Rozprawy doktorskie na temat „Permeable reactive barrier”
Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Permeable reactive barrier.
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Permeable reactive barrier”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Abunada, Ziyad. "Innovative soil mix technology constructed permeable reactive barrier for groundwater remediation". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709154.
Pełny tekst źródła
2
Painter, Brett Duncan Murray. "Optimisation of permeable reactive barrier systems for the remediation of contaminated groundwater". Phd thesis, Lincoln University. Environment, Society and Design Division, 2005. http://theses.lincoln.ac.nz/public/adt-NZLIU20061220.151030/.
Pełny tekst źródłaStreszczenie:
Permeable reactive barriers (PRBs) are one of the leading technologies being developed in the search for alternatives to the pump-and-treat method for the remediation of contaminated groundwater. A new optimising design methodology is proposed to aid decision-makers in finding minimum cost PRB designs for remediation problems in the presence of input uncertainty. The unique aspects of the proposed methodology are considered to be: design enhancements to improve the hydraulic performance of PRB systems; elimination of a time-consuming simulation model by determination of approximating functions relating design variables and performance measures for fully penetrating PRB systems; a versatile, spreadsheet-based optimisation model that locates minimum cost PRB designs using Excel's standard non-linear solver; and the incorporation of realistic input variability and uncertainty into the optimisation process via sensitivity analysis, scenario analysis and factorial analysis. The design methodology is developed in the context of the remediation of nitrate contamination due to current concerns with nitrate in New Zealand. Three-dimensional computer modelling identified significant variation in capture and residence time, caused by up-gradient funnels and/or a gate hydraulic conductivity that is significantly different from the surrounding aquifer. The unique design enhancements to control this variation are considered to be the customised down-gradient gate face and emplacement of funnels and side walls deeper than the gate. The use of velocity equalisation walls and manipulation of a PRB's hydraulic conductivity within certain bounds were also found to provide some control over variation in capture and residence time. Accurate functional relationships between PRB design variables and PRB performance measures were shown to be achievable for fully penetrating systems. The chosen design variables were gate length, gate width, funnel width and the reactive material proportion. The chosen performance measures were edge residence, centreline residence and capture width. A method for laboratory characterisation of reactive and non-reactive material combinations was shown to produce data points that could realistically be part of smooth polynomial interpolation functions. The use of smooth approximating functions to characterise PRB inputs and determine PRB performance enabled the creation of an efficient spreadsheet model that ran more quickly and accurately with Excel's standard non-linear solver than with the LGO global solver or Evolver genetic-algorithm based solver. The PRB optimisation model will run on a standard computer and only takes a couple of minutes per optimisation run. Significant variation is expected in inputs to PRB design, particularly in aquifer and plume characteristics. Not all of this variation is quantifiable without significant expenditure. Stochastic models that include parameter variability have historically been difficult to apply to realistic remediation design due to their size and complexity. Scenario and factorial analysis are proposed as an efficient alternative for quantifying the effects of input variability on optimal PRB design. Scenario analysis is especially recommended when high quality input information is available and variation is not expected in many input parameters. Factorial analysis is recommended for most other situations as it separates out the effects of multiple input parameters at multiple levels without an excessive number of experimental runs.
3
Painter, Brett D. M. "Optimisation of permeable reactive barrier systems for the remediation of contaminated groundwater". Diss., Lincoln University, 2005. http://hdl.handle.net/10182/12.
Pełny tekst źródłaStreszczenie:
Permeable reactive barriers (PRBs) are one of the leading technologies being developed in the search for alternatives to the pump-and-treat method for the remediation of contaminated groundwater. A new optimising design methodology is proposed to aid decision-makers in finding minimum cost PRB designs for remediation problems in the presence of input uncertainty. The unique aspects of the proposed methodology are considered to be: design enhancements to improve the hydraulic performance of PRB systems; elimination of a time-consuming simulation model by determination of approximating functions relating design variables and performance measures for fully penetrating PRB systems; a versatile, spreadsheet-based optimisation model that locates minimum cost PRB designs using Excel's standard non-linear solver; and the incorporation of realistic input variability and uncertainty into the optimisation process via sensitivity analysis, scenario analysis and factorial analysis. The design methodology is developed in the context of the remediation of nitrate contamination due to current concerns with nitrate in New Zealand. Three-dimensional computer modelling identified significant variation in capture and residence time, caused by up-gradient funnels and/or a gate hydraulic conductivity that is significantly different from the surrounding aquifer. The unique design enhancements to control this variation are considered to be the customised down-gradient gate face and emplacement of funnels and side walls deeper than the gate. The use of velocity equalisation walls and manipulation of a PRB's hydraulic conductivity within certain bounds were also found to provide some control over variation in capture and residence time. Accurate functional relationships between PRB design variables and PRB performance measures were shown to be achievable for fully penetrating systems. The chosen design variables were gate length, gate width, funnel width and the reactive material proportion. The chosen performance measures were edge residence, centreline residence and capture width. A method for laboratory characterisation of reactive and non-reactive material combinations was shown to produce data points that could realistically be part of smooth polynomial interpolation functions. The use of smooth approximating functions to characterise PRB inputs and determine PRB performance enabled the creation of an efficient spreadsheet model that ran more quickly and accurately with Excel's standard non-linear solver than with the LGO global solver or Evolver genetic-algorithm based solver. The PRB optimisation model will run on a standard computer and only takes a couple of minutes per optimisation run. Significant variation is expected in inputs to PRB design, particularly in aquifer and plume characteristics. Not all of this variation is quantifiable without significant expenditure. Stochastic models that include parameter variability have historically been difficult to apply to realistic remediation design due to their size and complexity. Scenario and factorial analysis are proposed as an efficient alternative for quantifying the effects of input variability on optimal PRB design. Scenario analysis is especially recommended when high quality input information is available and variation is not expected in many input parameters. Factorial analysis is recommended for most other situations as it separates out the effects of multiple input parameters at multiple levels without an excessive number of experimental runs.
4
Bulley, Jonathan A. "Improving performance of a permeable reactive barrier in the degradation of trichloroethylene using ultrasound". FIU Digital Commons, 2004. http://digitalcommons.fiu.edu/etd/1820.
Pełny tekst źródłaStreszczenie:
The impact of ultrasound on improving the performance of a granular iron Permeable Reactive Barrier (PRB) in the degradation of Trichloroethylene (TCE) was evaluated.
Two treatment columns made of clear Plexiglas with a height of 1ft and a diameter of 2 inches and filled with granular iron were used. One was fitted with 25Khz ultrasound probes. A solution of TCE was run through at constant flow rate. Samples obtained from the column at different residence times before and after sonication were analyzed for concentrations of TCE and used to generate concentration profiles to obtain rate constants, which were compared.
An improvement of 23.4% in the reaction rate of TCE degradation was observed after sonication of the iron media suggesting that ultrasound may contribute to improving the performance of PRBs in the degradation of TCE in contaminated groundwater.
5
Ulsamer, Signe Martha. "A Model to Characterize the Kinetics of Dechlorination of Tetrachloroethylene and trichloroethylene By a Zero Valent Iron Permeable Reactive Barrier". Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-theses/979.
Pełny tekst źródłaStreszczenie:
"A one dimensional, multiple reaction pathway model of the dechlorination reactions of trichloroethylene (TCE) and tetrachloroethylene (PCE) as these species pass through a zero valent iron permeable reactive barrier (PRB) was produced. Three different types of rate equations were tested; first order, surface controlled with interspecies competition, and surface controlled with inter and intra species competition. The first order rate equations predicted the most accurate results when compared to actual data from permeable reactive barriers. Sensitivity analysis shows that the most important variable in determining TCE concentration in the barrier is the first order rate constant for the degradation of TCE. The velocity of the water through the barrier is the second most important variable determining TCE concentration. For PCE the concentration in the barrier is most sensitive to the velocity of the water and to the first order degradation rate constant for the PCE to dichloroacetylene reaction. Overall, zero valent iron barriers are more effective for the treatment of TCE than PCE. "
6
Luo, Ping. "Quantification of morphological changes in zero valent iron (ZVI) : effect on permeable reactive barrier (PRB) longevity". Thesis, University of Nottingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503921.
Pełny tekst źródłaStreszczenie:
Permeable Reactive Barriers (PRBs) have been used world-wide to remediate chlorinated solvents, metals and radionuclides from contaminated groundwater by precipitation, sorption, ion exchange and biodegradation in the last two ;ades. There is still however limited information regarding the formation of byproducts and subsequent pore clogging with respect to attaining the predicted, significant life spans (>50 years), even on the most popular PRE materials such as ZVI. This project aimed to visually examine and quantify morphological :hanges on ZVI barriers and subsequently to quantify the PRE longevity due to the occlusions.
7
Doherty, R. D. "Modelling of a permeable reactive barrier (PRB) in a manufactured gas plant site, Portadown, Northern Ireland". Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269086.
Pełny tekst źródła
8
McGeough, K. L. "Kinetics of contaminant removal : a comparative study of site specific treatability studies for permeable reactive barrier design". Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426659.
Pełny tekst źródła
9
Lai, Chun Kit. "Laboratory and full-scale studies of a permeable reactive barrier on the dechlorination of chlorinated aliphatic hydrocarbons /". View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20LAI.
Pełny tekst źródłaStreszczenie:
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 203-227). Also available in electronic version. Access restricted to campus users.
10
Uyusur, Burcu. "Laboratory Investigation Of The Treatment Of Chromium Contaminated Groundwater With Iron-based Permeable Reactive Barriers". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607550/index.pdf.
Pełny tekst źródłaStreszczenie:
Chromium is a common groundwater pollutant originating from industrial processes such as metal plating, leather tanning and pigment manufacturing. Permeable reactive barriers (PRBs) have proven to be viable and cost-effective systems for remediation of chromium contaminated groundwater at many sites. The purpose of this research presented in this thesis is to focus on two parameters that affect the performance of PRB on chromium removal, namely the concentration of reactive media and groundwater flux by analyzing the data obtained from laboratory column studies. Laboratory scale columns packed with different amounts of iron powder and quartz sand mixtures were fed with 20 mg/l chromium influent solution under different fluxes. When chromium treatment
efficiencies of the columns were compared with respect to iron powder/quartz sand ratio, the amount of iron powder was found to be an important parameter for treatment efficiency of PRBs. The formation of H2 gas and the reddish-brown precipitates throughout the column matrix were observed, suggesting the reductive precipitation reactions. SEM-EDX analysis of the iron surface after the breakthrough illustrated
chromium precipitation. In addition to chromiumcalcium and significant amount of iron-oxides or -hydroxides was also detected on the iron surfaces. When the same experiments were conducted at higher fluxes, an increase was observed in the treatment efficiency in the column containing 50% iron. This suggested that the precipitates may not be accumulating at higher fluxes which, in turn, create available surface area for reduction. Extraction experiments were also performed to determine the fraction of chromium that adsorbed to ironhydroxides. The analysis showed that chromium was not removed by adsorption to oxyhydroxides and that reduction is the only removal mechanism in the laboratory experiments. The observed rate of Cr(VI) removal was calculated for each reactive mixture which ranged from 48.86 hour-1 to 3804.13 hour-1. These rate constants and complete removal efficiency values were thought to be important design parameters in the field scale permeable reactive barrier applications.
11
Madaffari, Maria Grazia. "New mixtures to be used in permeable reactive barrier for heavy-metals contaminated groundwater remediation : long-term removal efficiency and hydraulic behavior". Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2015. http://www.theses.fr/2015ECAP0025/document.
Pełny tekst źródłaStreszczenie:
La dépollution des eaux souterraines est actuellement une des principaux défis environnementaux, considérant le nombre de sites contaminés et le risque posé à la santé humaine et à l'environnement par l'exposition à la contamination des eaux souterraines. La barrière réactive perméable (PRB) est une technologie in situ passive pour la remédiation des eaux souterraines contaminées. Il se compose d'une barrière placée perpendiculairement à l'écoulement des contaminants et constituée d'un matériau réactif qui traite la panache de contaminants le traversant sous le gradient hydraulique naturel. C’est la technologie de remédiation des eaux souterraines la plus rentable ; elle permet l'utilisation des terres de surface et réduit l'exposition des travailleurs aux polluants. Le matériau réactif le plus utilisé est le fer à valence zéro (ZVI), qui peut dépolluer l'eau souterraine contaminée par une large gamme de contaminants au moyen de mécanismes chimiques et physiques différents. Le problème principal de l'utilisation de ZVI granulaire est la réduction de la porosité du milieu poreux, en raison de la nature expansive de produits de corrosion, des précipités et la formation de gaz. Pour surmonter ce problème, des mélanges de matériaux granulaires et ZVI ont été testés afin de déterminer leur efficacité de dépollution et le comportement hydraulique à long terme. L'utilisation de Lapillus volcaniques à mélanger avec ZVI pour dépolluer les eaux souterraines contaminées par métaux lourds est proposée dans ce travail. Des essais sur Lapillus ont montré une efficacité d'élimination de métaux lourds non négligeable, tandis que les tests en colonne effectuée en utilisant des mélanges n’ont pas montré une réduction élevée de la conductivité hydraulique au cours du temps.La modélisation des essais batch et colonne en tant qu’outil pour la compréhension des mécanismes impliqués dans les milieux poreux réactifs a été mis en place. L’étude de la sensibilité des paramètres des modèles sur leurs réponses a également été exploréeGroundwater remediation is currently one of the major environmental challenges, considering the number of contaminated sites and the risk posed to human health and to the environment by exposure to groundwater contamination. Permeable reactive barrier (PRB) is a passive in situ technology for the remediation of contaminated groundwater. It consists of a barrier placed perpendicularly to the contaminant flow and made of reactive material that treats contaminant plume flowing through it under the natural hydraulic gradient. It is the most cost-effective groundwater remediation technology; it allows the use of surface land and reduces the exposure of workers to contaminants. The most used reactive material is Zero Valent Iron (ZVI), which is able to remediate groundwater contaminated by a large range of contaminants by means of different chemical and physical mechanisms. The main issue of granular ZVI use regards the reduction of the porous medium porosity, because of the expansive nature of corrosion products, precipitates and gas formation. To overcome this problem, mixtures of ZVI and granular materials were tested to investigate their long-term removal efficiency and hydraulic behavior. The use of volcanic Lapillus to be mixed with ZVI to remediate heavy-metals contaminated groundwater is proposed in this work. Tests on Lapillus showed a not negligible heavy metal removal efficiency of the volcanic material, while the hydraulic monitoring of column tests performed using mixtures showed a not high reduction of hydraulic conductivity over time.Modelling batch and column tests as a tool for understanding the mechanisms involved in the reactive porous media has been set up. The analysis of the sensitivity of the models response with respect to the input parameters has also been explored
12
Callahan, Thomas Patrick. "Non-Newtonian fluid injection into granular media". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39618.
Pełny tekst źródłaStreszczenie:
The process of fluid injection into granular media is relevant to a wide number of applications such as enhanced oil recovery, grouting, and the construction of permeable reactive barriers. The response of the subsurface is dependent on multiple factors such as in-situ stresses, fluid properties, flow rate, and formation type. Based on these conditions a variety of response mechanisms can be initiated ranging from simple porous infiltration to hydraulic fracturing.
Currently, the mechanics of fluid injection into competent rock are well understood and can be sufficiently modeled using linear elastic fracture mechanics. Because the grains in rock formations are individually cemented together, they exhibit cohesion and are able to support tensile stresses. The linear elastic method assumes tensile failure due to stress concentrations at the fracture tip. A fracture propagates when the stress intensity factor exceeds the material toughness (Detournay, 1988)
However, understanding fluid injection in cohesionless granular media presents a much larger obstacle. Currently, no theoretical models have been developed to deal with granular media displacements due to fluid injection. Difficulty arises from the complexity of fluid rheology and composition used in engineering processes, the strong coupling between fluid flow and mechanical deformation, the non-linear response of subsurface media, and the multi-scale nature of the problem.
The structure of this thesis is intended to first give the reader a basic background of some of the fundamental concepts for non-Newtonian fluid flow in granular media. Fluid properties as well as some interaction mechanisms are described in relation to the injection process. Next, the results from an experimental series of injection tests are presented with a discussion of the failure/flow processes taking place.
We developed a novel technique which allows us to visualize the injection process by use of a transparent Hele-Shaw cell. Specifically, we will be using polyacrylamide solutions at a variety of concentrations to study non-Newtonian effects on the response within the Hele-Shaw cell. By performing tests at a range of solution concentrations and injection rates we are to be able to identify a transition from an infiltration dominated flow regime to a fracturing dominated regime.
13
Newton, B. T. "Applied gas tracing or permeable reactive barriers (PRBs)". Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602710.
Pełny tekst źródłaStreszczenie:
The aim of my thesis is to evaluate the use of applied dissolved noble gas tracers for the estimation of flow and transport parameters in permeable reactive barriers (PRBs) and for the assessment of changes in those parameters over time. PRBs consist of reactive materials that are p l aced in the subsurface to intercept a contaminant plume. PRBs have been proven to effectively remediate a variety of groundwater contaminants. The main limitation to the use PRBs as a remediation tool is the build up of mineral precipitates and gases that may inhibit water flow through the barrier, decrease the reactivity of the PRB medium, and reduce the residence time of contaminated water. Applied chemical tracers provide the most direct measurement of how water moves through PRBs to assess the effects of mineral precipitation and gas evolution on flow and transport parameters in PRBs. Tracer experiments in laboratory columns and full scale permeable reactive barriers are described in detail , highlighting advantages and disadvantages of using noble gases as applied tracers. The volatility of noble gases presents advantages and disadvantages. The retardation of dissolved gas tracers, as a result of interactions with gas bubbles trapped in pore spaces, provides information about the volume of a gas phase that is present in the system. However, the degassing of dissolved gas tracers during tracer injection, sampling , and sample preparation can result in many uncertainties with respect initial tracer concentrations. These uncertainties are best dealt with by using multiple noble gas tracers along with a "conservative" tracer such as Bromide or Chloride. This thesis demonstrates that noble gases can be used effectively as applied tracers to assess the long - term effectiveness of PRBs.
14
Audí, Miró Carme. "Compound Specific Isotope Analysis ((13)C, (37)Cl,( 2)H) to trace induced attenuation of chlorinated organic contaminants in groundwater". Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/145921.
Pełny tekst źródłaStreszczenie:
Chloroform (CF), tetrachloroethene (PCE) and trichloroethene (TCE) are dense chloro-aliphatic hydrocarbons (CAH) extensively used as industrial solvents. These compounds have been largely released to the environment due to poor waste management.
In this thesis, the effect of a ZVI-PRB installed at a field site contaminated mainly with PCE, TCE and cis-DCE was evaluated. Moreover, a novel strategy to degrade the recalcitrant CF -alkaline hydrolysis induced by concrete-based recycled construction wastes- was proposed and developed in order to test its efficiency in degrading this pollutant. Compound specific isotope analysis (CSIA) is a valuable tool for monitoring an environmental treatment in the field, based on the isotope fractionation of an element during transformation reactions.
Therefore, the general aim of this thesis is to use compound specific isotope analysis of 13C, 37Cl and 2H as a tool to assess both induced attenuation processes 1) chlorinated ethenes degradation by a ZVI-PRB installed at the field sited; and, 2) the proposed new remediation technique based on the use of concrete-based recycled construction wastes to degrade chloroform (CF) by alkaline hydrolysis applied at a site contaminated by this pollutant.
First, laboratory experiments were conducted to study both ZVI and concrete effects on the chlorinated ethenes and the chloroform, respectively. ZVI experiments yielded carbon isotope fractionation values of the chlorinated ethenes degradation by the specific ZVI used in the field application, as well as, the first chlorine isotope fractionation values of TCE and cis-DCE associated to this reaction. Two promising approaches to discriminate the abiotic ZVI degradation versus biotic degradation present at the field site were brought forward 1) the dual isotope C-Cl approach, which distinguished slopes 4 times lower than for biodegradation of cis-DCE by the commercially available Dehalococcoides-containing culture mixed culture KB-1; and 2) the product-specific carbon isotope fractionation that showed a 10‰ difference between those products coming from β-dichloroelimination and hydrogenolysis reactions. Concrete experiments with CF achieved a 95% CF degradation after 28 d, accompanied by a significant carbon isotope fractionation. The carbon isotopic fractionation associated with alkaline hydrolysis of CF was -53±3‰.
The obtained laboratory data permitted the assessment of the respective induced degradation treatments applied at the field site. At the site with the ZVI-PRB treatment, both, occurrence of biodegradation and degradation by ZVI-PRB were evidenced by means of detected metabolites and 13C data, with quantitative estimates of ZVI-PRB efficiency of less than 10% and 2% for PCE and cis-DCE, respectively. Dual element 13C-37Cl isotope plots confirmed that the effect of the ZVI-PRB was masked by biodegradation. Based on carbon isotopes data, 49% and almost 100% of PCE and TCE, respectively, were estimated to be removed by biodegradation. Finally the combination of 2H with 13C and 37Cl discriminated two different sources of contamination spilled from the same industry. This indicates the potential of δ2H to discriminate if a compound is of industrial origin, or whether it is formed as a daughter product during degradation. Regarding CF hydrolysis, field-scale pilot experiments were used to test the efficiency of the concrete-base recycled construction wastes to induce alkaline hydrolysis. The carbon isotopic fractionation obtained at the lab scale allowed the calculation of the percentage of chloroform degradation in the field-scale pilot experiments where alkaline conditions were induced in two recharge water interception trenches filled with concrete-based construction wastes. A maximum of approximately 30-40% of chloroform degradation was achieved. Although further research is required, the treatment of chloroform in groundwater through the use of concrete-based construction wastes is proposed. This strategy would also imply the recycling of construction and demolition wastes for use in value-added applications to increase economic and environmental benefits.El chloroform (CF), el tetracloroetè (PCE) i el tricloretè (TCE) són hidrocarburs clor-alifàtics densos usats extensament com a solvents industrials. Aquests compostos s’han alliberat al medi degut a un tractament inadequat dels seus residus. En aquesta tesi, l’efecte d’una barrera permeable reactiva de ferro zero valent (BPR-FZV) instal•lada en un emplaçament contaminat majoritàriament amb PCE, TCE i cis-dicloretè (cis-DCE, subproducte de TCE) ha estat avaluada. A més a més, s’ha proposat i desenvolupat una nova estratègia per a degradar el CF, el qual és un compost recalcitrant, consistent en la inducció de la hidròlisi alcalina del CF mitjançant residus de construcció basats en formigó. L’ànàlisi isotòpic de compost específic (AICE) és una eina valuosa per al monitoreig d’un sistema de tractament medi ambiental, basant-se en el fraccionament isotòpic d’un element durant les reaccions de transformació. L’objectiu general d’aquesta tesi és l’ús de l’anàlisi isotòpic de compost específic de 13C, 37Cl i 2H com una eina per a controlar els dos processos d’atenuació 1) la degradació dels eten-clorats mitjançant una BPR-FZV instal•lada en el camp; i, 2) la nova tècnica de remediació de CF proposada basada en l’ús de residus reciclats de la construcció per tal d’induir la hidròlisi alcalina del CF. En general, mitjançant la combinació dels isòtops de C, Cl i H, aquesta tesi aporta noves eines per discriminar la degradació dels compostos organoclorats d’estudi mitjançant FZV, respecte la biodegradació en el camp, així com també per a identificar fonts de contaminació d’origen industrial o de productes formats, entre d’altres aportacions. A més a més, el nou mètode proposat per a degradar el CF basat en la seva hidròlisi alcalina mitjançant l’ús de residus de construcció reciclats ha demostrat ser eficient en la degradació d’aquest contaminant, així com també, mitjançant l’ús de isòtops de carboni, ha demostrat funcionar en experiments pilot monitorejats a escala de camp.
15
Mohammed, Mubeen Lee Jejung. "Effect of geological heterogeneity on permeable reactive barriers in groundwater remediation". Diss., UMK access, 2006.
Znajdź pełny tekst źródłaStreszczenie:
Thesis (M.S.)--Dept. of Geosciences. University of Missouri--Kansas City, 2006."A thesis in urban environmental geology." Typescript. Advisor: Jejung Lee. Vita. Title from "catalog record" of the print edition Description based on contents viewed Jan. 29, 2007. Includes bibliographical references (leaves 60-62). Online version of the print edition.
16
Hafsi, Amine. "Design Methodology for Permeable Reactive Barriers Combined With Monitored Natural Attenuation". Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/32264.
Pełny tekst źródłaStreszczenie:
Permeable reactive barrier (PRB) technology is increasingly considered for in situ treatment of contaminated groundwater; however, current design formulas for PRBs are limited and do not properly account for all major physical and attenuation processes driving remediation. This study focused on developing a simple methodology to design PRBs that is easy to implement while improving accuracy and being more conservative than the available design methodologies. An empirical design equation and a simple analytical design equation were obtained to calculate the thickness of a PRB capable of degrading a contaminant from a source contaminant concentration to a maximum contaminant level at a Point of compliance . Both equations integrate the fundamental components that drive the natural attenuation process of the aquifer and the reactive capacity of the PRB.The empirical design equation was derived from a dataset of random hypothetical cases that used the solutions of the PRB conceptual model (Solution I). The analytical design equation was derived from particular solutions of the model (Solution II) which the study showed fit the complex solutions of the model well. Using the hypothetical cases, the analytical equation has shown that it gives an estimated thickness of the PRB just 15 % lower or higher than the real thickness of the PRB 95 percent of the time. To calculate the design thickness of a PRB, Natural attenuation capacity of the aquifer can be estimated from the observed contaminant concentration changes along aquifer flowpaths prior to the installation of a PRB. Bench-scale or pilot testing can provide good estimates of the required residence times ( Gavaskar et al. 2000) , which will provide the reactive capacity of the PRB needed for the calculation. The results of this study suggest also that the installation location downgradient from the source of contaminant is flexible. If a PRB is installed in two different locations, it will achieve the same remediation goals. This important finding gives engineers and scientists the choice to adjust the location of their PRBs so that the overall project can be the most feasible and cost effective.Master of Science
17
Somayajula, Sreerama Murthy Kasi. "In Situ Groundwater Remediation using Enricher Reactor-Permeable Reactive Biobarrier". Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26648.
Pełny tekst źródłaStreszczenie:
Permeable reactive biobarrier (PRBB) is a flow-through zone where microorganisms degrade contaminants in groundwater. Discontinuous presence of contaminants in groundwater causes performance loss of a PRBB in removing the target contaminant. A novel enricher reactor (ER) - PRBB system was developed to treat groundwater with contaminants that reappear after an absence period. ER is an offline reactor for enriching contaminant degraders, which were used for augmenting PRBB to maintain its performance after a period of contaminant absence. The ER-PRBB concept was initially applied to remove benzene that reappeared after absence periods of 10 and 25 days. PRBBs without ER augmentation experienced performance losses of up to 15% higher than ER-PRBBs. The role of inducer compounds in the ER to enrich bacteria that can degrade a mixture of benzene, toluene, ethylbenzene, and xylene (BTEX) was investigated with an objective to minimize the use of toxic chemicals as inducers. Three inducer types were studied: individual BTEX compounds, BTEX mixture, and benzoate (a non toxic and a common intermediate for BTEX biodegradation). Complete BTEX removal was observed for degraders enriched on all three inducer types; however, the removal rates were dependent on the inducer type. Degraders enriched on toluene and BTEX had the highest degradation rates for BTEX of 0.006 to 0.014 day-1 and 0.006 to 0.012 day-1, respectively, while degraders enriched on benzoate showed the lowest degradation rates of 0.004 to 0.009 day-1.
The ER-PRBB technique was finally applied to address the performance loss of a PRBB due to inhibition interactions among BTEX, when the mixture reappeared after a 10 day absence period. The ER-PRBBs experienced minimal to no performance loss, while PRBBs without ER augmentation experienced performance losses between 11% and 35%. Presence of ethanol during the BTEX absence period increased the performance loss of PRBB for benzene removal. PRBBs augmented with degraders enriched on toluene alone overcame the inhibition interaction between benzene and toluene indicating that toluene can be used as a single effective inducer in an ER. The ER-PRBB was demonstrated to be a promising remediation technique and has potential for applications to a wide range of organic contaminants.
18
Moore, Angela Mary. "Anion reactions at iron surfaces : implications for perchlorate remediation using permeable reactive barriers /". For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
Pełny tekst źródła
19
Morar, Doina Lorena. "Release of inorganic and organic contaminants from fly ash amended permeable reactive barriers". College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/7855.
Pełny tekst źródłaStreszczenie:
Thesis (M.S.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Civil and Environmental Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
20
Ouellet-Plamondon, Claudiane. "Characterisation and performance of innovative aluminosilicates for soil mix technology permeable reactive barriers". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610261.
Pełny tekst źródła
21
Visser, Gunnar Lieb. "Permeable reaction barrier system for the treatment of textile wastewater using cobalt oxide". Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2631.
Pełny tekst źródłaStreszczenie:
Thesis (MEng (Chemical Engineering))--Cape Peninsula University of Technology, 2018.Advanced oxidation processes (AOPs) have gained considerable interest in the wastewater treatment industry. Low selectivity to organic pollutants and the high oxidation potentials provided by the free radicals produced from these processes are the root of this interest. Hydroxyl radical based AOPs seemed to dominate the field but recently sulphate radical based AOPs started to become more popular due to their even higher oxidation potential. The textile industry is known to be a considerable contributor to wastewater production. Many pollutants in this wastewater are organic pollutants which are very persistent to the more traditional treatment processes such as biological treatment and membrane filtration. Numerous studies have shown the potential and success of catalytic AOPs for the degradation of organic pollutants in wastewater. One such process is the use of a cobalt oxide nano-catalyst in conjunction with a peroxymonosulfate (PMS) oxidizer (Co3O4/PMS). The shortcoming with nano-catalysts however are the difficulty of recovering the catalyst in a slurry system or the effective immobilization of the catalyst in a continuous system. To address the issue of nano-catalyst immobilization, two different methods were used in the study to effectively immobilize the catalyst in a substrate. The methods were compared by utilizing the permeable reaction barriers in a continuous flow reactor. A bench scale reactor of 2.4 L/hr was designed and used to study the effect of PMS, catalyst mass and flow rate on the degradation efficiency and to determine the residence time and catalyst per PRB cross-sectional area ratio. A scale up rationale was formulated based on a constant residence time and the catalyst mass per PRB cross-sectional area ratio. Two design correlations were developed to predict the size of the permeable barrier and the catalyst mass required for the scale up PRB system. These parameters were used to design a reactor 30 times that of the bench scale reactor. In both reactors the optimum degradation occurred within 2 minutes indicating the success for catalyst immobilization and the development of a continuous reactor utilizing the Co3O4/PMS advanced oxidation technology.
22
Franklin, Phoebe. "Are permeable reactive barriers (PRBS) a viable technology for remediation of diffuse nitrate pollution?" Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523068.
Pełny tekst źródła
23
Wantanaphong, Janthawan. "Physico-chemical quantification of natural and waste materials for remediation of metal contaminated groundwaters using permeable reactive barriers". Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408622.
Pełny tekst źródła
24
Meza, Maria I. "The use of PRBs (permeable reactive barriers) for attenuation of cadmium and hexavalent chromium from industrial contaminated soil". Muncie, Ind. : Ball State University, 2009. http://cardinalscholar.bsu.edu/432.
Pełny tekst źródła
25
Goo, Holly Shu Chai. "Barriers to demonstrating and implementing innovative technologies at hazardous waste sites : case study of the permeable reactive wall at the Massachusetts Military Reservation". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41367.
Pełny tekst źródłaStreszczenie:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1996.Includes bibliographical references (leaves 104-188).
by Holly Shu Chai Goo.
M.Eng.
26
Gibert, Agulló Oriol. "Processos físico-químics i biològics en el tractament d'aigües àcides de mina: Aplicació a barreres permeables reactives". Doctoral thesis, Universitat Politècnica de Catalunya, 2004. http://hdl.handle.net/10803/6443.
Pełny tekst źródłaStreszczenie:
CATALA La contaminació de les aigües superficials i subterrànies representa el problema mediambiental més greu a què s'ha d'enfrontar la indústria minera, a causa de les denominades aigües àcides de mina (AAM), generades com a resultat de la lixiviació dels residus finals dipositats a les basses d'emmagatzematge.
Els jaciments minerals que contenen sulfurs metàl·lics són una font potencial d'AAM. L'exposició d'aquests materials als agents atmosfèrics, com l'oxigen i l'aigua, dóna lloc a la generació d'un lixiviat fortament contaminat, amb una elevada acidesa (pH4), alts continguts de SO42- (100-7000 mg dm-3) i quantitats variables de ions metàl·lics. En aquestes noves condicions d'acidesa i d'oxidació-reducció, les AAM poden escórrer-se pel sòl i els elements químics poden viatjar amb les aigües subterrànies, amb les consegüents repercussions per a l'ecosistema aquàtic.
El tractament de les aigües subterrànies ha generat un gran interès en el camp de la biotecnologia ambiental. La tècnica més recent és el tractament in situ del plomall contaminat mitjançant una barrera permeable reactiva (BPR), que consisteix en la instal·lació d'un material reactiu a l'aqüífer capaç d'induir processos fisicoquímics i biològics que eliminin els contaminants de l'aigua. La tecnologia de les BPR per al tractament d'AAM és relativament moderna, sense precedents a Europa fins la instal·lació, l'any 2000, d'una BPR a l'aqüífer del riu Agrio, fortament contaminat per AAM després del trencament de la bassa de residus de la mina d'Aznalcóllar. L'enfocament biològic per al tractament de les AAM mitjançant una BPR es basa en l'ús de bacteris sulfato-reductors (BSR), capaços de reduir SO42- a S2-, que precipiten en presència de metalls en forma de sulfurs metàl·lics.
L'objectiu primordial d'aquesta tesi és el d'estudiar, a escala de laboratori, els processos físico-químics i biològics involucrats en el tractament d'AAM mitjançant una BPR com la instal·lada a Aznalcóllar.
Amb aquest propòsit, es va procedir a simular la barrera en experiments en columna, en què es va avaluar la capacitat de mescles reactives -a base de compost vegetal, calcita i puntualment Fe0- per al tractament d'una AAM sintètica. Els resultats van mostrar que el compost utilitzat és una font de carboni massa poc biodegradable per promoure l'activitat dels BSR. Malgrat la falta de condicions sulfato-reductores, la majoria dels metalls fou eliminada de forma significativa, la qual cosa va suggerir l'existència de processos diferents de la precipitació de sulfurs. En experiments posteriors es va demostrar que la precipitació d'(oxi)hidròxids i carbonats metàl·lics, la co-precipitació amb aquests, i l'adsorció sobre el compost són responsables de la disminució de la concentració de metalls. Aquest darrer mecanisme va ser objecte d'un estudi més exhaustiu, que va demostrar que els grups àcids presents a la superfície del compost poden adsorbir Zn i Cu. Posteriorment, i constatada la poca idoneïtat del compost per engegar un procés de sulfato-reducció bacteriana, l'objecte d'estudi es va orientar cap a la recerca d'altres matèries orgàniques, i més concretament, d'una metodologia per predir-ne la biodegradabilitat. Es va comparar, així, la composició química de quatre substrats orgànics (compost vegetal, fulles vegetals, i fems d'ovella i de cavall) amb la seva capacitat de promoure condicions sulfato-reductores. Els resultats van mostrar que la biodegradabilitat d'una matèria orgànica està estretament relacionada amb el seu contingut de lignina, i que aquest pot ser utilitzat per a la predicció de la seva biodegradabilitat. Dels substrats orgànics assajats, la mostra de fems d'ovella va resultar ser la més favorable, per la qual cosa es va seleccionar per a experiments posteriors en el tractament d'AAM. Els resultats d'aquests últims experiments van indicar que la presència de metalls a altes concentracions a l'aigua a tractar pot exercir efectes toxicològics als BSR i inhibir-ne el metabolisme.
ANGLES
The contamination of surface and groundwater represents the most serious environmental concern associated with the mining industry around the world, owing to the so-called acid mine drainage (AMD), which is generated as the result of the leaching of the residual wastes disposed of in open-air impoundments.
Mineral deposits containing metal sulphides represent a potential source of AMD. The exposition of these residues to the atmospheric agents, like oxygen and water, results in the generation of a heavily contaminated-leachate characterised by a high acidity (pH<4), high contents in SO42- (100-7000 mg dm-3) and variable amounts of metallic ions. In these new acidic and redox conditions, these acidic waters can drain through the soil and enter into the groundwater system, resulting in a potential risk to aquatic and terrestrial ecosystems.
The treatment of such groundwaters has in the last decades drawn the attention in the field of environmental biotechnology. A recent economically attractive technology in the in-situ treatment of AMD are the permeable reactive barriers (PRB), which consist of the installation into the aquifer of an appropriate reactive material able to induce physico-chemical and biological processes that remedy contaminated groundwater that flows through it. The PRB technology has emerged as a cost-effective alternative, without any precedent in Europe until the installation, in 2000, of a PRB into the Agrio river aquifer, which was heavily contaminated by AMD after the break down of the tailing pond in the pyritic mine of Aznalcóllar. The biological approach of the AMD treatment by means of a PRB is based on the use of sulphate-reducing bacteria (BSR), able to reduce SO42- to S2-, which can precipitate in presence of metals as metal sulphides.
The present Thesis forms part of the research work on the PRB in Aznalcóllar, and its aim is the study, at the laboratory-scale, of the physico-chemical and biological processes taking place in the PRB in Aznalcóllar.
For this purpose, the PRB was simulated in column experiments, in which the capacity of reactive mixtures -based on vegetal compost, calcite, and occasionally Fe0- was evaluated in the treatment of a synthetic AMD. The results showed that the compost used in this study is a too poor biodegradable carbon source to promote the SRB activity. Despite the lack of sulpahte-reducing conditons, most of metals were significantly removed, suggesting the existence of other processes than the sulphide precipitation. In subsequent experiments, the metallic (oxy)hydroxide and carbonate precipitation, the co-precipitation with them, and sorption onto the compost were demonstrated to be responsible of the decrease of the metal concentration. This latter mechanism was object of a more exhaustive study, which demonstrated that acidic groups on the compost surface can sorb Zn and Cu present in the solution. Subsequently, and because compost was found to be not suitable in promoting the bacterial sulphate-reducing process, the object of the study was directed towards the research of other organic matters and, more specifically, of a methodology for predicting their biodegradabity. The chemical composition of four organic substrates (vegetal compost, vegetal leaves, and sheep and poultry manure) and their ability in promoting sulphate-reducing conditions in a metal-free medium were compared. Results showed that the biodegradability of an organic matter is closely linked to its lignin content, which can be used as a predictable parameter. Among the assessed organic substrates, sheep manure resulted to be the most favourable in terms of sulphate-reduction, and was selected for the treatment of AMD. Results of these further experiments indicated that the presence of metals at high concentrations in the water can exert toxicological effects to the SRB and inhibit their metabolism.
27
Trindade, Giuliano Bordin. "Estudo da remediação de um aquífero contaminado com sulfato e metais através de barreira reativa permeável orgânica". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-11052016-153629/.
Pełny tekst źródłaStreszczenie:
Este trabalho teve como objetivo geral estudar a viabilidade técnica de utilizar bagaço de cana como meio reativo de barreiras reativas permeáveis (BRP) para remoção de sulfato e metais de águas subterrâneas contaminadas. O estudo baseou-se em investigação experimental, por meio de ensaios laboratoriais de coluna, e em modelagem matemática, para a qual utilizaram-se também alguns dados obtidos em um estudo de caso de uma unidade industrial contaminada com sulfato e metais. Neste local contaminado, as características hidrogeológicas e topográficas propiciam a utilização de uma barreira reativa permeável como técnica de remediação. Barreiras reativas permeáveis são uma alternativa para remediação de águas subterrâneas que vem progredindo rapidamente na última década, a partir de ensaios de bancada e coluna em laboratório para implementação em escala real em campo. Três colunas bióticas foram montadas utilizando bagaço de cana como meio reativo e um material de base poroso constituído de areia e cascalho para fornecer adequada condutividade hidráulica, com a proporção de 1:28 em massa seca. Também foi adicionado ao meio reativo um inóculo bacteriano composto por esterco bovino dissolvido. Uma quarta coluna, sem inóculo e contendo um agente biocida, compôs o experimento branco (abiótico). Uma solução sintética foi introduzida nas colunas simulando condições da água subterrânea do estudo de caso, com velocidade de Darcy em torno de 2,0x10-7 m/s composta por sulfato e metais (zinco e níquel) com concentrações de 6.000 mg/L e 15 mg/L, respectivamente. Os resultados das análises da fase líquida das colunas bióticas apresentaram: (i) média da taxa de remoção de sulfato durante todo o tempo do experimento de 49 mg/L/dia; (ii) as concentrações de Zn e Ni diminuíram de 15 mg/L para valores não detectáveis pela técnica analítica utilizada (< 0,01 mg/L); (iii) aumento do pH de 5.5-5.8 para valores entre 6,8-8,0; (iv) redução do valor do potencial de óxido redução (Eh) para valores de até -200mV. Não foram observadas reduções das concentrações de metais e sulfato na fase líquida da coluna abiótica e os valores de pH e Eh permaneceram dentro das faixas iniciais. Análises nas fases sólidas das colunas bióticas por MEV e EDS após o término do experimento identificaram a presença de Ni, Zn, S e Mn, indicando a precipitação desses metais em forma de sulfetos. Estes elementos não foram detectados na fase sólida da coluna abiótica. Assim, pôde-se inferir que toda a remoção de sulfato verificada nas colunas bióticas pode ser atribuída a redução bacteriana de sulfato. A partir das condições experimentais dos ensaios, foi realizada a modelagem e o dimensionamento da BRP. Para a estimativa da cinética de redução de sulfato, aplicou-se a solução analítica de Van Genuchten para transporte de contaminantes com degradação, obtendo-se uma taxa de decaimento de primeira ordem de 0,01 dia-1. A determinação da espessura e tempo de residência da barreira foi realizada considerando que a concentração de sulfato na saída da barreira fosse menor ou igual a 250 mg/L. O resultado do dimensionamento de uma BRP preenchida com bagaço de cana e areia nas proporções de 1:28 em massa seca resultaria em uma BRP de 7,1 m de espessura, com tempo de residência de 950 dias, no local de estudo de caso. Caso fosse utilizado o dobro da proporção de bagaço de cana e areia em massa seca (1:14), a implantação da BRP apresentar-se-ia viável, com espessura aproximada de 4 m. Através destes resultados, pôde ser comprovada a hipótese de que bagaço de cana como substrato e esterco bovino como inóculo compõem um meio reativo viável para a redução de sulfato e precipitação de metais em uma BRP.This research had as general objective to study the technical feasibility of use sugarcane bagasse as reactive medium of permeable reactive barriers (PRB) for removal of sulfate and metals from contaminated groundwater. The study was based on experimental investigation, through laboratory column tests and by mathematical modeling, for which data of a case study of an industrial unit contaminated with sulfate and metals was used. At this contaminated unit, the hydrogeological and topographical features propitiate the utilization of a permeable reactive barrier as remediation technique. Reactive permeable barriers are an alternative to groundwater remediation that comes progressing quickly in the last decade, from bench and column tests in the laboratory to full-scale implementation in the field. Three biotic columns were assembled using bagasse as a reactive medium and a porous base material consisting of sand and gravel to provide adequate hydraulic conductivity, with the proportion of 1:28 by dry mass. It was also added to the reactive medium a bacterial inoculum consisting of dissolved cow manure. A fourth column, without inoculum, and containing a biocidal agent composed the blank experiment (abiotic). A synthetic solution was introduced in columns simulating groundwater conditions of the case study, with Darcy velocity around 2, 0x10-7 m/s, composed by sulfate and metals (zinc and nickel) with concentrations of 6,000 mg/L and 15 mg/L, respectively. The results of the analyses of the liquid phase of the biotic columns showed: (i) the average of sulfate removal rate during all the time of the experiment of 49 mg/L/day; (ii) the concentrations of Zn and Ni decreased from 15 mg/L to non-detectable values by the used analytical technique (0.01 mg/L); (iii) increase in the pH of 5.5-5.8 for values between 6.8-8.0; (iv) reduction in the value of the oxidation-reduction potential (Eh) for values up to -200mV. The reductions were not observed in concentrations of metals and sulfate in liquid phase of abiotic column and the values of pH and Eh remained within the initial tracks. Analyses on solid phases of biotic columns by SEM and EDS after experiment finalization have identified the presence of Ni, Zn, S and Mn, indicating the precipitation of these metals in the form of sulfides. These elements were not detected in the solid phase of the abiotic column. So, it might be inferred that any reduction in sulfate removal biotic columns can be attributed to bacterial sulfate reduction. Base on the experimental conditions of the tests, it was conducted the modeling and PRB dimensioning. For the sulfate reduction kinetics estimation, the analytical solution of Van Genuchten was applied for contamination degradation and transport, obtaining a first-order decay rate of 0.01 day-1. The determination of the thickness and residence time of the barrier was performed considering the concentration of sulfate in the output of the barrier being less than or equal to 250 mg/L. The result of the dimensioning of the PRB filled with bagasse and sand in 1:28 dry mass ratios would result in a PRB of 7.1 m thick, with 950 days residence time on the site of case study. If the proportion of bagasse and sand were 1:14 by dry mass (twice), the deployment of the PRB would be feasible, with approximate thickness of 4 m. Through these results, it might be concluded that the hypothesis that sugarcane bagasse as a substrate and cow manure as inoculum make up a reactive medium viable for the reduction of sulfate and precipitation of metals in a PRB.
28
Zakaria, Khaled. "Caractérisation d'un nouveau matériau et valorisation dans les barrières perméables réactives". Phd thesis, Ecole Centrale de Lille, 2012. http://tel.archives-ouvertes.fr/tel-00805274.
Pełny tekst źródłaStreszczenie:
La valorisation des déchets industriels est de nos jour un défit international ayant des intérêts économiques et environnementaux. Dans ce cadre, l'entreprise Solvay travail sur la gestion de ses déchets et plus particulièrement ceux produits de la fabrication du carbonate de sodium " soude ". Ils sont actuellement stockés dans des bassins de décantation. Cependant, des contraintes règlementaires sont récemment apparues limitant ainsi la construction de nouveaux bassins. La valorisation de ces déchets est par conséquent impérative pour l'entreprise. Plusieurs voies de valorisation sont envisageables, notamment le recours à des nouveaux procédés qui permettraient d'en produire de nouveaux matériaux.En effet, un nouveau matériau issu des déchets industriels appelé " Gel d'Apatite " fait l'objet de ce travail de thèse. L'objectif est de caractériser le Gel d'Apatite et de proposer et d'étudier une voie permettant sa valorisation. Ce matériau est constitué principalement d'hydroxyapatite et de l'eau. Il se distingue par un comportement thixotropique et par sa capacité de rétention des métaux lourds. Cette dernière propriété a permis d'envisager sa valorisation dans la dépollution et la protection des nappes phréatiques. La voie étudiée dans ce travail de recherche est la valorisation du Gel d'Apatite dans les Barrières Perméables Réactives " BPR(s)"; technique passive de traitement des eaux souterraines in-situ.La finalité de ces travaux de recherche serait de dresser un cahier de charge du Gel d'Apatite et de définir un mélange conforme au mode de valorisation étudié
29
Hsu, Chia-Ping, i 徐嘉彬. "Groundwater Nitrate Removal by Zero-Valent Iron Permeable Reactive Barrier". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/59266737515942053622.
Pełny tekst źródłaStreszczenie:
碩士國立臺北科技大學
環境規劃與管理研究所
92
Laboratory scale column tests were conducted to obtain the field design parameters and possible operation problems after field installation. For the nitrate contaminant water made in the laboratory, nitrate reduction by zero-valent iron was found affected by the coating or metal oxide on the ZVI surface. Without pretreatment of ZVI, nitrate removal rate was only 30%. Surface coating can be removed by strong reduction agent (NaBH4) or acid washing, but acid washing was shown better efficiency in this study. In the column tests, 1 mg ZVI can only remove 2.14 mg nitrate and the used ZVI was only 3.42% according to the stoichiometric ratio, and which is an evidence of surface reaction for the ZVI. The reduction of ZVI becomes iron oxides coating on the ZVI surface. In the column test, iron color was grayish in the beginning (pure ZVI) and became deep black after the ZVI was used. Effluent soluble iron concentration was below 1 mg/L. ESCA analysis was conducted for the surface species of the ZVI and Fe2O3 was found on the coated surface. Effluent pH was directly related to the initial nitrate concentration and removal rate and effluent ORP was decreased during the experiment. Therefore, pH is suggested as an indicator for nitrate removal efficiency for field operation. Increasing flux leads to increasing nitrate removal percentage. For the same flux, hydraulic resident time (HRT) and removal rate had no relationship, but higher HRT would increase operation time. The problem for field operation (using actual groundwater) was the clogging in the column. The reason for clogging was due to mineral precipitates after the increased pH and gas production. The mineral precipitates include Fe2O3, FeCO3, CaCO3. ZVI mixed with sand in the column can solve the clogging, but operation time was decreased. Transfer zone in the column were proportionately related to flow rate and flux. For pretreated ZVI by acid wash (5 r.pm with 157 cm3/cm2day), transfer zone were from1.85 to 3.03 cm and real hydraulic retention time were from 10 to 16 minutes. For determination of reaction constants, Thomas Equation was applicable, where R square was above 0.8 and reaction constants were between 0.0240 and 0.0553 (L/mg-day). Column tests were scaled up using two methods including Kinetic Approach and Scale-Up Approach. The differences were small comparing the calculated to the actual breakthrough volume and time using Kinetic Approach. For calculation of PRB installation, W/A (mass of zero-valent iron/cross-sectional plume) was below 1 kg/m2, and iron well was below 16 cm. It was low comparing to the literature value and it was due to that the ZVI used in this study was pretreated.
30
Mieles, John Michael. "Semi-Analytical Solutions of One-Dimensional Multispecies Reactive Transport in a Permeable Reactive Barrier-Aquifer System". Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9167.
Pełny tekst źródłaStreszczenie:
At many sites it has become apparent that most chemicals of concern (COCs) in groundwater are persistent and not effectively treated by conventional remediation methods. In recent years, the permeable reactive barrier (PRB) technology has proven to be more cost-efficient in the long-run and capable of rapidly reducing COC concentrations by up to several orders of magnitude. In its simplest form, the PRB is a vertically emplaced rectangular porous medium in which impacted groundwater passively enters a narrow treatment zone. In the treatment zone dissolved COCs are rapidly degraded as they come in contact with the reactive material. As a result, the effluent groundwater contains significantly lower solute concentrations as it re-enters the aquifer and flows towards the plane of compliance (POC). Effective implementation of the PRB relies on accurate site characterization to identify the existing COCs, their interactions, and their required residence time in the PRB and aquifer. Ensuring adequate residence time in the PRB-aquifer system allows COCs to react longer, hence improving the probability that regulatory concentrations are achieved at the POC.
In this study, the Park and Zhan solution technique is used to derive steady-state analytical and transient semi-analytical solutions to multispecies reactive transport in a permeable reactive barrier-aquifer (dual domain) system. The advantage of the dual domain model is that it can account for the potential existence of natural degradation in the aquifer, when designing the required PRB thickness. Also, like the single-species Park and Zhan solution, the solutions presented here were derived using the total mass flux (third-type) boundary condition in PRB-aquifer system. The study focuses primarily on the steady-state analytical solutions of the tetrachloroethylene (PCE) serial degradation pathway and secondly on the analytical solutions of the parallel degradation pathway.
Lastly, the solutions in this study are not restricted solely to the PRB-aquifer model. They can also be applied to other types of dual domain systems with distinct flow and transport properties, and up to four other species reacting in serial or parallel degradation pathways. Although the solutions are long, the results of this study are novel in that the solutions provide improved modeling flexibility. For example: 1) every species can have unique first-order reaction rates and unique retardation factors, 2) higher order daughter species can be modeled solely as byproducts by neglecting their input concentrations, 3) entire segments of the parallel degradation pathway can be neglected depending on the desired degradation pathway model, and 4) converging multi-parent reactions can be modeled. As part of the study, separate Excel spreadsheet programs were created to facilitate prompt application of the steady-state analytical solutions, for both the serial and parallel degradation pathways. The spreadsheet programs are included as supplementary material.
31
McLean, Neil Ross. "Use of Drains for Passive Control of Flow Through a Permeable Reactive Barrier". Thesis, 2007. http://hdl.handle.net/10012/3375.
Pełny tekst źródłaStreszczenie:
Abstract
Permeable reactive barrier technology is a cost effective means of treating near surface groundwater contaminant plumes. However, current reactive barrier technology lacks the capacity to manipulate flow rates and thus hydraulic retention time (HRT) within the barriers in order to maximize the effectiveness and longevity of the media. This study examines the effectiveness of tile drains as passive controls on the flow rate of ground-water through an existing wood particle media permeable reactive barrier treating agricultural nitrate. The use of upgradient and downgradient tile drains allowed HRT to be increased from 4.5 to 10 days in one trial and then to be decreased from 11.1 to 0.8 days in a second trial. Influent groundwater NO3-N concentrations of ~100 mg/L were attenuated to detection limit (0.02 mg/L) only 12% of the 4 m long barrier with HRTs of 4.5 to 10 days. During the second trial, HRT was decreased to 0.8 days and NO3-N penetrated to the downgradient edge of the PRB at 1.8 mg/L. The behaviour of SO4 in the PRB was also affected by flow rate. SO4 entered the PRB at 60 to 71 mg/L during the first trial. Under a HRT of 10 days it was depleted to detection limit after traveling through only 13% of the barrier. When HRT was decreased to 4.5 days, SO4 was able to penetrate the downgradient edge of the PRB at concentrations from 4 to 6 mg/L. With a 0.8 day HRT SO4 reduction was highly restricted as calculations showed 90% of available carbon in the PRB was being used to reduce NO3-N, compared to 7.5% being used for SO4 reduction at that time. In comparison, at the 10 day HRT, 61% of carbon being used for NO3-N reduction, 8.7% for SO4 reduction, 0.7 for dissolved oxygen and 29% was lost through DOC leaching. These calculations suggest that barrier efficiency can be greatly enhanced by manipulation of HRT through use of tile drains.
32
FANG, YEH JU, i 葉如芳. "Microbial Community Dynamics in a Permeable Reactive Barrier using Real-time PCR Technique". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/22789166291578300902.
Pełny tekst źródłaStreszczenie:
碩士大葉大學
環境工程學系碩士班
96
This study was conducted with the application of denaturing gradient gel electrophoresis (DGGE), and real-time quantitative polymerase chain reaction (real-time PCR) molecular biotechnology for monitoring the permeable reactive barrier (PRB) in the relation with BTEX decomposition efficiency and the distribution of microbial community. Various amounts of nitrogen nutrients and BTEX were added to examine the treatment efficiencies. It was shown that the high sodium nitrate amount had improved the BTEX removal, which was an evidence of effects on BTEX treatment. The results of benzene and toluene removal efficiencies revealed that it was completely degraded for both two compounds at the concentrations of 20, 40 and 80 ppm. Increasing the concentrations of these two compounds to 120, 160, 240 and 320 ppm resulted in the decreasing in treatment efficiencies, and the concentrations remained 40, 60, 65, 90 and 100 % for benzene, and 10, 40, 55, 90 % for Toluene, respectively. Furthermore, the microbial variations at various concentrations were consistent via optical density (OD), DGGE analysis and real-time PCR results. Each column test was conducted for 20 days to investigate the effectiveness of oxygen releasing compound (ORC). It was indicated that the highest dissolved oxygen was achieved, which was 5.08 mg/L (equal to 0.25 mg O2/day/g-ORC) at 40 % of CaO2. The results of long-term stability tests of oxygen releasing from PRB system showed that: (1) Oxygen released from ORC was sufficient for the demand of bacteria. (2) In shock-loading of BTEX tests, the removal efficiencies were reduced by 21%, 19%, 17% and 10 % for benzene, toluene, ethylbenzene and xylene, respectively. (3) Removal efficiencies were then recovered in the ascending order of as follow: xylene> ethylbenzene> benzene> toluene. (4) ORC can be used for 40 days. (5) DGGE analysis showed the changing in the microbial community structure before (13 groups) and after shock-loading (reduced to 9 groups), that implied the shock-loading was harmful to bacteria. (6) The results from real-time PCR in the study of catechol 2,3-dioxygenase gene revealed that the quantification of this gene has been declined after shock-loading, but it was latter well again at the 79th day.
33
Lai, Ranee Wan Man. "The use of clinoptilolite as permeable reactive barrier substrate for acid rock drainage". Thesis, 2005. http://hdl.handle.net/2429/17004.
Pełny tekst źródłaStreszczenie:
This study investigated the use of clinoptilolite as a permeable reactive barrier (PRB) substrate for retaining heavy metals from Acid Rock Drainage (ARD). PRBs are one of the options for retaining metals from ARD, allowing a cleaned groundwater plume to the receiving water bodies. The mineral clinoptilolite, a molecular sieve which has high cation exchange capacity, can retain heavy metals. Clinoptilolite is available in many locations and is inexpensive (~CDN$100-200/tonne). The suitability of clinoptilolite for the use as a PRB substrate was evaluated based on its chemical stability and metal retention in acidic environments. Results showed that clinoptilolite is chemically stable in ARD environment, the clinoptilolite structure is stable at pH >1.5. Clinoptilolite was found to retain 130.6mg Cu/kg soil (63.8% of Cu), 22.65mg Fe/kg soil (82.1% of Fe), 158mg Zn/kg soil (39.5% of Zn) and 215.4mg Al/kg soil (89.7% of Al) from the Britannia Mine natural ARD (pH 3.28) in batch equilibrium adsorption tests. Pretreatment of clinoptilolite with NaCl solution helped improve the retention of metals and reduced the leaching of Mn from the clinoptilolite. The performance of the clinoptilolite was evaluated using column leaching tests to simulate on-site conditions. Breakthrough curves were obtained at various flowrates and influent metal concentrations. Copper and zinc were the major contaminants of concern in the ARD. The breakthrough of copper occurs at 40 pore volumes (pv), manganese at 13 pv, zinc at 45 pv and aluminum at 38 pv, whereas iron precipitated once introduced to the leaching cell. Metal retention was found to be dependant on the flow rate. Selective extractions of metals on the clinoptilolite was conducted. Results indicated that partitioning was dependent on the flow conditions and the chemical characteristics of the leachate (pH and chemical composition). An algorithm was developed in the geochemical model PHREEQC for the design of the clinoptilolite barrier. The model helps to predict the performance and the transport of contaminants based on the amount of exchange sites, influent composition and concentration within the clinoptilolite PRB system, which are useful for estimating the service life and thickness required in the design of clinoptilolite PRB systems.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
34
Lin, Ming-Hei, i 林明憙. "Electrolysis-Enhanced Permeable Reactive Barrier Packed with Nano-Pd/Fe Bimetallic Particles of Perchloroethylene". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/52050176023193793112.
Pełny tekst źródłaStreszczenie:
碩士國立屏東科技大學
環境工程與科學系所
100
The aim of this study is to investigate the degradation efficiency of target pollutant, perchloroethylene (PCE), by nano-palladium/iron (Pd/Fe) bimetallic metal particles enhanced by electrolysis. The experiments were divided into four stages. The first stage was to characterize the properties of quartz sand and nano-Pd/Fe particles. The second stage was to conduct the batch tests under various pH values (pH 8-9) on the effects of PCE degradation with nano-Pd/Fe. The third stage was to observe the transport behaviors of solutes through the porous media in a bench-scale sand box. And the fourth stage was to identify the variations of nano-Pd/Fe before and after the reaction with PCE by SEM-EDS and FTIR analysis. The average size and specific surface area of lab-synthesized nano-Pd/Fe particles were 111.1 nm and 56.05 m2 g-1, respectively. The absorption peaks of nano-Pd/Fe analyzed by the X-ray diffraction detector (XRD) only identified Fe. That may be due to the trace amount of Pd on bimetallic metals. For the tests of various pH values (pH 8-9) on PCE degradation with nano-Pd/Fe, the efficiency decreased with higher pH values. The concentration of Cl- released from PCE degradation was close to the theoretical values. The PCE degradation levels were positive correlated with the release amounts of Cl-. In this study, the by-products of PCE degradation such as trichlorethylene (TCE), cis-1,2-dichloroethylene (cis-1,2-DCE), trans-1,2-dichloroethylene (trans-1,2-DCE), 1,1-dichloroethylene (1,1-DCE), and vinyl chloride (VC) were not detected. Via the tracer tests, the average residence time was about 1.7 times higher than the theoretical value. For the test of permeable reactive barrier (PRB) packed with nano-Pd/Fe on PCE degradation, the duration of reactivity of nano-Pd/Fe could be maintained about 28 hr which was around 2 to 4 times higher than that of nano zero valent iron. During the tests, ORP values were steadily maintained below -300 mV in the PRB showing a reduction state was kept in the system. Dechlorination of PCE with nano-Pd/Fe particles were identified by the significant increase of Cl- concentration. The test of nano-Pd/Fe PRB enhanced by electrolysis on PCE degradation, H+ released near the anode was able to acid-washed the surface of Pd/Fe particles to increase their reactivity. The results showed that PCE was not completely degraded by the nano-Pd/Fe particles. The reactivity of Pd/Fe was observed to maintain about 16 to 20 hr. Therefore, more researches on the aspects of current, potential, and electrolyte to the performance of electrolysis enhanced PRB packed with nano-Pd/Fe technology are needs to facilitate its application to in-situ remediation of groundwater contaminated by chlorinated solvents. From the images observed by SEM-EDS, the surface morphology of nano-Pd/Fe particles displayed chain-like structure and irregular flakes pre-reacted and post-reacted with PCE, respectively. The spectrum of fresh nano-Pd/Fe particles analyzed by FTIR showed that a strong and broad absorption signal ranged from 3200 to 3500 cm-1 was identified to be O-H and at 1539, 1385, 967 cm-1 to be the nitro compounds (NO2), alkane (CH3), and alkene (C = CH), respectively. Finally, a signal ranged from 600 to 800 cm-1 was C-Cl. Keywords: perchloroethylene, nano-palladium/iron, tracer, permeable reactive barrier, electrolysis
35
Hoppe, Jutta. "Geochemical Characterization and Longevity Estimates of a Permeable Reactive Barrier System Remediating a 90Sr plume". Thesis, 2012. http://hdl.handle.net/10012/7293.
Pełny tekst źródłaStreszczenie:
In 1998, a permeable reactive barrier system was installed at the Atomic Energy of Canada Ltd. (AECL) Chalk River Laboratories in Chalk River, Ontario, to prevent the discharge of a 90Sr plume into a nearby swamp. The system known as the “Wall and Curtain” contains clinoptilolite, a zeolite, as a reactive material to sorb 90Sr. The overall objective of this study was to provide refined estimates of the efficiency and longevity of the system. To better understand the flow in the aquifer and through the Wall and Curtain, a detailed physical field characterization of the site was performed. Borehole-dilution tests were performed in 19 mm (¾ inch) drive-point piezometers. The results indicate that the Wall and Curtain system intercepted deeper, contaminated groundwater as intended. Hydraulic conductivities (K) determined through slug tests indicate that the aquifer was relatively homogeneous. Average linear groundwater velocities determined through borehole dilution compared well with velocities determined through the Darcy equation based on slug-test K estimates. The measurements from the field study were used to develop a three dimensional physical flow model. The numerical computer code HydroGeoSphere was used to provide an approximate representation of groundwater flow in the aquifer and through the Wall and Curtain. The model was calibrated by comparing simulated and observed hydraulic head values across the site. The model showed good agreement with the observed heads and acceptable agreement with the field estimates of groundwater velocities.
A detailed geochemical characterization of the aquifer and the reactive material, clinoptilolite, was performed through field and laboratory work. Pore-water samples were taken from multiple locations in the aquifer. Solid and pore-water samples from the reactive material were used to determine distribution coefficients for 90Sr and competing cations. Sequential leach tests were performed on small amounts of the radioactive solid samples. Results indicate that the system was highly efficient in treating an average mass flux of > 17,000 Bq/m2day-1. The leading edge of the plume was found to have only reached 40 cm into the 2 m thick Curtain of clinoptilolite after nearly 14 years of operation. The reactive material readily sorbed 90Sr, with a distribution coefficient of > 76,000 mL/g for beta activity. Kinetically controlled ion exchange was the main mechanism of sorption onto the clinoptilolite for most cations. The results indicate that the system was highly efficient.
Reactive transport models of the site using two different numerical codes, HydroGeoSphere and MIN3P, were constructed to provide refined estimates of the longevity of the system. The model constructed in HydroGeoSphere included five solutes. Zoned distribution coefficients were specified for the transported solutes. In MIN3P, only the reactive material was used as a model domain. Typical concentrations of the plume were specified. Ion exchange was considered in the simulation, as well as radioactive decay of Sr. An updated version of MIN3P was used which also considers kinetic sorption of Sr. Longevity estimates of the different simulations ranged between 30 years and over 200 years for the Wall and Curtain system. Based on field and laboratory experiments, longevity estimates of 80 years to 100 years seemed more reasonable. Results of the numerical simulation indicate that by that time, the system would have remediated 1200 MBq of 90Sr. Continuous monitoring of the outflow will ensure that the time-to-replacement of the system will be met.
36
Dam, Quoc-Khanh, i 譚國卿. "Integration of Permeable Reactive Barrier Technology and Immobilization for MTBE and BTEX Contaminated Groundwater Treatment". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/16976578381407097320.
Pełny tekst źródłaStreszczenie:
碩士大葉大學
環境工程學系碩士班
97
The purpose of this study was integration of permeable reactive barriers (PRB) technology and immobilization for MTBE and BTEX contaminated groundwater treatment. This study was first investigated to make the immobilized bead highly strong stability. After conducting batch and column tests, it was integrated with PRB system. PRB was run at various concentrations of substrate and removal efficiency was monitored. Results revealed that (1) Bead was formed with high stability with 2.46 hours and 6 hours immersed in solution of (5% H3BO3, 2.5% CaCl2) and 5% KH2PO4. (2) Bead has pore structure for bacteria occupancy, allowing oxygen and substrates transfer. (3) Results from batch experiments showed that: (3a) For toluene-degrading Pseudomonas sp. YATO411 strain, the most suitable value of initial biomass concentration for immobilizing was 26.7 mg/L; (3b) Rate of toluene removal was highest with 12.4 mg/L.h; (3c) When exposing at high concentration of toluene, immobilized cells were more effective than suspended cells; (3d) Pseudomonas sp. YATO411 was not only degrading toluene, but also used benzene and ethylbenzene as the source of carbon and energy; (3e) Methylibium petroleiphilum PM1 can be used for immobilization when bead was immersed in (H3BO3, CaCl2) for 0.5 hours, and KH2PO4 for 2.5 hours. (4) Results from column test showed that toluene removal increased along with increasing amount of bead. (5) Results from long term PRB monitoring showed that: (5a) MTBE removal has only shown significant increasing to 42.4% when Methylibium petroleiphilum PM1 was introduced to PRB system; (5b) When BTEX was shock loading to 80 ppm, integration PRB with immobilization of Pseudomonas sp. YATO411 has increased removal efficiency of B, T, and E to 99.4, 98.2, and 97.5 (%) comparing to 49.2, 48.6, and 62.9 (%), respectively, incase of non-integration.
37
Wu, Shih-Kai, i 吳士愷. "Analytical model for multispecies transport in a permeable reactive barrier- aquifer system subject to nonequilibrium". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/26xht7.
Pełny tekst źródłaStreszczenie:
碩士國立中央大學
應用地質研究所
106
The transport behavior of contaminants in a permeable reactive barrier (PRB)- aquifer system is complicated because of the differences in the physical and chemical properties of the PRB and the aquifer. However, dual-domain contaminant transport models are efficient tools for predicting and describing the movement of contaminants in a PRB–aquifer system. Multispecies transport models should have the ability to account for mass accumulation of the parent species while simultaneously considering the distinct transport and reactive properties of both the parent and daughter species during the transport of a degradable contaminant such as a dissolved chlorinated solvent. For mathematical simplicity, the current multispecies dual-domain transport analytical models are derived assuming equilibrium sorption. However, experimental and theoretical studies have indicated that this assumption may not be adequate and that nonequilibrium sorption could have a profound effect upon solute transport in the subsurface environment. This study presents an analytical model for multispecies transport in a PRB-aquifer system subject to nonequilibrium sorption in which the first-order reversible kinetic sorption reaction equation systems are incorporated into two sets of simultaneous advection-dispersion equations coupled together by a sequential first-order decay reaction that describes multispecies nonequilibrium transport in both the PRB and the aquifer. The analytical solutions to the complicated governing equation systems are derived with the aid of the Laplace transform and verified by comparing the computational results against those obtained using a numerical model in which the same governing systems are solved using the advanced Laplace transform finite difference method. Finally, the derived analytical model is used to investigate how the sorption reaction rate influences the performance of a PRB-aquifer system.
38
Pan, Chi-liang, i 潘祈良. "The Application of Biological Permeable Reactive Barrier with Immobilized Cell Technique for Diesel-Contaminated Groundwater Remediation". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/89255219361384725452.
Pełny tekst źródłaStreszczenie:
碩士國立成功大學
環境工程學系碩博士班
97
Soil and groundwater petroleum contamination is becoming more and more serious in recent years due to oil-leaking from storage tanks. Among current remediation technologies, bioremediation is getting more and more popular for its effectiveness, lower operational cost and milder environmental impacts. In this study, diesel degrading bacteria were utilized to treat the contaminated groundwater. However, the bacteria may be washed out from the contaminated zone by the groundwater flow and lowered the removal efficiency. Therefore in this study, we used the entrapment technique to immobilize the bacteria cell in alginate gel (AG) beads and developed a biological permeable reactive barrier (B-PRB) with the AG beads as monomers. This makes in-situ bioremediation of groundwater possible. There were two main parts in this study. First, repeated batch tests using AG beads were conducted to evaluate the diesel degradation efficiency and duration of the beads. Three different types of bacteria mixing techniques were used. Initial diesel concentration was about 500 ppm TPH-d. Also, the carbon to nitrogen ratio (C/N ratio) was changed during the repeated batches. The repeated batches were conducted for about one year. Results showed that the diesel degradation efficiency achieved more than 80% for all three batches at C/N=100:2. However, when C/N ratio changed to 100:0.5, the diesel degradation efficiency decreased to about 45%. This shows that appropriate C/N ratio is an important factor for groundwater diesel degradation. When we supplied sufficient nitrogen source (C/N=100:2) after this decrease, the diesel degradation efficiency recovered to above 80%. This indicates that the beads can mitigate the impact due to the change of the environment. In the last few runs, synthetic groundwater (C/N=100:1) was used and the diesel degradation efficiency was about 90%. From the results, we can conclude that the AG beads remained active for diesel degradation after a long period of operation. Also the structure of the beads remained. This shows that the AG beads can applied to continuous flow B-PRB. In the second part of this study, a lab-scale continuous flow B-PRB column was developed to study the possibility of in-situ groundwater remediation with B-PRB. Synthetic groundwater with saturated diesel (11±0.5 ppm TPH-d) was used as influent. Results showed that the diesel degradation efficiency was about 70% during the whole operational period (200 days). This shows that the B-PRB retained good removal efficiency after a long period of operation.
39
Wang, Dong-Yi, i 王東毅. "Treatment of Trichloroethylene in Groundwater Using Permeable Nano-Scale Iron Reactive Barrier Coupled with Persulfate - Sand Box Experiments". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/57574939524067079118.
Pełny tekst źródłaStreszczenie:
碩士國立屏東科技大學
環境工程與科學系所
96
Organic chlorinated solvents are widely used in industrial processes, such as trichloroethylene (TCE) and perchloroethylene (PCE). If those chlorinated solvents are not properly handled, they may possibly leak into soil and further pollute the aquifer. The objective of this study is to investigate the treatment efficiency of aqueous trichloroethylene by permeable reactive barrier (PRB) filled with nano-sacle iron and coupled with persulfate (Na2S2O8). The experiments were designed to simulate the solutes transporting through the porous media and the remediation of TCE contaminated aquifer. The results from preliminary study showed that the average particle size and BET specific surface area of lab synthesized nano-scale iron were 525.6 nm and 125.1 m2/g, respectively. The iron component of particles was detected through X-ray powder diffraction(XRD) examination at 2θ＝44.960. The results from transport experiments through porous media showed that the breakthrough time of persulfate transport was slightly quicker than that of water flow owing to the influence of advection and dispersion. From the results of TCE transport experiments, TCE concentration reduced with the increase of distance from 128 mg/L to 47 mg/L between sampling Point A and Point D, which were 20 cm and 80 cm away from the injection well, respectively. Sampling Point A、B、C、D away from the injection well 20、40、60、80 cm, respectively. With addition of 0.75 g, i.e. 1500 mg/L, sodium persulfate (Na2S2O8), TCE concentration at sampling point A decreased from 365 mg/L to 225 mg/L. But TCE concentration gradually increased with test time implicated that TCE was not effective degraded by Na2S2O8. Degradation of TCE by Na2S2O8 was observed between point A and point C which were 20 and 40 cm away from the injection well. Addition of 45.15 g nano-scale iron into PRB with thickness of 1 cm, TCE concentration at sampling point C reduced from 230 mg/L to 30 mg/L during 40~50 hours and further reduced to 17 mg/L at sampling point D at the 62nd hour. Conductivity and concentration of chloride and ferrous increased with test time. The transport distance of ferrous ions (Fe2+) was about 10 cm in the design sandbox. TCE removal efficiencies at sampling points C and D of 5-cm thickness of PRB filled with 98.45 g nano-scale iron were worse than those of 1-cm thickness of PRB and transport distance of ferrous ions was restricted. Addition of 200 mL and 1500 mg/L Na2S2O8 from injection well at 64th hour, short-term TCE concentration at sampling point D decreased at 68th hour. Under the influence of aqueous pH and dissolved oxygen (DO), ferrous ions were easily oxidized to ferric ions (Fe3+) and formed ferric hydroxide precipitation due to high pH resulting in the clogging of PRB. The transport distance of ferrous ions were restricted by the precipitation of ferric hydroxide that caused Na2S2O8 not activated by ferrous ions. Thus that reduced the removal efficiency of TCE. This study shows TCE in aquifer can be effectively degraded by PRB filled with nano-sacle iron. The parameters concerned for activation of sodium persulfate by ferrous ions includes the transport distance of ferrous ions, dissolved oxygen and pH. The proposed technique combined the advantages of redox reaction of nano-scale iron and persulfate can be applied to effectively degrade TCE in aquifer. This study can be referred as an alternative for in-situ remediation of organic chlorinated solvents in aquifer.
40
Chi, Hao-Jan, i 季皓然. "Effect of polarity reversal on electrokinetic remediation of Bisphenol A contaminated soil: with or without permeable reactive barrier and sodium persulfate". Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5087011%22.&searchmode=basic.
Pełny tekst źródłaStreszczenie:
碩士國立中興大學
環境工程學系所
107
Bisphenol A (BPA) is an artificial industrial raw material and is widely used in the manufacture of various products. However, BPA is also a type of endocrine disrupting chemical (EDCs) which may affect human endocrine, reproductive, and nervous systems. Electrokinetic (EK) soil remediation is a remarkable technology, which especially recommended for the in-situ treatment of low permeability soils with low hydraulic conductivity values. In addition, EK remediation could combine with other soil remediation technologies to improve the efficiency. Sodium persulfate (SPS) is a common reagent for in-situ chemical oxidation. It is highly soluble, and it will not cause the secondary pollution after the reaction. Nevertheless, the reaction rate of SPS is so slow that we have to activate it by using electricity, heat, transition metal, alkali or other methods in order to generate sulfate radicals. Permeable reactive barriers (PRB) filled with reactive materials such as granular activated carbon (GAC) could intercept contaminants. The more contact of the contaminants with the PRB, the better efficiency of the process would be. Besides, periodic reversion in the polarity does not only improve the efficiency but it also helps to regulate the pH and to avoid the depletion of ionic species in the soil. The study includes three parts. In the first part, EK remediation would combine with PRB or SPS. In the next part, we have replaced EK with REK remediation. In the last part, REK remediation combined with SPS and PRB simultaneously. In part I (test 1~3), the removal rates were 27.01 %, 52.00 %, and 34.97%. The results revealed that electroosmosis flow was higher for test 3 (EK+SPS), and the distribution of residual BPA concentrations were similar for test 1 and 3. Electroosmosis flow was lower for test 2 (EK+PRB), but PRB successfully intercepted contaminants from left part of the soil. In part II (test 4~6), electrodes were reversed periodically, and the removal rates were 44.38 %, 78.52 %, and 47.50%. The removal rate of test 5 was the highest in this study, because that the polarity reversal let PRB intercept contaminants from both sides of the soil. Also, test 4’s and 6’s removal rates were higher than part I, and the residual BPA concentrated in the middle of all the soils. According to the results, periodic reversion in the polarity did improve the transport efficiency and degradation efficiency. For the last part (test 7 and 8), the removal rates were 61.45 % and 51.93 %. Base on the batch experiments results, the surface of GAC exhibited significant changes after contacting with SPS, which reduced adsorption capacity of GAC. Therefore removal rates for this part weren’t higher than test 5.
41
Guo, Qiang. "Some Aspects of Arsenic and Antimony Geochemistry in High Temperature Granitic Melt – Aqueous Fluid System and in Low Temperature Permeable Reactive Barrier – Groundwater System". Thesis, 2008. http://hdl.handle.net/10012/3579.
Pełny tekst źródłaStreszczenie:
Arsenic and antimony are important trace elements in magmatic-hydrothermal systems, geothermal systems and epithermal deposits, but their partitioning behavior between melt and aqueous fluid is not well understood. The partitioning of arsenic and antimony between aqueous fluid and granitic melt has been studied in the system SiO2-Al2O3-Na2O-K2O-H2O at 800 degree C and 200 MPa. The partition coefficients of As and Sb between aqueous fluid and melt, are 1.4 +- 0.5 and 0.8 +- 0.5, respectively. The partitioning of As is not affected by aluminum saturation index (ASI) or SiO2 content of the melt, or by oxygen fugacity under oxidized conditions (log fO2 > the nickel-nickel oxide buffer, NNO). The partitioning of Sb is independent of and SiO2 content of the melt. However, aluminum saturation index (ASI) does affect Sb partitioning and Sb partition coefficient for peralkaline melt (0.1 +- 0.01) is much smaller than that for metaluminous melts (0.8 +- 0.4) and that for peraluminous melts (1.3 +- 0.7). Thermodynamic calculations show that As(III) is dominant in aqueous fluid at 800 degree C and 200 MPa and XPS analysis of run product glass indicate that only As(III) exists in melt, which confirms the finding that does not affect As partitioning between fluid and melt. XPS analysis of run product glass show that Sb(V) is dominant in melt at oxidized conditions (log fO2 > -10). The peralkaline effect only exhibits on Sb partitioning, not on As partitioning at oxidized conditions, which is consistent with the x-ray photoelectron spectroscopy (XPS) measurements that As(III) and Sb(V) are dominant oxidation states in melt under oxidized conditions, because the peralkaline effect is stronger for pentavalent than trivalent cations. Permeable reactive barriers (PRBs) are an alternative technology to treat mine drainage containing sulfate and heavy metals. Two column experiments were conducted to assess the suitability of an organic carbon (OC) based reactive mixture and an Fe0-bearing organic carbon (FeOC) based reactive mixture, under controlled groundwater flow conditions. The organic carbon (OC) column showed an initial sulfate reduction rate of 0.4 μmol g(oc)-1 d-1 and exhausted its capacity to promote sulfate reduction after 30 pore volumes (PVs), or 9 months of flow. The Fe0-bearing organic carbon (FeOC) column sustained a relative constant sulfate reduction rate of 0.9 μmol g(oc)-1 d-1 for at least 65 PVs (17 months). The microbial enumerations and isotopic measurements indicate that the sulfate reduction was mediated by sulfate reducing bacteria (SRB). The cathodic production of H2 by anaerobic corrosion of Fe probably is the cause of the difference in sulfate reduction rates between the two reactive mixtures. Zero-valent iron can be used to provide an electron donor in sulfate reducing PRBs and Fe0-bearing organic carbon reactive mixture has a potential to improve the performance of organic carbon PRBs. The δ34S values can be used to determine the extent of sulfate reduction, but the fractionation is not consistent between reactive materials. The δ13C values indicate that methanogenesis is occurring in the front part of both columns. Arsenic and antimony in groundwater are great threats to human health. The PRB technology potentially is an efficient and cost-effective approach to remediate organic and inorganic contamination in groundwater. Two column experiments were conducted to assess the rates and capacities of organic carbon (OC) PRB and Fe-bearing organic carbon (FeOC) PRB to remove As and Sb under controlled groundwater flow conditions. The average As removal rate for the OC column was 13 nmole day-1 g-1 (dry weight of organic carbon) and its removal capacity was 11 μmole g-1 (dry weight of organic carbon). The remove rate of the FeOC material was 165 nmole day-1 g-1 (dry weight of organic carbon) and its minimum removal capacity was 105 mole g-1 (dry weight of organic carbon). Antimony removal rate of the OC material decreases from 8.2 to 1.4 nmole day-1 g-1 (dry weight of organic carbon) and its removal capacity is 2.4 μmole g-1 (dry weight of organic carbon). The minimum removal rate of FeOC material is 13 nmole day-1 g-1 (dry weight of organic carbon) and its minimum removal capacity is 8.4 μmole g-1 (dry weight of organic carbon). The As(III) : [As(III)+As(V)] ratio increased from 1% in the influent to 50% at 5.5 cm from the influent end, and to 80% at 15.5 cm from the influent end of the OC column. X-ray absorption near edge spectroscopy (XANES) shows As(III)-sulfide species on solid samples. These results suggest that As(V) is reduced to As(III) both in pore water and precipitate as As sulfides or coprecipitate with iron sulfides. The arsenic reduction rate suggests that As(V) reduction is mediated by bacterial activity in the OC column and that both abiotic reduction and bacterial reduction could be important in FeOC.
42
Elder, Carl R. "Evaluation and design of permeable reactive barriers amidst heterogeneity". 2000. http://www.library.wisc.edu/databases/connect/dissertations.html.
Pełny tekst źródła
43
Lee, Taeyoon. "Using waste foundry sands as a reactive media in permeable reactive barriers". 2002. http://www.library.wisc.edu/databases/connect/dissertations.html.
Pełny tekst źródła
44
Apte, Sachin V. "Reactive media for chromium reduction under alkaline conditions for use in permeable reactive barriers". Thesis, 2001. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2001-011.
Pełny tekst źródła
45
Hung, Hsu-Wen, i 洪旭文. "Remediation of MTBE-contaminated Groundwater Using Adsorbent-based Permeable Reactive Barriers". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/05362762873510117875.
Pełny tekst źródłaStreszczenie:
博士國立成功大學
環境工程學系碩博士班
94
Methyl tert-butyl ether (MTBE) is the most common oxygenated fuel additive used to increase the octane rating and to enhance the combustion efficiency of gasoline. As a consequence of widespread use of MTBE, it has been found to be a ubiquitous and recalcitrant contaminant in groundwater and surface water due to its physicochemical properties. To remediate MTBE-contaminated groundwater, the passive in-situ permeable reactive barriers (PRBs) with different types of adsorbing media including granular activated carbon (GAC), carbonaceous resin and zeolite were used in this study. Although this research focuses mainly on simplified natural and engineering environmental systems, the results may provide useful information and insights for more complex large-scale experimental systems and for field applications. To evaluate the performances of the adsorbent-based PRBs for treating MTBE-contaminated groundwater, equilibrium and kinetic adsorption of MTBE onto the adsorbent pellets of activated carbons (F600, F400, F300, Unicarb and WPH), carbonaceous resins (Ambersorb 563 and 572) and zeolites (mordenite and HiSiv 1000) in different natural waters located in Taiwan and Germany were first explored. The experimental results revealed that adsorption isotherms of MTBE for the activated carbons and carbonaceous resins in natural waters were different than those in deionized water. It was suggested that natural organic matter (NOM) competed with MTBE for the adsorption sites of the adsorbents tested. The initial concentration of MTBE has great influence on the equilibrium capacity for the activated carbons and resins in the presence of NOM. The lower the applied initial concentration, the higher the extent of competition was founded. Additionally, the NOM fraction of low-molecular weight and adsorbent properties, such as pore size distribution, aperture size and the SiO2/Al2O3 ratio for zeolite, have considerable influences on the equilibrium capacity of MTBE for the adsorbents tested in different water matrix. No competitive adsorption of NOM and MTBE was observed for mordenite whose aperture size is highly uniform and concentrated due to molecular sieve effect. A predictive method, called the SCAM-EBC approach, based on the well-known equivalent background compound (EBC) and simplified competitive adsorption model (SCAM) was developed to describe the competitive adsorption of NOM. The results revealed that the SCAM-EBC approach has excellent predictive ability of the isotherms at different initial concentrations for all the activated carbons/carbonaceous resins/natural water systems. Besides MTBE, several other pollutants, including strongly adsorbing compounds (TCP, atrazine, and chloroform) and two taste and odor causing compounds (MIB and geosmin) onto different activated carbons in natural and artificial groundwaters, were tested to verify the SCAM-EBC approach. Moreover, the relative adsorptivity based on the SCAM-EBC approach was proposed to quantify and predict the extent of isotherm curvature occurred at lower applying absorbent dosage. The marked isotherm curvature was found when the relative adsorptivity is larger than 2.0 to 4.0, called critical relative adsorptivity, for all the systems tested. The transport of MTBE onto those three types of adsorbent pellets in different water matrixes was simulated by intraparticle surface diffusion model (SDM) and pore diffusion model (PDM) combined with either the SCAM-EBC approach or IAST-EBC model. Both the intraparticle diffusion models fit the experimental kinetic data fairly well and successfully predicted the transport of MTBE within all of the adsorbents under different experimental conditions. The intraparticle surface and pore diffusivities showed different in deionized water and natural water systems and were attributed to the hindering effect and tortuous pathways. The results indicated that NOM seems to have no obvious impact on the transport of MTBE onto the activated carbons and resins. For mordenite, NOM may, however, block the surface opening aperture and hinder the diffusional paths of MTBE, causing slower adsorption kinetics. Finally, laboratory column experiments of the GACs, the rapid small scale column tests (RSSCTs), were conducted to simulate the transport of MTBE through the PRBs. Steeper breakthrough curves (BTCs) and smaller integrated column capacities of the RSSCTs for F600 and F300 GACs in groundwaters and river waters were found compared with those in deionized water. Like the batch adsorption systems for the activated carbons and resins used, both initial concentration effect and competitive adsorption between NOM and MTBE were found in the RSSCT column studies. The influent MTBE concentrations have great influences on the integrated column capacities as well as the spreading of BTCs for the RSSCTs under different empty bed contact times (EBCTs). A fixed-bed model based on a combination of the SDM and the SCAM-EBC approach was employed to simulate the experimental BTCs. The model predictions were compared with the BTCs of RSSCTs under different conditions. No adjustable parameters were required in modeling the fixed-bed BTCs. All the model input parameters were either extracted from the batch equilibrium and kinetic experiments or calculated from empirical correlations. The models successfully predicted the experimental BTCs at different EBCTs and influent concentrations of MTBE. Although the conditions tested in this study are simplified, the elucidation of clean up mechanisms and interactions taking place between the adsorbent media and MTBE plumes in this study should be informative enough to give a useful perspective when attempting to remediate MTBE-contaminated groundwater using adsorbent-based permeable reactive barriers (PRBs).
46
Sapp, Mandy M. "Uranium and technetium bio-immobilization in intermediate-scale permeable reactive scale barriers". Thesis, 2003. http://hdl.handle.net/1957/30056.
Pełny tekst źródłaStreszczenie:
Groundwater at Oak Ridge National Laboratory's Field Research Center
(FRC) is contaminated with U(VI) and Tc(VII), has pH values as low as 3.3, and
nitrate concentrations as high as 120 mM. The objective of this research was to
determine if in-situ bio-immobilization is a viable treatment alternative for this water.
A laboratory column packed with crushed limestone and bicarbonate was used
to model in-situ pH adjustment. Denitrification and metal reduction were modeled in
columns packed with FRC sediment with ethanol as the electron donor. Two
intermediate-scale physical models deployed in the field were packed with limestone
and sediment and were stimulated with ethanol to support denitrification, U(VI)
reduction, and Tc(VII) reduction of FRC groundwater.
The limestone/bicarbonate column maintained a pH of above 5 for nearly one
hundred pore volumes without significant loss in hydraulic conductivity. The high-nitrate
(~120 mM) column study provided rates of denitrification (~15.25 mM/day),
ethanol utilization (~13 mM/day), and technetium reduction (~120 pM/day) by
sediment microorganisms, but no uranium reduction was detected. Results of the low
nitrate (3 mM) column study indicate that once the pH of FRC water is adjusted to pH
~7 and nitrate is removed, uranium (~3 μM) and technetium (~500 pM) reduction
occurred with ethanol as the electron donor at rates of 0.5 μM/day and 57 pM/day.
Similar results were obtained in two intermediate-scale (~3 m long) physical
models. Data from the high-nitrate, low-pH model indicate that the pH was increased
and nitrate and technetium reduction were occurring. Decreased U(VI) concentrations
were measured in the presence of high nitrate concentrations. Thus, U(VI) precipitates
may form or sorption of U(VI) may occur near the inlet in the pH adjustment region.
The maximum pseudo-first order rates of reduction measured during the seventh week
of model operation were: nitrate at 0.76 day⁻¹, Tc(VII) at 0.28 day⁻¹, and U(VI) at 0.12
day⁻¹. Ethanol concentrations were reduced from ~180 mM to zero in ~10 days
during the seventh week of model operation. No Fe(II) production was measured.
Concentration data collected from the low nitrate, neutral pH model indicate
that nitrate, uranium, and technetium reduction were occurring, though the model had
been operational for only ~6 weeks. No Fe(II) production was detected but sulfate
reduction was occurring.
The results of the laboratory experiments and the performance of the
intermediate-scale physical models suggest that bio-immobilization is a viable
treatment alternative for the contaminated groundwater at the FRC.Graduation date: 2004
47
Williams, Randi Lee. "Using dissolved gas analysis to investigate the performance of permeable reactive barriers". Thesis, 2005. http://hdl.handle.net/2429/16438.
Pełny tekst źródłaStreszczenie:
The strongly reducing nature of permeable reactive barrier (PRB) treatment
materials can lead to gas production, potentially resulting in the formation of gas bubbles
and ebullition. For this work degassing in the saturated zone of PRB systems due to the
production of gases (primarily CO₂ and CH₄) is investigated using the depletion of Aland
N₂, naturally present non-reactive gases, in order to identify, confirm, and possibly
quantify chemical and physical processes occurring. Dissolved gas sampling and
analysis were conducted at three PRB sites designed for the treatment of groundwater
contaminated by mining and industrial activities: the Nickel Rim Mine Organic Carbon
PRB Site (Site I), the Campbell Mine Zero-Valent Iron (Fe⁰)/ Organic Carbon Test Cell
PRB (Site II), and the Columbia Nitrogen Fe⁰/ Organic Carbon Mixed PRB Site (Site III).
At Site I, residence times within the PRB are sufficiently long to allow gas
production and degassing. A simple four-gas degassing model was used to analyze the
data set, and the results indicate that sulfate reduction is by far the main process of
organic carbon consumption within the barrier. The data provided additional information
to delineate rates of microbially mediated sulfate reduction and to determine slow and
fast flow zones within the barrier. Degassing was incorporated into reactive transport
simulations for Site I in order to model 8 years of barrier operation. The simulations
adequately reproduce observed dissolved gas trends, although no information on the
volume change due to bubble formation or the fate of the trapped gas could be obtained.
At Site II, residence times were short and the dissolved gas data could be used
primarily as a transport tracer. Zones of preferential and of low flow could be identified
within the PRB. At Site III, the strong resemblance of water composition upgradient and downgradient of the PRB suggested that residence times are long and that there is little
flow through the PRB. The dissolved gas data could primarily be used as a reaction
tracer. The data suggested that gas production and reaction rates are relatively
insignificant in the barrier system.
The success and failures at Sites I-III could be used to create a set of criteria under
which dissolved gas analysis is useful for PRB systems. Treatment material composition,
dissolved gas composition in the groundwater influent to the PRB, and residence times
through the PRB are important factors to consider.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
48
Mergener, Elizabeth A. "Assessing clogging of permeable reactive barriers in heterogeneous aquifers using a geochemical model". 2002. http://catalog.hathitrust.org/api/volumes/oclc/50263619.html.
Pełny tekst źródłaStreszczenie:
Thesis (M.S.)--University of Wisconsin--Madison, 2002.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 74-76).
49
Hung, Tsung-Po, i 洪琮博. "Removal of Pentachlorophenol in Groundwater by E-Fenton Coupled with Permeable Reactive Barriers". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/45698301935868727660.
Pełny tekst źródłaStreszczenie:
碩士國立中興大學
環境工程學系所
96
Permeabe reactive barrier(PRB) embedded with zero-valent iron(Fe0) has been used as the remediation technology of ground water. The method develops greatly in the recent years for the dechlorination or completely destroy of pentachlorophenol(PCP). The E-Fenton method is a popular waste water treatment technique that could produce hydrogen peroxide by cathode, which then react with ferrous iron (called Fenton processes). Fenton reaction could degrade PCP by oxidation. The purpose of this study is to estimate the removal of PCP by E-Fenton coupled with PRB in a recirculating batch experiment, and to gain the best condition for this system and the removal mechanism of PCP. Based on the results of background experiment, 0.7 L/min air applying could produce 5.2×10-3 mg/min hydrogen peroxide. PCP of 5 mg/L could be degraded for 63%, and mineralized for 26% when initial pH is 4, flow direction is cathode to anode, PRB consists of Fe0/quartz sand(QS)=1/60(g/g), current density is 0.75mA/cm2, and flow rate is 20 mL/min. The removal efficiency and mineralization of E-Fenton is better than those of traditional Fenton process. Because of the concentration of Fe2+ is too high in this system, when the efficiency increased proportionally, the producing ratio of hydrogen peroxide increased.
50
Li-Hsuan, Chen, i 陳立軒. "A Study on Biodegradation Capability and Microbial Community Dynamics using Permeable Reactive Barriers". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/19660992833794328970.
Pełny tekst źródłaStreszczenie:
碩士大葉大學
環境工程學系碩士班
95
The purposes of this study are to evaluate the bioremediation capabilities using two laboratory-scale permeable reactive barriers (PRB) in a BTEX-contaminated groundwater, and to explore the changes in microbial community in the reactor by using PCR-SSCP. The bioremediation capabilities were evaluated by introducing biostimulation (addition of oxygen-releasing materials and nitrogen) and bioaugmentation (addition of BTEX-degrading cultures). A relationship among biodegradation capability, changes in microbial community and total plate count of microorganisms was determined. Results of oxygen-releasing materials in laboratory column tests indicates that the oxygen release rates increase with the addition of CaO2 and achieve a constant value of 0.22 mg O2-day-1 g-1-ORC while increasing CaO2 to 30 %–60 %, thereby revealing that the linear relationship between oxygen release rates and addition of CaO2 is not consistently observed while keeping increasing CaO2. Moreover, it is found that the total packing amounts of ORC and inlet flowrate had no significant effects on oxygen release rate and the ORC releasing system could consistently release oxygen for at least thirty five days. Results of the permeable reactive barriers show that (1)the removal capability for BTEX decreases in the order of ethylbeneze, p-xylene, toluene, benzene for both nitrogen addition and no nitrogen addition under BTEX concentrations at 30 mg l-1; (2)the removal efficiency of PRB is higher in the nitrogen addition condition for biostimulation comparing with no nitrogen addition condition, and an increased pattern for removal was observed during the bioaugmentation process; (3) the BTEX removals for nitrogen addition and no nitrogen addition are 52.4 % and 38.9 % for benzene, 72.3 % and 51.6 % for toluene, 80.2 % and 71.4 % for ethylbenzene, and 72 % and 71 % for p-xylene; (4)the amount of dissolved oxygen is found to be inversely proportional to the distance from PRB, as evidenced by the average bacteria densities are two orders higher in a location at 15 cm than at 30 cm from the PRB), thereby revealing that the primary aerobic biodegradation zone is in the ranges from 5 to 30 cm downstream of the PRB; (5)the microbial community structure is similar in both the nitrogen addition and in no nitrogen addition conditions, though the removal efficiency of BTEX and the bacteria densities increase, indicating the nitrogen addition stimulates the activity of microorganisms; and (6)determination the relationship among the BTEX removal efficiency, COD, DO, bacteria densities and the microbial community structure provides assistance in evaluating the feasibility of bioremediation using PRB in a BTEX-contaminated groundwater.