IOM) during the disinfection process of chlorination, chloramination, or ultraviolet (UV) irradiation. The effects of a variety of factors, including reaction times, disinfectant dosages and pH, on the NDMA formation by three different disinfection methods were investigated. Additionally, this study evaluated the nitrogen sources involved in NDMA formation during chloramination of EOM and IOM using 15N-labeled monochloramine. The results showed that the NDMA formation by three different disinfection methods were ranked in the order of chlorination > UV irradiation ≈ chloramination and the specific yield from EOM was greater than that from IOM regardless of disinfection method. The yields of NDMA firstly increased and then plateaued as time prolonged during the chlorination and chloramination of AOM. Similarly, the NDMA formation from EOM was firstly increased and then remained constant with the increase of the disinfectant dosage, while it was gradually increased for IOM. The solution pH highly influenced the NDMA formation during chlorination and chloramination, while exhibited a little impact under UV irradiation. Moreover, fluorescence excitation-emission (EEM) analysis confirmed that soluble microbial by-product-like (SMPs) in EOM and IOM were the major precursors in algal-derived organic matter that contributed to the NDMA formation. Chloramination of EOM and IOM using isotope 15N-labeled monochloramine indicated that the nitroso group of the formed NDMA originates mainly from EOM and IOM of algal cells.
Collapse
Affiliation(s)
- Decai Liu
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China
| | - La Rao
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China
| | - Xiaoyang Shi
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China
| | - Jiayu Du
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China
| | - Chen Chen
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China
| | - Wenjie Sun
- Department of Atmospheric and Hydrologic Science, St. Cloud State University, 720 4th Avenue South, St. Cloud, MN 56301, USA
| | - Ming-Lai Fu
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China
| | - Baoling Yuan
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China; Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118, PR China.
| |
Collapse
|
10
|
Hua Z, Li J, Zhou Z, Zheng S, Zhang Y, Fang J. Exploring Pathways and Mechanisms for Dichloroacetonitrile Formation from Typical Amino Compounds during UV/Chlorine Treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:9712-9721. [PMID: 35703371 DOI: 10.1021/acs.est.2c01495] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The formation of disinfection byproducts (DBPs) during UV/chlorine treatment, especially nitrogenous DBPs, is not well understood. This study investigated the formation mechanisms for dichloroacetonitrile (DCAN) from typical amino compounds during UV/chlorine treatment. Compared to chlorination, the yields of DCAN increase by 88-240% during UV/chlorine treatment from real waters, while the yields of DCAN from amino compounds increase by 3.3-5724 times. Amino compounds with electron-withdrawing side chains show much higher DCAN formation than those with electron-donating side chains. Phenylethylamine, l- phenylalanine, and l-phenylalanyl-l-phenylalanine were selected to represent amines, amino acids, and peptides, respectively, to investigate the formation pathways for DCAN during UV/chlorine treatment. First, chlorination of amines, amino acids, and peptides rapidly forms N-chloramines via chlorine substitution. Then, UV photolysis but not radicals promotes the transformation from N-chloramines to N-chloroaldimines and then to phenylacetonitrile, with yields of 5.4, 51.0, and 19.8% from chlorinated phenylethylamine, l-phenylalanine, and l-phenylalanyl-l-phenylalanine to phenylacetonitrile, respectively. Finally, phenylacetonitrile is transformed to DCAN with conversion ratios of 14.2-25.6%, which is attributed to radical oxidation, as indicated by scavenging experiments and density functional theory calculations. This study elucidates the pathways and mechanisms for DCAN formation from typical amino compounds during UV/chlorine treatment.
Collapse
Affiliation(s)
- Zhechao Hua
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Junfang Li
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Zhihong Zhou
- Guangzhou Ecological Environmental Monitoring Center, Guangzhou 510006, China
| | - Shanshan Zheng
- Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Yifei Zhang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Jingyun Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| |
Collapse
|
11
|
Wu G, Zhao H, Wan Q, Xu X, Cao R, Li K, Wang J, Huang T, Lu J, Wen G. Inactivation and subsequent reactivation of Aspergillus species by the combination of UV and monochloramine: Comparisons with UV/chlorine. J Environ Sci (China) 2022; 117:105-118. [PMID: 35725063 DOI: 10.1016/j.jes.2022.03.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 02/20/2022] [Accepted: 03/09/2022] [Indexed: 11/18/2022]
Abstract
Ultraviolet (UV)/monochloramine (NH2Cl) as an advanced oxidation process was firstly applied for Aspergillus spores inactivation. This study aims to: i) clarify the inactivation and photoreactivation characteristics of UV/NH2Cl process, ii) compared with UV/Cl2 in inactivation efficiency, photoreactivation and energy consumption. The results illustrated that UV/NH2Cl showed better inactivation efficiency than that of UV alone and UV/Cl2, and could effectively control the photoreactivation. For instance, the inactivation rates for Aspergillus flavus, Aspergillus niger and Aspergillus fumigatus in the processes of UV/NH2Cl (2.0 mg/L) was 0.034, 0.030 and 0.061 cm2/mJ, respectively, which were higher than that of UV alone (0.027, 0.026 and 0.024 cm2/mJ) and UV/Cl2 (0.023, 0.026 and 0.031 cm2/mJ). However, there was no synergistic effect for Aspergillus flavus and Aspergillus fumigatus. As for Aspergillus niger, the best synergistic effect can reach 1.86-log10. This may be due to their different resistance to disinfectants, which were related to the size, an outer layer of rodlets (hydrophobins) and pigments. After UV/NH2Cl inactivation, the degree of cell membrane damage and intracellular reactive oxygen species were higher than that of UV alone. UV/NH2Cl had the advantages of high inactivation efficiency and inhibition of photoreactivation, which provides a new entry point for the disinfection of waterborne fungi.
Collapse
Affiliation(s)
- Gehui Wu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; State Key Laboratory of Green Building in Western China, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Hui Zhao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Qiqi Wan
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Xiangqian Xu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Ruihua Cao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Kai Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Jingyi Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Jinsuo Lu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; State Key Laboratory of Green Building in Western China, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Gang Wen
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; State Key Laboratory of Green Building in Western China, Xi'an University of Architecture and Technology, Xi'an 710055, China.
| |
Collapse
|
12
|
Bloodgood MA, Chowdary SA, Daiber EJ, Shi H, Granger CO, Richardson SD. A balancing act: Optimizing free chlorine contact time to minimize iodo-DBPs, NDMA, and regulated DBPs in chloraminated drinking water. J Environ Sci (China) 2022; 117:315-325. [PMID: 35725085 DOI: 10.1016/j.jes.2022.05.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/10/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
Many drinking water treatment plants in the U.S. have switched from chlorination to chloramination to lower levels of regulated trihalomethane (THM) and haloacetic acid (HAA) disinfection byproducts (DBPs) in drinking water and meet the current regulations. However, chloramination can also produce other highly toxic/carcinogenic, unregulated DBPs: iodo-acids, iodo-THMs, and N-nitrosodimethylamine (NDMA). In practice, chloramines are generated by the addition of chlorine with ammonia, and plants use varying amounts of free chlorine contact time prior to ammonia addition to effectively kill pathogens and meet DBP regulations. However, iodo-DBPs and nitrosamines are generally not considered in this balancing of free chlorine contact time. The goal of our work was to determine whether an optimal free chlorine contact time could be established in which iodo-DBPs and NDMA could be minimized, while keeping regulated THMs and HAAs below their regulatory limits. The effect of free chlorine contact time was evaluated for the formation of six iodo-trihalomethanes (iodo-THMs), six iodo-acids, and NDMA during the chloramination of drinking water. Ten different free chlorine contact times were examined for two source waters with different dissolved organic carbon (DOC) and bromide/iodide. For the low DOC water at pH 7 and 8, an optimized free chlorine contact time of up to 1 h could control regulated THMs and HAAs, as well as iodo-DBPs and NDMA. For the high DOC water, a free chlorine contact time of 5 min could control iodo-DBPs and NDMA at both pHs, but the regulated DBPs could exceed the regulations at pH 7.
Collapse
Affiliation(s)
- Matthew A Bloodgood
- Student Services Authority, U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, GA 30605, USA
| | - Sridevi Anduri Chowdary
- Student Services Authority, U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, GA 30605, USA
| | - Eric J Daiber
- Student Services Authority, U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, GA 30605, USA
| | - Honglan Shi
- Department of Chemistry, Missouri University of Science and Technology, Rolla, MO 65409, USA
| | - Caroline O Granger
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
| | - Susan D Richardson
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
| |
Collapse
|
13
|
Deng L, Huang T, Wen L, Hu J, Prasad Singh R, Tan C. Impact of bromide ion on the formation and transformation of halonitromethanes from poly(diallyldimethylammonium chloride) during the UV/chlorine treatment. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
14
|
Cao Z, Yu X, Zheng Y, Aghdam E, Sun B, Song M, Wang A, Han J, Zhang J. Micropollutant abatement by the UV/chloramine process in potable water reuse: A review. JOURNAL OF HAZARDOUS MATERIALS 2022; 424:127341. [PMID: 34634702 DOI: 10.1016/j.jhazmat.2021.127341] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 06/13/2023]
Abstract
The need in using reclaimed water increased significantly to address the water shortage and its continuing quality deterioration in sustaining societal development. Degrading micropollutants in wastewater treatment plant effluents is one of the most important tasks in supplying safe drinking water, which is often achieved by full advanced treatment technologies (FATs), including reverse osmosis (RO) and the UV-based advanced oxidation process (AOP). As an emerging AOP, UV/chloramine process shows many noteworthy advantages in the scenario of potable water reuse, including membrane biological fouling control by chloramine, producing highly reactive radicals (e.g., Cl•, HO•, Cl2•-, and reactive nitrogen-containing species) to degrade the RO permeated pollutants, and acting as long-lasting disinfectant in the potable water distribution system. In addition, chloramine is often designedly produced by taking advantage of the ammonia in source. Thus, UV/chloramine processes gather much attention from researcher and published papers on UV/chloramine process have drastically increased since 2016, which were thoroughly reviewed in this paper. The fundamentals of chloramine photolysis, including the photolysis kinetics, the quantum yield, the generation and transformation of radicals and the final products, were scrutinized. Further, the impacts of reaction conditions such as pH, chloramine dosage and water matrix on the degradation of micropollutants by the UV/chloramine process are discussed. Moreover, the formation potential of disinfection by-products is debated. The opportunity of application of the UV/chloramine process in real-world practice is also presented, emphasizing the need for extensive efforts to remove currently prevalent knowledge roadblocks.
Collapse
Affiliation(s)
- Zhenfeng Cao
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao, Shandong 266237, PR China
| | - Ximing Yu
- Taiwei Energy Group Co., Ltd., Jinan, Shandong 250001, PR China
| | - Yuzhen Zheng
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao, Shandong 266237, PR China
| | - Ehsan Aghdam
- Department of Civil and Environmental Engineering, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Bo Sun
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao, Shandong 266237, PR China; Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
| | - Mingming Song
- School of Environmental Science & Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong 250353, PR China
| | - Aijie Wang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China; School of Civil & Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, PR China
| | - Jinglong Han
- School of Civil & Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, PR China
| | - Jian Zhang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao, Shandong 266237, PR China.
| |
Collapse
|
15
|
Wu Y, Zhang W, Bu L, Zhu S, Wang J, Zhou S. UV-induced activation of organic chloramine: Radicals generation, transformation pathway and DBP formation. JOURNAL OF HAZARDOUS MATERIALS 2022; 421:126459. [PMID: 34365233 DOI: 10.1016/j.jhazmat.2021.126459] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/03/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Organic chloramines of little disinfection efficacy commonly exist in disinfection process (chlor(am)ination) due to the wide presence of organic amines in water, of which N-chlorodimethylamine (CDMA) is a typical one. For the first time, UV photolysis for the activation of CDMA was investigated. UV photolysis caused the cleavage of N-Cl bond in CDMA to form Cl• and subsequently HO•, both of which are dominant contributors to the destruction of model contaminant bisphenol A (BPA). Typical spectra of HO• were detected by electron paramagnetic resonance (EPR) experiments, while spectra of reactive nitrogen species (RNS) were not detected during UV photolysis of CDMA. The increase of pH (6.0-8.0), HCO3-/CO32-, Cl- and nature organic matter inhibited the degradation of BPA. We proposed pathways of CDMA and BPA degradation based on the identified transformation products. UV photolysis of CDMA and BPA reduced the formation of N-nitrosodimethylamine (NDMA) at pH 8.0, but increased the formation of trichloronitromethane (TCNM) at pH 7.0 and 8.0. The increasing toxicity and the formation of TCNM and NDMA gave us a hint that formation of organic chloramines should be concerned.
Collapse
Affiliation(s)
- Yangtao Wu
- Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha 410082, China
| | - Weiqiu Zhang
- School of Civil and Environmental Engineering and the Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Lingjun Bu
- Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha 410082, China
| | - Shumin Zhu
- Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha 410082, China.
| | - Jue Wang
- Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha 410082, China
| | - Shiqing Zhou
- Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha 410082, China
| |
Collapse
|
16
|
Wang Y, Dong H, Qin W, Li J, Qiang Z. Activation of organic chloramine by UV photolysis: A non-negligible oxidant for micro-pollutant abatement and disinfection by-product formation. WATER RESEARCH 2021; 207:117795. [PMID: 34736003 DOI: 10.1016/j.watres.2021.117795] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/05/2021] [Accepted: 10/19/2021] [Indexed: 06/13/2023]
Abstract
Due to the wide-presence of organic amines in natural waters, organic chloramines are commonly formed during (pre-)chlorination. With the increasing application of UV disinfection in water treatment, both the activation mechanism of organic chloramine by UV photolysis and its subsequent impact on water quality are not clear. Using sarcosine (Sar) as an amine group-containing compound, it was found that organic chloramines (i.e., Cl-Sar) would be firstly formed during chlorination even in the presence of natural organic matter. Compared with self-decay of Cl-Sar, UV photolysis accelerated Cl-Sar decomposition and induced NCl bond cleavage. Using metoprolol (MTP) as a model micro-pollutant, UV-activated Cl-Sar (UV/Cl-Sar) can accelerate micro-pollutant degradation, attributed to reactive radicals formation. HO• and Cl• were important contributors, with a total contribution of 45%‒64%. Moreover, the degradation rate of MTP by UV/Cl-Sar was pH-dependent, which monotonically increased from 0.044 to 0.065 min‒1 under pHs 5.5‒8.5. Although the activation of organic chloramine by UV could accelerate micro-pollutant degradation, UV/Cl-Sar treatment could also enhance disinfection by-products formation. Trichloromethane (TCM) formation was observed during MTP degradation by UV/Cl-Sar. After post-chlorination, TCM, 1,1-dichloropropanone, 1,1,1-trichloropropanone, and dichloroacetonitrile were detected. Their individual and total concentrations were all positively proportional to UV/Cl-Sar treatment time. The total concentration with 30 min treatment (66.93 μg L‒1) was about 2.3 times that with 1 min treatment (28.76 μg L‒1). Finally, the accelerated effect was verified with Cl-glycine and Cl-alanine. It is expected to unravel the non-negligible role of organic chloramine on water quality during UV disinfection.
Collapse
Affiliation(s)
- Yan Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huiyu Dong
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenlei Qin
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jin Li
- School of Environmental Science and Engineering, Qingdao University, Qingdao 266071, China.
| | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| |
Collapse
|
17
|
Chen C, Wu Z, Hua Z, Guo K, Zhou Y, Wang D, Xia B, Fang J. Mechanistic and kinetic understanding of micropollutant degradation by the UV/NH 2Cl process in simulated drinking water. WATER RESEARCH 2021; 204:117569. [PMID: 34461497 DOI: 10.1016/j.watres.2021.117569] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 08/12/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
The UV/monochloramine (UV/NH2Cl) process has attracted increasing attention in water treatment, in which hydroxyl radicals (HO•), reactive chlorine species (RCS) and reactive nitrogen species (RNS) are produced. This study investigated the effects of water matrices including halides, natural organic matter (NOM), alkalinity and pH, on the degradation kinetic of a variety of micropollutants and radical chemistry in the UV/NH2Cl process. The presence of chloride blunted HO• and Cl• impacts, but enhanced Cl2•- effect on micropollutants reactive toward Cl2•-. The presence of 30 μM bromide led to an 82% decrease in the specific pseudo-first-order rate constants (k') by HO• (kHO•'), and significantly diminished RCS efficacy. Reactive bromine species (RBS) were formed in the presence of bromide, while the contribution could not compensate for the decrease of HO• and RCS due to their lower reactivity toward micropollutants. Iodide rapidly transformed to HOI via reacting with NH2Cl, which resulted in a 59% decrease of kHO•' and 12% ∼ 100% decreases of k' by reactive halogen species (RHS) and RNS (kRHS + RNS') for most micropollutants. Nevertheless, k' of phenolic compounds, such as paracetamol, bisphenol A and salbutamol, increased in the presence of iodide by 78%, 360% and 130%, respectively, due to the roles of HOI and reactive iodine species (RIS). Bicarbonate decreased the contributions of HO• and RCS, but enhanced that of CO3•- for micropollutants reactive toward CO3•-. The presence of 1 mg/L NOM scavenged over half the amount of HO•, and also consumed RCS and RNS, resulting in significantly decreased removal of micropollutants. High pH value witnessed enhanced degradation for those micropollutants reactive toward RCS and RNS through deprotonation. The degradation of most micropollutants was inhibited in real drinking water and in the coexistence of halides. This study provides a better understanding of radical chemistry in the UV/NH2Cl process under a practical water treatment condition.
Collapse
Affiliation(s)
- Chunyan Chen
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Zihao Wu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Zhechao Hua
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Kaiheng Guo
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yujie Zhou
- Hainan Provincial Department of Ecological Environment, Haikou 570203, China
| | - Ding Wang
- General Institute of Water Resources and Hydropower Planning and Design, Beijing 100120, China
| | - Beicheng Xia
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Jingyun Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
| |
Collapse
|
18
|
Mustapha S, Jimoh T, Ndamitso M, Abdulkareem SA, Taye SD, Mohammed AK, Amigun AT. The Occurrence of N-nitrosodimethylamine (NDMA) in Swimming Pools: An Overview. ENVIRONMENTAL HEALTH INSIGHTS 2021; 15:11786302211036520. [PMID: 34376989 PMCID: PMC8335839 DOI: 10.1177/11786302211036520] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 07/12/2021] [Indexed: 05/23/2023]
Abstract
The occurrence of several disinfectant byproducts has been investigated in swimming pools. Until now, there are only a few studies on nitrosamine, particularly N-nitrosodimethylamine in swimming pool water. This could be due to the lack of a suitable method that is sensitive enough for the measurement of N-nitrosodimethylamine in pool waters. Other disinfectant byproducts formed in pool water widely documented are trihalomethanes, haloacetic acids, halonitromethanes, and chloramines but inadequate information on N-nitrosodimethylamine. This paper provides a review of the nitrogenous disinfectant byproduct in swimming pools and its health implications. Anthropogenic substances introduced by swimmers such as sweat, lotions, and urine contribute to the formation of N-nitrosodimethylamine. The reaction of secondary amines such as dimethylamine with mono/dichloroamines produced dimethyl hydrazine and further undergo oxidation to form N-nitrosodimethylamine. The reaction of chlorine and other disinfectants with these anthropogenic sources in swimming pools cause cancer and asthma in human tissues. Thus, the assessment of N-nitrosodimethylamine in the swimming pool is less well documented. Therefore, the health consequences, mutagenic, and genotoxic potentials of N-nitrosodimethylamine should be the focus of more research studies.
Collapse
Affiliation(s)
- Saheed Mustapha
- Department of Chemistry, Federal University of Technology, Minna, Nigeria
- Nanotechnology Research Group, Center for Genetic Engineering and Biotechnology, Federal University of Technology, Minna, Niger, Nigeria
| | - Tijani Jimoh
- Department of Chemistry, Federal University of Technology, Minna, Nigeria
- Nanotechnology Research Group, Center for Genetic Engineering and Biotechnology, Federal University of Technology, Minna, Niger, Nigeria
| | - Muhammed Ndamitso
- Department of Chemistry, Federal University of Technology, Minna, Nigeria
- Nanotechnology Research Group, Center for Genetic Engineering and Biotechnology, Federal University of Technology, Minna, Niger, Nigeria
| | - Saka Ambali Abdulkareem
- Nanotechnology Research Group, Center for Genetic Engineering and Biotechnology, Federal University of Technology, Minna, Niger, Nigeria
- Department of Chemical Engineering, Federal University of Technology, Minna, Niger, Nigeria
| | - Shuaib Damola Taye
- Department of Chemistry, Illinois Institute of Technology, Chicago, IL, USA
| | - Abdul Kabir Mohammed
- Department of Chemistry and Biochemistry, North Carolina Central University, Durham, NC, USA
| | - Azeezah Taiwo Amigun
- Department of Chemical and Geological Sciences, Al-Hikmah University, Ilorin, Nigeria
| |
Collapse
|
19
|
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. JOURNAL OF HAZARDOUS MATERIALS 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] [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.
Collapse
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.
| |
Collapse
|
20
|
Chen C, Du Y, Zhou Y, Wu Q, Zheng S, Fang J. Formation of nitro(so) and chlorinated products and toxicity alteration during the UV/monochloramine treatment of phenol. WATER RESEARCH 2021; 194:116914. [PMID: 33636667 DOI: 10.1016/j.watres.2021.116914] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
The UV/monochloramine (UV/NH2Cl) process is an emerging advanced oxidation process (AOP) to remove organic contaminants in water treatment with radicals including hydroxyl radicals (HO•), reactive chlorine species (RCS) and reactive nitrogen species (RNS). This study investigated the formation of nitro(so) and chlorinated products and toxicity alteration during the UV/NH2Cl treatment of phenol. RNS and/or RCS induced the formation of nitro(so), chlorinated and polymeric compounds during phenol transformation by UV/NH2Cl. These compounds dramatically increased the cytotoxicity to Chinese hamster ovary cells after 20 min UV/NH2Cl treatment, which was 10 times higher than that after 24 h chloramination. The increase of cytotoxicity in UV/NH2Cl was primarily attributable to 4-nitrosophenol, and the cytotoxicity followed the order of 4-nitrosophenol >> 4-nitrophenol > 2,4,6-trichlorophenol > 2,4-dichlorophenol > phenol. 4-Nitrosophenol was significantly generated by the combination of •NO and phenoxy radical, where the maximum conversion rates of phenol to 4-nitrosophenol increased from 4.9% to 62.4% when pH increased from 5 to 10. The highest conversion rate was at pH 10 because the •NO concentration increased with increasing pH from 5 to 10 in UV/NH2Cl, as verified by the electron paramagnetic resonance (EPR) analysis. Nitrophenols were also detected at much lower concentrations than 4-nitrosophenol, which were mainly formed by the oxidation of 4-nitrosophenol and the combination of •NO2 with phenoxy radicals. RCS was responsible for the formation of chlorinated products mainly through Cl• addition and the reactions of Cl•/Cl2•- with phenoxy radicals. Also, RCS and RNS significantly enhanced the formation of carbonaceous (i.e., chloroform and chloral hydrate) and nitrogenous disinfection byproducts (i.e., chloropicrin and dichloroacetonitrile) in UV/NH2Cl. This study indicates that the UV/NH2Cl treatment significantly increased toxicity and validates the roles of RNS and RCS in producing toxic nitro(so) and chlorinated products.
Collapse
Affiliation(s)
- Chunyan Chen
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, PR China
| | - Ye Du
- Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, Shenzhen, 518055, PR China
| | - Yujie Zhou
- Hainan Provincial Department of Ecological Environment, Haikou, 570203, PR China
| | - Qianyuan Wu
- Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, Shenzhen, 518055, PR China
| | - Shanshan Zheng
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, PR China
| | - Jingyun Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, PR China.
| |
Collapse
|
21
|
Su Q, Schittich AR, Jensen MM, Ng H, Smets BF. Role of Ammonia Oxidation in Organic Micropollutant Transformation during Wastewater Treatment: Insights from Molecular, Cellular, and Community Level Observations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:2173-2188. [PMID: 33543927 DOI: 10.1021/acs.est.0c06466] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Organic micropollutants (OMPs) are a threat to aquatic environments, and wastewater treatment plants may act as a source or a barrier of OMPs entering the environment. Understanding the fate of OMPs in wastewater treatment processes is needed to establish efficient OMP removal strategies. Enhanced OMP biotransformation has been documented during biological nitrogen removal and has been attributed to the cometabolic activity of ammonia-oxidizing bacteria (AOB) and, specifically, to the ammonia monooxygenase (AMO) enzyme. Yet, the exact mechanisms of OMP biotransformation are often unknown. This critical review aims to fundamentally and quantitatively evaluate the role of ammonia oxidation in OMP biotransformation during wastewater treatment processes. OMPs can be transformed by AOB via direct and indirect enzymatic reactions: AMO directly transforms OMPs primarily via hydroxylation, while biologically produced reactive nitrogen species (hydroxylamine (NH2OH), nitrite (NO2-), and nitric oxide (NO)) can chemically transform OMPs through nitration, hydroxylation, and deamination and can contribute significantly to the observed OMP transformations. OMPs containing alkyl, aliphatic hydroxyl, ether, and sulfide functional groups as well as substituted aromatic rings and aromatic primary amines can be biotransformed by AMO, while OMPs containing alkyl groups, phenols, secondary amines, and aromatic primary amines can undergo abiotic transformations mediated by reactive nitrogen species. Higher OMP biotransformation efficiencies and rates are obtained in AOB-dominant microbial communities, especially in autotrophic reactors performing nitrification or nitritation, than in non-AOB-dominant microbial communities. The biotransformations of OMPs in wastewater treatment systems can often be linked to ammonium (NH4+) removal following two central lines of evidence: (i) Similar transformation products (i.e., hydroxylated, nitrated, and desaminated TPs) are detected in wastewater treatment systems as in AOB pure cultures. (ii) Consistency in OMP biotransformation (rbio, μmol/g VSS/d) to NH4+ removal (rNH4+, mol/g VSS/d) rate ratios (rbio/rNH4+) is observed for individual OMPs across different systems with similar rNH4+ and AOB abundances. In this review, we conclude that AOB are the main drivers of OMP biotransformation during wastewater treatment processes. The importance of biologically driven abiotic OMP transformation is quantitatively assessed, and functional groups susceptible to transformations by AMO and reactive nitrogen species are systematically classified. This critical review will improve the prediction of OMP transformation and facilitate the design of efficient OMP removal strategies during wastewater treatment.
Collapse
Affiliation(s)
- Qingxian Su
- National University of Singapore Environmental Research Institute, 5A Engineering Drive 1, 117411 Singapore, Singapore
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Anna-Ricarda Schittich
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Marlene Mark Jensen
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Howyong Ng
- National University of Singapore Environmental Research Institute, 5A Engineering Drive 1, 117411 Singapore, Singapore
- Centre for Water Research, Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576 Singapore, Singapore
| | - Barth F Smets
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| |
Collapse
|
22
|
Szczuka A, Huang N, MacDonald JA, Nayak A, Zhang Z, Mitch WA. N-Nitrosodimethylamine Formation during UV/Hydrogen Peroxide and UV/Chlorine Advanced Oxidation Process Treatment Following Reverse Osmosis for Potable Reuse. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15465-15475. [PMID: 33185421 DOI: 10.1021/acs.est.0c05704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Chloramines applied to control microfiltration and reverse osmosis (RO) membrane biofouling in potable reuse trains form the potent carcinogen, N-nitrosodimethylamine (NDMA). In addition to degrading other contaminants, UV-based advanced oxidation processes (AOPs) strive to degrade NDMA by direct photolysis. The UV/chlorine AOP is gaining attention because of its potential to degrade other contaminants at lower UV fluence than the UV/hydrogen peroxide AOP, although previous pilot studies have observed that the UV/chlorine AOP was less effective for NDMA control. Using dimethylamine (DMA) as a model precursor and secondary municipal wastewater effluent, this study evaluated NDMA formation during the AOP treatment via two pathways. First, NDMA formation by UV treatment of monochloramine (NH2Cl) and chlorinated DMA (Cl-DMA) passing through RO membranes was maximized at 350 mJ/cm2 UV fluence, declining at higher fluence, where NDMA photolysis outweighed NDMA formation. Second, this study demonstrated that chlorine addition to the chloramine-containing RO permeate during the UV/chlorine AOP treatment initiated rapid NDMA formation by dark breakpoint reactions associated with reactive intermediates from the hydrolysis of dichloramine. At pH 5.7, this formation was maximized at a chlorine/ammonia molar ratio of 3 (out of 0-10), conditions typical for UV/chlorine AOPs. At 700 mJ/cm2 UV fluence, which is applicable to current practice, NDMA photolysis degraded a portion of the NDMA formed by breakpoint reactions. Lowering UV fluence to ∼350 mJ/cm2 when switching to the UV/chlorine AOP exacerbates effluent NDMA concentrations because of concurrent NDMA formation via the UV/NH2Cl/Cl-DMA and breakpoint chlorination pathways. Fluence >700 mJ/cm2 or chlorine doses greater than the 3:1 chlorine/ammonia molar ratios under consideration for the UV/HOCl AOP treatment are needed to achieve NDMA control.
Collapse
Affiliation(s)
- Aleksandra Szczuka
- Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Stanford, California 94305, United States
- National Science Foundation Engineering Re-Inventing the Nation's Urban Water Infrastructure (ReNUWIt), Stanford, California 94305United States
| | - Nan Huang
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Jessica A MacDonald
- Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Stanford, California 94305, United States
- National Science Foundation Engineering Re-Inventing the Nation's Urban Water Infrastructure (ReNUWIt), Stanford, California 94305United States
| | - Adam Nayak
- Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Stanford, California 94305, United States
- National Science Foundation Engineering Re-Inventing the Nation's Urban Water Infrastructure (ReNUWIt), Stanford, California 94305United States
| | - Zhong Zhang
- Institute of Environmental & Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - William A Mitch
- Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Stanford, California 94305, United States
- National Science Foundation Engineering Re-Inventing the Nation's Urban Water Infrastructure (ReNUWIt), Stanford, California 94305United States
| |
Collapse
|
23
|
Zhang S, Lin T, Chen H, Xu H, Chen W, Tao H. Precursors of typical nitrogenous disinfection byproducts: Characteristics, removal, and toxicity formation potential. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 742:140566. [PMID: 32721729 DOI: 10.1016/j.scitotenv.2020.140566] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 06/20/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
The emergence of nitrogenous disinfection byproducts (N-DBPs) in drinking water has become a widespread concern. In this study, dichloroacetonitrile (DCAN), dicholoacetamide (DCAcAm) and trichloronitromethane (TCNM) were chosen as representatives to clarify the characteristics of N-DBP precursors in the raw waters of Taihu Lake, the Yangtze River, and Gaoyou Lake. Removal of DCAN and DCAcAm precursors must focus on nonpolar and positively charged organics, but more attention should be paid to micromolecular, polar and non-positively charged organics as TCNM precursors. Compared to molecular weight (MW) and hydrophilicity fractionation, polarity and electrical classification have higher selectivity to intercept N-DBP precursors. The properties of N-DBP precursors are relatively fixed and traceable in water systems, which could contribute to their targeted removal. Based on investigation of their characteristics, the removal efficiency and preferences of organic precursors under different processes were studied in three drinking water treatment plants (DWTPs). The TCNM precursors produced in preozonation can be effectively removed during coagulation. The cumulative removal efficiency of conventional processes on N-DBP precursors was approximately 20-30%, but O3/BAC process improved removal by about 40%. The key to improving the removal efficiency of N-DBP precursors by O3/BAC is that it can significantly remove low-MW, nonpolar, positively charged, hydrophilic and transphilic organics. In combined toxicity trials, both cytotoxicity and genotoxicity showed a synergistic effect when DCAN, DCAcAm, and TCNM coexisted, which means that low-level toxicity enhancement in the actual water merits attention. DCAN precursors dominated in the toxicity formation potential (TFP), followed by TCNM precursors. In addition, the removal rate of total N-DBP precursors may be higher than that of TFP, leading to overly optimistic evaluation of precursor removal in water treatment practice. Therefore, the removal effect on TFP must also be considered.
Collapse
Affiliation(s)
- Shisheng Zhang
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Tao Lin
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Han Chen
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Hang Xu
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Wei Chen
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Hui Tao
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| |
Collapse
|
24
|
Seid MG, Cho K, Hong SW. UV/sulfite chemistry to reduce N-nitrosodimethylamine formation in chlor(am)inated water. WATER RESEARCH 2020; 185:116243. [PMID: 32750569 DOI: 10.1016/j.watres.2020.116243] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/16/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
The disinfection by-product N-nitrosodimethylamine (NDMA) is a major concern in water quality management due to its carcinogenicity. Thus, a proper pretreatment is necessary to mitigate NDMA formation upon periodic chloramination by removing precursors, such as ranitidine (RNT). This study investigated the effect of UV/sulfite pretreatment on NDMA formation from an RNT-spiked tap and chloraminated synthetic swimming pool (SSP) water. At UVC intensity of 2.1 mW cm-2 and 0.5 mM of sulfite, UV/sulfite chemistry showed complete degradation of 20 µM RNT within 30 min. It was found that SO4•- primarily reduced the NDMA formation potential (FP) of RNT, while hydrated electrons effectively mitigated the pre-formed NDMA in the SSP water. The UV/sulfite pretreatment alleviated NDMA formation during post-chloramination (24 h) by up to 82%, outperforming the commonly employed advanced oxidation processes such as UV/H2O2. However, in the presence of bromide ions, the effectiveness of UV/sulfite pretreatment was seriously deteriorated, although the bromide ion itself was found to inhibit the NDMA formation from RNT especially at pH < 8 during chloramination. Mass spectrometric analysis indicated that the NDMA-FP of RNT could be removed by UV/sulfite principally via N-methylation, dealkylation, and oxygen transfer pathways. Consequently, UV/sulfite could be used as an alternative unit process for water treatment with reduced NDMA formation.
Collapse
Affiliation(s)
- Mingizem Gashaw Seid
- Division of Energy and Environment Technology, KIST-School, University of Science and Technology, Seoul 02792, Republic of Korea; Water Cycle Research Center, Korea Institute of Science and Technology, Hwarangro 14 gil, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Kangwoo Cho
- Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea; Institute for Convergence Research and Education in Advanced Technology (I-CREATE), Yonsei University International Campus, Incheon 21983, Republic of Korea.
| | - Seok Won Hong
- Division of Energy and Environment Technology, KIST-School, University of Science and Technology, Seoul 02792, Republic of Korea; Water Cycle Research Center, Korea Institute of Science and Technology, Hwarangro 14 gil, Seongbuk-gu, Seoul 136-791, Republic of Korea.
| |
Collapse
|
25
|
Zhang Z, Zhao Q, Song H, Zhang J, Wang L, Qi J, Liu Y, Ma J. Comparative study about oxidation of trace N-nitrosamines by seven oxidation processes with a sensitivity improved determination method. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2019.116009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
26
|
Wu Z, Chen C, Zhu BZ, Huang CH, An T, Meng F, Fang J. Reactive Nitrogen Species Are Also Involved in the Transformation of Micropollutants by the UV/Monochloramine Process. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:11142-11152. [PMID: 31411457 DOI: 10.1021/acs.est.9b01212] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The UV/monochloramine (NH2Cl) process is an emerging advanced oxidation process (AOP) in water treatment via radicals produced from the UV photolysis of NH2Cl. This study investigated the degradation of micropollutants by the UV/NH2Cl AOP, with ibuprofen (IBP) and naproxen (NPX) selected as representative micropollutants. Hydroxyl radical (HO•) and chlorine atom (Cl•) were identified in the process, and unexpectedly, we found that reactive nitrogen species (RNS) also played important roles in the transformation of micropollutants. The electron paramagnetic resonance (EPR) analysis proved the production of •NO as well as HO•. The concentrations of HO•, Cl•, and •NO in UV/NH2Cl remained constant at pH 6.0-8.6, resulting in the slightly changed UV fluence-based pseudo-first-order rate constants (k') of IBP and NPX, which were about 1.65 × 10-3 and 2.54 × 10-3 cm2/mJ, respectively. For IBP, the relative contribution of RNS to k' was 27.8% at pH 7 and 50 μM NH2Cl, which was higher than that of Cl• (6.5%) but lower than that of HO• (58.7%). For NPX, the relative contribution of RNS to k' was 13.6%, which was lower than both Cl• (23.2%) and HO• (46.9%). The concentrations of HO•, Cl•, and •NO increased with the increasing NH2Cl dosage. Water matrix components of natural organic matter (NOM) and bicarbonate can scavenge HO•, Cl•, and RNS. The presence of 5 mg/L NOM decreased the k' of IBP and NPX by 66.9 and 57.6%, respectively, while 2 mM bicarbonate decreased the k' of IBP by 57.4% but increased the k' of NPX by 10.5% due to the contribution of CO3•- to NPX degradation. Products containing nitroso-, hydroxyl-, and chlorine-groups were detected during the degradation of IBP and NPX by UV/NH2Cl, indicating the role of nitrogen oxide radical (•NO) as well as HO• and Cl•. Trichloronitromethane formation was strongly enhanced in the UV/NH2Cl-treated samples, further indicating the important roles of RNS in this process. This study first demonstrates the involvement of RNS in the transformation of micropollutants in UV/NH2Cl.
Collapse
Affiliation(s)
- Zihao Wu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering , Sun Yat-Sen University , Guangzhou 510275 , China
| | - Chunyan Chen
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering , Sun Yat-Sen University , Guangzhou 510275 , China
| | - Ben-Zhan Zhu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100085 , P. R. China
| | - Chun-Hua Huang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100085 , P. R. China
| | - Taicheng An
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control , Guangdong University of Technology , Guangzhou 510006 , China
| | - Fangang Meng
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering , Sun Yat-Sen University , Guangzhou 510275 , China
| | - Jingyun Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering , Sun Yat-Sen University , Guangzhou 510275 , China
| |
Collapse
|
27
|
Ra J, Yoom H, Son H, Hwang TM, Lee Y. Transformation of an Amine Moiety of Atenolol during Water Treatment with Chlorine/UV: Reaction Kinetics, Products, and Mechanisms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:7653-7662. [PMID: 31244072 DOI: 10.1021/acs.est.9b01412] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Transformation of atenolol (ATN), a micropollutant containing a secondary (2°) amine moiety, can be significantly enhanced in water treatment with sequential and combined use of chlorine and UV (chlorine/UV) through photolysis of the N-Cl bond. This study investigated the transformation kinetics, products, and mechanisms of the amine moiety of ATN in chlorine/UV (254 nm). The fluence-based, photolysis rate constant for N-Cl ATN was 2.0 × 10-3 cm2/mJ. Transformation products (TPs) with primary (1°) amines were mainly produced, but TPs with 2° and 3° amines were also formed, on the basis of liquid chromatography (LC)/quadrupole-time-of-flight/mass spectrometry and LC/UV analyses. The amine-containing TPs could be further transformed in chlorine/UV (with residual chlorine in post UV) via formation and photolysis of new N-Cl bonds. Photolysis of N-Cl 1° amine TPs produced ammonia as a major product. These data could be explained by a reaction mechanism in which the N-Cl bond was cleaved by UV, forming aminyl radicals that were transformed via 1,2-hydrogen shift, β-scission, intramolecular addition, and 1,2-alkyl shift. Among these, the 1,2-alkyl shift is newly discovered in this study. Despite enhanced transformation, only partial mineralization of the ATN's amine moiety was expected, even under chlorine/UV advanced oxidation process conditions. Overall, the kinetic and mechanistic information from this study can be useful for predicting the transformation of amine moieties by chlorine/UV water treatment.
Collapse
Affiliation(s)
- Jiwoon Ra
- School of Earth Sciences and Environmental Engineering , Gwangju Institute of Science and Technology (GIST) , Gwangju 61005 , Republic of Korea
| | - Hoonsik Yoom
- Busan Water Quality Institute , Gimhae , Gyeongsangnam 621-813 , Republic of Korea
| | - Heejong Son
- Busan Water Quality Institute , Gimhae , Gyeongsangnam 621-813 , Republic of Korea
| | - Tae-Mun Hwang
- Water Resources and Environmental Research Division , Korea Institute of Construction Technology , 2311, Goyang , Gyeonggi 411-712 , Republic of Korea
| | - Yunho Lee
- School of Earth Sciences and Environmental Engineering , Gwangju Institute of Science and Technology (GIST) , Gwangju 61005 , Republic of Korea
| |
Collapse
|
28
|
Carter RAA, Allard S, Croué JP, Joll CA. Occurrence of disinfection by-products in swimming pools and the estimated resulting cytotoxicity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 664:851-864. [PMID: 30769309 DOI: 10.1016/j.scitotenv.2019.01.428] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/28/2019] [Accepted: 01/31/2019] [Indexed: 05/27/2023]
Abstract
Swimming pools are disinfected to protect against the risk of microbial disease, however, the formation of disinfection by-products (DBPs) is an unwanted consequence. While many studies have reported the occurrence of commonly investigated DBPs (trihalomethanes and haloacetic acids) in pools, few studies have investigated emerging DBP classes, such as the haloketones or haloacetaldehydes, and the nitrogenous haloacetamides, halonitromethanes, haloacetonitriles and N-nitrosamines. This study investigated the occurrence of sixty four DBPs from the eight aforementioned DBP classes in pools employing different treatment methods. Approximately 70% of the DBPs were detected in at least one of the pools, with most concentrations being equal to or greater than those previously reported. Chloral hydrate (trichloroacetaldehyde) was one of many DBPs detected in all chlorinated waters (202 to 1313 μg/L), and, on a molar basis, was the predominant DBP. Several other DBPs, namely chloroacetic acid, dichloroacetic acid, trichloroacetic acid, dichloroacetamide, dibromoacetamide, dibromochloroacetamide and trichloroacetamide, and many of the N-nitrosamines, were measured at concentrations greater than previously reported: up to 200 to 479 μg/L for the haloacetic acids, 56 to 736 μg/L for the haloacetamides and up to 1093 ng/L for some N-nitrosamines. The higher disinfectant residuals required to be employed in Australian pools, and poor pool management (e.g. of chlorine residual and pH) are likely factors contributing to these relatively high DBP concentrations. Where possible, the cytotoxicity values of the investigated DBPs were evaluated, with chloral hydrate representing over 90% of the total chronic cytotoxicity despite only representing up to 64% of the total molar DBP concentration. This study is the first report of bromodichloroacetaldehyde and bromochloroacetaldehyde in pools and is the first investigation of N-nitrosamines in a brominated pool. Furthermore, this work aids in understanding DBPs in both chlorine and bromine treated pools, the latter being the subject of only limited previous studies.
Collapse
Affiliation(s)
- Rhys A A Carter
- Curtin Water Quality Research Centre (CWQRC), Chemistry, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Sébastien Allard
- Curtin Water Quality Research Centre (CWQRC), Chemistry, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Jean-Philippe Croué
- Curtin Water Quality Research Centre (CWQRC), Chemistry, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Cynthia A Joll
- Curtin Water Quality Research Centre (CWQRC), Chemistry, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia.
| |
Collapse
|
29
|
Skibinski B, Worch E, Uhl W. N 2 yields from monochloramine conversion by granular activated carbons are decisive for effective swimming pool water treatment. WATER RESEARCH 2019; 152:74-86. [PMID: 30660903 DOI: 10.1016/j.watres.2018.11.068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 11/21/2018] [Accepted: 11/26/2018] [Indexed: 06/09/2023]
Abstract
Inorganic chloramines (mono-, di- and trichloramine) are formed in swimming pool water from the unintended reaction of free chlorine with ammonia that is introduced by bathers. Monochloramine is of particular interest as it is known to react further in pool water forming harmful DBPs, such carcinogenic N-nitrosodimethylamine (NDMA). During pool water treatment with granular activated carbon (GAC) filters, monochloramine is transformed by chemical reactions on the carbon surface to N2 and ammonia. As ammonia is led back into the pool where it is chlorinated again under the renewed formation of inorganic chloramines, it is recommended to use GACs with a high N2 yield for monochloramine transformation in pool water treatment. In this study, yields of N2 and ammonia from monochloramine conversion by commercially available GACs were determined using a fixed-bed reactor system under conditions that are typical for swimming pool water treatment. The N2 yields remained constant with on-going exposure of the GAC to monochloramine and ranged from 0.5% to 21.3%, depending on the type of GAC used. Correlation analyses were conducted to identify carbon properties that can determine the N2 yield for monochloramine conversion, such as the amount of oxygen groups, the elemental composition and the trace metal content. It was found that the N2 yield significantly correlates with the copper content of the tested carbons. Model calculations combining pool hydraulics with formation/abatement of inorganic chloramines and NDMA as well as chloramine transformations in GAC filters showed that the concentration of inorganic chloramines and carcinogenic NDMA can be decreased by a factor of ∼2, if the tested GACs could be modified to convert up to ∼50% of the monochloramine to N2.
Collapse
Affiliation(s)
- Bertram Skibinski
- Technische Universität Dresden, Chair of Water Supply Engineering, 01062, Dresden, Germany.
| | - Eckhard Worch
- Technische Universität Dresden, Chair of Hydrochemistry, 01062, Dresden, Germany
| | - Wolfgang Uhl
- Technische Universität Dresden, Chair of Water Supply Engineering, 01062, Dresden, Germany; Norwegian Institute for Water Research (NIVA), 0349, Oslo, Norway; Norwegian University of Science and Technology (NTNU), Institute of Civil and Environmental Engineering, 7491, Trondheim, Norway.
| |
Collapse
|
30
|
Saleem S, Dyck R, Hu G, Hewage K, Rodriguez M, Sadiq R. Investigating the effects of design and management factors on DBPs levels in indoor aquatic centres. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 651:775-786. [PMID: 30253359 DOI: 10.1016/j.scitotenv.2018.09.172] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 06/08/2023]
Abstract
Disinfection by-products (DBPs) in indoor swimming pool water and air have long been a critical human health risk concern. This study investigated the effects of several indoor swimming pool design and management factors (e.g. ventilation, water treatment, pool operations, pool type) on the concentrations of DBPs, such as trihalomethanes (THMs) and chloramines, in pool water and air. Two sampling campaigns, A and B, were carried out to measure the concentrations of DBPs under different conditions. In both campaigns, 46 pool water samples, seven tap water samples, and 28 ambient air samples were collected and analyzed. Regression models were also developed and validated for investigating the combined effects of design and management factors on total trihalomethanes (TTHM) and trichloramine. The model results show that pool water characteristics (e.g., total organic content, temperature, conductivity, pH and alkalinity) and management factors (e.g., the number of bathers and sprayers) have direct effects on DBP concentrations. Pool water characteristics such as UV absorbance, hardness, and oxidation-reduction potential and a management factor UV intensity have inverse effects on DBPs levels. Based on the correlation analysis, other factors such as fan speed, fresh air, pool age, and basin area were found to be correlated with the concentrations of individual THMs and trichloramine in both water and air. It was also observed that the concentration of THMs varies with pool type. It is note worthy that the effects of the number of sprayers was quantified for the first time. This study comprehensively assessed pool design and management factors and identified their effects on DBPs, providing indoor swimming pool facilities with useful information to control DBPs in the indoor swimming environment.
Collapse
Affiliation(s)
- Sana Saleem
- School of Engineering, University of British Columbia, Okanagan Campus, Kelowna, BC, Canada V1V 1V7.
| | - Roberta Dyck
- School of Engineering, University of British Columbia, Okanagan Campus, Kelowna, BC, Canada V1V 1V7.
| | - Guangji Hu
- School of Engineering, University of British Columbia, Okanagan Campus, Kelowna, BC, Canada V1V 1V7.
| | - Kasun Hewage
- School of Engineering, University of British Columbia, Okanagan Campus, Kelowna, BC, Canada V1V 1V7.
| | - Manuel Rodriguez
- Université Laval, Pavillon Félix-Antoine-Savard, 2325 rue des Bibliothèques, Local 1628, QC G1V 0A6, Canada.
| | - Rehan Sadiq
- School of Engineering, University of British Columbia, Okanagan Campus, Kelowna, BC, Canada V1V 1V7.
| |
Collapse
|
31
|
Ge Y, Shen W, Wang X, Feng H, Feng L. Synthesis and bactericidal action of Fe3O4/AgO bifunctional magnetic-bactericidal nanocomposite. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2018.11.063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|
32
|
Yang L, Chen X, She Q, Cao G, Liu Y, Chang VWC, Tang CY. Regulation, formation, exposure, and treatment of disinfection by-products (DBPs) in swimming pool waters: A critical review. ENVIRONMENT INTERNATIONAL 2018; 121:1039-1057. [PMID: 30392941 DOI: 10.1016/j.envint.2018.10.024] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 10/10/2018] [Accepted: 10/13/2018] [Indexed: 06/08/2023]
Abstract
The microbial safety of swimming pool waters (SPWs) becomes increasingly important with the popularity of swimming activities. Disinfection aiming at killing microbes in SPWs produces disinfection by-products (DBPs), which has attracted considerable public attentions due to their high frequency of occurrence, considerable concentrations and potent toxicity. We reviewed the latest research progress within the last four decades on the regulation, formation, exposure, and treatment of DBPs in the context of SPWs. This paper specifically discussed DBP regulations in different regions, formation mechanisms related with disinfectants, precursors and other various conditions, human exposure assessment reflected by biomarkers or epidemiological evidence, and the control and treatment of DBPs. Compared to drinking water with natural organic matter as the main organic precursor of DBPs, the additional human inputs (i.e., body fluids and personal care products) to SPWs make the water matrix more complicated and lead to the formation of more types and greater concentrations of DBPs. Dermal absorption and inhalation are two main exposure pathways for trihalomethanes while ingestion for haloacetic acids, reflected by DBP occurrence in human matrices including exhaled air, urine, blood, and plasma. Studies show that membrane filtration, advanced oxidation processes, biodegradation, thermal degradation, chemical reduction, and some hybrid processes are the potential DBP treatment technologies. The removal efficiency, possible mechanisms and future challenges of these DBP treatment methods are summarized in this review, which may facilitate their full-scale applications and provide potential directions for further research extension.
Collapse
Affiliation(s)
- Linyan Yang
- School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, PR China; Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore; Residues and Resource Reclamation Centre (R3C), Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Xueming Chen
- Process and Systems Engineering Center (PROSYS), Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Qianhong She
- School of Chemical and Biomolecular Engineering, The University of Sydney, NSW 2006, Australia
| | - Guomin Cao
- School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Yongdi Liu
- School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Victor W-C Chang
- Residues and Resource Reclamation Centre (R3C), Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; Department of Civil Engineering, Monash University, VIC 3800, Australia.
| | - Chuyang Y Tang
- Department of Civil Engineering, University of Hong Kong, Pokfulam, Hong Kong.
| |
Collapse
|
33
|
Gushgari AJ, Halden RU. Critical review of major sources of human exposure to N-nitrosamines. CHEMOSPHERE 2018; 210:1124-1136. [PMID: 30208538 DOI: 10.1016/j.chemosphere.2018.07.098] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 07/16/2018] [Accepted: 07/17/2018] [Indexed: 05/21/2023]
Abstract
More than 24 N-nitrosamine compounds contribute to the total N-nitrosamine (TNA) burden monitored routinely to assess human exposure to this important group of known and suspected human carcinogens. A literature review (n = 122) identified multiple sources of human exposure to TNAs, including waters (40 ± 10.5 ng/L; average ± standard deviation), food and beverages (6.7 ± 0.8 ng/g), tobacco (16,100 ± 3650 ng/g) and personal care products (1500 ± 750 ng/g). Due to source control interventions, levels of TNAs in beer have dropped by about 96% between 1980 and 1990, whereas N-nitrosamine levels in other known sources have shown little to no change. Maximum daily TNA exposure in the U.S. in units of ng/d is estimated at 25,000 ± 4,950, driven by consumption of tobacco products (22,000 ± 4350), food (1900 ± 380), alcohol (1000 ± 200), and drinking water (120 ± 24). Behavioral choices of individuals in non-occupational settings were calculated to result in a spectrum of exposure values ranging from a lower bound of 1900 ± 380 ng/d to a higher bound of 25,000 ± 4950 ng/d, indicating opportunities for a possible 12-fold reduction in TNA exposure to 8% of the above maximum through deliberate choices in diet and lifestyle.
Collapse
Affiliation(s)
- Adam J Gushgari
- Biodesign Center for Environmental Health Engineering, The Biodesign Institute, School of Sustainable Engineering and the Built Environment, Arizona State University, 781 E. Terrace Mall, Tempe, AZ 85287, USA
| | - Rolf U Halden
- Biodesign Center for Environmental Health Engineering, The Biodesign Institute, School of Sustainable Engineering and the Built Environment, Arizona State University, 781 E. Terrace Mall, Tempe, AZ 85287, USA.
| |
Collapse
|
34
|
Fujioka T, Ishida KP, Shintani T, Kodamatani H. High rejection reverse osmosis membrane for removal of N-nitrosamines and their precursors. WATER RESEARCH 2018; 131:45-51. [PMID: 29268083 DOI: 10.1016/j.watres.2017.12.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 12/11/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Direct potable reuse is becoming a feasible option to cope with water shortages. It requires more stringent water quality assurance than indirect potable reuse. Thus, the development of a high-rejection reverse osmosis (RO) membrane for the removal of one of the most challenging chemicals in potable reuse - N-nitrosodimethylamine (NDMA) - ensures further system confidence in reclaimed water quality. This study aimed to achieve over 90% removal of NDMA by modifying three commercial and one prototype RO membrane using heat treatment. Application of heat treatment to a prototype membrane resulted in a record high removal of 92% (1.1-log) of NDMA. Heat treatment reduced conductivity rejection and permeability, while secondary amines, selected as N-nitrosamine precursors, were still well rejected (>98%) regardless of RO membrane type. This study also demonstrated the highly stable separation performance of the heat-treated prototype membrane under conditions of varying feed temperature and permeate flux. Fouling propensity of the prototype membrane was lower than a commercial RO membrane. This study identified a need to develop highly selective RO membranes with high permeability to ensure the feasibility of using these membranes at full scale.
Collapse
Affiliation(s)
- Takahiro Fujioka
- Water and Environmental Engineering, Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
| | - Kenneth P Ishida
- Research & Development Department, Orange County Water District, 18700 Ward Street, Fountain Valley, CA 92708, USA
| | - Takuji Shintani
- Division of Advanced Membrane Science and Technology, Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Kobe 657-8501, Japan
| | - Hitoshi Kodamatani
- Division of Earth and Environmental Science, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan
| |
Collapse
|
35
|
Sgroi M, Vagliasindi FGA, Snyder SA, Roccaro P. N-Nitrosodimethylamine (NDMA) and its precursors in water and wastewater: A review on formation and removal. CHEMOSPHERE 2018; 191:685-703. [PMID: 29078192 DOI: 10.1016/j.chemosphere.2017.10.089] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 10/05/2017] [Accepted: 10/14/2017] [Indexed: 06/07/2023]
Abstract
This review summarizes major findings over the last decade related to N-Nitrosodimethylamine (NDMA) in water and wastewater. In particular, the review is focused on the removal of NDMA and of its precursors by conventional and advanced water and wastewater treatment processes. New information regarding formation mechanisms and precursors are discussed as well. NDMA precursors are generally of anthropogenic origin and their main source in water have been recognized to be wastewater discharges. Chloramination is the most common process that results in formation of NDMA during water and wastewater treatment. However, ozonation of wastewater or highly contaminated surface water can also generate significant levels of NDMA. Thus, NDMA formation control and remediation has become of increasing interest, particularly during treatment of wastewater-impacted water and during potable reuse application. NDMA formation has also been associated with the use of quaternary amine-based coagulants and anion exchange resins. UV photolysis with UV fluence far higher than typical disinfection doses is generally considered the most efficient technology for NDMA mitigation. However, recent studies on the optimization of biological processes offer a potentially lower-energy solution. Options for NDMA control include attenuation of precursor materials through physical removal, biological treatment, and/or deactivation by application of oxidants. Nevertheless, NDMA precursor identification and removal can be challenging and additional research and optimization is needed. As municipal wastewater becomes increasingly used as a source water for drinking, NDMA formation and mitigation strategies will become increasingly more important. The following review provides a summary of the most recent information available.
Collapse
Affiliation(s)
- Massimiliano Sgroi
- Department of Civil Engineering and Architecture, University of Catania, Viale A. Doria 6, 95125, Catania, Italy.
| | - Federico G A Vagliasindi
- Department of Civil Engineering and Architecture, University of Catania, Viale A. Doria 6, 95125, Catania, Italy
| | - Shane A Snyder
- Department of Chemical & Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ, 85721, USA; National University of Singapore, NUS Environmental Research Institute (NERI), 5A Engineering Drive 1; T-Lab Building, #02-01, 117411, Singapore
| | - Paolo Roccaro
- Department of Civil Engineering and Architecture, University of Catania, Viale A. Doria 6, 95125, Catania, Italy
| |
Collapse
|
36
|
Weng S, Yang JY, Li YH, Blatchley ER. UV-induced effects on toxicity of model disinfection byproducts. THE SCIENCE OF THE TOTAL ENVIRONMENT 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] [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.
Collapse
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.
| |
Collapse
|
37
|
Spahr S, von Gunten U, Hofstetter TB. Carbon, Hydrogen, and Nitrogen Isotope Fractionation Trends in N-Nitrosodimethylamine Reflect the Formation Pathway during Chloramination of Tertiary Amines. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:13170-13179. [PMID: 29032675 DOI: 10.1021/acs.est.7b03919] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Assessing the precursors and reactions leading to the carcinogenic N-nitrosodimethylamine (NDMA) during drinking water disinfection is a major challenge. Here, we investigate whether changes of 13C/12C, 2H/1H, and 15N/14N ratios of NDMA give rise to isotope fractionation trends that can be used to infer NDMA formation pathways. We carried out compound-specific isotope analysis (CSIA) of NDMA during chloramination of four tertiary amines that produce NDMA at high yields, namely ranitidine, 5-(dimethylaminomethyl)furfuryl alcohol, N,N-dimethylthiophene-2-methylamine, and N,N-dimethylbenzylamine. Carbon and hydrogen isotope ratios of NDMA function as fingerprints of the N(CH3)2 moiety and exhibit only minor isotope fractionation during the disinfection process. Nitrogen isotope ratios showed that NH2Cl is the source of the N atom of the nitroso group. The large enrichment of 15N in NDMA was indicative of the isotope effects pertinent to bond-cleavage and bond-formation reactions during chloramination of the tertiary amines. Correlation of δ15N versus δ13C values of NDMA resulted in trend lines that were not affected by the type of tertiary amine and treatment conditions, suggesting that the observed C and N isotope fractionation in NDMA may be diagnostic for NDMA precursors and formation pathways during chloramination.
Collapse
Affiliation(s)
- Stephanie Spahr
- Eawag, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland
- School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Federale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Urs von Gunten
- Eawag, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland
- School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Federale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich , CH-8092 Zürich, Switzerland
| | - Thomas B Hofstetter
- Eawag, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich , CH-8092 Zürich, Switzerland
| |
Collapse
|
38
|
Wang WL, Zhang X, Wu QY, Du Y, Hu HY. Degradation of natural organic matter by UV/chlorine oxidation: Molecular decomposition, formation of oxidation byproducts and cytotoxicity. WATER RESEARCH 2017; 124:251-258. [PMID: 28763641 DOI: 10.1016/j.watres.2017.07.029] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 06/12/2017] [Accepted: 07/13/2017] [Indexed: 06/07/2023]
Abstract
The degradation of natural organic matters (NOMs) by the combination of UV and chlorine (UV/chlorine) was investigated in this study. UV/chlorine oxidation can effectively degrade NOMs, with the degradation of chromophores (∼80%) and fluorophores (76.4-80.8%) being more efficient than that of DOC (15.1-18.6%). This effect was attributed to the chromophores and fluorophores (double bonds, aromatic groups and phenolic groups) being preferentially degraded by UV/chlorine oxidation, particularly reactive groups with high electron donating capacity. Radical species •OH and •Cl were generated during UV/chlorine oxidation, with the contribution of •OH 1.4 times as high as that of •Cl. The degradation kinetics of different molecular weight (MW) fractions suggests that UV/chlorine oxidation degrades high MW fractions into low MW fractions, with the degradation rates of high MW fractions (>3000 Da) 4.5 times of those of medium MW fractions (1000-3000 Da). In comparison with chlorination alone, UV/chlorine oxidation did not increase the formation (30 min) and formation potential (24 h) of trihalomethanes, but instead promoted the formation and formation potential of haloacetic acids and chloral hydrate. Adsorbable organic halogen (AOX) formed from UV/chlorine oxidation of NOM were 0.8 times higher than those formed from chlorination. Cytotoxicity studies indicated that the cytotoxicity of NOM increased after both chlorination and UV/chlorine oxidation, which may be due to the formation of AOX.
Collapse
Affiliation(s)
- Wen-Long Wang
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Xue Zhang
- Collaborative Innovation Center for Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, PR China
| | - Qian-Yuan Wu
- Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
| | - Ye Du
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Hong-Ying Hu
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, Shenzhen 518055, PR China.
| |
Collapse
|
39
|
Dong H, Qiang Z, Hu J, Qu J. Degradation of chloramphenicol by UV/chlorine treatment: Kinetics, mechanism and enhanced formation of halonitromethanes. WATER RESEARCH 2017; 121:178-185. [PMID: 28527979 DOI: 10.1016/j.watres.2017.05.030] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 05/12/2017] [Accepted: 05/13/2017] [Indexed: 05/12/2023]
Abstract
Ultraviolet (UV)/chlorine process is considered as an emerging advanced oxidation process for the degradation of micropollutants. This study investigated the degradation of chloramphenicol (CAP) and formation of disinfection by-products (DBPs) during the UV/chlorine treatment. It was found that CAP degradation was enhanced by combined UV/chlorine treatment compared to that of UV and chlorination treatment alone. The pseudo-first-order rate constant of the UV/chlorine process at pH 7.0 reached 0.016 s-1, which was 10.0 and 2.0 folds that observed from UV and chlorination alone, respectively. The enhancement can be attributed to the formation of diverse radicals (HO and reactive chlorine species (RCSs)), and the contribution of RCSs maintained more stable than that of HO at pH 5.5-8.5. Meanwhile, enhanced DBPs formation during the UV/chlorine treatment was observed. Both the simultaneous formation and 24-h halonitromethanes formation potential (HNMsFP) were positively correlated with the UV/chlorine treatment time. Although the simultaneous trichloronitromethane (TCNM) formation decreased with the prolonged UV irradiation, TCNM dominated the formation of HNMs after 24 h (>97.0%). According to structural analysis of transformation by-products, both the accelerated CAP degradation and enhanced HNMs formation steps were proposed. Overall, the formation of diverse radicals during the UV/chlorine treatment accelerated the degradation of CAP, while also enhanced the formation of DBPs simultaneously, indicating the need for DBPs evaluation before the application of combined UV/chlorine process.
Collapse
Affiliation(s)
- Huiyu Dong
- 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.
| | - Jun Hu
- 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
| | - Jiuhui Qu
- 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
| |
Collapse
|
40
|
Carter RAA, Joll CA. Occurrence and formation of disinfection by-products in the swimming pool environment: A critical review. J Environ Sci (China) 2017; 58:19-50. [PMID: 28774608 DOI: 10.1016/j.jes.2017.06.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 06/11/2017] [Accepted: 06/13/2017] [Indexed: 06/07/2023]
Abstract
Disinfection of water for human use is essential to protect against microbial disease; however, disinfection also leads to formation of disinfection by-products (DBPs), some of which are of health concern. From a chemical perspective, swimming pools are a complex matrix, with continual addition of a wide range of natural and anthropogenic chemicals via filling waters, disinfectant addition, pharmaceuticals and personal care products and human body excretions. Natural organic matter, trace amounts of DBPs and chlorine or chloramines may be introduced by the filling water, which is commonly disinfected distributed drinking water. Chlorine and/or bromine is continually introduced via the addition of chemical disinfectants to the pool. Human body excretions (sweat, urine and saliva) and pharmaceuticals and personal care products (sunscreens, cosmetics, hair products and lotions) are introduced by swimmers. High addition of disinfectant leads to a high formation of DBPs from reaction of some of the chemicals with the disinfectant. Swimming pool air is also of concern as volatile DBPs partition into the air above the pool. The presence of bromine leads to the formation of a wide range of bromo- and bromo/chloro-DBPs, and Br-DBPs are more toxic than their chlorinated analogues. This is particularly important for seawater-filled pools or pools using a bromine-based disinfectant. This review summarises chemical contaminants and DBPs in swimming pool waters, as well as in the air above pools. Factors that have been found to affect DBP formation in pools are discussed. The impact of the swimming pool environment on human health is reviewed.
Collapse
Affiliation(s)
- Rhys A A Carter
- Curtin Water Quality Research Centre, Department of Chemistry, Curtin University, Perth, Western Australia 6102, Australia
| | - Cynthia A Joll
- Curtin Water Quality Research Centre, Department of Chemistry, Curtin University, Perth, Western Australia 6102, Australia.
| |
Collapse
|
41
|
Tardif R, Rodriguez M, Catto C, Charest-Tardif G, Simard S. Concentrations of disinfection by-products in swimming pool following modifications of the water treatment process: An exploratory study. J Environ Sci (China) 2017; 58:163-172. [PMID: 28774605 DOI: 10.1016/j.jes.2017.05.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 05/11/2017] [Accepted: 05/12/2017] [Indexed: 06/07/2023]
Abstract
The formation and concentration of disinfection by-products (DBPs) in pool water and the ambient air vary according to the type of water treatment process used. This exploratory study was aimed at investigating the short-term impact of modifications of the water treatment process on traditional DBP levels (e.g., trihalomethanes (THMs), chloramines) and emerging DBPs (e.g., Halonitromethanes, Haloketones, NDMA) in swimming pool water and/or air. A sampling program was carried to understand the impact of the following changes made successively to the standard water treatment process: activation of ultraviolet (UV) photoreactor, halt of air stripping with continuation of air extraction from the buffer tank, halt of air stripping and suppression of air extraction from the buffer tank, suppression of the polyaluminium silicate sulfate (PASS) coagulant. UV caused a high increase of Halonitromethanes (8.4 fold), Haloketones (2.1 fold), and THMs in the water (1.7 fold) and, of THMs in the air (1.6 fold) and contributed to reducing the level of chloramines in the air (1.6 fold) and NDMA in the water (2.1 fold). The results highlight the positive impact of air stripping in reducing volatile contaminants. The PASS did not change the presence of DBPs, except for the THMs, which decrease slightly with the use of this coagulant. This study shows that modifications affecting the water treatment process can rapidly produce important and variable impacts on DBP levels in water and air and suggests that implementation of any water treatment process to reduce DBP levels should take into account the specific context of each swimming pool.
Collapse
Affiliation(s)
- Robert Tardif
- Department of Environmental and Occupational Health, School of Public Health, Université de Montréal, Canada.
| | - Manuel Rodriguez
- NSERC Industrial Research Chair on Drinking Water, Université Laval, Québec City, Canada
| | - Cyril Catto
- Department of Environmental and Occupational Health, School of Public Health, Université de Montréal, Canada
| | - Ginette Charest-Tardif
- Department of Environmental and Occupational Health, School of Public Health, Université de Montréal, Canada
| | - Sabrina Simard
- NSERC Industrial Research Chair on Drinking Water, Université Laval, Québec City, Canada
| |
Collapse
|
42
|
Brienza M, Duwig C, Pérez S, Chiron S. 4-nitroso-sulfamethoxazole generation in soil under denitrifying conditions: Field observations versus laboratory results. JOURNAL OF HAZARDOUS MATERIALS 2017; 334:185-192. [PMID: 28412628 DOI: 10.1016/j.jhazmat.2017.04.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/04/2017] [Accepted: 04/05/2017] [Indexed: 06/07/2023]
Abstract
The formation of 4-nitroso-sulfamethoxazole and 4-nitro-SMX, two transformation products (TPs) of sulfamethoxazole (SMX) was investigated under batch soil slurry experiments and in a field study. Due to their low occurrence levels (ng/L) in environmental waters, a suitable analytical method based on liquid chromatography - high resolution - mass spectrometry was developed. Consequently, field observations revealed, for the first time, the occurrence of 4-nitroso-SMX in groundwater at concentrations as high as 18ng/L.Nitric oxide (NO) steady-state concentrations were determined in soil slurry experiments because this reactive specie accounted for the formation of 4-nitroso-SMX and 4-nitro-SMX. Measurements revealed that environmental SMX concentrations (0.2-2μg/L) at neutral pH induced the accumulation of nitric oxide. Under acidic conditions (pH<6), nitrous acid (HONO) was the major source of nitric oxide while under neutral/basic conditions nitric oxide release was related to the inhibition of denitrification processes. Under laboratory experiments, SMX nitration reaction appeared to be an irreversible transformation pathway, while 4-nitroso-SMX was slowly transformed over time. The occurrence of 4-nitroso-SMX conditions was therefore unexpected in the field study but could be due to its continuous input from soil and/or its relative persistence under anoxic conditions. A mechanism for 4-nitroso-SMX formation was proposed involving a nitrosative desamination pathway through a phenyl radical.
Collapse
Affiliation(s)
- Monica Brienza
- UMR HydroSciences 5569, IRD, Montpellier University, 15 Avenue Ch. Flahault, 34093 Montpellier Cedex 5, France
| | - Céline Duwig
- UMR LTHE 5564, IRD, Grenoble University, 70, rue de la physique - Domaine Universitaire, 38041 Grenoble Cedex 9, France
| | - Sandra Pérez
- Water and Soil Quality Research Group, IDAEA-CSIC, c/Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Serge Chiron
- UMR HydroSciences 5569, IRD, Montpellier University, 15 Avenue Ch. Flahault, 34093 Montpellier Cedex 5, France.
| |
Collapse
|
43
|
Occurrence, origin, and toxicity of disinfection byproducts in chlorinated swimming pools: An overview. Int J Hyg Environ Health 2017; 220:591-603. [DOI: 10.1016/j.ijheh.2017.01.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 01/16/2017] [Accepted: 01/24/2017] [Indexed: 10/20/2022]
|
44
|
Li D, Stanford B, Dickenson E, Khunjar WO, Homme CL, Rosenfeldt EJ, Sharp JO. Effect of advanced oxidation on N-nitrosodimethylamine (NDMA) formation and microbial ecology during pilot-scale biological activated carbon filtration. WATER RESEARCH 2017; 113:160-170. [PMID: 28213337 DOI: 10.1016/j.watres.2017.02.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/31/2017] [Accepted: 02/02/2017] [Indexed: 06/06/2023]
Abstract
Water treatment combining advanced oxidative processes with subsequent exposure to biological activated carbon (BAC) holds promise for the attenuation of recalcitrant pollutants. Here we contrast oxidation and subsequent biofiltration of treated wastewater effluent employing either ozone or UV/H2O2 followed by BAC during pilot-scale implementation. Both treatment trains largely met target water quality goals by facilitating the removal of a suite of trace organics and bulk water parameters. N-nitrosodimethylamine (NDMA) formation was observed in ozone fed BAC columns during biofiltration and to a lesser extent in UV/H2O2 fed columns and was most pronounced at 20 min of empty bed contact time (EBCT) when compared to shorter EBCTs evaluated. While microbial populations were highly similar in the upper reaches, deeper samples revealed a divergence within and between BAC filtration systems where EBCT was identified to be a significant environmental predictor for shifts in microbial populations. The abundance of Nitrospira in the top samples of both columns provides an explanation for the oxidation of nitrite and corresponding increases in nitrate concentrations during BAC transit and support interplay between nitrogen cycling with nitrosamine formation. The results of this study demonstrate that pretreatments using ozone versus UV/H2O2 impart modest differences to the overall BAC microbial population structural and functional attributes, and further highlight the need to evaluate NDMA formation prior to full-scale implementation of BAC in potable reuse applications.
Collapse
Affiliation(s)
- Dong Li
- NSF Engineering Research Center ReNUWIt, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA
| | | | - Eric Dickenson
- NSF Engineering Research Center ReNUWIt, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA; Water Quality Research and Development Division, Southern Nevada Water Authority, Henderson, NV 89015, USA
| | | | - Carissa L Homme
- NSF Engineering Research Center ReNUWIt, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA
| | | | - Jonathan O Sharp
- NSF Engineering Research Center ReNUWIt, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA.
| |
Collapse
|
45
|
Heeb MB, Kristiana I, Trogolo D, Arey JS, von Gunten U. Formation and reactivity of inorganic and organic chloramines and bromamines during oxidative water treatment. WATER RESEARCH 2017; 110:91-101. [PMID: 27998787 DOI: 10.1016/j.watres.2016.11.065] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 11/26/2016] [Accepted: 11/29/2016] [Indexed: 06/06/2023]
Abstract
The formation and further reactions of halamines during oxidative water treatment can be relevant for water quality. In this study, we investigated the formation and reactivity of several inorganic and organic halamines (monochloramine, N-chloromethylamine, N-chlorodimethylamine, monobromamine, dibromamine, N-bromomethylamine, N,N-dibromomethylamine, and N-bromodimethylamine) by kinetic experiments, transformation product analysis, and quantum chemical computations. Kinetic model simulations were conducted to evaluate the relevance of halamines for various water treatment scenarios. Halamines were quickly formed from the reaction of chlorine and bromine with ammonia or organic amines. Species-specific second-order rate constants for the reaction of chlorine and bromine with ammonia, methyl- and dimethylamine were in the order of 106-108 M-1s-1. The formed halamines were found to be reactive towards phenolic compounds, forming halogenated phenols via electrophilic aromatic substitution (phenol and resorcinol) or quinones via electron transfer (catechol and hydroquinone). At near neutral pH, apparent second-order rate constants for these reactions were in the order of 10-4-10-1 M-1s-1 for chloramines and 101-102 M-1s-1 for bromamines. Quantum chemical computations were used to determine previously unknown aqueous pKa values, gas phase bond dissociation energies (BDE) and partial atomic charges of the halamines, allowing a better understanding of their reactivities. Kinetic model simulations, based on the results of this study, showed that during chlorination inorganic and organic chloramines are the main halamines formed. However, their further reactions with organic matter are outcompeted kinetically by chlorine. During ozonation, mainly inorganic bromamines are formed, since ozone quickly oxidizes organic amines. The further reactions of bromamine are typically outcompeted by ozone and thus generally of minor importance. The use of peracetic acid for saline ballast water treatment can result in the formation of substantial amounts of bromamines, which can react with dissolved organic matter and contribute to the formation of brominated products.
Collapse
Affiliation(s)
- Michèle B Heeb
- School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Ina Kristiana
- School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Curtin Water Quality Research Centre, Curtin University, Perth, Western Australia, Australia
| | - Daniela Trogolo
- School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - J Samuel Arey
- School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Urs von Gunten
- School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zürich, Switzerland.
| |
Collapse
|
46
|
Li J, Li K, Zhou Y, Li X, Tao T. Kinetic analysis of Legionella inactivation using ozone in wastewater. CHEMOSPHERE 2017; 168:630-637. [PMID: 27836266 DOI: 10.1016/j.chemosphere.2016.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 11/03/2016] [Accepted: 11/03/2016] [Indexed: 06/06/2023]
Abstract
Legionella inactivation using ozone was studied in wastewater using kinetic analysis and modeling. The experimental results indicate that the relationship between the ozone concentration, germ concentration, and chemical oxygen demand (COD) can be used to predict variations in germ and COD concentrations. The ozone reaction with COD and inactivation of Legionella occurred simultaneously, but the reaction with COD likely occurred at a higher rate than the inactivation, as COD is more easily oxidized by ozone than Legionella. Higher initial COD concentrations resulted in a lower inactivation rate and higher lnN/N0. Higher temperature led to a higher inactivation efficiency. The relationship of the initial O3 concentration and Legionella inactivation rate was not linear, and thus, the Ct value required for a 99.99% reduction was not constant. The initial O3 concentration was more important than the contact time, and a reduction of the initial O3 concentration could not be compensated by increasing the contact time. The Ct values were compared over a narrow range of initial concentrations; the Ct values could only be contrasted when the initial O3 concentrations were very similar. A higher initial O3 concentration led to a higher inflection point value for the lnN/N0 vs C0t curve. Energy consumption using a plasma corona was lower than when using boron-doped diamond electrodes.
Collapse
Affiliation(s)
- Jun Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, 18 Xuezheng Street, Xiasha Gaojiaoyuan District, Hangzhou, Zhejiang, 310018, China.
| | - Kunquan Li
- College of Engineering, Nanjing Agricultural University, 40 Dianjiangtai Road, Pukou District, Nanjing, Jiangsu, 210031, China
| | - Yan Zhou
- Department of Road Traffic and Engineering Planning, Zhejiang Urban & Rural Planning Design Institute, 238 Baochu Road, Xihu District, Hangzhou, Zhejiang, 310007, China
| | - Xuebin Li
- Department of Management and Information Technology, Nantong Shipping College, 185 Tongsheng Road, Nantong, Jiangsu, 226010, China
| | - Tao Tao
- School of Environmental Science and Engineering, Huazhong University of Science & Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China
| |
Collapse
|
47
|
Spahr S, Cirpka OA, von Gunten U, Hofstetter TB. Formation of N-Nitrosodimethylamine during Chloramination of Secondary and Tertiary Amines: Role of Molecular Oxygen and Radical Intermediates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:280-290. [PMID: 27958701 DOI: 10.1021/acs.est.6b04780] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
N-Nitrosodimethylamine (NDMA) is a carcinogenic disinfection byproduct from water chloramination. Despite the identification of numerous NDMA precursors, essential parts of the reaction mechanism such as the incorporation of molecular O2 are poorly understood. In laboratory model systems for the chloramination of secondary and tertiary amines, we investigated the kinetics of precursor disappearance and NDMA formation, quantified the stoichiometries of monochloramine (NH2Cl) and aqueous O2 consumption, derived 18O-kinetic isotope effects (18O-KIE) for the reactions of aqueous O2, and studied the impact of radical scavengers on NDMA formation. Although the molar NDMA yields from five N,N-dimethylamine-containing precursors varied between 1.4% and 90%, we observed the stoichiometric removal of one O2 per N,N-dimethylamine group of the precursor indicating that the oxygenation of N atoms did not determine the molar NDMA yield. Small 18O-KIEs between 1.0026 ± 0.0003 and 1.0092 ± 0.0009 found for all precursors as well as completely inhibited NDMA formation in the presence of radical scavengers (ABTS and trolox) imply that O2 reacted with radical species. Our study suggests that aminyl radicals from the oxidation of organic amines by NH2Cl and N-peroxyl radicals from the reaction of aminyl radicals with aqueous O2 are part of the NDMA formation mechanism.
Collapse
Affiliation(s)
- Stephanie Spahr
- Eawag, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland
- School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Federale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Olaf A Cirpka
- Center for Applied Geoscience, University of Tübingen , D-72074 Tübingen, Germany
| | - Urs von Gunten
- Eawag, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland
- School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Federale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich , CH-8092 Zürich, Switzerland
| | - Thomas B Hofstetter
- Eawag, Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich , CH-8092 Zürich, Switzerland
| |
Collapse
|
48
|
Sun P, Lee WN, Zhang R, Huang CH. Degradation of DEET and Caffeine under UV/Chlorine and Simulated Sunlight/Chlorine Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:13265-13273. [PMID: 27993038 DOI: 10.1021/acs.est.6b02287] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Photoactivation of aqueous chlorine could promote degradation of chlorine-resistant and photochemically stable chemicals accumulated in swimming pools. This study investigated the degradation of two such chemicals, N,N-diethyl-3-methylbenzamide (DEET) and caffeine, by low pressure ultraviolet (UV) light and simulated sunlight (SS) activated free chlorine (FC) in different water matrices. Both DEET and caffeine were rapidly degraded by UV/FC and SS/FC but exhibited different kinetic behaviors. The degradation of DEET followed pseudo-first-order kinetics, whereas the degradation of caffeine accelerated with reaction. Mechanistic study revealed that, under UV/FC, ·OH and Cl· were responsible for degradation of DEET, whereas ClO· related reactive species (ClOrrs), generated by the reaction between FC and ·OH/Cl·, played a major role in addition to ·OH and Cl· in degrading caffeine. Reaction rate constants of DEET and caffeine with the respective radical species were estimated. The imidazole moiety of caffeine was critical for the special reactivity with ClOrrs. Water matrix such as pH had a stronger impact on the UV/FC process than the SS/FC process. In saltwater matrix under UV/FC and SS/FC, the degradation of DEET was significantly inhibited, but the degradation of caffeine was much faster than that in nonsalty solutions. The interaction between Br- and Cl- may play an important role in the degradation of caffeine by UV/FC in saltwater. Reaction product analysis showed similar product patterns by UV/FC and SS/FC and minimal formation of chlorinated intermediates and disinfection byproducts.
Collapse
Affiliation(s)
- Peizhe Sun
- School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Wan-Ning Lee
- School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | | | - Ching-Hua Huang
- School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| |
Collapse
|
49
|
Zare Afifi M, Blatchley ER. Effects of UV-based treatment on volatile disinfection byproducts in a chlorinated, indoor swimming pool. WATER RESEARCH 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] [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.
Collapse
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.
| |
Collapse
|
50
|
Tardif R, Catto C, Haddad S, Simard S, Rodriguez M. Assessment of air and water contamination by disinfection by-products at 41 indoor swimming pools. ENVIRONMENTAL RESEARCH 2016; 148:411-420. [PMID: 27131795 DOI: 10.1016/j.envres.2016.04.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/07/2016] [Accepted: 04/09/2016] [Indexed: 06/05/2023]
Abstract
This study was aimed at assessing the profiles (occurrence and speciation) of disinfection by-product (DBP) contamination in air and water of a group of 41 public indoor swimming pools in Québec (Canada). The contaminants measured in the water included the traditional DBPs [i.e., four trihalomethanes (THMs), six haloacetic acids (HAAs)] but also several emergent DBPs [i.e., halonitriles, halonitromethanes, haloketones and nitrosodimethylamine (NDMA)]. Those measured in the air comprised THMs and chloramines (CAMs). Overall, extremely variable DBP levels were found from one pool to another (both quantitatively and in terms of speciation). For instance, in water, among the four THMs, chloroform was usually the most abundant compound (37.9±25.7µg/L). Nevertheless, the sum of the three other brominated THMs represented more than 25% of total THMs at almost half the facilities visited (19 cases). In 13 of them, the levels of brominated THMs (66±24.2µg/L) even greatly outweighed the levels of chloroform (15.2±6.31µg/L). Much higher levels of HAAs (294.8±157.6µg/L) were observed, with a consistent preponderance of brominated HAAs in the swimming pools with more brominated THMs. NDMA levels which were measured in a subset of 8 pools ranged between 2.8ng/L and 105ng/L. With respect to air, chloroform was still the most abundant THM globally (119.4±74.2µg/m(3)) but significant levels of brominated THMs were also observed in various cases, particularly in the previously evoked group of 13 swimming pools with preponderant levels of brominated THMs in water. CAM levels (0.23±0.15mg/m(3)) varied highly, ranging from not detected to 0.56mg/m(3). Overall, the levels were generally relatively high compared to current guidelines or reference values from several countries, and they point to a relatively atypical presence of brominated compounds, and to significant levels of emergent DBPs for which health risk is less documented.
Collapse
Affiliation(s)
- Robert Tardif
- Department of Environmental and Occupational Health, School of Public Health, Université de Montréal, Canada.
| | - Cyril Catto
- Department of Environmental and Occupational Health, School of Public Health, Université de Montréal, Canada
| | - Sami Haddad
- Department of Environmental and Occupational Health, School of Public Health, Université de Montréal, Canada
| | - Sabrina Simard
- Research Chair on Drinking Water, Université Laval, Québec City, Canada
| | - Manuel Rodriguez
- Research Chair on Drinking Water, Université Laval, Québec City, Canada
| |
Collapse
|