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Wan Q, Ke J, Cao R, Wang J, Huang T, Wen G. Enhanced inactivation of Aspergillus niger biofilms by the combination of UV-LEDs with chlorine-based disinfectants. WATER RESEARCH 2024; 267:122451. [PMID: 39293342 DOI: 10.1016/j.watres.2024.122451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 09/12/2024] [Accepted: 09/13/2024] [Indexed: 09/20/2024]
Abstract
The presence of pathogenic fungal biofilms in drinking water distribution systems poses significant challenges in maintaining the safety of drinking water. This research delved into the formation of Aspergillus niger (A. niger) biofilms and evaluated their susceptibility to inactivation using combinations of ultraviolet light emitting diodes (UV-LEDs) with chlorine-based disinfectants, including UV-LEDs/chlorine (Cl2), UV-LEDs/chlorine dioxide (ClO2), and UV-LEDs/chloramine (NH2Cl) at 265 nm, 280 nm and 265/280 nm. Results indicated that A. niger biofilms reached initial maturity within 24 h, with matured three-dimensional filamentous structures and conidiospores by 96 h. UV-LEDs combined with chlorine-based disinfectants enhanced A. niger biofilm inactivation compared to UV-LEDs alone and low-pressure UV combined with chlorine-based disinfectants. At an UV fluence of 400 mJ/cm2, log reductions of UV265, UV280, and UV265/280 combined with chlorine-based disinfectants were 2.95-fold, 3.20-fold, and 2.38-fold higher than that of UV265, UV280, and UV265/280, respectively. During the inactivation, A. niger biofilm cells experienced increased membrane permeability and intracellular reactive oxygen species levels, resulting in cellular apoptosis. Extracellular polymeric substances contributed to the higher resistance of biofilms. Regarding electrical energy consumption, the order was: UV-LEDs/ClO2 > UV-LEDs/NH2Cl > UV-LEDs/Cl2. These findings provide insights into the effective utilization of UV-LEDs for fungal biofilm disinfection.
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Affiliation(s)
- Qiqi Wan
- Shaanxi Provincial Field Scientific Observation and Research Station of Water Quality in Qinling Mountains, 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, PR China
| | - Jian Ke
- Shaanxi Provincial Field Scientific Observation and Research Station of Water Quality in Qinling Mountains, 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, PR China
| | - Ruihua Cao
- Shaanxi Provincial Field Scientific Observation and Research Station of Water Quality in Qinling Mountains, 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, PR China
| | - Jingyi Wang
- Shaanxi Provincial Field Scientific Observation and Research Station of Water Quality in Qinling Mountains, 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, PR China
| | - Tinglin Huang
- Shaanxi Provincial Field Scientific Observation and Research Station of Water Quality in Qinling Mountains, 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, PR China
| | - Gang Wen
- Shaanxi Provincial Field Scientific Observation and Research Station of Water Quality in Qinling Mountains, 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, PR China; Collaborative Innovation Center of Water Pollution Control and Water Quality Security Assurance of Shaanxi Province, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China.
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Yang T, Zeng G, Jiang M, Su P, Liu C, Lv Q, Li W, Hou X, Li J. Matching periodate peak absorbance by far UVC at 222 nm promotes the degradation of micropollutants and energy efficiency. JOURNAL OF HAZARDOUS MATERIALS 2024; 476:134978. [PMID: 38905986 DOI: 10.1016/j.jhazmat.2024.134978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/09/2024] [Accepted: 06/18/2024] [Indexed: 06/23/2024]
Abstract
Periodate (PI)-based advanced oxidation processes have gained increasing interest. This study for the first time elevates the light-activation capacity of PI by using far UVC at 222 nm (UV222/PI) without extra chemical inputs. The effectiveness and the underlying mechanisms of UV222/PI for the remediation of micropollutants were studied by selecting atenolol (ATL) as a representative. PI possessed a high molar absorption coefficient of 9480-6120 M-1 cm-1 at 222 nm in the pH range of 5.0-9.0, and it was rapidly decomposed by UV222 with first-order rate constants of 0.0055 to 0.002 s-1. ATL and the six other organic compounds were effectively degraded by the UV222/PI process under different conditions with the fluence-based rate constants generally two to hundred times higher than by UVA photolysis. Hydroxyl radical and ozone were confirmed as the major contributors to ATL degradation, while direct photolysis also played a role at higher pH or lower PI dosages. Degradation pathways of ATL were proposed including hydroxylation, demethylation, and oxidation. The high energy efficiency of the UV222/PI process was also confirmed. This study provides a cost-effective and convenient approach to enhance PI light-response activity for the treatment of micropollutants.
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Affiliation(s)
- Tao Yang
- Jiangmen Key Laboratory of Synthetic Chemistry and Cleaner Production, School of Environmental and Chemical Engineering, Wuyi University, Jiangmen 529020, Guangdong Province, China; Institute of Carbon Peaking and Carbon Neutralization, Wuyi University, Jiangmen 529020, Guangdong Province, China
| | - Ge Zeng
- Jiangmen Key Laboratory of Synthetic Chemistry and Cleaner Production, School of Environmental and Chemical Engineering, Wuyi University, Jiangmen 529020, Guangdong Province, China
| | - Maoju Jiang
- Jiangmen Key Laboratory of Synthetic Chemistry and Cleaner Production, School of Environmental and Chemical Engineering, Wuyi University, Jiangmen 529020, Guangdong Province, China
| | - Peng Su
- Jiangmen Key Laboratory of Synthetic Chemistry and Cleaner Production, School of Environmental and Chemical Engineering, Wuyi University, Jiangmen 529020, Guangdong Province, China
| | - Chenlong Liu
- Jiangmen Key Laboratory of Synthetic Chemistry and Cleaner Production, School of Environmental and Chemical Engineering, Wuyi University, Jiangmen 529020, Guangdong Province, China
| | - Qixiao Lv
- Jiangmen Key Laboratory of Synthetic Chemistry and Cleaner Production, School of Environmental and Chemical Engineering, Wuyi University, Jiangmen 529020, Guangdong Province, China
| | - Wenqi Li
- Jiangmen Key Laboratory of Synthetic Chemistry and Cleaner Production, School of Environmental and Chemical Engineering, Wuyi University, Jiangmen 529020, Guangdong Province, China
| | - Xiangyang Hou
- Jiangmen Key Laboratory of Synthetic Chemistry and Cleaner Production, School of Environmental and Chemical Engineering, Wuyi University, Jiangmen 529020, Guangdong Province, China
| | - Juan Li
- Advanced Interdisciplinary Institute of Environment and Ecology, Guangdong Provincial Key Laboratory of Wastewater Information Analysis and Early Warning, Beijing Normal University, Zhuhai 519087, China.
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Griffin DT, Gourlay T, Maclean M. The Antibacterial Efficacy of Far-UVC Light: A Combined-Method Study Exploring the Effects of Experimental and Bacterial Variables on Dose-Response. Pathogens 2024; 13:698. [PMID: 39204298 PMCID: PMC11357679 DOI: 10.3390/pathogens13080698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2024] [Revised: 08/07/2024] [Accepted: 08/08/2024] [Indexed: 09/03/2024] Open
Abstract
Far-ultraviolet C light, with a wavelength of 200-230 nm, has demonstrated broad-spectrum germicidal efficacy. However, due to increased interest in its use as an alternative antimicrobial, further knowledge about its fundamental bactericidal efficacy is required. This study had two objectives. Firstly, it investigated experimentally the Far-UVC dose-response of common bacteria suspended at various cell densities in transparent buffer, ensuring no influence from photosensitive suspending media. Increasing doses of Far-UVC were delivered to Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus in PBS at 101, 102, 103, 105 and 107 CFU·mL-1, with surviving colony-forming units enumerated (n ≥ 3). Secondly, through a systematised literature review, this work sought to explore the impact of genus/species, Gram type, cell form, cell density and irradiance on dose-response. The screening of 483 publications was performed with 25 included in the study. Data for 30 species were collated, analysed and compared with the experimental results. Overall, Gram-positive species showed greater resilience to Far-UVC than Gram-negative; some inter-species and inter-genera differences in resilience were identified; endospores were more resilient than vegetative cells; the results suggested that inactivation efficiency may decrease as cell density increases; and no significant correlation was identified between irradiance and bactericidal dose effect. In conclusion, this study has shown Far-UVC light to be an effective decontamination tool against a vast range of bacterial vegetative cells and endospores.
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Affiliation(s)
- David T. Griffin
- Department of Biomedical Engineering, University of Strathclyde, Wolfson Building, 106 Rottenrow, Glasgow G4 0NW, UK; (D.T.G.); (T.G.)
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Royal College Building, 204 George St, Glasgow G1 1XW, UK
| | - Terence Gourlay
- Department of Biomedical Engineering, University of Strathclyde, Wolfson Building, 106 Rottenrow, Glasgow G4 0NW, UK; (D.T.G.); (T.G.)
| | - Michelle Maclean
- Department of Biomedical Engineering, University of Strathclyde, Wolfson Building, 106 Rottenrow, Glasgow G4 0NW, UK; (D.T.G.); (T.G.)
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Royal College Building, 204 George St, Glasgow G1 1XW, UK
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Lu S, Peng J, Shang C, Yin R. Dissolved Organic Matter-Mediated Photosensitized Activation of Monochloramine for Micropollutant Abatement in Wastewater Effluent. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9370-9380. [PMID: 38743251 DOI: 10.1021/acs.est.4c00224] [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: 05/16/2024]
Abstract
Utilizing solar light and water matrix components in situ to reduce the chemical and energy demands would make treatment technologies more sustainable for micropollutant abatement in wastewater effluents. We herein propose a new strategy for micropollutant abatement through dissolved organic matter (DOM)-mediated photosensitized activation of monochloramine (NH2Cl). Exposing the chlorinated wastewater effluent with residual NH2Cl to solar irradiation (solar/DOM/NH2Cl process) degrades six structurally diverse micropollutants at rate constants 1.26-34.2 times of those by the solar photolysis of the dechlorinated effluent (solar/DOM process). Notably, among the six micropollutants, the degradation rate constants of estradiol, acetaminophen, bisphenol A, and atenolol by the solar/DOM/NH2Cl process are 1.13-4.32 times the summation of those by the solar/DOM and solar/NH2Cl processes. The synergism in micropollutant degradation is attributed to the generation of reactive nitrogen species (RNS) and hydroxyl radicals (HO·) from the photosensitized activation of NH2Cl. Triplet state-excited DOM (3DOM*) dominates the activation of NH2Cl, leading to the generation of RNS, while HO· is produced from the interactions between RNS and other photochemically produced reactive intermediates (e.g., O2·- and DOM·+/·-). The findings advance the knowledge of DOM-mediated photosensitization and offer a sustainable method for micropollutant abatement in wastewater effluents containing residual NH2Cl.
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Affiliation(s)
- Senhao Lu
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Jiadong Peng
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Chii Shang
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
- Hong Kong Branch of Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Ran Yin
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
- Institute for the Environment and Health, Nanjing University Suzhou Campus, Suzhou 215163, China
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Yin R, Heuzard A, Li T, Ruan X, Lu S, Shang C. Advanced oxidation of recalcitrant chromophores in full-scale MBR effluent for non-potable reuse of leachate co-treated municipal wastewater. CHEMOSPHERE 2024; 351:141228. [PMID: 38237782 DOI: 10.1016/j.chemosphere.2024.141228] [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: 11/30/2023] [Revised: 01/08/2024] [Accepted: 01/13/2024] [Indexed: 01/22/2024]
Abstract
Wastewater non-potable reuse involves further processing of secondary effluent to a quality level acceptable for reuse and is a promising solution to combating water scarcity. Recalcitrant chromophores in landfill leachate challenge the water quality for non-potable reuse when leachate is co-treated with municipal wastewater. In this study, we first use multivariate statistical analysis to reveal that leachate is an important source (with a Pearson's coefficient of 0.82) of recalcitrant chromophores in the full-scale membrane bioreactor (MBR) effluent. We then evaluate the removal efficacies of chromophores by chlorination, breakpoint chlorination, and the chlorination-UV/chlorine advanced oxidation treatment. Conventional chlorination and breakpoint chlorination only partially remove chromophores, leaving a colour level exceeding the standards for non-potable reuse (>20 Hazen units). We demonstrate that pre-chlorination (with an initial chlorine dosing of 20 mg/L as Cl2) followed by UV radiation (with a UV fluence of 500 mJ/cm2) effectively degraded recalcitrant chromophores (>90%). By quantifying the electron donating capacity (EDC) and radical scavenging capacity (RSC) of the reclaimed water, we demonstrate that pre-chlorination reduces EDC and RSC by up to 64%, increases UV transmittance by 32%, and increases radical yields from UV photolysis of chlorine by 1.7-2.2 times. The findings advance fundamental understanding of the alteration of dissolved coloured substances by (photo)chlorination treatment and provide implications for applying advanced oxidation processes in treating wastewater effluents towards sustainable non-potable reuse.
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Affiliation(s)
- Ran Yin
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
| | - Arnaud Heuzard
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Tao Li
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong; China State Construction Engineering (Hong Kong) Limited, Wan Chai, Hong Kong
| | - Xinyi Ruan
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Senhao Lu
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Chii Shang
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong; Hong Kong Branch of Chinese National Engineering Research Centre for Control & Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
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