Dissertations / Theses on the topic 'Chlorinated compound'
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Aeppli, Christoph. "Assessing the natural attenuation of chlorinated ethenes in groundwater using compound-specific stable isotope analysis /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17829.
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Cichocka, Danuta. "Assessment of microbial transformation of chlorinated ethenes by compound specific isotope analysis and cultivation techniques /." Leipzig : UFZ, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=017048800&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Slater, Gregory Franklin. "Constraining the fate of chlorinated ethenes in groundwater systems using stable carbon compound specific isotope analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58983.pdf.
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Brooks, George Patrick 1955. "Forced ventilation removal of chlorinated hydrocarbons in layered, unsaturated soil material: A laboratory evaluation." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276975.
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Helium tracer experiments were conducted to characterize conservative tracer behavior in a wedge-shaped lysimeter containing alternating layers of unsaturated silty sand, and clay loam. Experiments were conducted with trichloroethylene and 1,1,1-trichloroethane to determine if air stripping in unsaturated soil could be characterized by mass transfer from the sorbed to the liquid to the vapor phase. Batch experiments were conducted to measure liquid--vapor mass transfer. Solid-liquid-vapor mass transfer was characterized by measuring the vapor phase re-equilibration after the air stripping experiment. The Discrete State Compartment model was used to simulate a conservative gas tracer. The results were compared to the helium tracer. Liquid-vapor, and solid-liquid-vapor mass transfer were modeled by fitting simulated data to experimental data. The conservative tracer, and mass transfer models were combined to simulate air stripping in unsaturated soil.
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Heckel, Benjamin Matthäus [Verfasser], and Elsner [Akademischer Betreuer]. "Investigating Mechanisms of Reductive Chlorinated Hydrocarbon Degradation with Compound-Specific Isotope Analysis / Benjamin Matthäus Heckel ; Betreuer: Elsner." Tübingen : Universitätsbibliothek Tübingen, 2018. http://d-nb.info/1198972688/34.
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BERTOLINI, MARTINA. "GROUNDWATER BIOREMEDIATION: MICROBIAL POPULATIONS INVOLVED IN CHLOROETHENES AND BTEX CONTAMINATED AQUIFER PROCESSING." Doctoral thesis, Università degli Studi di Milano, 2021. http://hdl.handle.net/2434/809422.
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Groundwater plays an important role in water supply around the world. 2 billion of people use aquifers as drinking water. Consequently, contamination of groundwater has a great social and economic impacts.
The use of organisms (microorganisms and plants) to remediate contaminated matrices, called bioremediation, is becoming more and more frequent. These techniques are cheaper than chemical and physical remediation techniques.
Chloroethenes, aromatic and aliphatic hydrocarbons are widely contaminant compounds because of their intensive use in industrial activity. It is possible to lower their concentration in the environment by means of microbial biodegradation in anaerobic and aerobic conditions.
In this study, an aquifer (located near Porto Marghera, Venice, Italy) contaminated by a leaching from a former landfill was analyzed. The contamination comprised chlorinated solvents, benzene, toluene, ethylbenzene and xylenes (BTEX) and aliphatic hydrocarbons. In 1995, an intervention with a pump and treat reactor was installed. Due to low efficiency and high maintenance costs of the physic-chemical treatment, the installation of a biological treatment, based on two permeable reactive biobarriers, was planned. After preliminary characterization of the microbial community at the site in order to evidence the presence of natural microbial populations involved in decontamination processes, in February 2016 a first biobarrier was installed to stimulate bacterial anaerobic organohalide respiration to dechlorinate chloroethenes. The injection of a reducing substrate was set up to create strong reducing conditions to improve the activity of anaerobic bacteria. A second biobarrier was meant to stimulate bacterial aerobic biodegradation of BTEX and aliphatic hydrocarbons. Urea, ammonium phosphate and O2 were planned to be injected in the aquifer. Moreover, this treatment was also forecasted to be used for complete vinyl chloride aerobic biodegradation.
In order to define the presence of organo-halide respiring bacteria at the aquifer, laboratory-based anaerobic microcosm study was set up. The effect of the biostimulation intervention (i.e., the addition of a reducing substrate) was also monitored in comparison with natural attenuation processes. Chlorinated ethenes were analyzed through gas-chromatography coupled to mass spectrophotometry (GC-MS). At microcosms scale, the natural organohalide respiration activity was influenced by the presence of reducing substrate, showing an increase of dechlorination of highly chlorinated ethenes, with a concomitant accumulation of vinyl chloride. Landfill active microbial community composition was determined through Illumina 16S rRNA sequencing of cDNA from RNA extracted from groundwater samples. Active organo-halide bacteria were quantified by quantitative Real Time PCR (q-PCR). Phylogenetic bacterial biomarkers for Dehalococcoides, Geobacteriaceae, and functional biomarkers tceA and vcrA, coding for chlorinated ethenes reductases, were applied. The ability of aerobic biodegradation of vinyl chloride, BTEX, aliphatic hydrocarbons and chlorobenzene was studied by the Most Probable Number (MPN) technique and q-PCR of etnC and tbmD genes, coding for alkene and toluene-benzene monooxygenases, respectively.
Once established the presence of bacterial natural attenuation activities for all the compounds, chemical and microbiological analyses were performed at field scale in order to monitor the efficacy of the bioremediation treatments. Moreover, the microbial community composition of anaerobic biobarrier was analyzed before and after 22 months of treatment, by 16S rRNA Illumina sequencing. Reducing substrate addition affected the microbial community composition at the site, causing an increase of fermentative bacteria, mainly belonging to Archaea domain, whereas typically recognized bacteria involved in organohalide respiration were not displayed. These data, along with a decrease in chlorinated solvents measured at the site, suggest a possible presence of a still unexplored biodiversity of OHR bacteria and further culturomics efforts will help to elucidate this. At the plume fringe in the aerobic part of aquifer, BTEX, chlorobenzene and aliphatic hydrocarbon degrading bacteria were characterized. Moreover, microbial consortia able to use vinyl chloride as sole carbon and energy form were selected, demonstrating the feasibility to remediate the site from the carcinogenic intermediate of organohalide respiration.
The microbiological work carried out during this Doctorate, along with hydrogeochemical data, demonstrated that a bioremediation intervention could successfully decontaminate this historical and naturalistically important site. Since the beginning of 2020, a full-scale biobarrier plant has been established and it is expected to run for 30 years in order to completely remediate the aquifer.
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Audí, Miró Carme. "Compound Specific Isotope Analysis ((13)C, (37)Cl,( 2)H) to trace induced attenuation of chlorinated organic contaminants in groundwater." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/145921.
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Chloroform (CF), tetrachloroethene (PCE) and trichloroethene (TCE) are dense chloro-aliphatic hydrocarbons (CAH) extensively used as industrial solvents. These compounds have been largely released to the environment due to poor waste management.
In this thesis, the effect of a ZVI-PRB installed at a field site contaminated mainly with PCE, TCE and cis-DCE was evaluated. Moreover, a novel strategy to degrade the recalcitrant CF -alkaline hydrolysis induced by concrete-based recycled construction wastes- was proposed and developed in order to test its efficiency in degrading this pollutant. Compound specific isotope analysis (CSIA) is a valuable tool for monitoring an environmental treatment in the field, based on the isotope fractionation of an element during transformation reactions.
Therefore, the general aim of this thesis is to use compound specific isotope analysis of 13C, 37Cl and 2H as a tool to assess both induced attenuation processes 1) chlorinated ethenes degradation by a ZVI-PRB installed at the field sited; and, 2) the proposed new remediation technique based on the use of concrete-based recycled construction wastes to degrade chloroform (CF) by alkaline hydrolysis applied at a site contaminated by this pollutant.
First, laboratory experiments were conducted to study both ZVI and concrete effects on the chlorinated ethenes and the chloroform, respectively. ZVI experiments yielded carbon isotope fractionation values of the chlorinated ethenes degradation by the specific ZVI used in the field application, as well as, the first chlorine isotope fractionation values of TCE and cis-DCE associated to this reaction. Two promising approaches to discriminate the abiotic ZVI degradation versus biotic degradation present at the field site were brought forward 1) the dual isotope C-Cl approach, which distinguished slopes 4 times lower than for biodegradation of cis-DCE by the commercially available Dehalococcoides-containing culture mixed culture KB-1; and 2) the product-specific carbon isotope fractionation that showed a 10‰ difference between those products coming from β-dichloroelimination and hydrogenolysis reactions. Concrete experiments with CF achieved a 95% CF degradation after 28 d, accompanied by a significant carbon isotope fractionation. The carbon isotopic fractionation associated with alkaline hydrolysis of CF was -53±3‰.
The obtained laboratory data permitted the assessment of the respective induced degradation treatments applied at the field site. At the site with the ZVI-PRB treatment, both, occurrence of biodegradation and degradation by ZVI-PRB were evidenced by means of detected metabolites and 13C data, with quantitative estimates of ZVI-PRB efficiency of less than 10% and 2% for PCE and cis-DCE, respectively. Dual element 13C-37Cl isotope plots confirmed that the effect of the ZVI-PRB was masked by biodegradation. Based on carbon isotopes data, 49% and almost 100% of PCE and TCE, respectively, were estimated to be removed by biodegradation. Finally the combination of 2H with 13C and 37Cl discriminated two different sources of contamination spilled from the same industry. This indicates the potential of δ2H to discriminate if a compound is of industrial origin, or whether it is formed as a daughter product during degradation. Regarding CF hydrolysis, field-scale pilot experiments were used to test the efficiency of the concrete-base recycled construction wastes to induce alkaline hydrolysis. The carbon isotopic fractionation obtained at the lab scale allowed the calculation of the percentage of chloroform degradation in the field-scale pilot experiments where alkaline conditions were induced in two recharge water interception trenches filled with concrete-based construction wastes. A maximum of approximately 30-40% of chloroform degradation was achieved. Although further research is required, the treatment of chloroform in groundwater through the use of concrete-based construction wastes is proposed. This strategy would also imply the recycling of construction and demolition wastes for use in value-added applications to increase economic and environmental benefits.El chloroform (CF), el tetracloroetè (PCE) i el tricloretè (TCE) són hidrocarburs clor-alifàtics densos usats extensament com a solvents industrials. Aquests compostos s’han alliberat al medi degut a un tractament inadequat dels seus residus. En aquesta tesi, l’efecte d’una barrera permeable reactiva de ferro zero valent (BPR-FZV) instal•lada en un emplaçament contaminat majoritàriament amb PCE, TCE i cis-dicloretè (cis-DCE, subproducte de TCE) ha estat avaluada. A més a més, s’ha proposat i desenvolupat una nova estratègia per a degradar el CF, el qual és un compost recalcitrant, consistent en la inducció de la hidròlisi alcalina del CF mitjançant residus de construcció basats en formigó. L’ànàlisi isotòpic de compost específic (AICE) és una eina valuosa per al monitoreig d’un sistema de tractament medi ambiental, basant-se en el fraccionament isotòpic d’un element durant les reaccions de transformació. L’objectiu general d’aquesta tesi és l’ús de l’anàlisi isotòpic de compost específic de 13C, 37Cl i 2H com una eina per a controlar els dos processos d’atenuació 1) la degradació dels eten-clorats mitjançant una BPR-FZV instal•lada en el camp; i, 2) la nova tècnica de remediació de CF proposada basada en l’ús de residus reciclats de la construcció per tal d’induir la hidròlisi alcalina del CF. En general, mitjançant la combinació dels isòtops de C, Cl i H, aquesta tesi aporta noves eines per discriminar la degradació dels compostos organoclorats d’estudi mitjançant FZV, respecte la biodegradació en el camp, així com també per a identificar fonts de contaminació d’origen industrial o de productes formats, entre d’altres aportacions. A més a més, el nou mètode proposat per a degradar el CF basat en la seva hidròlisi alcalina mitjançant l’ús de residus de construcció reciclats ha demostrat ser eficient en la degradació d’aquest contaminant, així com també, mitjançant l’ús de isòtops de carboni, ha demostrat funcionar en experiments pilot monitorejats a escala de camp.
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Pitkäaho, S. (Satu). "Catalytic oxidation of chlorinated volatile organic compounds, dichloromethane and perchloroethylene:new knowledge for the industrial CVOC emission abatement." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526201672.
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Abstract The releases of chlorinated volatile organic compounds (CVOCs) are controlled by strict regulations setting high demands for the abatement systems. Low temperature catalytic oxidation is a viable technology to economically destroy these often refractory emissions. Catalysts applied in the oxidation of CVOCs should be highly active and selective but also maintain a high resistance towards deactivation. In this study, a total of 33 different γ-Al2O3 containing metallic monoliths were studied in dichloromethane (DCM) and 25 of them in perchloroethylene (PCE) oxidation. The active compounds used were Pt, Pd, Rh or V2O5 alone or as mixtures. The catalysts were divided into three different testing sets: industrial, CVOC and research catalysts. ICP-OES, physisorption, chemisorption, XRD, UV-vis DRS, isotopic oxygen exchange, IC, NH3-TPD, H2-TPR and FESEM-EDS were used to characterise the catalysts. Screening of the industrial catalysts revealed that the addition of V2O5 improved the performance of the catalyst. DCM abatement was easily affected by the addition of VOC or water, but the effect on the PCE oxidation was only minor. Based on these screening tests, a set of CVOC catalysts were developed and installed into an industrial incinerator. The comparison between the laboratory and industrial scale studies showed that DCM oxidation in an industrial incinerator could be predicted relatively well. Instead, PCE was always seen to be oxidised far better in an industrial unit indicating that the transient oxidation conditions are beneficial for the PCE oxidation. Before starting the experiments with research catalysts, the water feed was optimised to 1.5 wt.%. Besides enhancing the HCl yields, water improved the DCM and PCE conversions. In the absence of oxygen, i.e. during destructive adsorption, the presence of water was seen to have an even more pronounced effect on the HCl formation and on the catalysts’ stability. In the DCM oxidation, the addition of the active compound on the catalyst support improved the selectivity, while the enhancing effect on the DCM conversion was only small. The high acidity together with the increased reducibility was seen to lead to an active catalyst. Among the research catalysts Pt/Al2O3 was the most active in the DCM oxidation. With PCE the addition of the active compound proved to be very beneficial also for the PCE conversion. Now Pt and Pd supported on Al2O3-CeO2 were the most active. The enhanced reducibility was seen to be the key feature of the catalyst in PCE oxidationTiivistelmä Klooratuille orgaanisille hiilivedyille (CVOC) on asetettu tiukat päästörajoitukset niiden haitallisten vaikutusten takia. Tästä johtuen myös puhdistusmenetelmien tulee olla tehokkaita. Katalyyttinen puhdistus on teknologia, jolla nämä usein vaikeasti käsiteltävät yhdisteet voidaan taloudellisesti tuhota. Käytettävien katalyyttien tulee olla aktiivisia ja selektiivisiä sekä hyvin kestäviä. Tässä työssä tutkittiin yhteensä 33 erilaista γ-Al2O3-pohjaista hapetuskatalyyttiä metyleenikloridin (DCM) käsittelyssä, niistä 25 testattiin myös perkloorietyleenin (PCE) hapetuksessa. Aktiivisina metalleina katalyyteissä käytettiin platinaa, palladiumia, rhodiumia ja vanadiinia yksin tai seoksina. Katalyytit jaettiin kolmeen ryhmään: teolliset-, CVOC- ja tutkimuskatalyytit. Aktiivisuuskokeiden lisäksi katalyyttejä karakterisoitiin ICP-OES-, fysiorptio-, kemisorptio-, XRD-, UV-vis DRS-, isotooppivaihto-, IC-, NH3-TPD-, H2-TPR- ja FESEM-EDS-pintatutkimusmenetelmillä. Koetulokset osoittivat, että vanadiini paransi teollisuuskatalyyttien aktiivisuutta ja selektiivisyyttä. VOC-yhdisteen tai veden lisäys paransi DCM:n hapettumista, mutta PCE:n hapettumiseen niillä ei ollut vaikutusta. Testien perusteella kehitettiin CVOC-katalyytit, jotka asennettiin teolliseen polttolaitokseen. Laboratoriossa ja teollisuudessa tehdyissä testeissä havaittiin, että DCM:n hapettuminen oli laboratoriokokeiden perusteella ennustettavissa. Sen sijaan PCE hapettui teollisuudessa aina paljon paremmin kuin laboratorio-olosuhteissa. Tämä osoittaa, että muuttuvat hapettumisolosuhteet vaikuttivat positiivisesti PCE:n hapettumiseen. Veden määrä syöttövirrassa optimoitiin 1,5 %:iin ennen tutkimuskatalyyttien testausta. Selektiivisyyden lisäksi vesi paransi DCM:n ja PCE:n konversiota. Hapettomissa olosuhteissa, ts. tuhoavien adsorptiokokeiden aikana, vesi paransi reaktion selektiivisyyttä HCl:ksi ja CO2:ksi vielä entisestään. Tämän lisäksi vesi lisäsi katalyytin stabiilisuutta. DCM:n hapetuksessa aktiivisen metallin lisäys paransi selektiivisyyttä, mutta sen sijaan vaikutus DCM:n konversioon oli hyvin pieni. Tulokset osoittivat, että aktiivisella DCM:n hapetuskatalyytillä tulee olla korkea happamuus ja hyvä pelkistyvyys. Pt/Al2O3 oli testatuista tutkimuskatalyyteistä aktiivisin. PCE:n hapetuksessa aktiivisen metallin lisäys paransi selektiivisyyden lisäksi huomattavasti myös konversiota. Katalyytin lisääntyneen pelkistymiskyvyn todettiin olevan keskeisin ominaisuus PCE:n hapettumisessa. Pt/Al2O3-CeO2 ja Pd/Al2O3-CeO2 olivat tutkimuskatalyyteistä aktiivisimpia
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Wiegert, Charline. "Application of two dimensional compound specific carbon-chlorine isotope analyses for degradation monitoring and assessment of organic pollutants in contaminated soil and groundwater." Doctoral thesis, Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-93923.
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Nearly 250,000 sites with past and present potentially polluting activities need urgent remediation within Europe. Major pollutants include organochlorines (OCls), e.g. chlorinated ethenes (CEs) and hexachlorocyclohexanes (HCHs), mainly used as industrial solvents and pesticides, respectively. Due to improper handling and disposal, OCls contaminants are present in the soil or groundwater surrounding sites, where they have been produced or used. CEs and HCHs can undergo degradation by microorganisms indigenous to the soil or groundwater. Therefore natural attenuation (NA), relying on the in situ biodegradation of pollutants, is considered as a cost effective remediation strategy, yet it requires accurate monitoring methods. Compound specific isotope analysis (CSIA) is a powerful tool to provide information on the extent of degradation and, when combining two isotope systems (2D-CSIA), such as carbon (δ13C) and chlorine (δ37Cl), on reaction mechanisms. The diagnostic reaction-specific isotope enrichment factors (εC and εCl) were determined in laboratory experiments for the anaerobic degradation of PCE, TCE (Paper II) and α-HCH (Paper III) by mixed bacterial cultures enriched from CEs and HCHs contaminated sites, respectively. The related mechanism-specific εCl/εC ratios were calculated as 0.35 ± 0.11 (PCE), 0.37 ± 0.11 (TCE) and 0.52 ± 0.23 (α-HCH). These values are smaller than previously reported values for pure cultures. This is explained by the microbial community composition changes observed during degradation of PCE and α-HCH, which also reflect the variability of the microbial community at the field level. Furthermore, εCl/εC ratio might be bacteria specific. These values allowed the estimation of the extent of contaminant degradation at the respective study sites (Paper III and IV). Application of both isotope systems (δ13C and δ37Cl) led to comparable estimates. However the choice of representative ε values is crucial for an accurate assessment. These studies show that CSIA is useful to quantify in situ degradation of OCls contaminants and identify reaction pathways, by combining δ13C and δ37Cl.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.
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Smith, Madelyn M. "Cometabolic Degradation of Halogenated Aliphatic Hydrocarbons by Aerobic Microorganisms Naturally Associated with Wetland Plant Roots." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1341854406.
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Romeo, Gino Anthony. "Dechlorination of toxic chlorinated compounds." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/289024.
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It was discovered in our laboratory that the bimetallic system palladium on iron (palladized-iron, Pd/Fe) rapidly and completely hydrodechlorinates aqueous solutions of ubiquitous chlorinated aliphatic and aromatic environmental contaminants such as TCE (trichloroethylene), chlorophenols and PCBs (polychlorobiphenyls) at room temperature and atmospheric pressure. When TCE comes in contact with the Pd/Fe surface, it forms ethane as the major gaseous product. Chlorophenols are converted to phenol and PCBs are converted to biphenyl. It was also discovered that through a series of redox reactions metallic iron completely reduces perchlorate to chloride. The objectives of this research are: to show that two iron materials can completely dechlorinate aqueous solutions of toxic chlorinated compounds; to begin to understand how these reactions occur, and; to understand the implications of oxidizing iron. In this research, batch and scaled-up systems were used for fundamental and practical studies of the Pd/Fe system. TCE, chlorophenols and PCBs were the model compounds for these studies. The batch reactions were performed in 1 OmL vials containing 2-5g Pd/Fe and 2-5mL of an aqueous solution of a reactant. The scaled-up reactions were performed in a closed-loop column apparatus with 700g of Pd/Fe and approximately 250mL of an aqueous solution of a reactant. The batch reactions were used to: show complete and rapid hydrodechlorination of the reactants to their products; demonstrate the performance of various types of iron; determine the sequential order of the removal of the chlorine substituents from chlorophenols and PCBs; observe the effect of an HCl-treated and an untreated iron surface prior to palladium deposition and the effects these surfaces have on the hydrodechlorination reactions of chlorophenols and PCBs; and determine what implications iron oxide build-up on the Pd/Fe surface may have on scaled-up Pd/Fe systems. The scaled-up column apparatus was used to determine the longevity of Pd/Fe surfaces and to find a suitable regeneration method. Because Pd/Fe was found to be a suitable reductant for chlorinated organic molecules, chlorine-containing ions such as ClO₄⁻ were also investigated. It was discovered that HCl-treated iron is a suitable reductant for the reduction of the perchlorate ion at room temperature and atmospheric pressure. Palladized-iron and zero-valent iron have been found to be suitable materials for the remediation of many ubiquitous environmental contammants. The hydrodechlorination of chlorinated compounds occurs completely and rapidly with Pd/Fe. Iron effectively reduces perchlorate ions to chloride ions. Both Pd/Fe and zero-valent iron surfaces are relatively easy to prepare, and can be used at room temperature and atmospheric pressure for the dechlorination reactions.
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Hermon, Louis. "Diagnostic microbiologique de sites contaminés par les solvants chlorés." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAJ113.
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Le potentiel de biodégradation des éthènes chlorés (ECs) et du dichlorométhane (DCM) dans les eaux souterraines de l’ancien site industriel de Themeroil (Varennes-le-Grand, France) a été évalué par des études en microcosmes, à travers l’utilisation de biomarqueurs moléculaires, et par analyse isotopique spécifique au composé (compound specific isotope analysis, CSIA). L’objectif de ce travail a été d’évaluer i) la biodégradation de ces polluants et la diversité bactérienne associée dans les eaux du site, et ii) l’impact de mélanges de contaminants et des conditions rédox dans ce processus. L’implication majeure d’un taxon bactérien affilié à Dehalococcoides dans la dégradation du PCE dans les eaux du site, et son lien potentiel aux gènes de déshalogénase pceA et vcrA associés au processus de déchloration, ont été mises en évidence. La dégradation du DCM en présence d’ECs dans les eaux du site a ensuite été démontrée, et des souches bactériennes dégradant le DCM ont été isolées à partir d’eaux du site et caractérisées. La CSIA a révélé une forte biodégradation du DCM in situ. Des analyses des eaux du site, par qPCR ciblant les gènes dcmA et dhlA de la biodégradation bactérienne du DCM, et par séquençage haut-débit du gène de l’ARNr 16S, ont permis d’évaluer le rôle potentiel de différents taxa bactériens associés à la dégradation du DCM. Il a ainsi été montré que la répartition spatiale de ces taxa sur site dépend dans une large mesure des conditions rédox et du niveau de contamination. L’influence de ces paramètres sur la biodégradation, étudiée ensuite en microcosmes, a été confirmée par l’observation de différents profils de dégradation dans des conditions rédox et de co-contamination distinctes. Ceci suggère la participation de différents types de métabolisme à la biodégradation des éthènes et alcanes chlorés sur site. Les résultats obtenus confirment la pertinence d’études en microcosme pour évaluer le potentiel de biodégradation des polluants halogénés dans les sites contaminés, et pour orienter les traitements de dépollution à privilégierThe biodegradation potential of chlorinated ethenes (CEs) and dichloromethane (DCM) in groundwater from the former industrial site of Themeroil (Varennes-le-Grand, France) was evaluated in microcosm studies, using molecular biomarkers and compound-specific isotope analysis (CSIA). The objective of this work was to evaluate i) the biodegradation of these pollutants and the associated bacterial diversity in site groundwater, and ii) the impact of contaminant mixtures and redox conditions on biodegradation. The major role of a taxon affiliated to Dehalococcoides in PCE degradation in site groundwater, and its potential link to dehalogenase genes pceA and vcrA associated with the process, were highlighted. Degradation of DCM in the presence of CEs in site groundwater was then demonstrated, and DCM-degrading strains were isolated from site groundwater and characterised. CSIA revealed a large extent of DCM biodegradation in situ. Analyses of groundwater from the site, targeting dcmA and dhlA genes for DCM biodegradation by qPCR, as well as by high-throughput sequencing of the 16S rRNA gene, allowed to evaluate the potential role of different bacterial taxa associated with DCM dehalogenation in DCM degradation on site. It was shown that the spatial distribution of these taxa on site depends significantly from redox conditions and contamination level. The influence of these parameters on biodegradation was also investigated in microcosms, and distinct degradation profiles were observed under different redox and co-contamination conditions. This suggests that different types of metabolism participate in biodegradation of chlorinated ethenes and alkanes on site. Obtained results confirm the relevance of microcosm studies in evaluating halogenated pollutants biodegradation potential on contaminated sites, and in guiding the choice of remediation approaches to be favoured
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David, Maude. "Bacterial adaptation to the chlorinated compounds." Thesis, Ecully, Ecole centrale de Lyon, 2009. http://www.theses.fr/2009ECDL0026/document.
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Le travail présenté dans cette thèse porte sur l'adaptation bactérienne aux molécules chlorées, tant au niveau des ressources génétiques nécessaires à la mise en place des gênes de dégradation qu'au niveau de la structure de la communauté microbienne observée durant la dégradation de ces composés. La première partie de ce document est une bibliographie qui se focalise sur les mécanismes développés par les bactéries pour répondre aux stress environnementaux, et sur les possibles origines des gènes responsables des premières étapes de dégradation des composés chlorés : les dehalogenases (qui réalisent les étapes de déchloration). Le deuxième chapitre de cette thèse porte sur des essais expérimentaux de remodelage génétique, dans le but de valider les hypothèses présentées lors de la bibliographie quant aux mécanismes qui ont pu conduire à la génération de nouveaux gênes de dégradation. Ces remodelages in vitro et in vivo ont été effectués en utilisant les gènes linB et dhaA. Le chapitre suivant examine la structure de la communauté bactérienne lors de la dégradation réductive du tetrachloroéthylène (PCE). Pour cette étude, des outils de biologie moléculaire, plus spécifiquement des puces phylogénétiques, ont été utilisés pour étudier la structure de la communauté microbienne depuis l'introduction du polluant jusqu'à sa dégradation. Afin d'élucider les fonctions métaboliques qui peuvent être corrélées avec la dégradation du PCE, les résultats des puces phylogénétiques ont été comparés avec un suivi chimique des métabolites de dégradation de ce composé, lors d'une étude en microcosmes. L'objectif du dernier chapitre de la thèse a été de relier la structure de la communauté microbienne avec la cinétique de dégradation des composés chimiques étudiés. Pour cela, une étude globale comportant à la fois un suivi chimique des métabolites de dégradation, une quantification des gènes de dégradation impliqués dans la déchloration réductive du PCE ainsi que l'étude de la structure de la communauté microbienne ont été mis en place. Cette étude a permis de corréler les conditions environnementales nécessaires à la déchloration et la communauté microbienne associée avec l'expression des déhalogénases quantifiées. En résumé, cette thèse explore à la fois les mécanismes mis en place par les bactéries pour dégrader ces composés polluants et la structure de la communauté bactérienne durant la dégradation de ce polluant. Comprendre ces deux étapes dans l'adaptation bactérienne peut contribuer à améliorer l'utilisation des capacités bactériennes utilisées en bioremédiationThis thesis concerns the bacterial adaptation to the chlorinated compounds at both the gene level and the microbial community level. The bibliography will focus on the adaptation mechanisms developed by bacteria to respond to environmental stresses and on the possible origins of the genes responsible for the first steps of chlorinated compound degradation, those encoding for the dehalogenases, which perform the dechlorination or chlorine removal step. The second chapter of the thesis consists of an experimental exploration of the gene shuffling hypothesis presented in the bibliography, using linB and dhaA genes. The next chapter examines the bacterial community structure in relation to compound degradation using the reductive dechlorination of tetrachloroethylene. For this study, molecular biology tools, specifically phylochip microarrays were used to examine bacterial community structure from the moment of pollutant introduction to the environment and during bioremediation. In order to elucidate the metabolic functions, which correlate the PCE degradation, phylogenetic results were compared with functional genes in the microcosms studied. The last chapter of this global study on chlorinated compound degradation genes was to link the microbial community structure kinetics with the chemical degradation kinetics. In order to evaluate the molecular biological parameters of the microbial community, all the genes known to be involved in the entire pathway of PCE reductive dechlorination were quantified. This global study, incorporating chemical monitoring, dehalogenase quantification and microbial community structure, produced correlations between the environmental conditions necessary for dechlorination and the microbial community associated with dehalogenase expression. In summary, both the mechanisms implemented by the bacteria to degrade this compound pollutant and the bacterial community structure during the pollutant degradation were addressed. Improving the understanding of these two steps in bacterial adaptation can contribute to the understanding of bacterial and environmental cleanup capabilities
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Yuan, Tao 1968. "Dechlorination of environmentally recalcitrant chlorinated aromatic compounds." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79208.
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Chlorinated aromatic compounds are an important group of compounds. Many of them have been produced in large quantities and they are indispensable to technological and societal benefits. But regulatory agencies have tightened regulations on the use and release of chlorinated aromatic compounds because of the scientific understanding of their toxicity, persistence, behavior in the environment and their potential to cause adverse effects on the ecosystem and human health.Pentachlorophenol (PCP), octachloronaphthalene and decachlorobiphenyl are all highly chlorinated aromatic compounds, of which, PCP has been used mainly as a biocide. Octachloronaphthalene and decachlorobiphenyl don't have practical use, but their congeners have been used widely as chemicals in industry. These compounds are toxic, recalcitrant and bio-accumulated within organisms. As the conventional treatment, incineration of these compounds can cause more serious problems, so that suitable alternatives need to be developed for their detoxification.
When compared with biodegradation or the thermal treatment of these compounds, chemical degradations have several merits. (Abstract shortened by UMI.)
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Lunt, P. "Microbial communities growing on chlorinated aromatic compounds." Thesis, Cardiff University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376824.
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Parkes, Michael Anthony. "Ionisation studies of chlorinated and fluorinated compounds." Thesis, University of Birmingham, 2007. http://etheses.bham.ac.uk//id/eprint/74/.
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Ionisation processes in gas-phase polyatomic molecules have been studied using threshold photoelectron photoion coincidence and selected ion flow tube techniques for cations and an electron attachment mass spectrometer for anions. Cation formation has been studied for fluoroform (CHF\(_3\)), octafluorocyclobutane (\(c\)-C\(_4\)F\(_8\)), octafluorocyclopentene (\(c\)-C\(_5\)F\(_8\)), monochloroethene (C\(_2\)H\(_3\)Cl), the three isomers of dichloroethene (C\(_2\)H\(_2\)Cl\(_2\)) (i.e. 1,1-dichloroethene, (\(Z\))-1,2-dichloroethene and (\(E\))-1,2-dichloroethene), trichloroethene (C\(_2\)HCl\(_3\)) and tetrachloroethene (C\(_2\)Cl\(_4\)). Comparison between the data from the photoionisation and the ion-molecule reactions show that the dominant charge-transfer mechanism is long-range in nature. Detailed studies of the reactions of cations with the three dichloroethenes have been performed to look for evidence of isomeric effects. Major differences are seen when the reactant ion is CF\(_3\)\(^+\); when 1,1-dichloroethene is the neutral reactant the only ionic product is C\(_2\)H\(_2\)Cl\(^+\), but if the neutral is 1,2-dichloroethene then the only product is CHCl\(_2\)\(^+\). Only minor differences are seen with other reagent ions. For the reactions of all six chloroethenes with CF\(_3\)\(^+\), product ions are observed which can only be formed by extensive rearrangement across the carbon-carbon double bond. Mechanisms are suggested involving bridged trigonal intermediates to explain the production of the different channels. Studies have been performed on several perfluorocarbons, CHF\(_3\), \(c\)-C\(_4\)F\(_8\) and \(c\)-C\(_5\)F\(_8\), due to their potential for use in industry. They are all excellent at etching substrates and have a lower global warming potential than the currently used gases. CHF\(_3\) shows signs of non-statistical dissociation following photoionisation, and is shown to react via a largely long-range charge transfer mechanism in the ion-molecule reactions studied. For \(c\)-C\(_5\)F\(_8\) the ground electronic state of the ion is found to be very weak under threshold conditions whilst being much more intense when He(I) photons are used. The existing electron attachment mass spectrometer is described, and also extensive modifications which have been made to this apparatus. The use of new electronics and acquisition system give excellent results in the new equipment. The new arrangement has been extensively characterised by studying attachment to seven molecules, including several perfluorocarbon molecules (e.g. the isomers of C\(_4\)F\(_8\)). Some isomeric effects on the measured rate coefficients are observed in the data.
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Collins, Jodi. "Enhancing the scrubbing of chlorinated compounds from air streams." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq36885.pdf.
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He, Jiahan. "Removal and degradation of chlorinated organic compounds in groundwater." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280357.
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The first part of this work demonstrates that membrane air-stripping (MAS) is an efficient method for separating volatile organic compounds from water. The introduction of a membrane barrier to separate the air and water phases provides several advantages without increasing the total mass transfer resistance. Efficient removal can be achieved at lower air/water ratios than are typically required in packed-tower. Mathematical models were developed to simulate the performances of both countercurrent-flow and cross-flow contractors. Model simulations indicate that the cross-flow contractor is more efficient than the countercurrent-flow contractor. The second part of this work demonstrates the degradation of aqueous-phase CT in a continuous-flow reactor with a porous copper electrode. Removal of CT increases with more negative cathode potentials until hydrogen evolution becomes excessive. At that point, the increase in solution potential offsets further change in cathode potential and limits further improvement in reactor performance. Removal efficiency was predicted to vary inversely with the liquid velocity. At solution conductivities less than 1.0 S/m, both experiment and simulation showed that reactor performance is seriously handicapped by solution potential. The model predictions were in reasonable agreement with experimental results for high conductivity solutions (≥1.0 S/m). At lower conductivities, the discrepancies between the predictions and experimental results are due to the loss of validity of the zero-solution-potential boundary condition at the downstream end of the cathode. The third part of this work investigates a cylindrical reactor geometry in which the anode is wrapped closely around the cathode. This arrangement eliminates the solution potential limitation encountered in the downstream-anode configuration, making it a promising tool for remediation of low-conductivity groundwater. Higher removals of CT are achieved under more negative cathode potential. Increasing the hydrodynamic residence time by increasing the cathode length is also an efficient way to improve the CT conversion even for low-conductivity solutions. An intrinsic drawback of this configuration is lowered current efficiency due to the high proton concentration at the perimeter of the cathode where most of the current is generated. However, low energy consumption due to small overall potential drop across the reactor at least partially compensates for the drawback.
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Liu, Zhijie. "Reductive dehalogenation of chlorinated aliphatic compounds in electrolytic systems." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/283929.
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A series of chlorinated low-molecular-weight alkanes and alkenes was transformed electrolytically at metal cathodes at potentials from -0.3 to -1.4V (vs. SHE). Products included nonchlorinated hydrocarbons and less chlorinated intermediates. Product distributions are highly dependent on cathode material and applied cathode potential. Kinetics was first-order in the concentration of the halogenated targets. The specific first-order rate constants are function of cathode potential, cathode material, solution characteristics, and reactant identify. When transformation kinetics was governed by polarization resistance, rate constants were correlated with degree of halogenation and standard reduction potential for the predominant transformation reaction (as indicated by product analysis). Log-transformed reaction rate constants for reduction of chlorinated alkanes, derived via experiments at the same cathode potential (E(c) = -1.0 or -1.2V vs. SHE), were linearly related to carbon-halogen bond dissociation energies. A physical model for the observed correlation was developed from transition-state theory. The chlorinated ethenes reacted much faster than predicted from bond enthalpy calculations, suggesting that alkenes are not transformed via the same mechanism as the chlorinated alkanes. Polarographic study demonstrated that the shift of E₁/₂ of CCl₄ reduction was correlated with water concentration in solvent-predominated mixtures. Successful interpretation of these findings with a physical model suggested that solvents involved the rate-determining step of CCl₄ electrolysis both kinetically and mechanistically. The capture of trichloromethyl radicals with a spin trap (PBN) in an electrochemical system provided direct evidence supporting the free radical mechanism in electrolytic reduction of CCl₄. Gas-phase reductions of chlorinated alkanes and alkenes were studied in a modified fuel cell. Reactor performance was a function of the metal catalyst amended to the reactor cathode, the reactor potential, cathode temperature, the target compound identity, the partial pressure of O₂(g) in the cathode chamber and the condition (time in service) of the cathode. Single-pass CCl₄ conversions could achieve 90 percent with a mean residence time for gases in the porous cathode much less than a second. Reactor performance deteriorated with the presence of oxygen and time in service. Conversion efficiency was restored, however, by temporarily eliminating the halogenated target(s) from the influent stream or by briefly reversing reactor polarity.
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Gess, Peter L. "Release of chlorinated organic compounds from a contaminiated estuarine sediment." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/20302.
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Yang, Xiaodong. "A Chemical Pathway to the Formation of Chlorinated Compounds During Combustion." TopSCHOLAR®, 1996. http://digitalcommons.wku.edu/theses/820.
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Two reactions, the Deacon reaction and the chlorination of phenol, which are the postulated starting steps for the formation of chlorinated dioxins during the incineration of the refuse derived fuel, were investigated in this work. Reactions were conducted in a tube furnace, and the products were trapped and analyzed by gas chromatography/mass spectroscopy. It was shown that the Deacon reaction was favored at higher temperatures. The chlorination of phenol in vapor phase was found to begin at temperatures as low as 250°C and to be favored at higher temperatures. The ortho and para positions in the phenol ring are the favored sites for chlorine substitution.
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Kabir, Anwar. "Dechlorination of chlorinated organic compounds by zero-valent and bimetallic mixture." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31246.
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Organochlorine (OC) compounds that include several pesticides as well as an array of industrial chemicals were very efficacious for their intended use but were also characterized by deleterious environmental impacts when released either intentionally or inadvertently. Their lipophilic nature, long persistence in the environment and threat to human health caused all the developed countries to ban the production of these chemicals as well as restricted the use of formulations containing these material for food production.A number of scientists have become involved in the development of intentional degradation methods/techniques for these compounds using zero-valent metals or bimetallic mixtures. To date, there is no single, simple and continuous procedure available to completely dechlorinate lindane or pentachlorophenol (PCP). This work describes the complete dechlorination of lindane and pentachlorophenol by zero-valent Zn, Fe and Fe/Ag bimetallic mixture as well as a supercritical fluid extraction technique for a more efficient mass transfer of the substrates to the surfaces of the metal catalyst. The dechlorination reaction occurs on the surface of metal particles with the removal of all the chlorine atoms from lindane and PCP in a matter of minute, and yields completely dechlorinated hydrocarbon molecules and chloride as products. (Abstract shortened by UMI.)
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Kurt, Zohre. "Biodegradation of chlorinated compounds at interfaces and biodegradation of 4-nitroaniline." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/50111.
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Most microbial activity in nature takes place at interfaces where redox discontinuities are present. Organic pollutants in groundwater encounter oxic/anoxic interfaces when they emerge to surface water bodies or volatilize above the plume. Such oxic/anoxic interfaces are key habitats for aerobic bacteria and are in turn created by the bacteria that degrade organic electron donors. In the absence of biodegradation, synthetic pollutants can migrate from the plume and impact a variety of receptors. The aims of our study were to determine whether microbes at oxic/anoxic interfaces can use synthetic chemicals as electron donors and protect the overlying vadose zone or surface water from groundwater pollutants. The approach was to design columns representing the interfaces and measure activities of the microbial communities responsible for the biodegradation of synthetic compounds.Taken together the above studies established clearly that contaminants recalcitrant under anaerobic conditions but degradable under aerobic conditions can be biodegraded at the narrow oxic/anoxic interface resulting in the protection of the overlying soil or water. The findings provide the basis for new approaches to natural attenuation that can serve to dramatically reduce the cost of bioremediation actions. Synthetic chemicals are widespread in the environment because of their extensive use in industry. These chemicals were recalcitrant until their microbial degradation pathways evolved. Currently the biodegradation pathways of many synthetic chemicals are known and serve as the basis for bioremediation strategies. The second part of the research described here involved discovery of the aerobic degradation pathway of a dye additive: 4-nitroaniline (4NA). Annotation of the whole genome sequence coupled with assays and supported with cloned enzymes revealed that the 4NA biodegradation pathway contains two monooxygenase steps prior to ring cleavage. Because nitroaniline degradation was not previously understood our work advanced the understanding of metabolic diversity in degradation of amino and nitro compounds by providing enzymes with unique activities.
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Chen, Nan. "Kinetics of the hydrodechlorination reaction of chlorinated compounds on palladium catalysts." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0823103-161859.
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Mussalo-Rauhamaa, Helena. "Residues of certain chlorinated and aromatic compounds in Finnish population groups." Helsinki : Finnish Society of Sciences and Letters, 1991. http://books.google.com/books?id=7opqAAAAMAAJ.
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Scherer, Michelle Marie. "Reduction of chlorinated aliphatic and nitro aromatic compounds at the Fe0-oxide-water interface /." Full text open access at:, 1998. http://content.ohsu.edu/u?/etd,201.
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Lachance, Russell Philip. "Oxidation and hydrolysis reactions in supercritical water : chlorinated hydrocarbons and organosulfur compounds." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/33533.
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Morrison, Candice N. "Innovative Methods for Characterizing Chlorinated Volatile Organic Compounds in the Vadose Zone." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/333041.
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Chlorinated solvents, such as tetrachloroethene (PCE), trichloroethene (TCE), and carbon tetrachloride (CT), are primary contaminants of concern for a vast majority of federal and state Superfund sites in the US due to their prior widespread use as solvents for numerous industrial and commercial applications. Source-zones containing large quantities of contaminant are typically present at sites contaminated by chlorinated solvents. Particularly in regions such as the SW US, these source zones reside, at least in part, in the extensive vadose zones typical of these regions. There are two primary concerns associated with sites that contain vadose-zone contaminant sources. First, discharge of contaminant vapor from the vadose-zone source may impact the underlying groundwater. This could contribute to overall risk posed by the site, and delay attainment of groundwater cleanup goals. Second, contaminant vapor from the vadose-zone source may migrate to the land surface and transfer into buildings, thereby causing vapor intrusion. The focus of this research is the development and application of innovative methods for characterizing vadose-zone contamination. Phytoscreening is a new, rapid, and relatively low-cost characterization technology that can be used to screen an area for the presence of select contaminants such as chlorinated VOCs. Phytoscreening is based on the sampling and analysis of plant tissues (branch, trunk, leaf, seed, needle) to detect the presence of contamination in soil and groundwater. Phytoscreening is applied to three sites in Arizona to evaluate its use in semi-arid environments. In addition, all available field data sets have been compiled to examine potential correlations between contaminant concentrations measured for tree tissue and those for groundwater. Contaminant concentrations were detected in tree tissue samples collected from two of the three Arizona sites. A review of the field site data suggests that a correlation exists between PCE and TCE concentrations measured for tree tissue and those measured in groundwater. The correlation can be used to estimate vegetation concentrations when groundwater concentrations are known. The reasonable degree of correlation supports the use of phytoscreening as a robust screening tool to provide a first-order characterization of anticipated concentrations of contaminants in groundwater. This tool can also be used to screen an area for vapor intrusion potential. A sampling method for the determination of chlorinated contaminant vapor concentrations present in the vadose zone, specifically trichloroethene (TCE), has been developed, and was applied at the Tucson International Airport Authority (TIAA) Superfund site. The method was modified from the NIOSH Manual of Analytical Methods (NMAM) # 1022 for TCE, and is targeted to situations requiring cost effective sample collection, particularly for cases when concentrations are at or below maximum contaminant levels (MCLs). In the modified NIOSH method, TCE vapor is sampled using a solid sorbent cartridge containing coconut shell charcoal arranged into primary and secondary sections. Gas Chromatography with Mass Spectrometry is used to confirm and quantify the presence of TCE. The results of laboratory tests demonstrate a maximum TCE vapor load of approximately 22 mg before breakthrough to the secondary section, and a recovery of approximately 97%. The results of a performance comparison test conducted in the field demonstrated that results obtained with the cartridge samplers were similar to those obtained with the use of standard Summa canisters. Landfill waste often serves as a long-term source of volatile organic compounds (VOCs) in the vadose zone. In turn this contamination can have a significant impact on groundwater and on residential or commercial indoor air quality through vapor intrusion. Sulfur hexafluoride (SF₆) was used as the non-reactive gas tracer. Gas samples were collected from a multiport monitoring well located 15.2 m from the injection well, and analyzed for SF₆, CH₄, CO₂, and VOCs. The travel times determined for SF₆ from the tracer test are approximately two to ten times smaller than estimated travel times that incorporate only gas phase diffusion. In addition, significant concentrations of CH₄ and CO₂ were measured, indicating production of landfill gas. Based on these results, it is hypothesized that the enhanced rates of transport observed for SF₆ are caused by advective transport associated with landfill gas generation. A method termed vapor-phase tomography has recently been proposed to characterize the distribution of volatile organic contaminant mass in vadose-zone source areas, and to measure associated three-dimensional distributions of local contaminant mass discharge. The method is based on measuring the spatial variability of vapor flux, and thus inherent to its effectiveness is the premise that the magnitudes and temporal variability of vapor concentrations measured at different monitoring points within the interrogated area will be a function of the geospatial positions of the points relative to the source location. A series of flow-cell experiments was conducted to evaluate this premise. A well-defined source zone was created by injection and extraction of a non-reactive gas (SF₆). Spatial and temporal concentration distributions obtained from the tests were compared to simulations produced with a mathematical model describing advective and diffusive transport. Tests were conducted to characterize both areal and vertical components of the application. Decreases in concentration over time were observed for monitoring points located on the opposite side of the source zone from the local-extraction point, whereas increases were observed for monitoring points located between the local-extraction point and the source zone. The results illustrate that comparison of temporal concentration profiles obtained at various monitoring points gives a general indication of the source location with respect to the extraction and monitoring points.
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Anand, Deepti. "SORPTION OF CHLORINATED COMPOUNDS ON CARBON NANO TUBES AND NANO TEXTURED SAND." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/theses/348.
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The release of carbon-based nanomaterials into the environment is causing great concern among environmental scientists and engineers due to their potential impacts on the fate and transport of environmental contaminants, deriving from their superior adsorption capacities. Chlorinated compounds are one of the most prevalent environmental contaminants in the United States, yet systematic studies concerning the adsorption and desorption mechanisms of chlorinated compounds on carbon nanotubes (CNTs) are scant. The objective of this study was to investigate the adsorption and desorption mechanisms of three chlorinated compounds with different molecular structures on multi-wall carbon nanotubes (MWCNTs) using a wide range of isotherms that were used as models to predict the adsorptive capacity of the MWCNT's. The results indicated that sorption capacities of chlorinated compounds to MWCNTs are greatly affected by the molecular structures and follows an order of 1,1,1-TCA < TCE < 1,3,5-TCB. Hysteresis was observed for all compounds on pristine MWCNTs. After thermal treatment of MWCNTs, sorption capacity of all three compounds was enhanced and sorption hysteresis was considerably reduced. The results highlighted the role of disorderly amorphous carbon in the adsorption and desorption process. We also conducted a study on how nano-texturing of sand surfaces using carbon nanotubes (CNT) can efficiently control the mobility and bioavailability of contaminants found in aquatic sediments. The CNT textured sand can be used as viable in-situ capping (ISC) materials to physically separate contaminated sediments from overlying water. Adsorption measurements of several common contaminants (chlorinated aliphatics) found in aquatic environment performed on CNT textured sand showed at least an order of magnitude increase in their sorption coefficients compared to traditional capping materials such as sand. It was also demonstrated that CNT textured sand can significantly reduce the migration of contaminants from sediments to overlying water and possess suitable geotechnical parameters needed for contaminant sequestration and sediment remediation technologies which can lead to clean and healthy aquatic environment.
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Chiang, Sheau-Yun. "Reductive dechlorination of chlorinated phenols in methanogenic wetland sediment slurries." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/21281.
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Wells, Jody. "The biological reductive dechlorination of chlorinated compounds in a high-rate anaerobic reactor." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq36913.pdf.
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MANIGAS, LUISA. "Use of membrane bioreactors for the bioremediation of groundwater polluted by chlorinated compounds." Doctoral thesis, Università degli Studi di Cagliari, 2008. http://hdl.handle.net/11584/265895.
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The aim of this experimental work has been the application of a new polluted waters treatment technology for the selection of a bacterial population capable of bioremediating a synthetic groundwater polluted by four different chlorinated compounds. The innovative technology applied in this study was the biological treatment system known as MSBR (Membrane Sequencing Bioreactor), which consists of a Sequencing Batch Reactor (SBR) coupled to a membrane module for the filtration of the biological sludge that degrades the chlorinated compounds present in the polluted water fed to the system. The synthetic groundwater used in this experimentation contained four chlorinated compounds: 1,2-dichloroethane, 1,2-dichlorobenzene, 2-chlorophenol and trichloroethylene. During the development of the research, the chlorinated compounds were fed either alone on in different mixtures in order to identify possible effects of each substrate on the degradability of the others. Some operational parameters were varied in order to check the possibility of implementing the system at a larger scale. The MSBR system equipped in this study was effective in the acclimation of a sludge to hardly biodegradable xenobiotic compounds, and the degradation rates achieved were comparable to other similar studies performed, even if in this experimentation, differing from all the others found in literature, good removal rates were achieved for the degradation of the substrates when they were fed in mixtures.
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Kim, Do Hyong. "Formation of Aromatic Compounds by Cyclopentadiene Moieties in Combustion Processes." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7241.
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Polycyclic aromatic hydrocarbon (PAH) formation and growth from cyclopentadiene (CPD) moieties have been investigated using a laminar flow reactor and molecular modeling. The resonance-stabilized cyclopentadienyl radical is readily formed in flames and can participate in PAH growth to soot by reaction with the ??onds of aromatic species. Both CPD pyrolysis and computational results indicate that formation of indene and benzene is favored at low temperatures (below 750oC) and formation of naphthalene is favored at high temperatures. Reaction pathways from CPD have further been extended to PAH formation from the reaction of CPD and aromatic compounds with different types of ??onds. Results indicate that, while the major products from the pyrolysis of CPD, acenaphthylene, styrene and phenanthrene mixtures are from the reaction of CPD to itself rather than to these aromatic compounds with different ??onds, CPD does add to these compounds to produce larger PAH.
Polychlorinated naphthalene (PCN) formation from chlorinated phenols has also been studied. In combustion exhaust gas, chlorinated phenols can produce dioxin as well as PCNs. PCN and polychlorinated dibenzofuran (PCDF) congener product distributions were consistent with proposed pathways involving phenoxy radical coupling at unchlorinated ortho-carbon sites. Tautomerization of the phenoxy radical coupling and subsequent fusion via H2O loss results in PCDF formation. Competing with this reaction pathway, CO elimination and subsequent fusion via hydrogen and/or chlorine loss was found to produce PCNs. PCDF isomer distributions were found to be weakly dependent to temperature, whereas PCN isomer distributions were found to be more temperature sensitive with selectivity to particular isomers decreasing with increasing temperature.
Results of this research contribute to a better understanding of chemical mechanisms involved in the formation of toxic byproducts and soot in combustion systems.
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Pressman, Jonathan G. "Development of a hollow fiber membrane bioreactor for cometabolic degradation of chlorinated solvents." Access restricted to users with UT Austin EID, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035166.
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Merica, Simona Gabriela. "Studies of the use of electrochemical methods for the destruction of chlorinated aromatic compounds." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ35806.pdf.
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Mass, Stacey Joanne. "Mass spectrometric methods for detecting chlorinated compounds in lipid extracts from various marine animals." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0019/MQ57333.pdf.
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Koch, Mathias 1965. "Decomposition of chlorinated organic compounds in gaseous hazardous waste using a tunable plasma reactor." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11988.
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MIHOPOULOS, PHILIP G. "ANAEROBIC BIOVENTING FOR TREATMENT OF VADOSE ZONE SOILS CONTAMINATED WITH HIGHLY CHLORINATED ORGANIC COMPOUNDS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin981746418.
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Washo, Dawn Llewellyn. "Using membrane interface probe (MIP) to characterize chlorinated volatile organic compounds in glacial sediments." Diss., Online access via UMI:, 2009.
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El, Assal Z. (Zouhair). "Synthesis and characterization of catalysts for the total oxidation of chlorinated volatile organic compounds." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526221267.
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Abstract The harmful emissions of chlorinated volatile organic compounds (CVOCs) originate only from man-made sources. CVOCs are used in a variety of applications from pharmaceuticals production to decaffeination of coffee. Currently, CVOC emissions are limited by strict legislation. For these reasons, efficient CVOC abatement technologies are required. Catalytic oxidation is very promising option for this purpose, since catalysts can be tailored to each case to maximize the efficiency and minimize the formation of unwanted products, such as dioxins or Cl2. The goal of this thesis was to study the role of the physico-chemical properties of catalysts in dichloromethane (DCM) oxidation. To reach the aim, several catalytic materials were prepared and characterized, and their performance was tested in total oxidation of DCM. The catalytic materials used were powders of four single metal oxides (γ-Al2O3, TiO2, CeO2, MgO), three mixed oxides (Al2O3-xSiO2) washcoated on a cordierite monolith and four active phases (Pt, Cu, V, Mn). At first, support properties were studied. It was found that the DCM conversion and HCl production are dependent on support acidity when the studied single oxides are considered. The best DCM conversions and HCl yields were observed with the support having the highest total acidity (γ-Al2O3). Further, the quality of the by-products formed was dependent on the type of the acid sites present on the support surface. Secondly, the impregnation of the active compound was observed to improve the selectivity of the material. From the tested active phases, Pt presented the best performance, but also V2O5 and CuO showed almost equal performances. Especially CuO supported on γ-Al2O3, that had less formation of by-products and is less toxic than V-containing oxides, seems to be a promising alternative to Pt. Concerning stability, no deactivation was observed after 55h of testing of Pt/Al2O3. Furthermore, in the used reaction conditions, the formation of CuCl2 is not thermodynamically favoured. Finally, the good characteristics of the powder form catalysts were successfully transferred to the monolith. The performance of the Pt/90Al2O3-10SiO2 catalyst in DCM oxidation was improved when the channel density was increased due to an increase in geometric surface area and mechanical integrity factor, and a decrease in open fraction area and thermal integrity factorTiivistelmä Haitallisten kloorattujen orgaanisten yhdisteiden (CVOC) päästöt ovat ihmisten aiheuttamia. CVOC-yhdisteitä käytetään mm. liuottimina lääkeaineiden valmistuksessa ja kofeiinin poistossa. Nykyisin CVOC-päästöjä rajoitetaan tiukalla lainsäädännöllä. Näistä syistä tehokas CVOC-yhdisteiden käsittelymenetelmä on tarpeen. Katalyyttinen hapetus on hyvä vaihtoehto tähän tarkoitukseen, koska katalyytit voidaan räätälöidä niin, että puhdistuksen tehokkuus saadaan maksimoitua samalla kun ei-haluttujen tuotteiden, kuten dioksiinit ja kloorikaasu, muodostuminen voidaan minimoida. Tämän väitöskirjatyön tavoitteena oli selvittää katalyyttien fysikaalis-kemiallisten ominaisuuksien yhteyksiä dikloorimetaanin (DCM) hapetukseen. Tavoitteen saavuttamiseksi valmistettiin useita katalyyttejä, jotka karakterisoitiin ja testattiin DCM:n kokonaishapetuksessa. Työssä tutkittiin neljää jauhemaista metallioksidia (γ-Al2O3, TiO2, CeO2 ja MgO), kolmea metallioksidiseosta (Al2O3-xSiO2), jotka pinnoitettiin kordieriittimonoliitille, sekä neljää aktiivista ainetta: Pt, Cu, V and Mn. Aluksi työssä keskityttiin tukiaineiden ominaisuuksiin. Työn tulokset osoittivat, että DCM:n konversio ja HCl:n tuotanto ovat riippuvaisia tukiaineen happamuudesta. Paras tulos saavutettiin alumiinioksidilla, jolla oli korkein kokonaishappamuus. Lisäksi havaittiin, että sivutuotteiden laatu riippuu tukiaineen pinnalla olevien happopaikkojen tyypistä. Aktiivisen aineen impregnointi tukiaineeseen paransi materiaalin selektiivisyyttä. Tutkituista aineista Pt osoittautui parhaimmaksi, mutta myös V2O5 ja CuO olivat lähes yhtä hyviä. Erityisesti CuO-katalyytti, joka tuotti vähemmän sivutuotteita ja joka on materiaalina vähemmän haitallinen kuin V2O5, osoittautui lupaavaksi jalometallikatalyyttien korvaajaksi. Materiaalien stabiilisuuteen liittyen Pt/Al2O3-katalyytin toiminnassa ei havaittu muutoksia 55 tunnin testauksen jälkeen. Lisäksi CuCl2:n muodostuminen ei mallinnuksen mukaan ole termodynaamisesti todennäköistä tutkituissa reaktio-olosuhteissa. Jauhemaisen katalyytin hyvät ominaisuudet pystyttiin pinnoituksessa siirtämään monoliittirakenteiseen katalyyttiin. Pt/90Al2O3-10SiO2 -katalyytin aktiivisuus DCM:n hapetuksessa tehostui, kun monoliitin aukkoluku kasvoi aiheutuen suuremmasta geometrisestä pinta-alasta ja mekaanisesta eheystekijästä sekä pienemmästä avoimen pinnan osuudesta ja termisestä eheystekijästä
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Driedger, Suzanne Michelle. "From science to policy practice and public discourse : claimsmaking and chlorinated drinking water /." *McMaster only, 2001.
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Sheehan, Emily Moore. "Time-weighted average solid-phase microextraction (TWA-SPME) for in-planta detection of chlorinated solvents." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Sheehan_09007dcc8067c9a4.pdf.
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Thesis (M.S.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 16, 2009). Includes bibliographical references (p. 63-66).
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Boving, Thomas Bernhard. "Performance and simulation of chemically enhanced solubilization and removal of residual chlorinated solvents from porous media." Diss., The University of Arizona, 1999. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1999_154_sip1_w.pdf&type=application/pdf.
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Saunders, Justin S. "Combined effects of termiticides, volatile organic compounds, and mechanical stress on chlorinated polyvinyl chloride (CPVC)." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0013263.
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Chahbandour, John III 1960. "Fate and transport of organo-chlorine compounds within the vadose zone during artificial recharge of chlorinated effluent." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277868.
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The effectiveness of soil aquifer treatment (SAT) to renovate both tertiary (Site 1) and secondary (Site 2) wastewater was investigated using two small recharge basins. Suction lysimeters collected soil water samples at various depths within the vadose zone from 0.5 to 20.0 feet. Total organic halide (TOX) and dissolved organic carbon (DOC) were evaluated to determine SAT efficiency in removing TOX and DOC found in the source waters. Approximately 77% of the TOX was removed from the tertiary wastewater during percolation through the vadose zone at Site 1, while the secondary source water underwent a maximum reduction of approximately 55% at Site 2. At Site 1 there was mobilization of in-situ humic materials causing increases in DOC concentrations at depth. These decreased with time and after 83 hours DOC concentrations at 20 feet were 51% of inflow concentration. At Site 2 DOC removal ranged from 44 to 73% at a depth of 15 feet for three flooding events. Discrepancies between the two locations are thought to reflect lithologic differences and dissimilarities in hydraulic loading rates.
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Morlando, Rebecca A. "Chemchar gasification of metal-bearing wastes, chlorinated organics and doe surrogate wastes /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841325.
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Tibui, Aloysius. "Biodegradation of Aliphatic Chlorinated Hydrocarbon (PCE, TCE and DCE) in Contaminated Soil." Thesis, Linköping University, The Tema Institute, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7908.
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Soil bottles and soil slurry experiments were conducted to investigate the effect of some additives on the aerobic and anaerobic biodegradation of chlorinated aliphatic hydrocarbons; tetrachloroethylene (PCE), trichloroethylene (TCE) and dichloroethylene (DCE) in a contaminated soil from Startvätten AB Linköping Sweden. For the aerobic degradation study the soil sample was divided into two groups, one was fertilised. The two groups of soil in the experimental bottles were treated to varying amount of methane in pairs. DCE and TCE were added to all samples while PCE was found in the contaminated soil. Both aerobic and anaerobic experiments were conducted. For aerobic study air was added to all bottles to serve as electron acceptor (oxygen). It was observed that all the samples showed a very small amount of methane consumption while the fertilised soil samples showed more oxygen consumption. For the chlorinated compounds the expected degradation could not be ascertained since the control and experimental set up were more or less the same.
For the anaerobic biodegradation study soil slurry was made with different media i.e. basic mineral medium (BM), BM and an organic compound (lactate), water and sulphide, phosphate buffer and sulphide and phosphate buffer, sulphide and ammonia. To assure anaerobic conditions, the headspace in the experimental bottles was changed to N2/CO2. As for the aerobic study all the samples were added DCE and TCE while PCE was found in the contaminated soil. The sample without the soil i.e. the control was also given PCE. It was observed that there was no clear decrease in the GC peak area of the pollutants in the different media. The decrease in GC peak area of the pollutants could not be seen, this may be so because more susceptible microorganisms are required, stringent addition of nutrients and to lower the risk of the high concentration of PCE and petroleum products in the soil from Startvätten AB.
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Åkesson, Nilsson Gunilla. "Determination of chlorinated fatty acids using SPE, XSD and GC/MS with particular regard to cultured human cells /." Uppsala : Dept. of Environmental Assessment, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/a493.pdf.
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Vereskuns, Gastons. "Chlorinated fatty acids in freshwater fish and some biological effects of dichlorostearic acid /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5717-3.pdf.
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Schuetze, Matthew P. (Matthew Paul). "Controlling a field test electron beam-generated plasma system for the decomposition of chlorinated volatile organic compounds in air streams." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/28109.
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