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He, Jianzhong. "Complete reductive dechlorination of chloroethenes to ethene and isolation of Dehalococcoides Sp. Strain BAV1." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180217/unrestricted/he%5Fjianzhong%5F200312%5Fphd.pdf.
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Fink, Samuel Donovan. "A study of the ternary system carbon-dioxide-toluene-1,1,1-trichloroethane /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487584612164254.
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Johns, Douglas O. "The effect of ethanol consumption on the biotransformation of 1,1,1-trichloroethane in human volunteers /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/8457.
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Mametja, Mapula Brenda. "An investigation of the molecular properties of 1,1,1-trichloroethane using laser spectroscopy / M.B. Mametja." Thesis, North-West University, 2008. http://hdl.handle.net/10394/4098.
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Makowa, Hazel Beverly. "The relationship between the insecticide dichloro-diphenyl-trichloroethane and chloroquine in Plasmodium falciparum resistance." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20310.
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Thesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Dichloro-diphenyl-trichloroethane (DDT) was extensively used in agriculture pest control and is still used for indoor residual spraying to control malaria. The lipophylicity of DDT and its breakdown product dichloro-diphenyl-dichloroethylene (DDE) dictates that they associate with membranes, lipids and hydrophobic proteins in the biological environment. Their poor degradable nature causes DDT and DDE to persist for decades in the environment and in individuals who are or were in contact with the pesticide. In many countries the synchronised resistance of the mosquito vector to insecticides and the malaria parasite towards antimalarial drugs led to a drastic rise in malaria cases and to malaria epidemics. This study assesses the influence of low level exposure of DDT and DDE on chloroquine (CQ) resistance of the dire human malaria parasite, Plasmodium falciparum. The in vitro activity of p,p’-DDT and p,p’-DDE towards blood stages of chloroquine sensitive (CQS) P. falciparum D10 and chloroquine resistant (CQR) P. falciparum Dd2 was determined using two complementary in vitro assays (Malstat and SYBR Green 1). The 50% inhibition concentrations (IC50s) of p,p’-DDT and p,p’-DDE were found to be ±14 to 38 μM (5-12 μg/mL) and highly similar towards CQS and CQR P. falciparum strains. This result indicated that the proteins involved in CQ resistance have no effect on the activity of the insecticide DDT and it breakdown product DDE. In order to assess the influence of DDT and DDE on CQ activity, in vitro fixed ratio drug combination assays were performed, as well as isobologram analysis. We found that CQ works in synergy with p,p’-DDT and p,p’-DDE against CQS P. falciparum D10. However, both p,p’-DDT and p,p’-DDE were antagonistic toward CQ activity in CQR P. falciparum Dd2. This indicated that p,p’-DDT and p,p’-DDE do have an effect on CQ resistance or on the action of CQ via a target other than hemozoin polymerization. The observation of reciprocal synergism of p,p’-DDT and p,p’-DDE with CQ against CQS D10 and antagonism against CQR Dd2 strain is highly significant and strongly indicates selection of CQ resistant strains in the presence of p,p’-DDT and p,p’-DDE. People who have low levels of circulating DDE and/or DDT could be at a high risk of contracting CQR malaria. However, medium term (nine days) DDE exposure of CQS P. falciparum D10 did not induce resistance, as no significant change in activity of CQ, p,p’-DDT and p,p’-DDE towards blood stages the CQS strain was observed. This exposure was, however, shorter than expected for a malaria infection and would be addressed in future studies. From our results on the interaction of CQ with p,p’-DDT and p,p’-DDE, it was important to assess the residual DDT and DDE variable and how much of residual p,p’-DDT and/or p,p’- DDE would enter into or remain in the different compartments (the RPMI media, erythrocytes and infected erythrocytes) over time. In combination with liquid-liquid extraction, we developed a sensitive GC-MS analyses method and a novel HPLC-UV analysis method for measuring DDT and DDE levels in malaria culturing blood and media. Whilst the HPLC-UV method was relatively cheaper, faster, and effective in determining high DDT and DDE concentrations, the optimised GC-MS method proved to be effective in detecting levels as low as 78 pg/mL (ppt) DDE and 7.8 ng/mL (ppb) DDT in biological media. Using both the HPLC and GC-MS methods we observed that malaria parasites influence distribution of the compounds between the erythrocytic and media fractions. P. falciparum D10 infection at ±10% parasitemia lead to must faster equilibration (less than 8 hours) between compartments. Equimolar distribution of p,p’-DDE was observed, but the parasites lead to trapping of the largest fraction of p,p’-DDT in the erythrocyte compartment. These results indicate that a substantial amount would reach the intra-erythrocytic parasite and could influence the parasite directly, possibly leading to either synergistic or antagonistic drug interactions. This study is the first to illustrate the “good and bad” of the insecticide DDT in terms of CQ resistance and sensitivity toward the human malaria parasite P. falciparum. These results will hopefully have an important influence on how future policies on malaria control and treatment particularly in endemic areas will be addressed and could also have an impact on the anti-malarial drug discovery approach.
AFRIKAANSE OPSOMMING: Dichlorodifenieltrichloroetaan (DDT) is op groot skaal in landbouplaagbeheer gebruik en word nog steeds gebruik vir binnenshuise oppervlakbespuiting om malaria te beheer. Die lipofilisiteit van DDT en sy afbraakproduk dichlorodifenieldichloroetileen (DDE) dikteer dat hulle met membrane, lipiede en hidrofobiese proteïene in die biologiese omgewing assosieer. Stadige afbraak veroorsaak dat DDT en DDE vir dekades in die omgewing agterbly, asook in individue wat in kontak is, of was met die insekdoder. In baie lande het gesinkroniseerde weerstand van die muskietvektor teenoor insekdoders en die malariaparasiet teenoor antimalariamiddels gelei tot 'n drastiese styging in malariagevalle en tot malariaepidemies. In hierdie studie word die invloed van lae vlak blootstelling van DDT en DDE op chlorokien (CQ) weerstand van die mens malariaparasiet, Plasmodium falciparum, geëvalueer. Die in vitro aktiwiteit van p,p'-DDT en p,p'-DDE teenoor die bloedstadia van chlorokiensensitiewe (CQS) P. falciparum D10 en chlorokien-weerstandbiedende (CQW) P. falciparum Dd2 is bepaal deur gebruik te maak van twee komplementêre in vitro toetse (Malstat en SYBR Groen toetse). Die 50% inhibisie konsentrasies (IC50s) van p,p'-DDT en p,p'-DDE is bepaal as ±14 to 38 μM (5-12 μg/mL) en was hoogs vergelykbaar tussen CQS en CQW P. falciparum stamme. Hierdie resultaat het aangedui dat die proteïene betrokke by CQ weerstand geen effek op die aktiwiteit van die insekdoder DDT en die afbraakproduk DDE het nie. Om die invloed van DDT en DDE op CQ aktiwiteit te evalueer, is die aktiwiteit van kombinasies van die verbindings in vaste verhoudings getoets, tesame met isobologram ontleding. Ons het gevind dat CQ sinergisties saam met p, p'-DDT en p, p'-DDE teen CQS P. falciparum D10 werk. Daarteenoor het beide p, p'-DDT en p, p'-DDE antagonistiese werking getoon teenoor CQ aktiwiteit met CQW P. falciparum Dd2 as teiken. Dit het aangedui dat p,p'-DDT en p, p'-DDE wel 'n invloed op CQ weerstand het of ‘n aktiwiteit van CQ, anders as hemozoin polimerisasie, beïnvloed. Die waarneming van resiproke sinergisme en antagonisme van p, p'-DDT en p, p'-DDE in kombinasie met CQ teenoor die CQS D10 en CQW DD2 stamme respektiewelik, is hoogs betekenisvol en dui op seleksie van CQweerstandige stamme in die teenwoordigheid van p, p'- DDT en p, p'-DDE. Mense wat lae vlakke van sirkulerende DDE/DDT het, het dus 'n hoër risiko om CQW malaria te kry. Verder is gevind dat medium termyn (nege dae) DDE blootstelling van CQS P. falciparum D10 nie weerstand nie veroorsaak nie, want geen beduidende verandering in die aktiwiteit van CQ, p,p'-DDT en p,p'-DDE teenoor die bloed stadiums van die CQS stam is waargeneem nie. Hierdie blootstelling is egter korter as in 'n malaria-infeksie en sal verder bestudeer word in toekomstige studies. Vanuit die interaksie resultate van CQ met p, p'-DDT en p, p'-DDE was dit belangrik om die residuele DDT en DDE veranderlike te evalueer, asook die distribusie van p,p'-DDT en p,p'- DDE tussen die verskillende kompartemente (die kultuurmedium, eritrosiete en geïnfekteerde rooibloedselle) oor verloop van tyd. In kombinasie met vloeistof-vloeistof ekstraksie, het ons 'n sensitiewe GC-MS en nuwe HPLC-UV analisemetode ontwikkel vir die meet van DDT en DDE-vlakke in bloed (normale en geïnfekteerde eritrosiete) en die kultuurmedium. Terwyl die HPLC-UV metode relatief goedkoper, vinniger en effektief in die bepaling van hoë DDT en DDE-konsentrasies is, was die geoptimaliseerde GC-MS metode doeltreffend in die opsporing van vlakke so laag as 78 pg/mL (dpt) DDE en 7.8 ng/mL (dpb) DDT in biologiese media. Met behulp van beide die HPLC-UV en GC-MS metodes is waargeneem dat die malariaparasiet die ekwilibrasie van die verbindings tussen die eritrosiet- en media kompartemente beïnvloed. P. falciparum D10 infeksie met ± 10% parasitemia lei tot vinniger ekwilibrasie (minder as 8 uur) tussen die kompartemente. Ekwimolêre verspreiding van p,p'- DDE is waargeneem, maar die parasiete het die grooste fraksie van p,p'-DDT in die eritrosiet kompartement vasgevang. Hierdie resultate wys dat 'n aansienlike fraksie die intraeritrositiese parasiet kan bereik en sodoende die parasiet direk kan beïnvloed en moontlik kan lei tot sinergistiese of antagonistiese middel interaksies. Hierdie studie is die eerste om die "goed en sleg" van die insekdoder DDT in terme van CQ weerstand en sensitiwiteit teenoor die menslike malariaparasiet P. falciparum te illustreer. Hierdie resultate sal hopelik 'n belangrike invloed hê op die toekomstige beleid oor die beheer van malaria en behandeling, veral in endemiese gebiede, en mag ook 'n impak hê op die antimalariamiddel navorsing.
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Melchiorre, Kenneth J. "Fate and transport of trichloroethane and trichloroethylene contaminated groundwater, Building 719, Dover Air Force Base, Delaware." Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/8393.
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Powell, Christina Lynn. "Biodegradation of Groundwater Pollutants (Chlorinated Hydrocarbons) in Vegetated Wetlands: Role of Aerobic Microbes Naturally Associated with Roots of Common Plants." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1289918991.
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McDougal, Rebecca, and n/a. "DDT residue degradation by soil bacteria." University of Otago. Department of Microbiology & Immunology, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070914.142931.
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1,1,1-trichloro-2,2-bis(4-chlorophenyl)-ethane (DDT) residues (DDTr) are widespread and persistent environmental contaminants, and have been classed as priority pollutants by the United Nations Environment Programme (UNEP). DDTr are potent endocrine disrupting molecules, and have been associated with reproductive abnormalities in juvenile alligators and rats. Microorganisms that metabolise DDTr both aerobically and anaerobically have been isolated and characterised. Bacteria that degrade DDTr aerobically typically utilise a dioxygenase to initiate degradative reactions through ring-hydroxylation, and convert DDTr to 4-chlorobenzoate without further degradation. Terrabacter sp. strain DDE-1 was isolated from DDTr-contaminated soil from Canterbury, New Zealand, and aerobically degrades 1,1-dichloro-2,2-bis-(4-chlorophenyl)-ethylene (DDE) to 4-chlorobenzoate, when grown in the presence of biphenyl (BP). The intermediates of degradation were inferred to be the end products of dioxygenase activity. Sequencing of a large linear plasmid, pBPH-1, from strain DDE-1 identified a cluster of genes with high levels of sequence similarity to BP-degradation genes from Rhodococcus spp. and Pseudomonas spp. This plasmid is lost at high frequency producing the plasmid-cured strain MJ-2, which has lost the ability to degrade BP or DDE. The aim of this study was to confirm that DDE-degradation in strain DDE-1 is encoded by the bph operon located on pBPH-1. No genetic systems to study gene function in either DDE-1 or MJ-2 could be developed using an array of broad-host range vectors. However, heterologous expression of the bph genes in Rhodococcus erythropolis strain TA422 was successful, with the recombinant strain TA425, obtaining the ability to utilise BP and DDE as a sole source of carbon and energy. DDE-1 was shown to convert indole to indigo, but MJ-2 could not, indicating that the biphenyl dioxygenase located on pBPH-1 is responsible for this activity. The bph genes from strain DDE-1 also conferred the ability to produce indigo from indole on strain TA425, confirming successful expression of the functional biphenyl dioxygenase in this strain. Despite several attempts to show quantitative degradation in strain TA425 using gas chromatography, the results were inconclusive Further analysis is needed to provide unequivocal evidence of DDE-degradation by strain TA425. Attempts to express the bph genes in rhizosphere-colonising bacteria, such a Rhizobium spp. or Pseudomonas spp., were unsuccessful, as evidenced by the inability to produce indigo, hence the lack of a functional biphenyl dioxygenase. However, RT-PCR did indeed indicate that P. aeruginosa strain Fin1 produced a bphA1 transcript, indicating that an error is occurring post-transcriptionally in these strains, to prevent production of the functional enzyme.
New Zealand has recently been shown to contain hotspots of DDTr-contamination. The second aim of this study was to determine the prevalence of DDTr-degrading bacteria and to gain insight into the types of bacteria that inhabit sites contaminated with DDTr. To investigate this, culture-dependent and culture-independent techniques were employed. Enrichment for DDTr-degrading bacteria yielded species of Rhodococcus and Ralstonia using DDTr-overlayer plate assays. The polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) were used to amplify and analyse the 16S rDNA and 16S rRNA for the identification of dominant and active bacteria in soil samples. The results of this analysis identified bacteria such as Williamsia spp. and Gordonia spp. that degrade other types of pollutants. This analysis did not identify a predominance of Rhodococcus or Ralstonia spp., or other bacteria that have been shown to degrade DDTr. To identify ecologically relevant members of the bacterial communities in DDTr-contaminated soils, and potentially important metabolic pathways, identification of ring-hydroxylating dioxygenase (RHD) genes was performed. PCR and restriction fragment length polymorphism (RFLP) analysis were employed together with phylogenetic analyses. The results showed that the RHD genes identified, clustered separately to those genes previously characterised from cultivated bacteria. Among these genes, one phylogenetic group was most closely related to the dioxygenase genes from Ralstonia eutropha H850, which is potent PCB-degrading bacterium that possesses a dioxygenase with a wide substrate range for many types of heavily chlorinated, PCB congeners. The identification of a predominance of genes with similarity to phenyl-propionate dioxygenases has been not been recognised previously in soil studies.
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Шпарій, Микола Володимирович. "Удосконалення технології хлорування етилену." Diss., Національний університет "Львівська політехніка", 2021. https://ena.lpnu.ua/handle/ntb/56688.
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В дисертаційному дослідженні розв’язана актуальна науково-практична задача: підвищення селективності процесу рідиннофазного прямого хлорування етилену до 1,2-дихлоретану шляхом модифікації промислового каталізатора на основі хлоридів заліза та натрію натрієвою сіллю перфорованої сульфокислоти. Уточнено механізм реакції прямого хлорування етилену і показано , що
швидкість реакції залежить від концентрації каталізатора і промотора та їх комплексної сполуки [NаFeСІ4], а також перехідного комплексу з етиленом [Na[Fe(С2Н4Cl)4] ) , і проходить у дифузійній зоні, що передбачає можливість утворення комплексних сполук між каталізатором, промотором та етиленом механізмом реакції. Показано, що застосування в якості стабілізаторів каталітичного комплексу хлориду амонію не дає позитивного ефекту, а натрієва сіль перфторованої сульфокислоти веде не тільки до зростання вмісту йонів натрію в каталітичній системі і досягнення проектних їх значень, але й до зростання чистоти 1,2-дихлоретану та зменшення вмісту побічних продуктів, при цьому дисперсність
каталітичної системи має другорядне значення. Встановлено, що модифікатор не тільки стабілізує каталітичний комплекс, але дозволяє скоротити час його приготування у два рази. Визначено оптимальну концентрацію стабілізатора. Визначено склад шламу, що засмічує газопровід від печі до парогенератора системи утилізації тепла при термічному знешкодженні кубових залишків виробництва вінілхлориду. Запропоновано принципи технології вилучення хлориду заліза - каталізатора прямого хлорування етилену - з технологічних потоків. Випущена дослідно-промислова партія модифікатора каталітичної системи процесу прямого хлорування етилену і проведені її дослідно-промислові
випробовування. Показано, що застосування натрієвої солі перфторованої сульфокислоти дозволяє підвищити селективність утворення 1,2-дихлоретану з 98,9% до 99,3%, при цьому вміст трихлоретану спадає з 0.42% до 0.29%, тобто у 1,8 раз. Dissertation research is devoted to the solving of the actual scientific and practical problem: increase of selectivity of process of liquid-phase direct chlorination of
ethylene to 1,2-dichloroethane by modification of the industrial catalyst on the basis of ferric chlorides and sodium salt of perforated sulfonic acid. By analyzing the stages of production of 1,2-dichloroethane, it was determined that the main factor influencing the selectivity of the process is the ratio of the components of the catalytic system, as well as its instability under the conditions of the reaction. It is established that the most effective method of stabilizing the catalytic system is the introduction of modifiers of different nature. It is these modifiers that affect the operation of the catalyst, so their search is aimed at dissertation research. The mechanism of the reaction of direct chlorination of ethylene is specified and it is shown that the reaction rate depends on the concentration of catalyst and promoter and their complex compound [NaFeСІ4], as well as the transition complex with ethylene [Na [Fe [С2Н4Cl) 4]), and takes place in the diffusion zone, providing the
possibility of formation of complex compounds between the catalyst, promoter and ethylene by a new reaction mechanism. It is shown that the use of ammonium chloride (electron-donor compound) as stabilizers of the catalytic complex does not give a positive effect, and the sodium salt of perfluorinated sulfonic acid (electron-acceptor compound) leads not only to an increase in the content of sodium ions in the catalytic system and to -achieving their design values, but also to increase the purity of 1,2-dichloroethane and reduce the content of by-products, while the dispersion of the catalytic system is of secondary importance. It is established that the modifier not only stabilizes the catalytic complex, but allows to reduce its preparation time by half. The optimal stabilizer concentration is determined.The composition of the sludge that clogs the gas pipeline from the furnace to the steam generator of the heat utilization system during thermal neutralization of vat residues of vinyl chloride production has been determined. The principles of technology of extraction of iron chloride - catalyst of direct chlorination of ethylene - from technological streams are offered and it is shown that extraction of iron compounds should be carried out with technical water at elevated (about 350K) temperature, and also methods of utilization of organochlorine waste of vinyl chloride production. A basic technological scheme for the extraction of iron-containing catalyst and ways to solve technological problems that arise during the combustion of organochlorine residues in the production of vinyl chloride have been developed. An experimental-industrial batch of a modifier of the catalytic system of the process of direct chlorination of ethylene was released and its experimental-industrial tests were carried out. It is shown that the use of sodium salt of perfluorinated sulfonic
acid can increase the selectivity of the formation of 1,2-dichloroethane from 98.9% to 99.3%, while the content of trichloroethane decreases from 0.42% to 0.29%, ie 1.8 times. Two licenses of Inter-Synthesis LLC, Boryslav, for the production of a catalytic system stabilizer and KARPATNAFTOKHIM LLC for its use in the process of direct chlorination of ethylene were sold. The actual economic effect achieved during the tests amounted to 88,000 UAH. The expected economic effect from the implementation is about 1 million UAH per year. В диссертационном исследовании разрешена актуальная научнопрактическая задача: повышение селективности процесса жидкофазного прямого хлорирования этилена до 1,2-дихлорэтана путем модификации промышленного катализатора на основе хлоридов железа и натрия натриевой солью
перфторированной сульфокислоты. Уточнен механизм реакции прямого хлорирования этилена и показано, что скорость реакции зависит от концентрации катализатора и промотора и их
комлексного соединения [NаFeСІ4], а также переходного комплекса с этиленом [Na[Fe(С2Н4Cl)4] и протекает в диффузионной области, что предусматривает образование комплексных соединений между катализатором, промотором и этиленом за новым механизмом. Показано, что использование в качестве стабилизатора каталитического комплекса хлорида аммония не дает положительного эффекта, а натриевая соль перфторированной кислоты благоприятствует не только увеличению содержания ионов натрия в каталитической системе , чистоты дихлорэтана но и уменьшению содержания побочных продуктов, при этом степень дисперсности каталитической системы имеет второстепенное значение. Установлено, что модификатор не только стабилизирует каталитический комплекс, но и сокращает время его приготовления в два раза. Определена оптимальная концентрация модификатора.
Определен состав шлама, загрязняющего газопровод от печи до парогенератора системы утилизации тепла при переработке кубовых остатков производства дихлорэтана. Предложены принципы технологии извлечения хлорида железа – катализатора прямого хлорирования этилена – из технологических потоков. Выпущена опытно-промышленная партия модификатора каталитической системы процесса прямого хлорирования этилена и проведены ее опытнопромышленные испытания. Показано, что использование натриевой соли перфторированной сульфокислоты позволяет увеличить селективность образования 1,2-дихлорэтана с 98,9% до 99,3%, при этом содержание трихлорэтана снижается с 0.42% до 0.29%, т.е.у 1,8 раза.
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Binner, Eleanor, and ebinner@iprimus com au. "Investigation of trichloroethene destruction for the degreasing industry." Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20051025.112548.
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The major objective of this project was to assess the application of atmospheric
pressure microwave induced plasmas to the control of trichloroethene vapour
emissions from industrial cleaning processes. Laboratory experiments, chemical
modelling and chemical analysis were the three major elements of the project. A
typical stream to be treated, as measured at the project test site, was 60 lmin-1 of air
contaminated with 2 % trichloroethene vapour.
The practical experiments carried out were trichloroethene dissociation by microwave
plasma, propane-assisted microwave plasma and conventional propane combustion.
Flow rates of 4 � 12 lmin-1, trichloroethene concentrations of 0 � 6 % in air and
plasma powers of up to 3 kW were investigated. The processes were simulated using
both equilibrium and kinetic modelling in CHEMKIN. Chemical analysis was done
using gas chromatography with an electron capture detector, with gas
chromatography/mass spectrometry to identify eluted compounds.
The destruction and removal efficiencies, by-products, temperature and robustness of
each process were investigated. A simple economic and environmental analysis was
done, and the results were compared with currently available processes.
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Wang, Lei. "Tetrachloroethene (PCE) and trichloroethene (TCE) biogradation with bioreactors /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3036865.
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Yu, Chunming, and Chunming Yu. "The effect of trichloroethene on the aqueous solubility of chlorobenzenes." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/626792.
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Cosolute effects of trichloroethene (TCE) on the solubility of seven
chlorobenzenes have been studied. The chlorobenzenes chosen for the study
were mono-, di- and trichlorobenzenes. The solubilities of these
chlorobenzenes were determined with and without the presence of TCE. TCE
concentrations used ranged from O to 3300 ppm (above solubility). It has
been found that reliable measurements demand relatively long mixing times
and settling times to minimize the effect of colloids. Experimental results
indicate that (1) most published solubility data for chlorobenzenes are
apparent solubilities (i.e., a function of experimental procedures); (2) the
solubilities of chlorobenzenes which are liquid at 25 °C decrease with
increasing concentrations of TCE; and (3) TCE does not decrease
solubilities of chlorobenzenes which are solid at 25 °C unless TCE present in
the organic phase dissolves the solid chlorobenzene. The model used to
predict the co-solute effects on aqueous solubilities indicates that near ideal
behavior 1s observed. These results suggest that chlorobenzene
concentrations below solubility do not necessarily indicate the absence of an
organic phase.
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Yupanqui, Zaa Carmen Lourdes. "Dechlorinating and Iron Reducing Bacteria Distribution in a Trichloroethene Contaminated Aquifer." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/41.
Full textAbstract:
The Operable Unit 5 (OU 5) area of Hill Air Force Base currently has two trichloroethene-contaminated groundwater plumes underneath residential areas in Sunset and Clinton, Utah. Bioremediation by biological reductive dechlorination can be an important mechanism for the removal of chlorinated compounds from the plumes. The presence of suitable bacteria to carry on reductive dechlorination is the key in the bioremediation process. The goal of this study was to determine the distribution and population density of the 16S rRNA genes of Bacteria, Dehalococcoides ethenogenes, Desulfuromonas michiganensis, Geobacter spp and Rhodoferax ferrireducens-like bacteria, as well as the functional genes trichloroethene reductive dehalogenase (tceA) and vinyl chloride reductase gene (vcrA). This study also evaluated the influence of the physical-chemical properties of the OU 5 aquifer material on the observed bacterial distribution. Twenty OU 5 soil cores were obtained from a 14-ha area that included a trichloroethene (TCE) plume. DNA was extracted from each core. Molecular analysis with qRT-PCR was used to quantify the densities of the mentioned 16S rRNA and functional genes. Separately, total arsenic and iron in the II and II+III oxidation states were extracted by two methods (HCl and hydroxylamine HCl in HCl) in each core. Concentrations of TCE, cis-dichloroethene (cis-DCE), vinyl chloride (VC) and ethane in well water were included. Dehalococcoides population density was low and its distribution was uneven with densities lower than 3.2x104 copies/g (detection limit of 2.5x103). D. michiganensis distribution was not uniform but was clustered near the TCE-source area with densities of 7.9x103-1x105 copies/g (detection limit of 6.3x103). Geobacter spp. distribution was uneven but broader, with densities of 4x103-1.6x106 copies/g (detection limit of 3.2x103). The vcrA gene distribution was relatively uniform and broad. Densities were the lowest measured (detection limit of 63 copies/g). TceA was measured in two cores with densities close to detection limit of 1.6x103 copies/g. Rhodoferax ferrireducens-like bacteria had a broader distribution with the highest densities of 1.6x106-1.3x108 copies/g (detection limit of 7.9x103). Total Bacteria were measured in all cores with densities 3.2x104-3.2x106 copies/g (detection limit of 1x103). Three multivariate statistical methods were used to determine the effect of physical-chemical properties on the target gene distributions. Cluster and discriminant analysis selected five properties (pH, sand and silt content, NO3--N and NH4+-N) as the most discriminating factors among thirty-one physical-chemical properties. However, no effect in the bacterial distribution was observed. The tree classification method identified nine variables that described higher or lower densities of the target genes. Variables such as Bacteria, Fe(II+III) (by hydroxylamine HCl in HCl), organic matter and cis-DCE were selected by the method.. All methods agreed on the selection of pH and sand content as the physical/chemical factors most influencing in the bacterial distribution. Based on the findings of low densities of dechlorinating bacteria and dechlorinating-associated functional genes, low available carbon donor and sandy mineral composition, the partial TCE-dechlorination at this site can be ascribed to the nature of the site and incomplete set of required factors for complete reductive dechlorination.
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Deeter, Jonathon Michael. "Degradation of Trichloroethene By Radicals Produced By Oxygenation of Various Reduced Iron Minerals." Wright State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=wright1598892463038822.
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Bao, Weiqun, and Weiqun Bao. "The effect of trichloroethene on sorption of chlorinated phenols on soils and coated silica." Thesis, The University of Arizona, 1994. http://hdl.handle.net/10150/626922.
Full textAbstract:
The cosolute effect of trichloroethene (TCE) on the sorption of neutral
chlorinated phenols by soils and silica coated with phenyl groups was
investigated. In the coated silica system (f0e = 2% ), the sorption of the chlorinated phenol was reduced in .the presence of TCE. The proposed mechanism is the competition between TCE and chlorophenols for adsorption sites. In soil systems with high organic carbon (f0e = 3.2 % ) and low organic carbon (f0e < 0.03 % ), the sorption coefficients of chlorinated phenol was not affected by the presence of TCE, indicating a partitioning mechanism. These results indicated that sorption of organic compounds depends on both the properties of the compound and the organic coating. Having this information is essential for modeling cosolute transport.
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Mukherjee, Abhijit. "Identification of natural attenuation of trichloroethene and technetium-99 along Little Bayou Creek, McCracken County, Kentucky." Lexington, Ky. : [University of Kentucky Libraries], 2003. http://lib.uky.edu/ETD/ukygeol2003t00080/abmthesis.pdf.
Full textAbstract:
Thesis (M.S.)--University of Kentucky, 2003.Title from document title page. Document formatted into pages; contains x, 163 p. : ill. Includes abstract. Includes bibliographical references (p. 151-161).
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Langer, Vera Waltraud. "Investigation of trichloroethene (TCE) transport in fractured porous media with emphasis on sorption onto stylolites and matrix diffusion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0011/NQ41616.pdf.
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Walecka-Hutchison, Claudia, and Claudia Walecka-Hutchison. "An Evaluation of Limiting Parameters of an In Situ Trichloroethene Bioremediation Project Based on Seven TCE Field Bioremediation Studies." Thesis, The University of Arizona, 1999. http://hdl.handle.net/10150/626785.
Full textAbstract:
Seven aerobic field trichloroethene (TCE) bioremediation projects were evaluated to
determine key parameters leading to in situ TCE bioremediation effectiveness. Key
parameters identified were: 1) presence of other contaminants, 2) efficacy of the cometabolic
inducer, 3) technology design, and 4) site soils and hydraulics. These four parameters were
then used to evaluate the pilot bioremediation operation at Air Force Plant #44 in Tucson,
Arizona. The pilot operation was poorly designed. Site characterization appeared
insufficient; laboratory studies were not representative of site conditions; 1, 1-dichloroethene
appeared to inhibit TCE degradation; the purpose of the injected methanol ( cometabolic
inducer) was unclear. Well design, specifically screen interval location, also contributed to
technology deficiency. Soil type appeared to be the most limiting component; hydraulic
conductivity (K) representative of the contaminated clay at the APP #44 site was estimated
at 1.5 x 10-5 cm/sec. Over the course of the trial, spatially averaged TCE concentrations
decreased by 41 %. Well chloride data calculations indicated that a 27% reduction may be
attributable to dilution, thereby suggesting that only a 14% decrease in concentrations may
be attributable to biological degradation.
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Weatherill, John James. "Investigating the natural attenuation and fate of a trichloroethene plume at the groundwater-surface water interface of a UK lowland river." Thesis, Keele University, 2015. http://eprints.keele.ac.uk/2339/.
Full textAbstract:
Legacy industrial contaminants, such as trichloroethene (TCE), that have been released to aquifers in the last century, now threaten the quality of groundwater baseflow to lowland rivers and streams. Before reaching these receptors, contaminant plumes must first transit the heterogeneous environment of the aquifer-river interface. This research investigates the fate and potential for in-situ natural attenuation at this interface where a poorly-defined TCE plume potentially threatens a ‘gaining’ lowland river in the UK. It was possible to reveal a well-defined discharge zone of the plume in the riverbed with limited dispersion occurring in the low-permeability floodplain deposits. Through electrical resistivity imaging and intrusive sampling, this alluvial aquitard was revealed to be laterally extensive along the river corridor. A dissolved TCE flux of 0.43–1.5 g d–1 to the river was estimated,with most of this discharge occurring over a 40 m long reach, centred on a meander bend in the floodplain. The location and magnitude of this flux is influenced by continuity of stratified silt and peat deposits extending riverward from the floodplain, which provide significant retardation capacity. Metre-scale heterogeneity in the spatial variability of the groundwater discharge through these deposits was revealed with riverbed temperature mapping. A dominance of aerobic and nitrate-rich water throughout the aquifer-river system maintains a large stoichiometric demand for organic carbon and prevents the onset of reducing conditions required for significant dechlorination of the plume. However, at discrete shallow locations in the riverbed and parts of the alluvium, partial dechlorination of the plume was observed. A grid of pore water samplers revealed more enhanced dechlorination to cis-1,2-dichloroethene and vinyl chloride in methanogenic zones of the shallow sediment that was influenced by river macrophyte growth. Although in-situ natural attenuation does exceed the up-gradient aquifer in places, overall these processes are unlikely to prevent migration of the majority of the contaminant mass to the river. However, surface water impacts from this particular plume are unlikely with the large dilution available in the river itself.
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Kurta, Mykola. "Environmental and Energy Saving Technologies of Vinyl Chloride Production." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4352.
Full textAbstract:
Recently, because of the increase of environmental concerns in process design, the need to enhance conversion to product and prevent generation of wasteful byproducts in the reactor network has become urgent. This prevents high cost treatment and separation costs downstream in the process. Therefore, in this thesis I focus on making production of vinyl chloride monomer (VCM) more efficient and on possible ways of industrial organochlorine waste (OCW) recycling. In particular, in the first experiment, we investigate how catalyst and its structure can affect product output.
Infrared spectroscopy and X-ray diffraction analysis were utilized to investigate the structure of the γ-Al2O3 carrier with CuCl2 catalyst on its surface. Structure of the two catalysts, HarshowX1 and MEDC-B, and their effect on the mechanism of ethylene oxidative chlorination reaction into 1,2-dichlorethane were studied. Differential thermal analysis and mass spectroscopy were applied to study the structure and the mechanism differences between the deposited and permeated CuCl2 catalysts.
The second experiment deals with ecological processing and recycling methods of wasteful byproduct that can be called chlororganic wastes. Typical waste products are 1,2-dichloroethane, 1,1,2-trichloroethane, vinylidene, and vinyl chloride monomer. Polymerization and copolymerization of typical waste products with their C5-C9 fraction resulted in non-toxic polymer products that can be used in construction and road-building industries. The possibility of joint chlorine and sulfide-containing chemical wastes recycling into polysulfide oligomeric products is discussed. This comprehensive recycling allows utilizing 80-90% of all wastes generated during synthesis of chlorinated products in the chemical industry.
The results of the studies aim to improve the conversion of ethylene to vinyl chloride and minimize the formation of byproducts.
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Quinlivan, Patricia Ann. "EFFECTS OF ACTIVATED CARBON SURFACE CHEMISTRY AND PORE STRUCTURE ON THE ADSORPTION OF METHYL TERTIARY-BUTYL ETHER AND TRICHLOROETHENE FROM NATURAL WATER." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010711-170529.
Full textAbstract:
Activated carbon adsorption is the best available treatment technology for thecontrol of many objectionable trace organic compounds. Activated carbons are frequentlycharacterized by the iodine number and BET surface area, but these parameters do notcorrelate well with trace organic compound removal from natural water. Therefore, theobjective of this research was to develop activated carbon selection criteria that assure theeffective removal of trace organic contaminants from natural water and to base theselection criteria on the adsorbent?s pore structure and surface chemistry. Tosystematically evaluate pore structure and surface chemistry effects, a matrix of activatedcarbon fibers (ACFs) with three activation levels and four surface chemistry levels wasstudied. To evaluate whether adsorption trends established for ACFs were also valid forgranular activated carbon (GAC), ACF results were compared with those obtained forthree commercially available GACs. Adsorption capacities were determined for naturalorganic matter (NOM), for relatively hydrophilic methyl tertiary-butyl ether (MTBE) andrelatively hydrophobic trichloroethene (TCE) in organic-free water, and for MTBE andTCE in the presence of NOM. NOM isotherms showed that DOC adsorption occurredprimarily in pores with diameters in the 11 to 500 Å range and that electrostaticinteractions between NOM and the carbon surface played a role in NOM adsorption.According to both single-solute isotherms and micropollutant isotherms in the presence of NOM, hydrophobic adsorbents more effectively removed TCE and MTBE thanhydrophilic adsorbents. Effective adsorbents for drinking water treatment shouldtherefore contain little oxygen and nitrogen whose presence increases the polarity of theadsorbent surface. Based on the elemental composition of the low-ash carbons evaluatedin this study, activated carbons should have oxygen and nitrogen contents that sum to nomore than 2 to 3 mmol/g to assure sufficient hydrophobicity. In addition, both single-soluteisotherms and isotherms in the presence of NOM indicated that adsorbents shouldexhibit a large pore volume in micropores with widths that are about 1.5 times larger thanthe kinetic diameter of the target adsorbate. Furthermore, based on the micropollutantisotherms in the presence of NOM, an effective adsorbent should possess a microporesize distribution that extends to widths that are approximately twice the kinetic diameterof the target adsorbate to prevent pore blockage or restriction as a result of NOMadsorption.
22
HENKE, EV. "Knock out - a missing C1s line in the photoelectron spectrum of aqueous chloral hydrate : Core electron spectroscopy of chloral hydrate, trichloroethanol and ethanol in aqueous solution and gas phase." Thesis, Uppsala University, Department of Physics and Astronomy, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-126257.
Full textAbstract:
Chloral hydrate Cl3C-C(OH)2H in aqueous solution has been studied by photoelectron spectroscopy using synchrotron radiation. The expected separation between the two carbon 1s lines due to different chemical environments could not be observed in the aqueous solution, but was clearly seen in following gas phase measurements. NMR measurements excluded sample damage in the aqueous solution and support the image of coincidence of the two carbon lines. The coincidence of the two lines is discussed in terms of experimental resolution and change in chemical shift in the aqueous phase. The observations are further compared to measurements of trichloroethanol and ethanol, which both exhibit the same characteristic C-C bond and at least one hydroxyl group. The present data showed no clear evidence of change in chemical shift in aqueous solution as compared to the gas phase, but such an effect might not be completely excluded.
The liquid measurements were performed using a liquid micro-jet, a recently developed technique for accessing volatile liquids in a high vacuum environment as required for photoelectron spectroscopy. The set-up is described in detail.
During the present project, I was involved into planning and performing experiments, sample preparation, data analysis and discussion.
23
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.
Full textAbstract:
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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"Synergistic Reductive Dechlorination of 1,1,1‐Trichloroethane and Trichloroethene and Aerobic Degradation of 1,4‐Dioxane." Master's thesis, 2018. http://hdl.handle.net/2286/R.I.51797.
Full textAbstract:
abstract: Widespread use of chlorinated solvents for commercial and industrial purposes makes co-occurring contamination by 1,1,1-trichloroethane (TCA), trichloroethene (TCE), and 1,4-dioxane (1,4-D) a serious problem for groundwater. TCE and TCA often are treated by reductive dechlorination, while 1,4-D resists reductive treatment. Aerobic bacteria are able to oxidize 1,4-D, but the biological oxidation of 1,4-D could be inhibited TCA, TCE, and their reductive transformation products. To overcome the challenges from co-occurring contamination, I propose a two-stage synergistic system. First, anaerobic reduction of the chlorinated hydrocarbons takes place in a H2-based hollow-fiber “X-film” (biofilm or catalyst-coated film) reactor (MXfR), where “X-film” can be a “bio-film” (MBfR) or an abiotic “palladium-film” (MPfR). Then, aerobic removal of 1,4-D and other organic compounds takes place in an O2-based MBfR. For the reductive part, I tested reductive bio-dechlorination of TCA and TCE simultaneously in an MBfR. I found that the community of anaerobic bacteria can rapidly reduce TCE to cis-dichloroethene (cis-DCE), but further reductions of cis-DCE to vinyl chloride (VC) and VC to ethene were inhibited by TCA. Also, it took months to grow a strong biofilm that could reduce TCA and TCE. Another problem with reductive dechlorination in the MBfR is that mono-chloroethane (MCA) was not reduced to ethane. In contrast, a film of palladium nano-particles (PdNPs), i.e., an MPfR, could the simultaneous reductions of TCA and TCE to mainly ethane, with only small amounts of intermediates: 1,1-dichloroethane (DCA) (~3% of total influent TCA and TCE) and MCA (~1%) in continuous operation. For aerobic oxidation, I enriched an ethanotrophic culture that could oxidize 1,4-D with ethane as the primary electron donor. An O2-based MBfR, inoculated with the enriched ethanotrophic culture, achieved over 99% 1,4-D removal with ethane as the primary electron donor in continuous operation. Finally, I evaluated two-stage treatment with a H2-based MPfR followed by an O2-MBfR. The two-stage system gave complete removal of TCA, TCE, and 1,4-D in continuous operation.Dissertation/Thesis
Masters Thesis Civil, Environmental and Sustainable Engineering 2018
25
Xie, Han-Kun, and 謝翰坤. "Catalytic Oxidation of 1,1,1-Trichloroethane." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/84284708528062070218.
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Yan-Fang, Chen, and 陳衍芳. "Incineration of Trichloroethane on Oxide Catalysts." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/56598615366818380650.
Full textAbstract:
碩士國立臺灣科技大學
化學工程研究所
83
The differences among Cr2O3/*-Al2O3, MnO2/Al2O3 and CuO/Al2O3 catalysts for the decomposition of trichloroethane were investigated. These catalysts were prepared by incipient impregnation and were characterized by BET surface, pore size, ESCA and ammonia adsorption. The decomposition was conducted under atmospheric pressure with the trichloroethane being continuously carried to the reactor with an air flow. CuO/Al2O3 appeared as the most active catalyst among the three for the decompostion. The reaction produced ethylene dichloride as an intermediate for all three catalysts. Further decomposition of ethylene dichloride into CO and CO2 was also examined. Cr2O3/Al2 O3 was the most active catalyst for this reaction, relating possibly to the catalyst''s high number of acid site.The reaction path for the productions of CO and CO2 varied withthe catalysts as demonstrated by the relation between the contact time and the selectivity. CO and CO2 were produced in sequence on Cr2O3/Al2O3 while these gases were yielded simultaneously on CuO/Al2O3 and MnO2/Al2O3. The selectivity of HCl and Cl2 was found to altered with the reaction temperature. Increasing the temperature resulted in a higher selectivity of chlorine. Phosgene was produced from the reaction between CO and Cl2.This toxic gas was found in the decomposition using CuO/Al2O3 as the catalyst but was not discovered using MnO2/Al2O3 and Cr2O3/Al2 O3.
27
Wang, Wen Che, and 王文哲. "Incineration of Trichloroethane on Chromium Oxide Catalyst." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/09877221923804273584.
Full textAbstract:
碩士國立臺灣科技大學
化學工程研究所
84
The decomposition of trichloroethane on chromium oxide cataly -st was investigated.The major interest was plead in finding the maximum chromium oxide loading,the optimal calcination temperatur -e and the mechanism trichloroethane reaction. Catalyat were prepared by inncipient impregnation and were charactreized by BET,ESCA,XRD,AA.The decomposition reaction was conducted under atmospheric pressure with a continuous trichloro ethane flow. The maximum loading was found to be 10wt% with an optimal calcinating temperature to be 773K.The raection products were ethylene dichloroide,hydrochloric acid, chlorine,carbon monoxide, carbon dioxide.The distribution of the products was affect by reaction temperature and space time. The reaction path could be found by analysing relation between the space time and the distribution of products.Ethylene dichloroide and hydrochloric acid werw the primary decomposition products from trichloroethane.The ethylene dichloroide was rther converted into carbon monoxide,carbon dioxide and hydro chloric acid.Part of the carbon monoxide react with oxygen to become carbon dioxide.Hydrochloric acid were produced in low temperature.Hydrochloric acid could react with oxygen to produce chlorine and water when the temperature was increase. A significant part of chromium oxide on the catalyst were losed after the reaction.It was likely that the chromium oxide reacted with one of the products to generate a volatile compound. The compound was carried away by the flowing gas through the catalyst bed and caused the catalyst deactivation.
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"Marketing strategy for 1,1,1 trichloroethane in Southern China." Chinese University of Hong Kong, 1995. http://library.cuhk.edu.hk/record=b5888307.
Full textAbstract:
by Ho Hoi-keung Elec.Thesis (M.B.A.)--Chinese University of Hong Kong, 1995.
Includes bibliographical references (leaves 53-54).
ABSTRACT --- p.ii
TABLE OF CONTENTS --- p.iii
INTRODUCTION --- p.1
COMPANY PROFILE REPORT --- p.4
PRODUCT PROFILE REPORT --- p.5
Areas of Use --- p.7
Supply Situation --- p.11
Other Substitute Products --- p.11
SWOT ANALYSIS --- p.14
Strength --- p.14
Weakness --- p.16
Opportunities --- p.18
Threats --- p.21
COMPETITIVE ANALYSIS --- p.23
MARKET PROFILE REPORT --- p.29
Textile Industry --- p.29
Electronic Industry --- p.30
Metal Degreasing Industry --- p.31
Demographic Consideration --- p.32
Hong Kong --- p.32
Shenzhen SEZ --- p.33
Zhuhai --- p.35
Xiamen --- p.37
TARGET GROUP ANALYSIS --- p.39
MARKET OBJECTIVES --- p.43
MARKETING STRATEGY --- p.44
ACTION PLAN --- p.49
BUDGET CONSIDERATIONS --- p.50
CONCLUSION & RECOMMENDATIONS --- p.52
BIBLIOGRAPHY --- p.53
29
Qiu, San, and 邱三. "Catalytic incineration of methylene chloride and 1,1,1-trichloroethane." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/96622075278808666226.
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QIU, SHAN, and 邱三. "Catalytic incineration of methylene chloride and 1,1,1-trichloroethane." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/11779484186253048055.
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Huang, Jen-Wei, and 黃仁瑋. "Reductive degradation of 1,1,1-trichloroethane with green tea/ferrous ion system in aqueous phase." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5087021%22.&searchmode=basic.
Full textAbstract:
碩士國立中興大學
環境工程學系所
107
1,1,1-Trichloroethane (TCA) as one of commonly seen contaminant in subsurface, and also its abiotic degradation byproduct 1,1-dichloroethene are regarded carcinogenic to human. Polyphenols are naturally abundant as antioxidants in the environment, which act to stabilize oxidative radicals and chelate and reduce metal ions. Catechins polyphenols are rich in green tea and alkaline pH can increase their antioxidant capacities. In this study, the feasibility of TCA (0.08 mM) degradation using green tea/Fe2+ solution system under alkaline pH was investigated. The experiments were conducted to invest the effects of pH adjusted reagent, different tea concentration, different Fe2+ concentration and different temperature. The results showed an activated energy of 18.15 kJ/mol required in the tea/Fe2+ degradation of TCA under conditions of 5 g/L green tea, 5 mM Fe2+, and 20oC in the (bi)carbonate buffer solution. The interactions between catechins and Fe2+ were analyzed by UV-visible spectrum under different pH conditions, and exhibited the formation of catechin-Fe chelation and gradual decreases of catechin concentration with reaction time. In examining TCA degradation kinetics, it was found that TCA degradations occurred with two steps: (1) the early stage of reaction (0-4 h) showed rapid TCA degradations due to the degradation induced by electrons released by Fe2+ in alkaline pH and the initial rates of the reaction were determined; (2) the later reaction (4-72 h) showed slow TCA degradations due to the electrons released during the interactions between catechin and Fe3+, in which Fe2+/Fe3+ were recycled by catechins to slowly release electrons and the TCA degradation behaved as first-order kinetics. Based on detections of TCA degradation byproducts including 1,1-dichloroethane, chloroethane, ethane, 1,1-DCE, vinyl chloride and ethane in the solution, which were at low concentrations (about 10-4 mM), TCA degradation pathway by green tea/Fe2+ system was proposed. In addition, the total mass of chloride ion detected during the course of TCA degradation accounts for an approximate 85% of chloride released upon TCA mineralized. Based on the results obtained in this study, it can be concluded that the green tea/Fe2+ system may serve as an reductive degradation process for TCA degradation.
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Wu, Mei-Hsuan, and 吳美萱. "Emulsion-enhanced anaerobic reductive dechlorination of soil contaminated by hexachlorocyclohexane and dichloro-diphenyl-trichloroethane." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5087053%22.&searchmode=basic.
Full textAbstract:
碩士國立中興大學
環境工程學系所
107
The soil of agricultural land in developing countries (such as East Asia, Southeast Asia, etc.) has been contaminated by pesticides for a long time. At present, the concentration of soil in the general agricultural land can still be measured in the soil, and DDT and Lindane account for a considerable proportion. DDT is an early commonly used herbicide, insecticide, killer for public health, and Lindane is the main active ingredient of insecticides. It has been proven that DDT and Lindane are neurotoxic to human body and are human carcinogens confirmed by IARC and those persistent organic pollutants also regulated at Stockholm Convention. Farmland’s pollution directly impacts food safety and human health. Therefore, how to remove or decompose pesticides in soil is an important issue in soil remediation. Batch biodegradation tests were conducted using an L9 (34) orthogonal table according to Taguchi method with four controlling factors: moisture content, pH values, emulsion concentrations, and organic matter contents. The results show that the moisture content and pH values are significant factors, the optimal removal of Lindane is over 98%, and the optimal removal of DDT as high as 84.5%, which is feasible to represent the degradation of the domesticated flora of . Er-Ren River.A single operation of ISPIE can achieve the removal of DDT and Lindane at as high as 40.6% and 27.1%, respectively. The best conditions were applied to the soil of the Sandbox Test. The results showed that the best removal of Lindane on the 28 days was over 80%, and the optimal removal of DDT on the 14th was over 90%. Compared with the bacteria phase analysis of the Sandbox Test, the results are quite different from the bacteria in the batch experiment, which represents the other soils containing other degradable DDT and Lindane.
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Chan, Calvin. "The Observed Stable Carbon Isotope Fractionation Effects of a Chloroform and 1,1,1-Trichloroethane Dechlorinating Culture." Thesis, 2012. http://hdl.handle.net/1807/33361.
Full textAbstract:
Little is known about the enzyme-substrate interactions occurring during the dechlorination of chloroform (CF) and 1,1,1-trichloroethane (1,1,1-TCA) by the enrichment culture containing Dehalobacters, hereafter called DHB-CF/MEL. Compound specific isotope analysis (CSIA) is used to investigate the factors which may affect the isotope fractionation observed for CF and 1,1,1-TCA dechlorination. This thesis reports the first isotope enrichment factors observed for CF biodegradation at -27.5‰ ± 0.9‰, thus providing fundamental information for comparing isotope enrichment factors observed during trichlorinated alkane degradation by DHB-CF/MEL. The thesis also reports how the presence of CF and 1,1,1-TCA influences isotope fractionation and explores the possible influence of substrate inhibition on isotope fractionation during 1,1,1-TCA dechlorination. The data suggests that substrate inhibition during 1,1,1-TCA dechlorination by DHB-CF/MEL may not affect carbon isotope fractionation. The results suggest that CSIA is a promising monitoring tool even for the simultaneous biodegradation of CF and 1,1,1-TCA at different 1,1,1-TCA starting concentration.
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Lin, Wan-Ting, and 林宛亭. "Determinations of 1,1,1-Trichloroethane, 1,4-Dioxane, and Phthalates in Water Simultaneously by Solid-Phase Microextraction." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/85811266175893882098.
Full textAbstract:
碩士國立臺灣大學
環境衛生研究所
101
Among contaminants of emerging concern(CECs), 1,4-dioxane is listed in the third contaminant candidate list(CCL3) of the U.S. EPA, while dimethyl phthalate(DMP), diethyl phthalate(DEP), dibutyl phthalate(DBP), butyl benzyl phthalate(BBP), and di (2-ethyl hexyl) phthalate(DEHP) were mentioned by the U.S. Clean Water Act that they should be considered as priority toxic pollutants. On the other hand, 1,1,1-trichloroethane(TCA) is considered to be co-contaminant of 1,4-dioxane. These seven chemicals are widely used and chances are they may enter the drinking water system. To assess the possible health risk, method of determining 1,1,1-trichloroethane, 1,4-dioxane, and phthalates in water simultaneously was developed in this research. Including dimethyl phthalate(DMP), diethyl phthalate(DEP), dibutyl phthalate(DBP), butyl benzyl phthalate(BBP), di (2-ethyl hexyl) phthalate(DEHP), 1,1,1-trichloroethane(TCA), and 1,4-dioxane were prepared in mixtures as the standard solutions. The samples were first equilibrated for 1 minute before the extraction. Hence, the 65 μm PDMS-DVB solid phase microextraction (SPME) fiber was used for direct sample immersion at 30°C for 30 minutes with 250 rpm. Afterwards, the SPME fiber was inserted into the injection port of the gas chromatography-mass spectrometry(GC-MS) for thermal desorption and further analysis. The SPME procedure coupled with GC/MS analysis for the determinations of 1,1,1-trichloroethane, 1,4-dioxane and phthalates in water sample simultaneously was established in this study. No carry-over effect was observed. The linear range of all compounds ranged from 0.5 to 50 μg l-1. Good linearity was presented. However, the precision and accuracy of target compounds in this study did not perform very well. The SPME procedure was applied in this study, while advantages over conventional methods, such as solve-free and time-saving, were reached. Besides, the sensitivities of the method for different compounds were low enough to determine the concentrations from environmental water samples. Further tests are needed to get better precision and accuracy.
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Sun, Lian-Hong, and 孫連鴻. "The Effect of the Primary Substrate Concentration , Sodium Acetate , on the Anaerobic Biodegradation of 1,1,1-Trichloroethane." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/89455088810250419285.
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Jitnuyanont, Pardi. "Comparison of indigenous and bioaugmented butane and propane-utilizers for transforming 1,1,1-trichloroethane in Moffett Field microcosms." Thesis, 1997. http://hdl.handle.net/1957/33964.
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Chan, Kun-Jie, and 詹坤潔. "Residue and Accumulation of Dichloro-Diphenyl-Trichloroethane (DDT) and Its Metabolites and Polychlorinated Biphenyls (PCBs) in Soils, Earthworms, and Moles in Taiwan." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/99347832645909495305.
Full textAbstract:
碩士東海大學
生命科學系
93
Abstract There were few bioaccumulation research reports regarding to the bioaccumulation of organochlorine pesticides (DDT and metabolites) and polychlorinated biphenyls (PCBs) in the food chain of terrestrial ecosystem in Taiwan. The main purpose of this study was to evaluate the residue accumulation of organochlorine pesticides and polychlorinated biphenyls (PCBs) in the terrestrial environment by examining the concentrations of organochlorine pesticides and polychlorinated biphenyls in soils and the tissues of earthworms and moles (Mogera insularis, Mogera sp.). Samples were collected from seven sites including five low elevation sites (Sihshoushan, Taipei; Hambol, Changhua; Jhihsyue, Hualien; Neipu, Pingtung; and Erjen River, Tainan) and two high elevation sites (Lulin Cottage, Tatacha, Nantou and Wasabi Farm, Alishan, Chiayi) in Taiwan. Additional soil samples were collected from three alpine forests, pine, Taiwan spruce, and Chinese hemlock at Tatacha to check the residue status at environments with limited human disturbance. Samples were processed with Soxhelt extraction and clean up procedures before they were introduced into HP gas chromatography with ECD for analysis. ΣDDT were below detection limits at all soil samples collected from the low elevation sites. The total PCBs were at low concentrations: ranged from below detection limit to 5.78 μg/kg. DDE was detected in the samples collected from the high elevation sites and DDT was detected in the samples collected from Lulin Cottage and Wasabi Farm. The highest soil concentrations of DDE and DDT (8.37 ± 3.44μg/kg and 69.15 ± 26.60 μg/kg, respectively) were found in the samples of Wasabi Farm, Alishan. The highest concentration of the total PCBs in soil was found in the sample collected at Tatachia pine forest (63.00 ± 19.95 μg/kg). However, the DDE residue of earthworm was only detected in the samples collected from the mountain areas. The highest concentration was found in the earthworm sample of Lulin Cottage (75.9 μg/kg). The residue of PCBs in earthworm tissue was detected in all study sites: the lowest levels was found in the sample of Hambol (5.1 μg/kg) and the highest levels was found in the sample of Wasabi Farm (111.9 μg/kg). The lowest concentrations of DDE in mole liver and muscle tissue (40.4 ± 19.4 μg/kg and 9.0 ± 3.8 μg/kg, respectively) were found in the samples of Sihshoushan. While the lowest residue level of total PCBs in mole livers and muscle were found at Jhihsyue (101.1 ± 27.7 μg/kg for liver) and Sihshoushan (45.8 ± 4.6 μg/kg for muscle) respectively. However, the highest concentrations of DDE and PCBs residue in mole were found at Alishan. The DDE and total PCBs residue of liver were 1784.2 ± 1108.3 μg/kg and 1732.9 ± 337.1 μg/kg, respectively. While the DDE and total PCBs residue of muscle were 986.0 ± 779.4μg/kg and 496.0 ± 227.7 μg/kg. The concentrations of total PCBs and ∑DDT in the three levels of food-chain at high altitude habitat were greater than the concentrations of total PCBs and ∑DDT detected at low elevation habitat. The total DDT residues in earthworms were 0.7-2.3 times of the residues found in the soil sample. While the concentation of total PCBs in earthworms were 1.6-12.5 times of total PCBs residue in soil. The concentrations of ∑DDT and total PCBs in mole muscle were1.7-13.8 and 2.6-12.9 times of the ∑DDT and total PCBs residues found in earthworms respectively. The bioaccumulation factors of ∑DDT and total PCBs from earthworm to the mole liver were16.2-24.9 and 6.0-25.0 respectively. The bioaccumulation regression model of PCBs established from this study can be applied to predict the residue concentration at higher trophic level such as mole at other study sites. The main component of PCB congeners in the soil samples were hexa- and hepta-PCBs. However, tri-PCBs and tetra-PCBs were the main component in the earthworm samples. While tri- and hepta-PCBs were the main component in mole samples. The residue levels of organochlorine were higher in the samples collected from the cultivated mountain areas than the residue levels of samples collected at the alpine forest with limited human activity. The accumulation of organochlorine residues in the food chain at high elevation habitat may affect the high trophic level of predators which consume mole as its food sources.
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JUBERG, DALAND RICHARD. "A MECHANISTIC INVESTIGATION INTO ORTHO, PARA-DICHLORODIPHENYL-TRICHLOROETHANE-DDT- AND PARA, PARA-DDD-STIMULATED INCREASES IN RAT UTERINE CONTRACTION FREQUENCY EX VIVO (INSECTICIDE, PRETERM BIRTH, PREGNANCY, DICHLORODIPHENYLTRICHLOROETHANE)." 1992. http://books.google.com/books?id=dF49AAAAMAAJ.
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Kokkinaki, Amalia. "Modelling of enhanced anaerobic biodegradation of trichloroethene." 2007. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=788851&T=F.
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Yung-Chun, Wu, and 吳永俊. "Near UV/TiO2 Photovatalytic Decomposition of Trichloroethene." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/89870755831410046370.
Full textAbstract:
碩士國立中山大學
環境工程研究所
84
The photocatalytic decomposition of trichloroethene (TCE) was investigated by near ultraviolet (UV) light illuminated titania (TiO2). The purpose of this investigation was to understand the feasibility of photoocatalytic decomposition of TCE. The effects of reaction parameters on heterogeneous photocatalytic reaction were also studied. The reaction parameters included TCE concentration, relative humidity (R. H.), flow rate (or retention time) and light intensity. In addition, the reaction kinetic was discus sed. The Langmuir- Hinshelwood kinetic equation was commonly used to rationalize the reaction kinetic of TiO2 heterogeneous photocatalytic reaction. If there was no titania, TCE couldn'''' t be degraded by directly irradiated near UV light at the wavelength of 365nm. In this investigation, Degussa P-25 Anatase TiO2 was coated on bead surface, which were then packed into a quartz tube. The highest reaction rate of TCE was 0.63 mmole/s-g at an initial TCE concentration of 29.8 ppm and a relative humidity of 0.6%. Experimental result indicated that the highest conversion of TCE was 100% and the highest quantum yield was 0.92. At a relative humidity of 50%, the reaction rate was controlled by reactant adsorption. At a relative humidity of 20%, reactant adsorption ─ products desorption controlled the reaction rate. The relative humidity was observed to inhibit significantly the reaction rate. The reaction rate decreased with increasing relative humidity and a linear relationship was observed. In addition, the reaction rate increased with increasing near UV light intensity which was the first order reaction of near UV light intensity. A modified
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Yang, Tsung-Hsien, and 楊宗憲. "Removal of Trichloroethene in Soils by Microbubble Ozonation." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/39279774828114626321.
Full textAbstract:
碩士東海大學
環境科學與工程學系
100
It has been well known that microbubble possesses a large surface area as well as a long retention time when it is present in water. When ozone microbubble is generated, both its solubility and half-life in water can be enhanced significantly. In this study, homogeneous and heterogeneous sand columns contaminated with TCE were prepared and flushed with solution containing ozone microbubble to test the removal efficiency of TCE NAPL by this new technique against pure water flushing. Degree of saturation and dissolved ozone concentration are two major parameters examined in both homogeneous and heterogeneous sand columns. From results of homogeneous sand columns, it is evident that the addition of ozone microbubble does not enhance the removal efficiency, compared to pure water flushing, under a high degree of TCE saturation. The enhancement is only evident under conditions of low degrees of TCE saturation. Analogously, the removal efficiency is still limited under a high degree of saturation for heterogeneous sand columns. When the degree of saturation is lowered to 7%, the highest enhancement is observed in heterogeneous sand columns.
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Hageman, Kimberly J. "Measuring in situ reductive dechlorination rates in trichloroethene-contaminated groundwater." Thesis, 2003. http://hdl.handle.net/1957/31130.
Full textAbstract:
Trichloroethene (TCE) is the most frequently detected organic contaminant in groundwater, is
classified as a probable human carcinogen, and exhibits toxicological effects on the human
endocrine, immune, developmental, and reproductive systems. While significant research
efforts have been devoted to the development of strategies for remediating TCE-contaminated
groundwater, their advancement is currently hindered by limitations in current methodologies
for measuring in situ reductive dechlorination rates, especially for sorbing solutes. This
dissertation describes the development, evaluation, and demonstration of a method for
measuring in situ reductive dechlorination rates that utilizes single-well, "push-pull" test
technology. Initial field tests indicated that trichlorofluoroethene (TCFE) could be used as a
surrogate for TCE in push-pull tests since (a) TCE and TCFE were transported similarly and
(b) TCFE underwent reductive dechlorination by a pathway analogous to that of TCE while
retaining the fluorine label. Because TCFE and TCE experienced sorption at the selected field
site, a novel data analysis technique called "forced mass balance" (FMB) was developed to
obtain in situ transformation rates of sorbing solutes from push-pull test data. The FMB
technique was evaluated by quantifying errors in rates derived by applying FMB to push-pull
test data generated by a numerical model. Results from simulated tests indicated that an
example in situ rate for the reductive dechlorination of TCFE, which was obtained by applying
FMB to field data, was underestimated relative to the true in situ rate by 10%. The utility of
the rate-determination method presented in this dissertation was demonstrated by using it to
evaluate the effectiveness of a chemical amendment, namely fumarate, at enhancing in situ
reductive dechlorination rates in TCE-contaminated groundwater. Reductive dechlorination
rates increased following three consecutive additions of fumarate in all five of the tested wells.
The development of the rate-determination method described in this dissertation advances the
state of bioremediation technology because methods for measuring in situ transformation rates
are needed to both assess the potential for natural attenuation and to quantify the effects of
bioremediation techniques in the field.Graduation date: 2003
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Sung, Jing-Hua, and 宋景樺. "Pilot study of trichloroethene-contaminated aquifer using vegetable oil emulsion." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/69136558638548289720.
Full textAbstract:
碩士國立中興大學
環境工程學系所
101
The family of chlorinatd ethenes has been widely used as a solvent and building block in industrial and pharmaceutical manufacturing. Some of the most common chlorinated alipathic hydrocarbons （CAHs） found in groundwater include perchloroethene （PCE）, trichloroethene （TCE）, 1,1,1-trichloroethane （1,1,1-TCA）, carbon tetrachloride （CT）. Enhanced reductive bioremediation （ERB） of halogenated organics has been appliedto reduce CAHs in groundwater. ERB involves the addition of carbon substrates to the subsurface to stimulate anaerobic bacteria capable of reductively dechlorinating CAHs. In this processes, CAHs play the roles as electron accepters, while an electron donor is required to provide energy. Researchers are developing all different kinds of electron doners. Vegetable oil emulsion is one of them that can slowly release hydrogen in the subsurface to enhanced reductive bioremediation. Our study focuses on the first phase of anaerobic reductive dechlorination reactions applying a self-developed soybean oil emulsion for a pilot study. We conducted two experiments on the site. From the first experiment, we know that monitoring wells MW-1 was not affected by injection well IW-1. So we changed the injection methods to improve the radius of influence of the emulsion. In addition to chemical analysis such as CAHs, daughter compounds, inorganic compounds, and total organic carbon, total count of bacteria and denaturing gradient gel electrophoresis were alos performed. We found that in injection wells IW-1 and IW-2, 21 days after the injection, TCE concentrations were already less than detection limit. In IW-2, 1,1-DCE dropped from 127.2 μg/L to 27.3 μg/L 95 days after injection. Thus we confirmed that this soybean oil emulsion can effectively enhanc 1,1-DCE and TCE biodegradation in a real world situation.
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Chang, Yen-Chen, and 張晏禎. "Reactivity of trichloroethene with nano zero-valent irons in oil phase." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/42248046006876791918.
Full textAbstract:
碩士國立臺灣大學
環境工程學研究所
101
Due to the special characteristics of dense non-aqueous phase liquids (DNAPLs), singnificant solubility and low mobility, the contamination of soil and groundwater by DNAPLs is still an intractable problem for environmental engineers. Even more, if DNAPLs were transported to impermeable boundary, they would form DNAPL pools and become continuous contamination sources. The application of nano zero-valent iron (nZVI) in soil and groundwater treatment is given increasing attention because of its high surface reactivity and transportation ability in the underground. However, the researches about the reaction of chlorinated aliphatic hydrocarbons with nZVI were mostly conducted in aqueous phase instead of in non-aqueous phase. The purpose of this research is to investigate the reaction rates and pathways of trichloroethene reduction by different nZVI with different water content and to shed light on the theory and values of the empirical parameters of the reaction. The results show that nZVI and bimetallic nZVI could reduce trichloroethene in non-aqueous phase. The trichloroethene reduction by physical vapor deposition (PVD) iron (F), PVD bimetallic iron (DF) and surface modified bimetallic iron (ADF) in non-aqueous phase were better to explained by zero-order reaction kinetics. The zero-order reaction rate, kSA, are 1.891×10-5，6.272×10-5，5.066×10-5 (mmol∙L∙h-1∙m-2). In this research, the molar equivalent of trichloroethene was higher than that of nZVI, so that the hydrogen ion produced was consumed immediately and its activity was low in the microcosm systems. The reduction rates of trichloroethene in non-aqueous phase are much slower than the rates in aqueous phase. Under the same nZVI dosage with different water content, the kSA with higher water content is higher in DF group, but with no significant difference in F and ADF groups.
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Li, Dong Lin, and 李東霖. "Fabrication of Zerovalent Iron/Reduced Graphene Oxide Nanocomposites for Dechlorination of Trichloroethene." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/15701969961873086125.
Full textAbstract:
碩士國立清華大學
生醫工程與環境科學系
104
Nanoscale zerovalent iron (nZVI) has been widely used in environmental remediation. It has low toxicity, abundance in the world, suitable potential for triggering the reduction make it a promising material in decades. However, the ferromagnetism of ZVI nanoparticles leads to aggregation, causing low reactivity and mobility. In recent years, using solid supports for nZVI is one of the methods enhancing its reactivity. In this study, a facile approach for the synthesis and immobilization of ZVI nanoparticles onto reduced graphene oxide (rGO) have developing by adding NaBH4 as reducing agent. By adjusting the weight ratio between iron precursors and graphene oxide, we can purchase the well-dispersed ZVI nanoparticles on reduced graphene oxide. In this study, the diameter of particles of rGO-Fe nanocomposites was about 44.1 nm. Its pseudo-first rate constant (kobs) of TCE degradation can reach to 9.40×10-3 h-1, which was 3 times higher than conventional ZVI. Due to synergetic effect, adding second metal ions can significantly enhanced the reactivity of rGO-Fe nanocomposites. The kobs for TCE degradation were 5.89, and 53.6 h-1 at 1.877 mM Ni(II), 0.105 mM Pd(II). Both of them are much higher than rGO-Fe nanocomposites alone ( 9.40×10-3 h-1). The result obtained in this study proving that immobilization of ZVI nanoparticles on reduced graphene oxide is successful in water treatment. Its high reactivity and large surface area make it have potential developing in multifunctional use in environmental application.
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Tsou, Feng-Ju, and 鄒奉儒. "Fabrication of multifunctional C/ZVI/TNT nanocomposites for the degradation of trichloroethene." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/51999349790805004970.
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Chien, Wei-Chieh, and 簡緯杰. "Comparing biological and non-biological mechanisms on trichloroethene degradation by compost samples." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/6sxdyz.
Full textAbstract:
碩士明志科技大學
環境與安全衛生工程系環境工程碩士班
104
Compost samples were selected as electron and microbial sources for trichlorethylene (TCE) reduction with initial concentration of 300μM. The effects of different compost maturity and different preparation procedures on the biotic and abiotic transformation of TCE were evaluated. The pH and ORP values in the system were observed during the experimental period of time. The conversion of iron sulfide crystal phase were analyzed by XRD method at end of experiment. Experimental results showed that two compost samples with different maturity had the ability to reduce TCE, and 3-month bagasse compost sample had better dechlorination capacity than 0-month sample. Three different operation procedures, including biotic, coexistence, and abiotic treatments, showed different effects on dechlorination efficiency. When the compost samples were prepared in solid form, the biotic treatment demonstrated better dechlorination efficiency than the abiotic treatment. However, when the compost samples were prepared in liquid form, the reverse result was observed. When the compost samples were prepared in either solid or liquid form, the coexistence treatment could reduce the most amount of TCE. The probably explanation was resulting from that the solid form of compost sample, no matter bagasse sample or 3-month bagasse compost sample, could provide larger amount of electron donor for TCE reduction in the biotic treatment than in the abiotic treatment. In contrast, when the compost was prepared in liquid form, the compost sample were not covered by the iron sulfide crystal, and thus the abiotic treatment had better reduction performance. In addition, the abiotic treatment showed higher pH (0LC = 7.6、3LC = 8.8), and favored the electron transfer process for TCE reduction. The XRD analysis suggested the main crystal form of iron sulfide was goethite when the compost was prepared in the solid form; while the main crystal form was mackinawite in the liquid form. Although different mineral form of iron sulfide had different reduction capacity for TEC dechlorination, the experimental data showed that all the mineral forms of iron sulfide could favor TCE reduction process.
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Roberts, Jeffery. "Bench Scale Performance of Partitioning Electron Donors for TCE DNAPL Bioremediation." Thesis, 2008. http://hdl.handle.net/10012/3645.
Full textAbstract:
Prior to the implementation of an enhanced bioremediation pilot study for a trichloroethene (TCE) source area at an industrial site in the United Kingdom (the Site), laboratory microcosm and column studies were performed. The purpose of this column study was to determine if TCE removal rates could be increased with the addition of partitioning electron donors and bioaugmentation with KB-1® culture. Three 1-meter continuous flow columns were constructed using aquifer solids from the Site and artificial groundwater. A TCE dense non-aqueous phase liquid (DNAPL) zone was emplaced in each column. SRS™, a commercially available emulsified vegetable oil (EVO) product, and n-butyl acetate (nBA) were evaluated as partitioning electron donors, while the third column acted as an unamended control. Both nBA and SRSTM were successfully used in previous microcosm studies with high concentrations of TCE (400 and 800 mg/L) to successfully promote the reductive dechlorination of TCE to ethene.
Dechlorination of TCE to cis-1,2-dichloroethene (cis-DCE) with trace amounts of vinyl chloride (VC) and ethene, as well as sulfate reduction, were observed in the SRSTM column effluent while DNAPL was present. A dissolution enhancement factor of 2.1 was calculated. The TCE source zone was depleted after approximately 300 days of column operation. Following depletion of the TCE DNAPL, high concentration (~400 mg/L) of TCE amended artificial groundwater was pumped through the column to simulate high TCE concentrations in a plume down gradient from a source zone. Dechlorination of TCE via cis-DCE and VC to ethene was observed in the column effluent along with increases in Dehalococcoides (Dhc) counts. Sulfate concentrations increased during the plume phase while dechlorination to ethene still occurred indicating that complete dechlorination to ethene was possible in the presence of sulfate.
Dechlorination of TCE to cis-DCE was observed, but neither VC nor ethene was detected in the nBA Amended column. The nBA was observed to degrade in the column to butyl alcohol and acetate, neither of which partition as strongly as nBA, and were not retained in the column. A continuous addition of nBA promoted the highest amount of cis-DCE production and sulfate reduction was also observed. Once the continuous addition was stopped, dechlorination and sulfate reduction halted indicating that electron donor retention in the column was not achieved. Dehalococcoides (Dhc) concentrations did not increase in the effluent of this column. A dissolution enhancement factor of 1.2 was calculated for the nBA column.
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Chan, Winnie Wing Man. "Characterization of Reductive Dehalogenases in a Chlorinated Ethene-degrading Bioaugmentation Culture." Thesis, 2010. http://hdl.handle.net/1807/24242.
Full textAbstract:
Perchloroethene and trichloroethene are among the most persistent groundwater pollutants, and Dehalococcoides is the only known species that can degrade these compounds completely to non-toxic ethene. Characterization of the reductive dehalogenase (RDase) enzymes responsible for dechlorination is important to understanding this process. A series of dechlorination assays were performed with whole cell suspensions and cell-free extracts of three Dehalococcoides-containing mixed microbial consortia to compare dechlorination kinetics and to characterize co-contaminant inhibition. Michaelis-Menten kinetic parameters Vmax and Km, as well as non-competitive inhibition coefficients for 1,1,1-trichloroethane and 1,1-dichloroethane inhibitors are reported. Secondly, blue native gel electrophoresis was developed as a method to isolate active protein complexes containing RDases. Thirdly, sources of variability in the isotopic fractionation of vinyl chloride to ethene reaction step were examined using cell-free extracts and whole-cell suspensions. Understanding the function and range of RDases are goals towards the successful application of Dehalococcoides-containing cultures to remediate contaminated sites.
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Sharmeen, Rubaiat. "Hydraulic Tomography and Trichloroethene Dissolution in a Fractured Dolostone: Small Scale Laboratory Experiments." Thesis, 2011. http://hdl.handle.net/10012/6419.
Full textAbstract:
In fractured geologic media, flow and contaminant transport are predominantly controlled by the fractures, their distribution and connectivity. The accurate characterization of fractured geologic medium, imaging of fracture patterns and their connectivity have been a challenge for decades. Given the complexities of fractured networks in the subsurface and Dense Non Aqueous Phase Liquid (DNAPL) contamination, in this thesis, transient hydraulic tomography (THT), a recently developed tool for characterizing aquifer heterogeneity is evaluated under laboratory conditions to delineate discrete fractures. Laboratory experiments and modeling studies are also conducted to understand TCE plume behavior.
A dolomite rock sample, which is 91.5 cm in length, 60.5 cm in height and 5 cm thick, was fractured in the laboratory to perform the experiments. After the fractured block was enclosed in a flow cell, flow-through and pumping tests were conducted to characterize the fractured rock block. The data from the pumping tests were then analyzed using the SSLE code developed by Zhu and Yeh [2005] and transient hydraulic tomography (THT) was conducted to image the fracture pattern and their connectivity through the delineation of K and Ss distributions (the tomograms). Synthetic pumping tests, identical in configuration to the laboratory ones were also conducted using HydroGeoSphere (HGS) [Therrien et al, 2009] in a synthetic replica of the fractured block to compare the observed and simulated drawdowns. Then synthetic THT analysis was performed utilizing the synthetic pumping test data to compare the tomograms obtained from the THT analysis of synthetic and laboratory pumping tests.
Results suggest that the THT analysis of multiple laboratory pumping tests captured the fracture pattern and their connectivity quite well and they became more vivid with the additional pumping tests. The estimated high hydraulic conductivity (K) and low specific storage (Ss) zones clearly show the fractures and their connectivity. The pattern of K and Ss tomograms obtained from the analyses of synthetic and laboratory pumping tests were similar. Estimated K and Ss values for the fractures and the matrix may not exactly replicate the actual K and Ss values for the fractured rock, but the model also provides uncertainty estimates associated with the resulting K and Ss tomograms.
In this study, two cases of transient hydraulic tomography (THT) analysis of the laboratory pumping tests were performed by changing the location of 2nd and 3rd pumping tests among the three to examine if there is any significant impact of these pumped location on the pattern of resulting hydraulic conductivity (K) and specific storage (Ss). The initial pumping test was the same for two cases. Results show that the patterns of estimated K and Ss tomograms obtained from these two cases are similar, although the pumped locations (2nd and 3rd tests among the three) utilized for the inversion were different for two cases suggesting that the location of these later pumping tests does not significantly impact the estimates for this fractured rock block. However, the initial test should be selected carefully as that seems to set the pattern of the tomograms.
The estimated K and Ss tomograms were validated by predicting five independent pumping tests conducted in the fractured rock block. These five pumping tests were not included during the construction of the K and Ss tomograms. For most of the independent pumping tests, good correspondence between the simulated and observed drawdown was achieved.
The study indicates that, it is possible to delineate discrete fractures, their pattern and connectivity by carefully applying of THT analysis of multiple pumping tests based on the inverse code SSLE [Zhu and Yeh, 2005]. In addition, hydraulic tomography seems to be a cost effective tool for characterizing fractured rock since it does not require the detailed information on fracture geometry parameters such as aperture, trace length, orientation, spatial distribution, and connectivity, which are difficult to quantify. These parameters are usually unavailable between boreholes. Therefore, THT appears to be a promising approach in delineating fractures and their connectivity in subsurface. However, it is still at the early stage as the study was conducted in the laboratory under controlled conditions. Small scale field experiments need to be conducted to validate THT as a tool for the characterization of hydraulic parameters of fractured rocks.
Upon completion of the hydraulic characterization, several conservative tracer tests were conducted using bromide (Br-) as a conservative tracer to aid in the design of TCE dissolution experiment. Once the tracer experiments were completed, a known volume of pure phase TCE was injected at a known location in the flow cell to create a well-defined source zone. A constant hydraulic gradient was maintained by fixing the hydraulic heads at the two head tanks to induce steady groundwater flow through the flow cell. Water samples were obtained at a down gradient monitoring port for 3 months to obtain a long-term breakthrough curve of TCE in the aqueous phase. The purpose of this experiment was to study TCE dissolution behaviour in the fractured rock sample. Then HydroGeoSphere (HGS) was used to model the aqueous phase TCE transport using two separate approaches: 1) the Discrete Fracture Network modeling approach and 2) the stochastic continuum approach, to investigate whether they can capture the dissolution behavior.
Both approaches were able to capture the pattern of the breakthrough curve in the fractured rock. The discrete fracture approach captured the observed TCE plume and the dissolution behavior quite well. On the other hand, the stochastic continuum approach, in which the fractured rock block was treated as porous medium having a heterogeneous K field obtained from THT analysis, also appeared to be promising in capturing the aqueous phase transport of TCE. Despite some early time deviation, the simulated breakthrough curve captured the overall observed concentration profile. However, the stochastic continuum approach seems to be more cost effective as it does not require detailed information about fracture aperture and their spatial distribution which are difficult if not impossible to obtain between boreholes. Note that, the studies were conducted based on a laboratory experiment conducted in a controlled environment. The experimental block was well characterized and the geometry of the experimental block as well as the flow through the system was well understood from the hydraulic and tracer experiments. Thus small scale field experiment is required to support this conclusion.