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Itani N, El Fadel M. Microbial inactivation kinetics of UV LEDs and effect of operating conditions: A methodological critical analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 885:163727. [PMID: 37120022 DOI: 10.1016/j.scitotenv.2023.163727] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/10/2023]
Abstract
Tiny ultraviolet (UV) light-emitting diodes (LED)s that are replacing the conventional energy-intensive mercury UV lamps have gained interest since the early 2000's because of their promising advantages. In the context of microbial inactivation (MI) of waterborne microbes, disinfection kinetics of those LEDs exhibited variations among studies, in terms of varying the UV wavelength, the exposure time, power, and dose (UV fluence) as well as other operational conditions. While reported results may appear contradictory when examined separately, they probably are not when analyzed collectively. As such, in this study, we carry out a quantitative collective regression analysis of the reported data to shed light on the kinetics of MI by the emerging UV LEDs technology alongside the effects of varying operational conditions. The main goal is to identify dose response requirements for UV LEDs and to compare them to traditional UV lamps in addition to ascertaining optimal settings that could help in achieving the optimal inactivation outcome for comparable UV doses. The analysis showed that kinetically, UV LEDs are as effective as conventional mercury lamps for water disinfection, and at times more effective, especially for UV resistant microbes. We defined the maximal efficiency at two wavelengths, 260-265 nm and 280 nm, among a wide range of available LED wavelengths. We also defined the UV fluence per log inactivation of tested microbes. At the operational level, we identified existing gaps and developed a framework for a comprehensive analysis program for future needs.
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Affiliation(s)
- N Itani
- Department of Civil Infrastructure and Environmental Engineering, Khalifa University, United Arab Emirates; Department of Civil and Environmental Engineering, American University of Beirut, Lebanon
| | - M El Fadel
- Department of Civil Infrastructure and Environmental Engineering, Khalifa University, United Arab Emirates; Department of Civil and Environmental Engineering, American University of Beirut, Lebanon.
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2
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Xu J, Guo Y, Yang Q, Bai X, Lu R, Liu M, Kuang Z, Zhang L, Li J. Enhanced cyanogen chloride formation after UV/PS and UV/H 2O 2 pre-oxidation and chlorination in natural river water. J Environ Sci (China) 2023; 126:48-57. [PMID: 36503774 DOI: 10.1016/j.jes.2022.03.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/29/2022] [Accepted: 03/29/2022] [Indexed: 06/17/2023]
Abstract
Ultraviolet/persulfate (UV/PS) and Ultraviolet/hydrogen peroxide (UV/H2O2) have attracted much attention in recent years as advanced oxidation processes for water treatment. However, it is not all clear how these two methods affect the formation of cyanogen chloride (CNCl) in the subsequent water chlorination process. In this study, it was found that both UV/H2O2 and UV/PS pre-oxidation promoted the formation of CNCl in six actual water samples collected from urban rivers. Glycine, uric acid, arginine and histidine were investigated as the model compounds to explore the effects of different methods on the production of CNCl. The results showed that compared with chlorination alone, pre-oxidation by UV/H2O2 and UV/PS can reduce the production of CNCl for glycine and uric acid by up to 95% during post-chlorination process. However, they can greatly promote the formation of CNCl for arginine and histidine by up to 120-fold. In a more detailed investigation, pre-oxidation of histidine formed highly reactive intermediates to chlorine, leading to increased CNCl formation and chlorine consumption. The results showed that the precursors of CNCl was altered after pre-oxidation, and need to be re-evaluated.
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Affiliation(s)
- Jie Xu
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Yang Guo
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Qian Yang
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Xueling Bai
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Runhua Lu
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Menghui Liu
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Zichen Kuang
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Luo Zhang
- Institute of Geographical Sciences, Henan Academy of Sciences, Zhengzhou 450052, China
| | - Jing Li
- Department of Chemistry, China Agricultural University, Beijing 100193, China.
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3
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Electrochemical Treatment of Effluent for the Removal of Contaminants of Emergent Concern and Culturable Microorganisms. WATER 2021. [DOI: 10.3390/w13040520] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The present work aims to study the electrochemical (EC) process applied for the removal of contaminants of emergent concern (CECs) from wastewater after secondary treatment and the effect of the process on the total culturable microorganisms. The EC experiments were performed in a cylindrical open reactor with 500 mL of effluent, and a fixed current density of 8 mA/cm² was applied through mixed metal oxide electrodes. The experiments were conducted in different sets. In the first round (Set 1), the effluent sample was spiked with three CECs (200 ppb each): caffeine (CAF), carbamazepine (CBZ), and oxybenzone (OXY). For the best treatment period, 6 h, electrodegradation rates ranged from 41 ± 7% for CAF to 95 ± 6% for OXY, with an 87% removal of total culturable microorganisms. In the second round (Set 2), aiming to assess EC process efficiency in a more complex CEC mixture, the effluent was spiked with six more CECs (200 ppb each): diclofenac (DCF), triclosan (TCS), bisphenol A (BPA), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and ibuprofen (IBU), giving a total of nine CECs. In this case, the EC process allowed decreasing the CEC content by 19–100% (below the limit of detection), depending on the effluent samples, and the culturable microorganisms by 99.98% after a 6 h treatment. By contributing to CEC degradation and microorganism removal, the EC process proved to be a viable remediation and disinfection technology for secondary effluent from wastewater treatment plants.
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Impact of Suspended Solids and Organic Matter on Chlorine and UV Disinfection Efficiency of Greywater. WATER 2021. [DOI: 10.3390/w13020214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Reusing greywater (GW) can lower domestic water consumption. However, the GW must be treated and disinfected for securing user health. This research studied at the laboratory scale, and in flow-through setups, which are generally used in full-scale GW treatment the disinfection efficiency of the two commonly used technologies (a) chlorination and (b) low-pressure UV irradiation. The disinfection methods were studied under a commonly found range of total suspended solids (TSS; 3.9–233 mg/L) and 5-d biochemical oxygen demand (BOD5) concentrations (0–107 mg/L) as a representative/proxy of bioavailable organic matter. The negative effect of TSS began even at low concentrations (<20 mg/L) and increased consistently with increasing TSS concentrations across all the concentrations tested. On the other hand, the negative effect of BOD5 on FC inactivation was observed only when its concentration was higher than 50 mg/L. Multiple linear regression models were developed following the laboratory results, establishing a correlation between FC inactivation by either chlorination or UV irradiation and initial FC, TSS, and BOD5 concentrations. The models were validated against the results from the flow-through reactors and explained the majority of the variability in the measured FC inactivation. Conversion factors between the laboratory scales and the flow-through reactor experiments were established. These enable the prediction of the required residual chlorine concentration or the UV dose needed for an on-site flow-through reactor. This approach is valuable from both operational and research perspectives.
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Beggs CB, Avital EJ. Upper-room ultraviolet air disinfection might help to reduce COVID-19 transmission in buildings: a feasibility study. PeerJ 2020; 8:e10196. [PMID: 33083158 PMCID: PMC7566754 DOI: 10.7717/peerj.10196] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/25/2020] [Indexed: 11/20/2022] Open
Abstract
As the world's economies come out of the lockdown imposed by the COVID-19 pandemic, there is an urgent need for technologies to mitigate COVID-19 transmission in confined spaces such as buildings. This feasibility study looks at one such technology, upper-room ultraviolet (UV) air disinfection, that can be safely used while humans are present in the room space, and which has already proven its efficacy as an intervention to inhibit the transmission of airborne diseases such as measles and tuberculosis. Using published data from various sources, it is shown that the SARS-CoV-2 virus, the causative agent of COVID-19, is highly likely to be susceptible to UV-C damage when suspended in air, with a UV susceptibility constant likely to be in the region 0.377-0.590 m2/J, similar to that for other aerosolised coronaviruses. As such, the UV-C flux required to disinfect the virus is expected to be acceptable and safe for upper-room applications. Through analysis of expected and worst-case scenarios, the efficacy of the upper-room UV-C approach for reducing COVID-19 transmission in confined spaces (with moderate but sufficient ceiling height) is demonstrated. Furthermore, it is shown that with SARS-CoV-2, it should be possible to achieve high equivalent air change rates using upper-room UV air disinfection, suggesting that the technology might be particularly applicable to poorly ventilated spaces.
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Affiliation(s)
- Clive B Beggs
- Carnegie School of Sport, Leeds Beckett University, Leeds, UK
| | - Eldad J Avital
- School of Engineering and Materials Science, Queen Mary University of London, London, UK
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Physical Factors Impacting the Survival and Occurrence of Escherichia coli in Secondary Habitats. WATER 2020. [DOI: 10.3390/w12061796] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Escherichia (E.) coli is a fecal microbe that inhabits the intestines of endotherms (primary habitat) and the natural environment (secondary habitats). Due to prevailing thinking regarding the limited capacity of E. coli to survive in the environment, relatively few published investigations exist regarding environmental factors influencing E. coli’s survival. To help guide future research in this area, an overview of factors known to impact the survival of E. coli in the environment is provided. Notably, the lack of historic field-based research holds two important implications: (1) large knowledge gaps regarding environmental factors influencing E. coli’s survival in the environment exist; and (2) the efficacy of implemented management strategies have rarely been assessed on larger field scales, thus leaving their actual impact(s) largely unknown. Moreover, the persistence of E. coli in the environment calls into question its widespread and frequent use as a fecal indicator microorganism. To address these shortcomings, future work should include more field-based studies, occurring in diverse physiographical regions and over larger spatial extents. This information will provide scientists and land-use managers with a new understanding regarding factors influencing E. coli concentrations in its secondary habitat, thereby providing insight to address problematic fecal contamination effectively.
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Umar M, Roddick F, Fan L. Moving from the traditional paradigm of pathogen inactivation to controlling antibiotic resistance in water - Role of ultraviolet irradiation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 662:923-939. [PMID: 30795480 DOI: 10.1016/j.scitotenv.2019.01.289] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 01/21/2019] [Accepted: 01/22/2019] [Indexed: 06/09/2023]
Abstract
Ultraviolet (UV) irradiation has proven an effective tool for inactivating microorganisms in water. There is, however, a need to look at disinfection from a different perspective because microbial inactivation alone may not be sufficient to ensure the microbiological safety of the treated water since pathogenic genes may still be present, even after disinfection. Antibiotic resistance genes (ARGs) are of a particular concern since they enable microorganisms to become resistant to antibiotics. UV irradiation has been widely used for disinfection and more recently for destroying ARGs. While UV lamps remain the principal technology to achieve this objective, UV light emitting diodes (UV-LEDs) are novel sources of UV irradiation and have increasingly been reported in lab-scale investigations as a potential alternative. This review discusses the current state of the applications of UV technology for controlling antibiotic resistance during water and wastewater treatment. Since UV-LEDs possess several attractive advantages over conventional UV lamps, the impact of UV-LED characteristics (single vs combined wavelengths, and operational parameters such as periodic or pulsed and continuous irradiation, pulse repetition frequencies, duty cycle), type of organism, and fluence response, are critically reviewed with a view to highlighting the research needs for addressing future disinfection challenges. The energy efficiency of the reported UV processes is also evaluated with a focus on relating the findings to disinfection efficacy. The greater experience with UV lamps could be useful for investigating UV-LEDs for similar applications (i.e., antibiotic resistance control), and hence identification of future research directions.
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Affiliation(s)
- Muhammad Umar
- Norwegian Institute for Water Research (NIVA), Gaustadallèen 21, NO-0349 Oslo, Norway.
| | - Felicity Roddick
- Department of Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne 3001, Australia
| | - Linhua Fan
- Department of Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne 3001, Australia
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8
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Obayomi O, Bernstein N, Edelstein M, Vonshak A, Ghazayarn L, Ben-Hur M, Tebbe CC, Gillor O. Importance of soil texture to the fate of pathogens introduced by irrigation with treated wastewater. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 653:886-896. [PMID: 30759614 DOI: 10.1016/j.scitotenv.2018.10.378] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/27/2018] [Accepted: 10/27/2018] [Indexed: 06/09/2023]
Abstract
World-wide water scarcity is urging the use of treated wastewater (TWW) for irrigation but this practice may have adverse effects on soil and crop contamination due to the introduction of potential microbial pathogens. The objective of this study was to evaluate the potential health risks caused by TWW irrigation of soils differing in their texture, i.e., soil particle fractions including sand, silt and clay. We predicted that the presence of fecal indicator bacteria (FIB) and pathogens would not be linked to TWW irrigation, yet their abundance would be favored by the smallest soil fraction (~2 nm, e.g., clay) as it provides the largest surface area. To test our hypotheses, culture dependent and independent techniques were used to monitor the presence, abundance and source of FIB and microbial pathogens (bacteria and protists) in water (TWW and potable water) and three irrigated soil types (clay, loam and loamy-sand) in a field study spanning two years. The results showed that FIB and pathogens' abundance were significantly different between water types, yet these differences did not carry to the irrigated soils. The abundance and presence of FIB and potential opportunistic or obligate human pathogens did not significantly differ (p > 0.05) between TWW and potable water irrigated soils. Moreover, the source of the FIB and potential pathogens could not be linked to irrigation with TWW. Yet, soil type significantly altered the potential pathogens' diversity (p < 0.05) and abundance (p < 0.05), and differences were affected by clay content, as predicted. The results gave no indication for potential adverse health effects associated with the application of TWW but demonstrated that clay has a particular stabilizing effect on the potential presence of microbial pathogens.
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Affiliation(s)
- Olabiyi Obayomi
- Zuckerberg Institute for Water Research, J. Blaustein Institutes for Desert Research, Ben Gurion University, Midreshet Ben Gurion 84990, Israel
| | - Nirit Bernstein
- Institute of Soil Water and Environmental Sciences, Volcani Center, POB 6, Bet-Dagan 50-250, Israel
| | - Menahem Edelstein
- Department of Vegetable Crops, Agricultural Research Organization (ARO), Newe Ya'ar Research Center, P. O. Box 1021, Ramat Yishay 30095, Israel
| | - Ahuva Vonshak
- Zuckerberg Institute for Water Research, J. Blaustein Institutes for Desert Research, Ben Gurion University, Midreshet Ben Gurion 84990, Israel
| | - Lusine Ghazayarn
- Zuckerberg Institute for Water Research, J. Blaustein Institutes for Desert Research, Ben Gurion University, Midreshet Ben Gurion 84990, Israel
| | - Meni Ben-Hur
- Institute of Soil Water and Environmental Sciences, Volcani Center, POB 6, Bet-Dagan 50-250, Israel
| | - Christoph C Tebbe
- Thünen Institute of Biodiversity, Bundesallee 65, 38116 Braunschweig, Germany
| | - Osnat Gillor
- Zuckerberg Institute for Water Research, J. Blaustein Institutes for Desert Research, Ben Gurion University, Midreshet Ben Gurion 84990, Israel.
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9
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Sousa-Castillo A, Furini LN, Tiu BDB, Cao PF, Topçu B, Comesaña-Hermo M, Rodríguez-González B, Baaziz W, Ersen O, Advincula RC, Pérez-Lorenzo M, Correa-Duarte MA. Plasmonic Retrofitting of Membrane Materials: Shifting from Self-Regulation to On-Command Control of Fluid Flow. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1707598. [PMID: 30003590 DOI: 10.1002/adma.201707598] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 02/21/2018] [Indexed: 05/18/2023]
Abstract
This work calls for a paradigm shift in order to change the operational patterns of self-regulated membranes in response to chemical signals. To this end, the fabrication of a retrofitting material is introduced aimed at developing an innovative generation of porous substrates endowed with symbiotic but fully independent sensing and actuating capabilities. This is accomplished by transferring carefully engineered plasmonic architectures onto commercial microfiltration membranes lacking of such features. The integration of these materials leads to the formation of a coating surface proficient for ultrasensitive detection and "on-command" gating. Both functionalities can be synergistically modulated by the spatial and temporal distribution of an impinging light beam offering an unprecedented control over the membrane performance in terms of permeability. The implementation of these hybrid nanocomposites in conventional polymeric porous materials holds great potential in applications ranging from intelligent fluid management to advanced filtration technologies and controlled release.
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Affiliation(s)
- Ana Sousa-Castillo
- Department of Physical Chemistry, Biomedical Research Center (CINBIO), Southern Galicia Institute of Health Research (IISGS), and Biomedical Research Networking Center for Mental Health (CIBERSAM), Universidade de Vigo, 36310, Vigo, Spain
| | - Leonardo N Furini
- Department of Physical Chemistry, Biomedical Research Center (CINBIO), Southern Galicia Institute of Health Research (IISGS), and Biomedical Research Networking Center for Mental Health (CIBERSAM), Universidade de Vigo, 36310, Vigo, Spain
| | - Brylee David B Tiu
- Department of Bioengineering, University of California Berkeley, Hearst Memorial Mining Building, Berkeley, CA, 94720-1760, USA
| | - Peng-Fei Cao
- Department of Macromolecular Science and Engineering, Case Western Reserve University School of Engineering, Cleveland, OH, 44106, USA
| | - Begüm Topçu
- Department of Physical Chemistry, Biomedical Research Center (CINBIO), Southern Galicia Institute of Health Research (IISGS), and Biomedical Research Networking Center for Mental Health (CIBERSAM), Universidade de Vigo, 36310, Vigo, Spain
| | - Miguel Comesaña-Hermo
- Department of Physical Chemistry, Biomedical Research Center (CINBIO), Southern Galicia Institute of Health Research (IISGS), and Biomedical Research Networking Center for Mental Health (CIBERSAM), Universidade de Vigo, 36310, Vigo, Spain
| | - Benito Rodríguez-González
- Department of Physical Chemistry, Biomedical Research Center (CINBIO), Southern Galicia Institute of Health Research (IISGS), and Biomedical Research Networking Center for Mental Health (CIBERSAM), Universidade de Vigo, 36310, Vigo, Spain
| | - Walid Baaziz
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 CNRS-Université de Strasbourg, 67037, Strasbourg Cedex 08, France
| | - Ovidiu Ersen
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 CNRS-Université de Strasbourg, 67037, Strasbourg Cedex 08, France
| | - Rigoberto C Advincula
- Department of Macromolecular Science and Engineering, Case Western Reserve University School of Engineering, Cleveland, OH, 44106, USA
| | - Moisés Pérez-Lorenzo
- Department of Physical Chemistry, Biomedical Research Center (CINBIO), Southern Galicia Institute of Health Research (IISGS), and Biomedical Research Networking Center for Mental Health (CIBERSAM), Universidade de Vigo, 36310, Vigo, Spain
| | - Miguel A Correa-Duarte
- Department of Physical Chemistry, Biomedical Research Center (CINBIO), Southern Galicia Institute of Health Research (IISGS), and Biomedical Research Networking Center for Mental Health (CIBERSAM), Universidade de Vigo, 36310, Vigo, Spain
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Nizri L, Vaizel-Ohayon D, Ben-Amram H, Sharaby Y, Halpern M, Mamane H. Development of a molecular method for testing the effectiveness of UV systems on-site. WATER RESEARCH 2017; 127:162-171. [PMID: 29049965 DOI: 10.1016/j.watres.2017.10.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/08/2017] [Accepted: 10/09/2017] [Indexed: 06/07/2023]
Abstract
We established a molecular method for quantifying ultraviolet (UV) disinfection efficacy using total bacterial DNA in a water sample. To evaluate UV damage to the DNA, we developed the "DNA damage" factor, which is a novel cultivation-independent approach that reveals UV-exposure efficiency by applying a simple PCR amplification method. The study's goal was to prove the feasibility of this method for demonstrating the efficiency of UV systems in the field using flow-through UV reactors. In laboratory-based experiments using seeded bacteria, the DNA damage tests demonstrated a good correlation between PCR products and UV dose. In the field, natural groundwater sampled before and after being subjected to the full-scale UV reactors was filtered, and the DNA extracted from the filtrate was subjected to PCR amplification for a 900-bp fragment of the 16S rRNA gene with initial DNA concentrations of 0.1 and 1 ng/μL. In both cases, the UV dose predicted and explained a significant proportion of the variance in the log inactivation ratio and DNA damage factor. Log inactivation ratio was very low, as expected in groundwater due to low initial bacterial counts, whereas the DNA damage factor was within the range of values obtained in the laboratory-based experiments. Consequently, the DNA damage factor reflected the true performance of the full-scale UV system during operational water flow by using the indigenous bacterial array present in a water sample. By applying this method, we were able to predict with high confidence, the UV reactor inactivation potential. For method validation, laboratory and field iterations are required to create a practical field calibration curve that can be used to determine the expected efficiency of the full-scale UV system in the field under actual operation.
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Affiliation(s)
- Limor Nizri
- School of Mechanical Engineering & Water Research Center, Faculty of Engineering, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Dalit Vaizel-Ohayon
- Central Laboratory, MEKOROT, Israel National Water Company, Eshkol, 1710500, Israel
| | - Hila Ben-Amram
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Yehonatan Sharaby
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Malka Halpern
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel; Department of Biology and Environment, University of Haifa at Oranim, Tivon, 36006, Israel
| | - Hadas Mamane
- School of Mechanical Engineering & Water Research Center, Faculty of Engineering, Tel-Aviv University, Tel Aviv 69978, Israel.
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11
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Li M, Li W, Wen D, Qiang Z, Blatchley ER. Experimental Evaluation of Turbidity Impact on the Fluence Rate Distribution in a UV Reactor Using a Microfluorescent Silica Detector. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:13241-13247. [PMID: 29068223 DOI: 10.1021/acs.est.7b02730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Turbidity is a common parameter used to assess particle concentration in water using visible light. However, the fact that particles play multiple roles (e.g., scattering, refraction, and reflection) in influencing the optical properties of aqueous suspensions complicates examinations of their effects on ultraviolet (UV) photoreactor performance. To address this issue, UV fluence rate (FR) distributions in a photoreactor containing various particle suspensions (SiO2, MgO, and TiO2) were measured using a microfluorescent silica detector (MFSD). Reflectance of solid particles, as well as transmittance and scattering properties of the suspensions were characterized at UV, visible, and infrared (IR) wavelengths. The results of these measurements indicated that the optical properties of all three particle types were similar at visible and IR wavelengths, but obvious differences were evident in the UV range. The FR results indicated that for turbidity associated with SiO2 and MgO suspensions, the weighted average FR (WAFR) increased relative to deionized water. These increases were attributed to low particle photon absorption and strong scattering. In contrast, the WAFR values decreased with increasing turbidity for TiO2 suspensions because of their high particle photon absorption and low scattering potential. The findings also indicate that measurements of scattering and transmittance at UV wavelengths can be used to quantify the effects of turbidity on UV FR distributions.
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Affiliation(s)
- Mengkai Li
- Lyles School of Civil Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Wentao Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Dong Wen
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 18 Shuang-qing Road, Beijing 100085, China
| | - Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Division of Environmental & Ecological Engineering, Purdue University , West Lafayette, Indiana 47907, United States
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12
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Liu L, Chu X, Chen P, Xiao Y, Hu J. Effects of water quality on inactivation and repair of Microcystis viridis and Tetraselmis suecica following medium-pressure UV irradiation. CHEMOSPHERE 2016; 163:209-216. [PMID: 27529385 DOI: 10.1016/j.chemosphere.2016.08.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 06/14/2016] [Accepted: 08/04/2016] [Indexed: 06/06/2023]
Abstract
The transfer of invasive organisms by ballast-water discharge has become a growing concern. UV treatment has become an attractive ballast water treatment technology due to its effectiveness, no harmful disinfection byproducts and easiness to handle. Two robust algae strains Microcystis viridis and Tetraselmis suecica were selected as indicator organisms to determine efficiency of medium-pressure (MP) UV-treatment on ballast water. Inactivation and potential repair of these two algae strains following MP UV irradiation were assessed under various turbidity, total organic carbon (TOC) and salinity conditions. The investigated range of UV doses was from 25 to 500 mJ/cm(2). For M. viridis, results indicated that disinfection efficiency was negatively correlated with all of these three factors at low doses (25-200 mJ/cm(2)). Photoreactivation and dark repair were promoted at high TOC levels (6-15 mg/L) with about 6-25% higher repair levels compared with those in distilled water, whereas no significant impacts were identified for turbidity and salinity on both of the photoreactivation and dark repair. For T. suecica, increased turbidity and TOC levels both hindered the performance of UV irradiation at high doses (200-500 mJ/cm(2)). Suppressive effects on photoreactivation and dark repair were consistently observed with changes of all of the three factors. In conclusion, generally these three factors resulted in repressive effects on UV disinfection efficiency, and TOC played a more significant role in the levels of reactivation than the other two. The responses of T. suecica to these three factors were more sensitive than M. viridis.
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Affiliation(s)
- Lei Liu
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore; School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Xiaona Chu
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Pengyu Chen
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore; School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Yan Xiao
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Jiangyong Hu
- Department of Civil & Environmental Engineering, National University of Singapore, Singapore 117576, Singapore.
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13
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Linden KG, Hull NM, Rodriguez RA. Comment on "UV Disinfection Induces a VBNC State in Escherichia coli and Pseudomonas aeruginosa". ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:10750-10751. [PMID: 26270787 DOI: 10.1021/acs.est.5b02534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- Karl G Linden
- University of Colorado Boulder , Boulder, Colorado 80309, United States
| | - Natalie M Hull
- University of Colorado Boulder , Boulder, Colorado 80309, United States
| | - Roberto A Rodriguez
- The University of Texas Health Science Center at Houston , El Paso, Texas 79902, United States
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14
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Benami M, Gillor O, Gross A. The question of pathogen quantification in disinfected graywater. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 506-507:496-504. [PMID: 25437766 DOI: 10.1016/j.scitotenv.2014.11.051] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 11/15/2014] [Accepted: 11/15/2014] [Indexed: 05/26/2023]
Abstract
Graywater (GW) reuse for irrigation is recognized as a sustainable solution for water conservation. One of the major impediments to GW reuse is the presence of pathogenic microorganisms. This study monitored three similar on-site GW treatment systems bi-monthly over the course of a year to compare the presence of pathogens and indicators in raw, biologically treated, and biologically treated and disinfected [by chlorine and ultraviolet light (UV)] GW. The systems were designed to allow the testing of the same batch (collection) of water as it passed through the treatment chain. The samples were analyzed using standard culture-dependent methods and the data were compared to culture-independent DNA-based methods. Results suggested that the presence and abundance of fecal coliforms, Escherichia coli, Salmonella enterica, Enterococcus spp., Staphylococcus aureus and Pseudomonas aeruginosa differ among the various GW streams (e.g. raw, biologically treated, and disinfected). The culture-dependent analyses suggested that both chlorine and UV inactivate most of the bacteria tested in the biologically treated GW, albeit at different efficiencies. Conversely, the DNA-based analyses indicated no significant differences in pathogenic bacterial abundance between the biologically treated GW with or without disinfection. To better understand the discrepancies between the results, we repeated the analysis in the laboratory under controlled conditions using Enterococcus faecalis as a model bacterium and obtained similar results. We suggest that disinfection of biologically treated GW with chlorine or UV is effective for treating pathogens, but that the inactivation efficiency cannot be estimated by DNA-based qPCR.
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Affiliation(s)
- Maya Benami
- Zuckerberg Institute for Water Research, Israel; Albert Katz International School for Desert Studies,; The Jacob Blaustein Institutes for Desert Research,; Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben Gurion 84990, Israel
| | - Osnat Gillor
- Zuckerberg Institute for Water Research, Israel; Albert Katz International School for Desert Studies,; The Jacob Blaustein Institutes for Desert Research,; Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben Gurion 84990, Israel.
| | - Amit Gross
- Zuckerberg Institute for Water Research, Israel; Albert Katz International School for Desert Studies,; The Jacob Blaustein Institutes for Desert Research,; Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben Gurion 84990, Israel.
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15
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Rajab M, Heim C, Letzel T, Drewes JE, Helmreich B. Electrochemical disinfection using boron-doped diamond electrode--the synergetic effects of in situ ozone and free chlorine generation. CHEMOSPHERE 2015; 121:47-53. [PMID: 25434271 DOI: 10.1016/j.chemosphere.2014.10.075] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/28/2014] [Accepted: 10/30/2014] [Indexed: 05/12/2023]
Abstract
This work investigated the capability of using a boron-doped diamond (BDD) electrode for bacterial disinfection in different water matrices containing varying amounts of chloride. The feed water containing Pseudomonas aeruginosa was electrochemically treated while applying different electrode conditions. Depending on the applied current density and the exposure time, inactivation between 4- and 8-log of the targeted microorganisms could be achieved. The disinfection efficiency was driven by the generation of free chlorine as a function of chloride concentration in the water. A synergetic effect of generating both free chlorine and ozone in situ during the disinfection process resulted in an effective bactericidal impact. The formation of the undesired by-products chlorate and perchlorate depended on the water matrix, the applied current density and the desired target disinfection level. In case of synthetic water with a low chloride concentration (20 mg L(-1)) and an applied current density of 167 mA cm(-2), a 6-log inactivation of Pseudomonas aeruginosa could be achieved after 5 min of exposure. The overall energy consumption ranged between 0.3 and 0.6 kW h m(-3) depending on the applied current density and water chemistry. Electrochemical water disinfection represents a suitable and efficient process for producing pathogen-free water without the use of any chemicals.
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Affiliation(s)
- Mohamad Rajab
- Technische Universität München, Chair of Urban Water Systems Engineering, Am Coulombwall 8, 85748 Garching, Germany.
| | - Carolin Heim
- Technische Universität München, Chair of Urban Water Systems Engineering, Am Coulombwall 8, 85748 Garching, Germany.
| | - Thomas Letzel
- Technische Universität München, Chair of Urban Water Systems Engineering, Am Coulombwall 8, 85748 Garching, Germany.
| | - Jörg E Drewes
- Technische Universität München, Chair of Urban Water Systems Engineering, Am Coulombwall 8, 85748 Garching, Germany.
| | - Brigitte Helmreich
- Technische Universität München, Chair of Urban Water Systems Engineering, Am Coulombwall 8, 85748 Garching, Germany.
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16
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Santos AL, Baptista I, Gomes NCM, Henriques I, Almeida A, Correia A, Cunha A. Contribution of chemical water properties to the differential responses of bacterioneuston and bacterioplankton to ultraviolet-B radiation. FEMS Microbiol Ecol 2013; 87:517-35. [PMID: 24164491 DOI: 10.1111/1574-6941.12239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 09/24/2013] [Accepted: 10/21/2013] [Indexed: 11/26/2022] Open
Abstract
The surface microlayer (SML) is characterized by different physicochemical properties from underlying waters (UW). However, whether these differences in abiotic factors underlie the distinct sensitivity of bacterioneuston (i.e. SML bacteria) and bacterioplankton to environmental stressors remains to be addressed. We investigated the contribution of abiotic factors to the UV-B sensitivity of bacterioneuston and bacterioplankton. Nutrients (especially nitrogen and phosphate) emerged as important determinants of bacterial UV-B sensitivity. The role of particles, nutrients, and dissolved organic components on bacterial UV-B sensitivity was further evaluated using dilution cultures. Filtered samples were twofold more UV sensitive than unfiltered samples, suggesting a UV-protective effect of particles. High nutrient concentrations attenuated bacterial UV-B sensitivity (up to 40%), compared with unamended conditions, by influencing bacterial physiology and/or community composition. Suspending cells in natural water, particularly from the SML, also attenuated UV-B sensitivity (up to 23%), compared with suspension in an artificial mineral solution. Bioassays using Pseudomonas sp. strain NT5I1.2B revealed that chemical water properties influence UV-induced oxidative damage. UV-B sensitivity was associated with high cell-specific activities. The chemical environment of the SML and UW influences UV-B effects on the corresponding bacterial communities. Maintaining low cell activities might be advantageous in stressful environments, like the SML.
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Affiliation(s)
- Ana L Santos
- Department of Biology and CESAM, University of Aveiro, Aveiro, Portugal
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17
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Cockayne syndrome b maintains neural precursor function. DNA Repair (Amst) 2012; 12:110-20. [PMID: 23245699 DOI: 10.1016/j.dnarep.2012.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 10/17/2012] [Accepted: 11/12/2012] [Indexed: 12/18/2022]
Abstract
Neurodevelopmental defects are observed in the hereditary disorder Cockayne syndrome (CS). The gene most frequently mutated in CS, Cockayne Syndrome B (CSB), is required for the repair of bulky DNA adducts in transcribed genes during transcription-coupled nucleotide excision repair. CSB also plays a role in chromatin remodeling and mitochondrial function. The role of CSB in neural development is poorly understood. Here we report that the abundance of neural progenitors is normal in Csb(-/-) mice and the frequency of apoptotic cells in the neurogenic niche of the adult subependymal zone is similar in Csb(-/-) and wild type mice. Both embryonic and adult Csb(-/-) neural precursors exhibited defective self-renewal in the neurosphere assay. In Csb(-/-) neural precursors, self-renewal progressively decreased in serially passaged neurospheres. The data also indicate that Csb and the nucleotide excision repair protein Xpa preserve embryonic neural stem cell self-renewal after UV DNA damage. Although Csb(-/-) neural precursors do not exhibit altered neuronal lineage commitment after low-dose UV (1J/m(2)) in vitro, neurons differentiated in vitro from Csb(-/-) neural precursors that had been irradiated with 1J/m(2) UV exhibited defective neurite outgrowth. These findings identify a function for Csb in neural precursors.
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18
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Kollu K, Ormeci B. Effect of particles and bioflocculation on ultraviolet disinfection of Escherichia coli. WATER RESEARCH 2012; 46:750-60. [PMID: 22172560 DOI: 10.1016/j.watres.2011.11.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 10/21/2011] [Accepted: 11/16/2011] [Indexed: 05/26/2023]
Abstract
Presence of particles is known to decrease the effectiveness of ultraviolet (UV) disinfection by shielding the targeted microorganisms from UV light. This study aims to provide an in-depth understanding on the effect of particles and flocs on UV disinfection by using a stable, well-defined and well-controlled synthetic system that can simulate the bioflocculation of particles and microorganisms in water and wastewater samples. The synthetic system was created by using Escherichia coli, latex particles (1, 3.2, 11, 25, and 45 μm), alginate, and divalent cations; and the bioflocculation of particles was achieved naturally, as it would occur in the environment, without using chemical coagulants. E. coli was quantified before and after UV disinfection using membrane filtration. Even in the absence of particles, some of the self-aggregated E. coli could survive a UV dose of 90 mJ/cm(2). E. coli inactivation levels measured in the presence of particles were lower than the inactivation levels measured in the absence of particles. At low UV doses (<9 mJ/cm(2)), neither particle size nor degree of flocculation had a significant effect on the inactivation of E. coli. Particle size had a significant effect on the inactivation of E. coli only at high UV doses (80 mJ/cm(2)), and larger particles (e.g., 25 μm) protected bacteria more compared to smaller particles (e.g., 3.2 and 11 μm). What size of particles flocs were made of (3.2, 11, and 25 μm) did not make a significant difference on the inactivation levels of E. coli. For 3.2 μm particles, there was no significant difference in E. coli inactivation between non-flocculated and flocculated samples at any UV dose. For 11 and 25 μm particles, there was a significant difference in E. coli inactivation between non-flocculated and flocculated samples at 80 mJ/cm(2). Degree of flocculation became a significant factor in determining the number of surviving bacteria only at high UV doses and only for larger particles.
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Affiliation(s)
- Kerim Kollu
- Department of Civil and Environmental Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
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Lakretz A, Ron EZ, Mamane H. Biofilm control in water by a UV-based advanced oxidation process. BIOFOULING 2011; 27:295-307. [PMID: 21390914 DOI: 10.1080/08927014.2011.561923] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
An ultraviolet (UV)-based advanced oxidation process (AOP), with hydrogen peroxide and medium-pressure (MP) UV light (H(2)O(2)/UV), was used as a pretreatment strategy for biofilm control in water. Suspended Pseudomonas aeruginosa cells were exposed to UV-based AOP treatment, and the adherent biofilm formed by the surviving cells was monitored. Control experiments using H(2)O(2) or MP UV irradiation alone could inhibit biofilm formation for only short periods of time (<24 h) post-treatment. In a H(2)O(2)/filtered-UV (>295 nm) system, an additive effect on biofilm control was shown vs filtered-UV irradiation alone, probably due to activity of the added hydroxyl radical (OH•). In a H(2)O(2)/full-UV (ie full UV spectrum, not filtered) system, this result was not obtained, possibly due to the germicidal UV photons overwhelming the AOP system. Generally, however, H(2)O(2)/UV prevented biofilm formation for longer periods (days) only when maintained with residual H(2)O(2). The ratio of surviving bacterial concentration post-treatment to residual H(2)O(2) concentration played an important role in biofilm prevention and bacterial regrowth. H(2)O(2) treatments alone resulted in poorer biofilm control compared to UV-based AOP treatments maintained with similar levels of residual H(2)O(2), indicating a possible advantage of AOP.
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Affiliation(s)
- Anat Lakretz
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
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20
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Lakretz A, Ron EZ, Mamane H. Biofouling control in water by various UVC wavelengths and doses. BIOFOULING 2010; 26:257-267. [PMID: 20024789 DOI: 10.1080/08927010903484154] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
UV light irradiation is being increasingly applied as a primary process for water disinfection, effectively used for inactivation of suspended (planktonic) cells. In this study, the use of UV irradiation was evaluated as a pretreatment strategy to control biofouling. The objective of this research was to elucidate the relative effectiveness of various targeted UV wavelengths and a polychromatic spectrum on bacterial inactivation and biofilm control. In a model system using Pseudomonas aeruginosa, the inactivation spectra corresponded to the DNA absorption spectra for all wavelengths between 220 and 280 nm, while wavelengths between 254 nm and 270 nm were the most effective for bacterial inactivation. Similar wavelengths of 254-260-270 nm were also more effective for biofilm control in most cases than targeted 239 and 280 nm. In addition, the prevention of biofilm formation by P. aeruginosa with a full polychromatic lamp was UV dose-dependent. It appears that biofilm control is improved when larger UV doses are given, while higher levels of inactivation are obtained when using a full polychromatic MP lamp. However, no significant differences were found between biofilms produced by bacteria that survived UV irradiation and biofilms produced by control bacteria at the same microbial counts. Moreover, the experiments showed that biofilm prevention depends on the post-treatment incubation time and nutrient availability, in addition to targeted wavelengths, UV spectrum and UV dose.
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Affiliation(s)
- Anat Lakretz
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
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