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Zhong Y, Chen Y, Ong SL, Hu J, Balakrishnan V, Ang WS. Disinfection by-products control in wastewater effluents treated with ozone and biological activated carbon followed by UV/Chlor(am)ine processes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 922:171317. [PMID: 38428610 DOI: 10.1016/j.scitotenv.2024.171317] [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: 11/09/2023] [Revised: 02/24/2024] [Accepted: 02/25/2024] [Indexed: 03/03/2024]
Abstract
Sequential utilization of ozone (O3) and biological activated carbon (BAC) followed by UV/chlor(am)ine advanced oxidation process (AOP) has drawn attention in water reuse. However, the formation of disinfection by-products (DBPs) in this process is less evaluated. This study investigated the DBP formation and the relevant toxicity during the O3-BAC-UV/chlor(am)ine treatment of sand-filtered municipal secondary effluent. DBP formation in UV/chlorine and UV/dichloramine (NHCl2) processes were compared, where the impact of key operational parameters (e.g., UV wavelength, pH) on DBP formation were comprehensively evaluated. O3-BAC significantly reduced DBP formation potential (DBPFP) (58.2 %). Compared to UV/chlorine AOP, UV/NHCl2 AOP reduced DBP formation by 29.7 % in short-time treatment, while insignificantly impacting on DBPFP (p > 0.05). UV/NHCl2 AOP also led to lower calculated cytotoxicity (67.7 %) and genotoxicity (55.9 %) of DBPs compared to UV/chlorine AOP. Compared to 254 nm UV light, the utilization of 285 nm UV light decreased the formation of DBPs in wastewater treated with the UV/chlorine AOP and UV/NHCl2 AOP by 31.3 % and 19.2 %, respectively. However, the cytotoxicity and genotoxicity in UV/NHCl2 AOP using 285 nm UV light increased by 83.4 % and 58.5 %, respectively, compared to 254 nm. The concentration of DBPs formed in the UV/NHCl2 AOP at pH 8 was 54.3 % lower than that at pH 7, suggesting a better control of DBPs at alkaline condition. In the presence of bromide, UV/NHCl2 AOP tended to generate more brominated DBPs than UV/chlorine AOP. Overall, UV/NHCl2 AOP resulted in lower concentration and toxicity of DBPs compared to UV/chlorine AOP.
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Affiliation(s)
- Yu Zhong
- Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore
| | - Yiwei Chen
- Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore
| | - Say Leong Ong
- Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore
| | - Jiangyong Hu
- Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore.
| | - Viswanath Balakrishnan
- Water Reclamation (Plants) Department, PUB Singapore, 40 Scotts Road, Environment Building, Singapore 228231, Singapore
| | - Wui Seng Ang
- Water Reclamation (Plants) Department, PUB Singapore, 40 Scotts Road, Environment Building, Singapore 228231, Singapore
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Ao X, Zhang X, Sun W, Linden KG, Payne EM, Mao T, Li Z. What is the role of nitrate/nitrite in trace organic contaminants degradation and transformation during UV-based advanced oxidation processes? WATER RESEARCH 2024; 253:121259. [PMID: 38377923 DOI: 10.1016/j.watres.2024.121259] [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: 12/27/2023] [Revised: 02/01/2024] [Accepted: 02/03/2024] [Indexed: 02/22/2024]
Abstract
The effectiveness of UV-based advanced oxidation processes (UV-AOPs) in degrading trace organic contaminants (TrOCs) can be significantly influenced by the ubiquitous presence of nitrate (NO3-) and nitrite (NO2-) in water and wastewater. Indeed, NO3-/NO2- can play multiple roles of NO3-/NO2- in UV-AOPs, leading to complexities and conflicting results observed in existing research. They can inhibit the degradation of TrOCs by scavenging reactive species and/or competitively absorbing UV light. Conversely, they can also enhance the elimination of TrOCs by generating additional •OH and reactive nitrogen species (RNS). Furthermore, the presence of NO3-/NO2- during UV-AOP treatment can affect the transformation pathways of TrOCs, potentially resulting in the nitration/nitrosation of TrOCs. The resulting nitro(so)-products are generally more toxic than the parent TrOCs and may become precursors of nitrogenous disinfection byproducts (N-DBPs) upon chlorination. Particularly, since the impact of NO3-/NO2- in UV-AOPs is largely due to the generation of RNS from NO3-/NO2- including NO•, NO2•, and peroxynitrite (ONOO-/ONOOH), this review covers the generation, properties, and detection methods of these RNS. From kinetic, mechanistic, and toxicologic perspectives, future research needs are proposed to advance the understanding of how NO3-/NO2- can be exploited to improve the performance of UV-AOPs treating TrOCs. This critical review provides a comprehensive framework outlining the multifaceted impact of NO3-/NO2- in UV-AOPs, contributing insights for basic research and practical applications of UV-AOPs containing NO3-/NO2-.
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Affiliation(s)
- Xiuwei Ao
- School of Energy and Environmental Engineering, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, International Science and Technology Cooperation Base for Environmental and Energy Technology of MOST, University of Science and Technology Beijing, Beijing, 100083, China
| | - Xi Zhang
- School of Energy and Environmental Engineering, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, International Science and Technology Cooperation Base for Environmental and Energy Technology of MOST, University of Science and Technology Beijing, Beijing, 100083, China
| | - Wenjun Sun
- School of Environment, Tsinghua University, Beijing 100084, China; Research Institute for Environmental Innovation (Suzhou) Tsinghua, Suzhou, 215163, China.
| | - Karl G Linden
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, 4001 Discovery Drive, Boulder, CO 80303, United States.
| | - Emma M Payne
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, 4001 Discovery Drive, Boulder, CO 80303, United States
| | - Ted Mao
- Research Institute for Environmental Innovation (Suzhou) Tsinghua, Suzhou, 215163, China; MW Technologies, Inc., Ontario L8N1E, Canada
| | - Zifu Li
- School of Energy and Environmental Engineering, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, International Science and Technology Cooperation Base for Environmental and Energy Technology of MOST, University of Science and Technology Beijing, Beijing, 100083, China
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Asghar A, Lipfert D, Kerpen K, Schmidt TC. Elucidating the inhibitory effects of natural organic matter on the photodegradation of organic micropollutants: Atrazine as a probe compound. CHEMOSPHERE 2024; 352:141390. [PMID: 38325617 DOI: 10.1016/j.chemosphere.2024.141390] [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: 12/04/2023] [Revised: 02/02/2024] [Accepted: 02/03/2024] [Indexed: 02/09/2024]
Abstract
Natural organic matter (NOM) is a complex mixture of heterogeneous compounds with varying functional groups and molecular sizes. Understanding the impact of NOM on the generation of photochemically produced reactive intermediates (PPRIs) and their potential inhibitory effects on photolysis has remained challenging due to the variations in the reactivities and concentrations of these functional groups. To address this gap, tannic acid (TA), gallic acid (GA), catechin (CAT), and tryptophan (Trp), were chosen as potential substitutes for NOM. Their effects on the photochemical transformation process were evaluated and compared with the widely used Suwannee River NOM (SRNOM). Atrazine (ATZ) was selected as a probe organic micropollutant (OMP). In this investigation, a significantly higher concentration of HO• was observed compared to O21, and the triplet excited state ( NOM*3). The findings suggest that the substituted phenols, particularly those with carboxylate-substitutions, played a substantial role in HO• formation, while electron-rich moieties acted as antioxidants, consuming NOM*3. Hydroxyl, carboxylic, and amino acid were the active groups for O21 formation. However, the inhibitory effects induced by the NOM surrogates were significant and mainly attributed to the direct photolysis inhibition caused by the inner filter effect. The scope of this work was further extended to include SRNOM, where similar trends with less pronounced formation of PPRIs and inner filter effects were observed. Therefore, this study sheds some light on the role of the functional groups in NOM during photochemical transformations of OMPs, thereby deepening our understanding of their fate in aqueous systems.
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Affiliation(s)
- Anam Asghar
- Instrumental Analytical Chemistry, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstraße 5, Essen, Germany.
| | - Daniel Lipfert
- Instrumental Analytical Chemistry, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstraße 5, Essen, Germany
| | - Klaus Kerpen
- Instrumental Analytical Chemistry, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstraße 5, Essen, Germany
| | - Torsten C Schmidt
- Instrumental Analytical Chemistry, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstraße 5, Essen, Germany; Centre for Water and Environmental Research (ZWU), Universitätsstraße 5, 45141, Essen, Germany; IWW Water Centre, Moritzstraße 26, 45476, Mülheim an der Ruhr, Germany
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Chen S, Sheng X, Zhao Z, Cui F. Chemical-free vacuum ultraviolet irradiation as ultrafiltration membrane pretreatment technique: Performance, mechanisms and DBPs formation. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119785. [PMID: 38081086 DOI: 10.1016/j.jenvman.2023.119785] [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: 07/09/2023] [Revised: 11/28/2023] [Accepted: 12/03/2023] [Indexed: 01/14/2024]
Abstract
Membrane fouling induced by natural organic matter (NOM) has seriously affected the further extensive application of ultrafiltration (UF). Herein, a simple, green and robust vacuum ultraviolet (VUV) technology was adopted as pretreatment before UF and ultraviolet (UV) technology was used for comparison. The results showed that control effect of VUV pretreatment on membrane fouling was better than that of UV pretreatment, as evidenced by the increase of normalized flux from 0.27 to 0.38 and 0.73 after 30 min UV or VUV pretreatment, respectively. This is related to the fact that VUV pretreatment exhibited stronger NOM degradation ability than UV pretreatment owing to the formation of HO•. The steady-state concentration of HO• was calculated as 3.04 × 10-13 M and the cumulative exposure of HO• reached 5.52 × 10-10 M s after 30 min of VUV irradiation. And the second-order rate constant between NOM and HO• was determined as 1.36 × 104 L mg-1 s-1. Furthermore, fluorescence EEM could be applied to predict membrane fouling induced by humic-enriched water. Standard blocking and cake filtration were major fouling mechanisms. Moreover, extension of UV pretreatment time increased the disinfection by-products (DBPs) formation, the DBPs concentration was enhanced from 322.36 to 1187.80 μg/L after 210 min pretreatment. However, VUV pretreatment for 150 min reduced DBPs content to 282.57 μg/L, and DBPs content continued to decrease with the extension of pretreatment time, revealing that VUV pretreatment achieved effective control of DBPs. The variation trend of cytotoxicity and health risk of DBPs was similar to that of DBPs concentration. In summary, VUV pretreatment exhibited excellent effect on membrane fouling alleviation, NOM degradation and DBPs control under a certain pretreatment time.
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Affiliation(s)
- Shengnan Chen
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China; Key Laboratory of the Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing, 400045, PR China
| | - Xin Sheng
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China; Key Laboratory of the Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing, 400045, PR China
| | - Zhiwei Zhao
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China; Key Laboratory of the Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing, 400045, PR China.
| | - Fuyi Cui
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China; Key Laboratory of the Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing, 400045, PR China
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Lara de Larrea J, MacIsaac SA, Rauch KD, Stoddart AK, Gagnon GA. Comparison of Legionella pneumophila and Pseudomonas fluorescens Quantification Methods for Assessing UV LED Disinfection. ACS ES&T WATER 2023; 3:3667-3675. [PMID: 37970541 PMCID: PMC10644340 DOI: 10.1021/acsestwater.3c00428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/19/2023] [Accepted: 10/19/2023] [Indexed: 11/17/2023]
Abstract
This study assesses the efficacy of ultraviolet light-emitting diodes (UV LEDs) for deactivating Legionella pneumophila (pure culture) and Pseudomonas fluorescens (pure culture and biofilms) on relevant drinking water distribution system surfaces (cast iron and stainless steel). UV LED treatment at 280 nm demonstrated superior performance compared to that at 365 nm, achieving a 4.8 log reduction value (LRV) for P. fluorescens pure cultures and, for biofilms, 4.02 LRV for stainless steel and 2.96 LRV for cast iron at 280 nm. Conversely, the results were less effective at 365 nm, with suspected photolytic reactions on cast iron. Quantification of L. pneumophila yielded varying results: 4 LRV using standard plate counts, 1.8 LRV with Legiolert, and 1 LRV with quantitative polymerase chain reaction at 280 nm, while the results were less than 1.5 LRV at 365 nm. This study provides insights into managing opportunistic pathogens and biofilms, emphasizing the need for improved quantification tools to better assess treatment efficacy.
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Affiliation(s)
- Jaser Lara de Larrea
- Centre for Water
Resources
Studies. Department of Civil & Resource Engineering, Dalhousie University, Halifax B3H 4R2, NS, Canada
| | - Sean A. MacIsaac
- Centre for Water
Resources
Studies. Department of Civil & Resource Engineering, Dalhousie University, Halifax B3H 4R2, NS, Canada
| | - Kyle D. Rauch
- Centre for Water
Resources
Studies. Department of Civil & Resource Engineering, Dalhousie University, Halifax B3H 4R2, NS, Canada
| | - Amina K. Stoddart
- Centre for Water
Resources
Studies. Department of Civil & Resource Engineering, Dalhousie University, Halifax B3H 4R2, NS, Canada
| | - Graham A. Gagnon
- Centre for Water
Resources
Studies. Department of Civil & Resource Engineering, Dalhousie University, Halifax B3H 4R2, NS, Canada
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