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Kirby, Daniel. "Hydrogeological study of a sequenced permeable reactive barrier." Thesis, Kirby, Daniel (2015) Hydrogeological study of a sequenced permeable reactive barrier. Other thesis, Murdoch University, 2015. https://researchrepository.murdoch.edu.au/id/eprint/28263/.
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A hydrogeological study of a sequenced permeable reactive barrier (PRB) was undertaken by environmental engineering student, Daniel Kirby, in fulfilment of the final year engineering thesis unit, ENG460 - Engineering Thesis, at Murdoch University, Perth, WA. The project was conducted in collaboration with Golder Associate. The study was conducted at contaminated site located in Bellevue, WA. In 2001 a large explosion and chemical fire occurred at a liquid waste treatment and recycling facility located at the site, in response to this contamination Golder Associates designed and installed a PRB treatment system in 2010. A permeable reactive barrier is a groundwater treatment design, which makes use of the natural groundwater flow to channel contaminants through an engineered in-situ treatment area. This treatment system was designed to consist of two different and separate barriers filled with two different reactive material. The first contains sawdust used to treat nitrates through the microbial process of denitrification. The second contains Zero Valent Iron (ZVI), a non-toxic granular material used to treat chlorinated solvents in the groundwater. The objective of this project was to study flow paths of the PRB at the contaminated site and identify potential for flow to bypass the PRB treatment system. Achieving this objective involved analysing groundwater level data from pressure transducers and previous historical monitoring rounds. In addition to the water level analysis, two tracer studies were conducted at two different locations at the site. The tracer studies involved using the organic dye fluorescein to further understand the flow paths of the site and to validate suspected flows that may bypass the PRB treatment system. The two tracer studies developed for use in this thesis were designed based on a literature review on relevant topics, and through liaising with academic staff at Murdoch University and the project manager at Golder Associates. The first tracer study aimed to validate contaminated flow that directly bypasses the ZVI barrier. The second tracer study, conducted at the centre of the PRB system, aimed to provide information on the lateral water movement and dispersivities through the PRB treatment system. The results of the groundwater level assessment identified areas that potential flow bypassing the treatment system could be present, the area of concern was identified to be the south-western portion of the PRB treatment system. The tracer study that was conducted within this area failed to validate the bypass, the source of this failure has been attributed to an error in the selection of the injection and monitoring wells. The second tracer study which was conducted at the centre of the PRB treatment system. The data obtained from the second study did not provide the ideal result as no significant tracer concentration was detection in the monitoring wells. A number of reasons for the lack of tracer detection have been discussed, including a lack of connectivity between injection and monitoring wells due to the presence of impermeable clay layers. It has been acknowledged that there is insufficient data collected during the study to accurately conclude on whether contaminated flow is bypassing the PRB treatment system.
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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.
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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/.
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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.
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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.
Full textAbstract:
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.
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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.
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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.
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Shukla, Pradeep. "Combined adsorption and oxidation technique for waste water treatment: potential application in permeable reactive barrier." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/212.
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This dissertation explores a combined adsorption and advanced oxidation technology for trapping and destruction of organic pollutants in waste water. The adsorbed/immobilized pollutant onto the surface of metal supported catalyst is oxidized via advanced oxidation technology. The advanced oxidation process is carried out using Co[superscript]2+/KHSO[subscript]5 (Cobalt/peroxymonosulphate) reagent to generate highly active sulphate radical (SO[subscript]4*), which can readily attack and oxidize the organic pollutants in waste water. The reaction mechanism of Co[superscript]2+/KHSO[subscript]5 reagent follows similarly to the Fenton reagent (Fe[superscript]2+/H[subscript]2O[subscript]2) which is used to generate hydroxyl radical (OH*). Co[superscript]2+/KHSO[subscript]5 reagent has been successfully utilized for bleaching applications and oxidation of organic contaminants. Compared to hydroxyl radical, the sulphate radical is highly potent to oxidize contaminants even at basic pH. However the biggest disadvantage of using Co[superscript]2+/KHSO[subscript]5 reagent is the dissolution of Co[superscript]2+ ion into the water which poses a severe environmental hazard. In the current study, cobalt ion is incorporated into supporting media and utilized for advanced oxidation.Very few studies have so far explored the heterogeneous oxidation technology based on Co[superscript]2+/KHSO[subscript]5 for the treatment of organic contaminants in water. With this research focus, various support media have been utilized to load cobalt ions, which included Zeolite A, Zeolite X, ZSM-5, SBA-15, Silica and Activated Carbon. Cobalt metal was incorporated into commercial Zeolites by ion exchange technique whereas in-situ cobalt loading was carried out during the synthesis of SBA-15. Cobalt loading was done into Silica and Activated Carbon by conventional impregnation technique. The choice of cobalt loading technique inherently determines the oxidation state of cobalt species loaded into the sample which in turn determines the oxidation efficiency. Furthermore, the choice of cobalt precursor significantly affects the metal-support bonding which has been investigated by loading on silica support with different types of cobalt precursor such as cobalt chloride, cobalt acetate and cobalt nitrate. Many of these supports such as Zeolite ZSM-5 and Activated Carbon have never been tested before for cobalt loading and oxidation via sulphate based oxidant and demonstrate efficient oxidation of phenolic pollutants.The investigation of organic oxidation using sulphate based oxidants was further extended into photocatalytic reactions. Photo degradation was carried out using artificial solar light and germicidal UV radiation in the presence of ZnO and oxidants such as peroxymonosulphate, peroxidisulphate and hydrogen peroxide. The comparison of photochemical and photocatalytic oxidation was carried out and their synergy of combination was explored.The thesis provides a thorough exploration of heterogeneous oxidation via sulphate based oxidant for the treatment of organic pollutants. The supported catalysts investigated here can be further improved and utilized as a PRB media for groundwater remediation. A final chapter discusses about the mathematical modeling of a column test to mimic a lab scale PRB in order to investigate the process parameters affecting the PRB design. The column modeling also directs towards a development of a novel “Reactive Adsorber” for the treatment of industrial waste by combined adsorption and oxidation.
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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.
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"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. "
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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Callahan, Thomas Patrick. "Non-Newtonian fluid injection into granular media." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39618.
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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.
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Audí, Miró Carme. "Compound Specific Isotope Analysis ((13)C, (37)Cl,( 2)H) to trace induced attenuation of chlorinated organic contaminants in groundwater." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/145921.
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Chloroform (CF), tetrachloroethene (PCE) and trichloroethene (TCE) are dense chloro-aliphatic hydrocarbons (CAH) extensively used as industrial solvents. These compounds have been largely released to the environment due to poor waste management.
In this thesis, the effect of a ZVI-PRB installed at a field site contaminated mainly with PCE, TCE and cis-DCE was evaluated. Moreover, a novel strategy to degrade the recalcitrant CF -alkaline hydrolysis induced by concrete-based recycled construction wastes- was proposed and developed in order to test its efficiency in degrading this pollutant. Compound specific isotope analysis (CSIA) is a valuable tool for monitoring an environmental treatment in the field, based on the isotope fractionation of an element during transformation reactions.
Therefore, the general aim of this thesis is to use compound specific isotope analysis of 13C, 37Cl and 2H as a tool to assess both induced attenuation processes 1) chlorinated ethenes degradation by a ZVI-PRB installed at the field sited; and, 2) the proposed new remediation technique based on the use of concrete-based recycled construction wastes to degrade chloroform (CF) by alkaline hydrolysis applied at a site contaminated by this pollutant.
First, laboratory experiments were conducted to study both ZVI and concrete effects on the chlorinated ethenes and the chloroform, respectively. ZVI experiments yielded carbon isotope fractionation values of the chlorinated ethenes degradation by the specific ZVI used in the field application, as well as, the first chlorine isotope fractionation values of TCE and cis-DCE associated to this reaction. Two promising approaches to discriminate the abiotic ZVI degradation versus biotic degradation present at the field site were brought forward 1) the dual isotope C-Cl approach, which distinguished slopes 4 times lower than for biodegradation of cis-DCE by the commercially available Dehalococcoides-containing culture mixed culture KB-1; and 2) the product-specific carbon isotope fractionation that showed a 10‰ difference between those products coming from β-dichloroelimination and hydrogenolysis reactions. Concrete experiments with CF achieved a 95% CF degradation after 28 d, accompanied by a significant carbon isotope fractionation. The carbon isotopic fractionation associated with alkaline hydrolysis of CF was -53±3‰.
The obtained laboratory data permitted the assessment of the respective induced degradation treatments applied at the field site. At the site with the ZVI-PRB treatment, both, occurrence of biodegradation and degradation by ZVI-PRB were evidenced by means of detected metabolites and 13C data, with quantitative estimates of ZVI-PRB efficiency of less than 10% and 2% for PCE and cis-DCE, respectively. Dual element 13C-37Cl isotope plots confirmed that the effect of the ZVI-PRB was masked by biodegradation. Based on carbon isotopes data, 49% and almost 100% of PCE and TCE, respectively, were estimated to be removed by biodegradation. Finally the combination of 2H with 13C and 37Cl discriminated two different sources of contamination spilled from the same industry. This indicates the potential of δ2H to discriminate if a compound is of industrial origin, or whether it is formed as a daughter product during degradation. Regarding CF hydrolysis, field-scale pilot experiments were used to test the efficiency of the concrete-base recycled construction wastes to induce alkaline hydrolysis. The carbon isotopic fractionation obtained at the lab scale allowed the calculation of the percentage of chloroform degradation in the field-scale pilot experiments where alkaline conditions were induced in two recharge water interception trenches filled with concrete-based construction wastes. A maximum of approximately 30-40% of chloroform degradation was achieved. Although further research is required, the treatment of chloroform in groundwater through the use of concrete-based construction wastes is proposed. This strategy would also imply the recycling of construction and demolition wastes for use in value-added applications to increase economic and environmental benefits.El chloroform (CF), el tetracloroetè (PCE) i el tricloretè (TCE) són hidrocarburs clor-alifàtics densos usats extensament com a solvents industrials. Aquests compostos s’han alliberat al medi degut a un tractament inadequat dels seus residus. En aquesta tesi, l’efecte d’una barrera permeable reactiva de ferro zero valent (BPR-FZV) instal•lada en un emplaçament contaminat majoritàriament amb PCE, TCE i cis-dicloretè (cis-DCE, subproducte de TCE) ha estat avaluada. A més a més, s’ha proposat i desenvolupat una nova estratègia per a degradar el CF, el qual és un compost recalcitrant, consistent en la inducció de la hidròlisi alcalina del CF mitjançant residus de construcció basats en formigó. L’ànàlisi isotòpic de compost específic (AICE) és una eina valuosa per al monitoreig d’un sistema de tractament medi ambiental, basant-se en el fraccionament isotòpic d’un element durant les reaccions de transformació. L’objectiu general d’aquesta tesi és l’ús de l’anàlisi isotòpic de compost específic de 13C, 37Cl i 2H com una eina per a controlar els dos processos d’atenuació 1) la degradació dels eten-clorats mitjançant una BPR-FZV instal•lada en el camp; i, 2) la nova tècnica de remediació de CF proposada basada en l’ús de residus reciclats de la construcció per tal d’induir la hidròlisi alcalina del CF. En general, mitjançant la combinació dels isòtops de C, Cl i H, aquesta tesi aporta noves eines per discriminar la degradació dels compostos organoclorats d’estudi mitjançant FZV, respecte la biodegradació en el camp, així com també per a identificar fonts de contaminació d’origen industrial o de productes formats, entre d’altres aportacions. A més a més, el nou mètode proposat per a degradar el CF basat en la seva hidròlisi alcalina mitjançant l’ús de residus de construcció reciclats ha demostrat ser eficient en la degradació d’aquest contaminant, així com també, mitjançant l’ús de isòtops de carboni, ha demostrat funcionar en experiments pilot monitorejats a escala de camp.
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Pandey, Pratiksha. "Hybrid multiobjective optimization approach for optimal design of in-situ permeable reactive barrier." Thesis, 2017. http://localhost:8080/iit/handle/2074/7357.
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Hsu, Chia-Ping, and 徐嘉彬. "Groundwater Nitrate Removal by Zero-Valent Iron Permeable Reactive Barrier." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/59266737515942053622.
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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.
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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.
Full textAbstract:
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.
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McLean, Neil Ross. "Use of Drains for Passive Control of Flow Through a Permeable Reactive Barrier." Thesis, 2007. http://hdl.handle.net/10012/3375.
Full textAbstract:
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.
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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.
Full textAbstract:
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
21
FANG, YEH JU, and 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.
Full textAbstract:
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.
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Lin, Ming-Hei, and 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.
Full textAbstract:
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
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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.
Full textAbstract:
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.
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Dam, Quoc-Khanh, and 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.
Full textAbstract:
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.
25
Wu, Shih-Kai, and 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.
Full textAbstract:
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.
26
Pan, Chi-liang, and 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.
Full textAbstract:
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.
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Wang, Dong-Yi, and 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.
Full textAbstract:
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.
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Chi, Hao-Jan, and 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.
Full textAbstract:
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.
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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.
Full textAbstract:
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.
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Hart, Jeffrey L. (Jeffrey Le). "Evaluating the rates of nitrate removal for a nitrate containing, low organic carbon wastewater interacting with carbon-containing solid substrates." Thesis, 2012. http://hdl.handle.net/1957/28584.
Full textAbstract:
The primary objective of this study was to evaluate the rates of nitrate removal for a nitrate containing, low organic carbon wastewater interacting with four different carbon-containing solid substrates (alder woodchips, corn silage, manure and woodchip biochar). Batch systems were tested for nitrate removal, and systems with a combination of three carbon substrates (75% woodchips, 12.5% silage, and 12.5% manure or woodchip biochar by mass) produced average nitrate removal rates of 571 and 275 mg-N L⁻¹ D⁻¹, and systems containing the carbon substrates individually produced rates between 11.4 - 3.3 mg-N L⁻¹ D⁻¹. Silage proved to be the dominant carbon substrate providing high quantities of organic carbon to fuel denitrification. With the introduction of semi-continuous flow, all systems had nitrate removal rates that converged to 13.3 – 6.4 mg-N L⁻¹ D⁻¹, which is approximately two orders of magnitude smaller than the rates of the mixture systems in the batch experiment. Silage appeared to be removed from of the systems with liquid exchange potentially causing the rate decreases. Columns filled with various volume fractions of woodchips (100%, 25%, 12.5%, and 0%) produced nitrate removal rates between 30.8 – 2.4 mg-N L⁻¹ D⁻¹ at a 24 hour and 12 hour hydraulic residence time (HRT). Greater nitrate removal was achieved with higher HRTs and larger fractions of woodchips (the 100% woodchip system at a 24 hour HRT produced the fastest nitrate removal rate of 30.8 mg-N L⁻¹ D⁻¹). When rates were normalized to the amount of woodchips in each column, higher efficiency was found in lower woodchip fraction systems (the 12.5% woodchip column produced the highest normalized nitrate removal rate of 56 mg-N L⁻¹ D⁻¹ L[subscript woodchips]⁻¹). Woodchips proved to be best suited as a long term carbon substrate for nitrate removal in a system containing a nitrate concentrated, low organic carbon wastewater. However, large amounts of woodchips were necessary to achieve nitrate removal greater than 50%. A 41 acre hypothetical wetland with a 3.3 day HRT and a nitrate influent concentration of 45 mg-N L⁻¹ would require 30,000 yd³ of woodchips to achieve 68% nitrate removal based on the values obtained in the bench scale column experiment.Graduation date: 2012