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Wang Z, Zheng M, Hu Z, Duan H, De Clippeleir H, Al-Omari A, Hu S, Yuan Z. Unravelling adaptation of nitrite-oxidizing bacteria in mainstream PN/A process: Mechanisms and counter-strategies. WATER RESEARCH 2021; 200:117239. [PMID: 34029873 DOI: 10.1016/j.watres.2021.117239] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 04/16/2021] [Accepted: 05/07/2021] [Indexed: 05/06/2023]
Abstract
Stable suppression of nitrite-oxidizing bacteria (NOB) is still a major challenge for the implementation of partial nitritation and anammox (PN/A) in mainstream treatment. Despite numerous suppression strategies demonstrated, it is increasingly recognized that NOB could develop resistance to these strategies, threatening the long-term stability of the mainstream PN/A process. This study aims to understand adaption mechanisms and develop counter-strategies to overcome the adaptation. To this end, three previously-demonstrated suppression strategies, including NOB inactivation via side stream sludge treatment with free ammonia (FA), the use of low dissolved oxygen (DO), and the use of anammox to scavenge nitrite, were stepwise applied, over a period of 800 days, to a laboratory-scale reactor treating effluent from a high-rate activated sludge (HRAS) plant. FA sludge treatment alone sustained nitrite accumulation for about two months, after which NOB adaptation occurred causing PN to fail. The FA adaptation was induced by a shift in the NOB community from Nitrospira to Ca. Nitrotoga. The latter was found to have higher resistance to FA and also a higher maximum specific growth rate. Low DO at 0.2-0.4 mg O2 L-1 was then applied, in conjunction with FA treatment, which successfully eliminated Ca. Nitrotoga and re-established PN. However, new and unidentified NOB with a higher apparent oxygen affinity emerged in three months, again leading to PN failure. Lastly, as the third strategy for NOB suppression, anammox was introduced as an in-situ nitrite-scavenger. The combo-strategy delivered reliable NOB suppression with no further adaptation in the remaining experimental period (eight months). The resulted one-stage PN/A reactor achieved a nitrogen removal efficiency of 84.2 ± 5.37%. A control reactor, operated in parallel under the same conditions but without FA treatment, only achieved 10.4 ± 4.6% nitrogen removal, with anammox completely outcompeted by NOB in the last phase.
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Affiliation(s)
- Zhiyao Wang
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Min Zheng
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
| | - Zhetai Hu
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Haoran Duan
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Haydée De Clippeleir
- District of Columbia Water and Sewer Authority, 5000 Overlook Ave. SW, Washington, DC 20032, USA
| | - Ahmed Al-Omari
- District of Columbia Water and Sewer Authority, 5000 Overlook Ave. SW, Washington, DC 20032, USA
| | - Shihu Hu
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Zhiguo Yuan
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
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Liu Y, Zhao T, Su Z, Zhu T, Ni BJ. Evaluating the roles of coexistence of sludge flocs on nitrogen removal and nitrous oxide production in a granule-based autotrophic nitrogen removal system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 730:139018. [PMID: 32413601 DOI: 10.1016/j.scitotenv.2020.139018] [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: 01/30/2020] [Revised: 04/24/2020] [Accepted: 04/24/2020] [Indexed: 06/11/2023]
Abstract
Certain levels of sludge flocs would always coexist in granule-based reactors due to the biomass detachment from granules. Such inevitable coexistence could affect both total nitrogen (TN) removal and nitrous oxide (N2O) production in autotrophic nitrogen removal systems. This work utilized a mathematical approach to systematically study the influence of the coexisting sludge flocs on TN removal and N2O production in a granular nitritation-anaerobic ammonium oxidation (Anammox) process for the first time, based on a 2-pathway N2O production model concept. The modelling results reveal that the highest TN removal efficiency decreases from ca. 87-88% to ca. 41-49% as the fraction of sludge flocs in the system increases from 10% to 40%, while the N2O production rate gradually increases with such increase. Meanwhile, both bulk dissolved oxygen (DO, 0.05-0.3 mg/L) and the size of granule (200-400 μm) could also influence the TN removal efficiency and N2O production. As the fraction of sludge flocs increases from 10% to 40%, the contribution of granular biomass to total N2O production is reduced due to increase of N2O-producing ammonia-oxidizing bacteria (AOB) in the sludge flocs, and the increase of granule size could intensify such decrease. In addition, the hydroxylamine oxidation pathway dominates the nitrifier denitrification pathway in both granules and sludge flocs under various testing conditions, whereas the increasing contribution of the latter would occur at a certain DO range, higher fraction of sludge flocs and smaller granule size. These results disclose an important influence of the coexisting sludge flocs on the performance of granular nitritation-Anammox systems.
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Affiliation(s)
- Yiwen Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China; Academy of Environment and Ecology, Tianjin University, Tianjin 300072, China
| | - Tianhang Zhao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Zhongxian Su
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Tingting Zhu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Bing-Jie Ni
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
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Liu Y, Ngo HH, Guo W, Wang D, Peng L, Wei W, Ni BJ. Impact of coexistence of sludge flocs on nitrous oxide production in a granule-based nitrification system: A model-based evaluation. WATER RESEARCH 2020; 170:115312. [PMID: 31760359 DOI: 10.1016/j.watres.2019.115312] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/20/2019] [Accepted: 11/14/2019] [Indexed: 06/10/2023]
Abstract
A common operational status of granule-based reactor is the inevitable coexistence of sludge flocs. Such hybrid system could have a profound impact on nitrous oxide (N2O) production in nitrifying process. In this work, a mathematical model is employed to evaluate the key role of the coexistence of sludge flocs on N2O production in a granule-based nitrifying system for the first time, by considering both nitrifier denitrification and hydroxylamine oxidation pathways. The modelling results show that the N2O production gradually decreases with the increase of the percentage of sludge flocs in the total biomass (10-60%). More N2O is tended to be generated in sludge flocs which has lower N2O production capacity compared to granular biomass, thus lowering the total N2O production. The relative contributions of two N2O production pathways are only affected by bulk dissolved oxygen (DO) for the sludge flocs in the hybrid system, whereas those are affected by both bulk DO and the fractions of sludge flocs for the granular biomass. The results reveal a substantial effect of the coexistence of sludge flocs on N2O production in granule-based nitrifying process, which should not be ignored in future design and operation.
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Affiliation(s)
- Yiwen Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300350, China; Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Huu Hao Ngo
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia.
| | - Wenshan Guo
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha, 410082, China
| | - Lai Peng
- School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China
| | - Wei Wei
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Bing-Jie Ni
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia.
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Laureni M, Weissbrodt DG, Villez K, Robin O, de Jonge N, Rosenthal A, Wells G, Nielsen JL, Morgenroth E, Joss A. Biomass segregation between biofilm and flocs improves the control of nitrite-oxidizing bacteria in mainstream partial nitritation and anammox processes. WATER RESEARCH 2019; 154:104-116. [PMID: 30782552 DOI: 10.1016/j.watres.2018.12.051] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 12/24/2018] [Accepted: 12/27/2018] [Indexed: 05/13/2023]
Abstract
The control of nitrite-oxidizing bacteria (NOB) challenges the implementation of partial nitritation and anammox (PN/A) processes under mainstream conditions. The aim of the present study was to understand how operating conditions impact microbial competition and the control of NOB in hybrid PN/A systems, where biofilm and flocs coexist. A hybrid PN/A moving-bed biofilm reactor (MBBR; also referred to as integrated fixed film activated sludge or IFAS) was operated at 15 °C on aerobically pre-treated municipal wastewater (23 mgNH4-N L-1). Ammonium-oxidizing bacteria (AOB) and NOB were enriched primarily in the flocs, and anammox bacteria (AMX) in the biofilm. After decreasing the dissolved oxygen concentration (DO) from 1.2 to 0.17 mgO2 L-1 - with all other operating conditions unchanged - washout of NOB from the flocs was observed. The activity of the minor NOB fraction remaining in the biofilm was suppressed at low DO. As a result, low effluent NO3- concentrations (0.5 mgN L-1) were consistently achieved at aerobic nitrogen removal rates (80 mgN L-1 d-1) comparable to those of conventional treatment plants. A simple dynamic mathematical model, assuming perfect biomass segregation with AOB and NOB in the flocs and AMX in the biofilm, was able to qualitatively reproduce the selective washout of NOB from the flocs in response to the decrease in DO-setpoint. Similarly, numerical simulations indicated that flocs removal is an effective operational strategy to achieve the selective washout of NOB. The direct competition for NO2- between NOB and AMX - the latter retained in the biofilm and acting as a "NO2-sink" - was identified by the model as key mechanism leading to a difference in the actual growth rates of AOB and NOB (i.e., μNOB < μAOB in flocs) and allowing for the selective NOB washout over a broad range of simulated sludge retention times (SRT = 6.8-24.5 d). Experimental results and model predictions demonstrate the increased operational flexibility, in terms of variables that can be easily controlled by operators, offered by hybrid systems as compared to solely biofilm systems for the control of NOB in mainstream PN/A applications.
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Affiliation(s)
- Michele Laureni
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Stefano-Franscini-Platz 5, CH-8093, Zürich, Switzerland.
| | - David G Weissbrodt
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, NL- 2629, HZ Delft, the Netherlands; Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, DK-9220, Aalborg, Denmark
| | - Kris Villez
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Orlane Robin
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Nadieh de Jonge
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, DK-9220, Aalborg, Denmark
| | - Alex Rosenthal
- Northwestern University, Department of Civil and Environmental Engineering, Evanston, IL, USA
| | - George Wells
- Northwestern University, Department of Civil and Environmental Engineering, Evanston, IL, USA
| | - Jeppe Lund Nielsen
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, DK-9220, Aalborg, Denmark
| | - Eberhard Morgenroth
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Stefano-Franscini-Platz 5, CH-8093, Zürich, Switzerland
| | - Adriano Joss
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland
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Wang G, Zhang D, Xu Y, Hua Y, Dai X. Comparing two start up strategies and the effect of temperature fluctuations on the performance of mainstream anammox reactors. CHEMOSPHERE 2018; 209:632-639. [PMID: 29957524 DOI: 10.1016/j.chemosphere.2018.06.134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 06/12/2018] [Accepted: 06/19/2018] [Indexed: 06/08/2023]
Abstract
Anammox cultivated with high substrate concentration (NH4+-N, 150 mg/L; NO2--N, 200 mg/L) at 35 °C was first used as seed sludge to start up reactors at 35 (Ra), 20 (Rb) and 15 °C (Rc) with low substrate concentration (NH4+-N 30 mg/L, NO2--N 40 mg/L). The results showed that anammox activity initially decreased in the three reactors, but that activity levels and nitrogen loading rate (NLR) increased as the bacteria gradually adapted to the new conditions (12-30 days). Temperature and concentration shift affected anammox activity jointly. In the process, the abundance of mRNA of the key functional genes of hdh and nirS, changed with time but this change did not reflect the change of anammox activity. When the reactors reached a stable state after 40 d, the effect of temperature fluctuations was tested. The results showed that anammox adapted to low temperatures as soon as temperature decreased (i.e., decreased from 35 °C to 15 °C). When temperature increased, 2-3 days were needed for activity recovery. From this result, it may be concluded that reactors with low temperatures and low substrate (mainstream) concentrations can be started up using anammox cultivated at a higher temperature (35 °C) with low substrate. Then anammox in Ra was used to start up a mainstream reactor at 15 °C and it was operated for 60 days. The results showed that the activity in Ra decreased sharply to the level as that of Rc at the stable state. After the experiment, microbiological analysis showed that the anammox was stable and that Candidatus Kuenenia was the dominant species.
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Affiliation(s)
- Guopeng Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Dong Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China.
| | - You Xu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Yu Hua
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Xiaohu Dai
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China.
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Leix C, Drewes JE, Ye L, Koch K. Strategies for enhanced deammonification performance and reduced nitrous oxide emissions. BIORESOURCE TECHNOLOGY 2017; 236:174-185. [PMID: 28402907 DOI: 10.1016/j.biortech.2017.03.182] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 03/27/2017] [Accepted: 03/30/2017] [Indexed: 06/07/2023]
Abstract
Deammonification's performance and associated nitrous oxide emissions (N2O) depend on operational conditions. While studies have investigated factors for high performances and low emissions separately, this study investigated optimizing deammonification performance while simultaneously reducing N2O emissions. Using a design of experiment (DoE) method, two models were developed for the prediction of the nitrogen removal rate and N2O emissions during single-stage deammonification considering three operational factors (i.e., pH value, feeding and aeration strategy). The emission factor varied between 0.7±0.5% and 4.1±1.2% at different DoE-conditions. The nitrogen removal rate was predicted to be maximized at settings of pH 7.46, intermittent feeding and aeration. Conversely, emissions were predicted to be minimized at the design edges at pH 7.80, single feeding, and continuous aeration. Results suggested a weak positive correlation between the nitrogen removal rate and N2O emissions, thus, a single optimizing operational set-point for maximized performance and minimized emissions did not exist.
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Affiliation(s)
- Carmen Leix
- Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
| | - Jörg E Drewes
- Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
| | - Liu Ye
- School of Chemical Engineering, The University of Queensland, St. Lucia, Queensland 4072, Australia.
| | - Konrad Koch
- Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
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Zhu B, Bradford L, Huang S, Szalay A, Leix C, Weissbach M, Táncsics A, Drewes JE, Lueders T. Unexpected Diversity and High Abundance of Putative Nitric Oxide Dismutase (Nod) Genes in Contaminated Aquifers and Wastewater Treatment Systems. Appl Environ Microbiol 2017; 83:e02750-16. [PMID: 27986721 PMCID: PMC5288823 DOI: 10.1128/aem.02750-16] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 12/02/2016] [Indexed: 11/20/2022] Open
Abstract
It has recently been suggested that oxygenic dismutation of NO into N2 and O2 may occur in the anaerobic methanotrophic "Candidatus Methylomirabilis oxyfera" and the alkane-oxidizing gammaproteobacterium HdN1. It may represent a new pathway in microbial nitrogen cycling catalyzed by a putative NO dismutase (Nod). The formed O2 enables microbes to employ aerobic catabolic pathways in anoxic habitats, suggesting an ecophysiological niche space of substantial appeal for bioremediation and water treatment. However, it is still unknown whether this physiology is limited to "Ca Methylomirabilis oxyfera" and HdN1 and whether it can be coupled to the oxidation of electron donors other than alkanes. Here, we report insights into an unexpected diversity and remarkable abundance of nod genes in natural and engineered water systems. Phylogenetically diverse nod genes were recovered from a range of contaminated aquifers and N-removing wastewater treatment systems. Together with nod genes from "Ca Methylomirabilis oxyfera" and HdN1, the novel environmental nod sequences formed no fewer than 6 well-supported phylogenetic clusters, clearly distinct from canonical NO reductase (quinol-dependent NO reductase [qNor] and cytochrome c-dependent NO reductase [cNor]) genes. The abundance of nod genes in the investigated samples ranged from 1.6 × 107 to 5.2 × 1010 copies · g-1 (wet weight) of sediment or sludge biomass, accounting for up to 10% of total bacterial 16S rRNA gene counts. In essence, NO dismutation could be a much more widespread physiology than currently perceived. Understanding the controls of this emergent microbial capacity could offer new routes for nitrogen elimination or pollutant remediation in natural and engineered water systems. IMPORTANCE NO dismutation into N2 and O2 is a novel process catalyzed by putative NO dismutase (Nod). To date, only two bacteria, the anaerobic methane-oxidizing bacterium "Ca Methylomirabilis oxyfera" and the alkane-oxidizing gammaproteobacterium HdN1, are known to harbor nod genes. In this study, we report efficient molecular tools that can detect and quantify a wide diversity of nod genes in environmental samples. A surprisingly high diversity and abundance of nod genes were found in contaminated aquifers as well as wastewater treatment systems. This evidence indicates that NO dismutation may be a much more widespread physiology in natural and man-made environments than currently perceived. The molecular tools presented here will facilitate further studies on these enigmatic microbes in the future.
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Affiliation(s)
- Baoli Zhu
- Institute of Groundwater Ecology, Helmholtz-Zentrum München, Neuherberg, Germany
| | - Lauren Bradford
- Institute of Groundwater Ecology, Helmholtz-Zentrum München, Neuherberg, Germany
| | - Sichao Huang
- Institute of Groundwater Ecology, Helmholtz-Zentrum München, Neuherberg, Germany
| | - Anna Szalay
- Institute of Groundwater Ecology, Helmholtz-Zentrum München, Neuherberg, Germany
| | - Carmen Leix
- Chair of Urban Water Systems Engineering, Technical University of Munich, Munich, Germany
| | - Max Weissbach
- Chair of Urban Water Systems Engineering, Technical University of Munich, Munich, Germany
| | | | - Jörg E Drewes
- Chair of Urban Water Systems Engineering, Technical University of Munich, Munich, Germany
| | - Tillmann Lueders
- Institute of Groundwater Ecology, Helmholtz-Zentrum München, Neuherberg, Germany
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Performance and N2O Formation of the Deammonification Process by Suspended Sludge and Biofilm Systems—A Pilot-Scale Study. WATER 2016. [DOI: 10.3390/w8120578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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