abstract: Widespread use of chlorinated solvents for commercial and industrial purposes makes co-occurring contamination by 1,1,1-trichloroethane (TCA), trichloroethene (TCE), and 1,4-dioxane (1,4-D) a serious problem for groundwater. TCE and TCA often are treated by reductive dechlorination, while 1,4-D resists reductive treatment. Aerobic bacteria are able to oxidize 1,4-D, but the biological oxidation of 1,4-D could be inhibited TCA, TCE, and their reductive transformation products. To overcome the challenges from co-occurring contamination, I propose a two-stage synergistic system. First, anaerobic reduction of the chlorinated hydrocarbons takes place in a H2-based hollow-fiber “X-film” (biofilm or catalyst-coated film) reactor (MXfR), where “X-film” can be a “bio-film” (MBfR) or an abiotic “palladium-film” (MPfR). Then, aerobic removal of 1,4-D and other organic compounds takes place in an O2-based MBfR. For the reductive part, I tested reductive bio-dechlorination of TCA and TCE simultaneously in an MBfR. I found that the community of anaerobic bacteria can rapidly reduce TCE to cis-dichloroethene (cis-DCE), but further reductions of cis-DCE to vinyl chloride (VC) and VC to ethene were inhibited by TCA. Also, it took months to grow a strong biofilm that could reduce TCA and TCE. Another problem with reductive dechlorination in the MBfR is that mono-chloroethane (MCA) was not reduced to ethane. In contrast, a film of palladium nano-particles (PdNPs), i.e., an MPfR, could the simultaneous reductions of TCA and TCE to mainly ethane, with only small amounts of intermediates: 1,1-dichloroethane (DCA) (~3% of total influent TCA and TCE) and MCA (~1%) in continuous operation. For aerobic oxidation, I enriched an ethanotrophic culture that could oxidize 1,4-D with ethane as the primary electron donor. An O2-based MBfR, inoculated with the enriched ethanotrophic culture, achieved over 99% 1,4-D removal with ethane as the primary electron donor in continuous operation. Finally, I evaluated two-stage treatment with a H2-based MPfR followed by an O2-MBfR. The two-stage system gave complete removal of TCA, TCE, and 1,4-D in continuous operation. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018

Providing access to clean drinking water will continue to be a challenge for civil engineers for generations to come. Since many communities around the world rely on groundwater as a source of drinking water, remediation technologies must be implemented at sites where groundwater contamination exists due to years of mismanagement of hazardous waste. Using nanosized zero-valent metals such as iron and zinc embedded within and on the surface of functionalized (PAA) membrane filters has shown to be an effective dechlorination technique for contaminated groundwater. Introducing a noble metal such as Pd or Ni increases reaction rates by acting a catalyst for the dechlorination reaction. This study focuses on the treatment of contaminated groundwater at a hazardous waste site in Louisville, Kentucky. Once a chlorinated organic chemical manufacturing plant, the site now operates a treatment system for the contaminated groundwater to prevent migration into the nearby Ohio River. A portable membrane treatment system, built at the University of Kentucky, incorporates this functionalized bimetallic membrane technology for treatment of the groundwater found at the former manufacturing plant. Three bench scale tests were performed with membrane treatment system using DI water spiked with the chemical trichloroethylene (TCE). Results showed that using the functionalized Fe/Pd membranes significant decreased TCE concentrations over time. While further tests should be conducted to verify the results of the preliminary bench-scale tests, the membrane treatment system shows potential for use at the hazardous waste site in Kentucky.

The photocatalytic oxidation of trichloroethylene (TCE), ethylene. ethane and toluene on TiO2, Pt/TiO2 and Ag/TiO2 were investigated in a dedicated reactor set-up operated at room temperature and ambient pressure condition. The gas phase experiments were carried out for both single and binary mixtures of these chemicals to identify the role of Pt and Ag metallisation in the photocatalytic oxidation of different contaminants. In a single contaminant system, the presence of Pt enhanced the oxidation of ethylene, ethane and toluene but detrimental to the oxidation of TCE. In the oxidation of ethylene, Pt enhanced the oxidation by acting as catalyst and as electron sink. However, in ethane oxidation, the enhancement was solely associated to the ability of Pt to act as electron sink. The detrimental effect observed in TCE oxidation was attributed to Pt and Cl interaction, which formed a persistent inorganic chlorine species decreasing the overall Pt/TiO2 photocatalyst performance. Interestingly, Ag did not show any significant effect to the oxidation of any single system degradation. In binary system degradation, where TCE and another organic compound either ethylene, ethane or toluene were degraded simultaneously, Pt always caused a detrimental effect due to its strong interaction with Cl. However, the presence of Ag and Cl gives a more synergetic effect. Ag was found to provide sites to temporarily trap chlorine radicals as AgCl. Under illumination, electrons transferred from Cl to Ag forming chlorine radicals that could react with the surface contaminant enhancing its breakdown and mineralization.

Chlorinated solvent are volatile organic substances that can be harmful for humans and for the environment. Examples of common chlorinated solvents are perchloroethene, PCE, and trichloroethene, TCE. Chlorinated solvents appear as contaminants in soils primarily where they have been used as washing fluids in dry-cleaning facilities or as degreasers in metal industries. Chlorinated solvents are DNAPLs (dense non-aqueous phase liquids), which means that they are not easily dissolved in water and that they sink to the bottom of the aquifer. Adsorption to soils is low so chlorinated solvents are mobile in soils. Chlorinated solvents can be harmful at low concentrations. Complete degradation can only occur under specific conditions. Because of the properties of these substances, investigation and analysis methodology are extra important for determining transport and risks in a contaminated area. In this work, investigation and analysis methods for chlorinated solvents are described. Planning, fieldwork, modeling and risk analysis are described. Projects concerning chlorinated solvents completed by Golder Associates AB have been compiled and analysed. Based on the compilation, conclusions have been drawn and statistics have been calculated. Investigations of the relation between concentrations in different media have been made as well as investigations of the relation between degradation products at different distances from the source and at different times after release. The data from the environmental investigations have been compared with theoretical literature values and modelling results. The results show that there is a large natural variation in the data and that the differences between different areas are quite large. The results confirm the theory that the percentage of degradation products increases with distance from the source and with time from release. In addition, solvents with a higher degree of chlorination seams to appear to a greater extent in the soil and the more volatile substances seams to appear to a greater extent in the soil air. / Klorerade lösningsmedel är flyktiga klorerade organiska ämnen som kan vara skadliga för människor och miljön. Exempel på vanliga klorerade lösningsmedel är perkloreten, PCE och trikloreten, TCE. Klorerade lösningsmedel förekommer som markföroreningar främst efter användning som tvättvätska i kemtvättar och som avfettningsmedel i metallindustrin. Klorerade lösningsmedel är DNAPLs (dense non-aqueous phase liquids), det innebär att de är svårlösliga i vatten och att de sjunker och lägger sig på botten av akviferen. Fastläggningen i jorden är liten hos klorerade lösningsmedel som därmed är rörliga i marken. De är farliga redan vid små koncentrationer och fullständig nedbrytning sker endast under vissa förutsättningar. Ämnenas egenskaper gör att undersöknings- och analysmetodiken är viktig för att riktigt kunna bestämma deras utbredning och risk på ett förorenat område. I detta arbete beskrivs undersöknings- och analysmetodiken för områden förorenade med klorerade lösningsmedel. Upplägg, fältarbete, modellering och riskbedömning beskrivs. Projekt som handlar om klorerade lösningsmedel utförda av Golder Associates AB har sammanställts. Sammanställningen har analyserats och utifrån den har olika slutsatser dragits och statistik beräknats. Bland annat har samband mellan halter i olika medier samt samband mellan halter av nedbrytningsprodukter på olika avstånd från källan respektive efter olika lång tid från läckage har undersökts. Data från miljöundersökningarna har även jämförts med teoretiska litteraturvärden samt modelleringsresultat. Resultatet visar att den naturliga spridningen av data är stor samt att resultaten skiljer sig åt mellan olika områden. Resultaten bekräftar teorierna att halten nedbrytningsprodukter ökar med avståndet från källan och med tiden samt att ämnen med högre kloreringsgrad finns i större utsträckning i jorden och att flyktigare ämnen finns i större utsträckning i porluften.

Much is known about natural attenuation of contaminants in granular aquifers because many contaminant plumes in these aquifers have been intensively monitored with detailed sampling along cross sections positioned across the plumes (i. e. transects). However, little is known about natural attenuation of contaminant plumes in fractured rock. In this thesis study, strong natural attenuation of a persistent co-mingled plume of trichloroethylene (TCE) and an herbicide (metolachlor) in a 100 <em>m</em> thick dolostone aquifer used for municipal water supply in Cambridge, Ontario is shown based on detailed delineation of groundwater contaminant concentrations along a single transect located 150 <em>m</em> downgradient from the area where the metolachlor entered the dolostone and 300 <em>m</em> downgradient from the TCE source area. This delineation was accomplished using depth-discrete, multilevel groundwater monitoring systems in five cored holes and detailed analyses of contaminant concentration in rock cores. The maximum metolachlor concentration on the transect is a factor of 20 below the maximum concentration in the metolachlor source area and the maximum TCE concentration on the transect is lower by a factor of 100 from the TCE source area. <br /><br /> Matrix diffusion and strong temporal variability of the groundwater flow system caused by pumping of nearby municipal wells have likely caused strong natural attenuation of metolachlor and TCE and degradation has likely contributed to even stronger TCE attenuation. The transect shows rock core concentrations much higher than the groundwater concentrations in the multilevel systems at the same locations and in the conventional monitoring wells, which indicates that plume persistence is likely maintained by back diffusion from the rock matrix, which has very low hydraulic conductivity but substantial porosity, into the active groundwater flow in the fractures. <br /><br /> Metolachlor has been observed at very low concentrations and has persisted at these concentrations in the nearest municipal pumping well located approximately 780 <em>m</em> downgradient of the transect, however this well shows no detectable TCE. The relatively low concentrations along the transect and the replenishment of the plume by back diffusion suggests that a substantial increase of metolachlor or TCE in the municipal well is unlikely.

A study was carried out in a sedimentary fractured rock site located in south central Wisconsin, US, which was impacted by DNAPL releases estimated to occur in the 1950’s and 1960’s. The majority of the DNAPL has accumulated in the upper portion of the Lone Rock Formation at a depth between 140 and 180 ft bgs referred as Layer 5 in this study. A groundwater VOC plume of more than 3km long has formed in this Layer. The DNAPL is mainly composed of 1,1,1-TCA, PCE, TCE and BTEX, while large amounts of biodegradation products such as cis-DCE and 1,1-DCA are present in the plume. Long term VOC data have been collected at the site and diverse geological and hydrogeological techniques have been applied to have a better understanding of the DNAPL history and behavior of the VOC plume. Evidence of biodegradation was also documented near the DNAPL source in these studies. The thesis objectives of the present study aimed first to have a better understanding of the long term contaminant distribution and degradation history at the site. This objective was accomplished reviewing the VOC historical concentration data collected from 1992 to 2006 in the wells tapping the most contaminated. hydrogeological unit in the bedrock (Layer 5) and in the overburden aquifer (referred as Layer 2). The second objective aimed to evaluate the current degree or extent of biodegradation of chlorinated compounds, which was accomplished evaluating the current groundwater redox conditions and using a combined analysis of VOC concentration and carbon isotope data collected in groundwater in September 2007. The historical data collected between1992 to 2006 showed the degradation of the VOC plume in Layer 5 was controlled by the availability of electron acceptors and redox conditions in the fracture bedrock aquifer. This pattern and the extension of the VOC plume were linked to different DNALP pumping events in the source zone and the operation of a Hydraulic Barrier System. The current geochemical and isotope study showed a different pattern of biodegradation of chlorinated compounds in different parts of the plume. The cis-DCE tend to accumulate in the area from the source to the middle of the plume and around 80 % of biodegradation of 1,1,1-TCA to 1,1-DCA was observed in this area. The fringes of the plume were characterized by a dominant presence of TCE and 1,1,1 TCA. These patterns were linked to different redox conditions and amount of electron acceptors. The cis-DCE dominated area is characterized by anaerobic conditions and the presence of relative high amount of BTEX. The TCE-dominated area is under aerobic condition and no BTEX was found in this area. The operation of the Hydraulic Barrier System seems to have change redox condition which influenced the extent of degradation in the plume, especially in the area between the extraction wells. The formation of large amounts of VC in Layer 2 and the more reducing (at least sulfate reducing and maybe methanogenic conditions) of the groundwater in this Layer compared to Layer 5 confirmed the extent of VOC biodegradation is linked to the availability of electron donors. This study provides information about the current degree of the biodegradation of chlorinated compounds at a fracture rock site. This information is very valuable for the evaluation of natural attenuation as strategy for long term plume management or for future remediation strategies such as biostimulation or bioaugmentation at the site. This study also shows the present and long term behavior of the chlorinated compounds (degradation history) in the most contaminated hydrogeologic unit (Layer 5), has mainly been controlled by plume management strategies including DNAPL pumping in the source and the creation of a Hydraulic Barrier System. The ketones and BTEX, that acted as electron donors and carbon substrate for the microbial community responsible for the dechlorination of chlorinated compounds were shown to have controlled the past and current redox conditions and thus the degree and potential of biodegradation of chlorinated ethenes and chlorinated ethanes at the study site.

Much is known about natural attenuation of contaminants in granular aquifers because many contaminant plumes in these aquifers have been intensively monitored with detailed sampling along cross sections positioned across the plumes (i. e. transects). However, little is known about natural attenuation of contaminant plumes in fractured rock. In this thesis study, strong natural attenuation of a persistent co-mingled plume of trichloroethylene (TCE) and an herbicide (metolachlor) in a 100 <em>m</em> thick dolostone aquifer used for municipal water supply in Cambridge, Ontario is shown based on detailed delineation of groundwater contaminant concentrations along a single transect located 150 <em>m</em> downgradient from the area where the metolachlor entered the dolostone and 300 <em>m</em> downgradient from the TCE source area. This delineation was accomplished using depth-discrete, multilevel groundwater monitoring systems in five cored holes and detailed analyses of contaminant concentration in rock cores. The maximum metolachlor concentration on the transect is a factor of 20 below the maximum concentration in the metolachlor source area and the maximum TCE concentration on the transect is lower by a factor of 100 from the TCE source area. <br /><br /> Matrix diffusion and strong temporal variability of the groundwater flow system caused by pumping of nearby municipal wells have likely caused strong natural attenuation of metolachlor and TCE and degradation has likely contributed to even stronger TCE attenuation. The transect shows rock core concentrations much higher than the groundwater concentrations in the multilevel systems at the same locations and in the conventional monitoring wells, which indicates that plume persistence is likely maintained by back diffusion from the rock matrix, which has very low hydraulic conductivity but substantial porosity, into the active groundwater flow in the fractures. <br /><br /> Metolachlor has been observed at very low concentrations and has persisted at these concentrations in the nearest municipal pumping well located approximately 780 <em>m</em> downgradient of the transect, however this well shows no detectable TCE. The relatively low concentrations along the transect and the replenishment of the plume by back diffusion suggests that a substantial increase of metolachlor or TCE in the municipal well is unlikely.

A study was carried out in a sedimentary fractured rock site located in south central Wisconsin, US, which was impacted by DNAPL releases estimated to occur in the 1950’s and 1960’s. The majority of the DNAPL has accumulated in the upper portion of the Lone Rock Formation at a depth between 140 and 180 ft bgs referred as Layer 5 in this study. A groundwater VOC plume of more than 3km long has formed in this Layer. The DNAPL is mainly composed of 1,1,1-TCA, PCE, TCE and BTEX, while large amounts of biodegradation products such as cis-DCE and 1,1-DCA are present in the plume. Long term VOC data have been collected at the site and diverse geological and hydrogeological techniques have been applied to have a better understanding of the DNAPL history and behavior of the VOC plume. Evidence of biodegradation was also documented near the DNAPL source in these studies. The thesis objectives of the present study aimed first to have a better understanding of the long term contaminant distribution and degradation history at the site. This objective was accomplished reviewing the VOC historical concentration data collected from 1992 to 2006 in the wells tapping the most contaminated. hydrogeological unit in the bedrock (Layer 5) and in the overburden aquifer (referred as Layer 2). The second objective aimed to evaluate the current degree or extent of biodegradation of chlorinated compounds, which was accomplished evaluating the current groundwater redox conditions and using a combined analysis of VOC concentration and carbon isotope data collected in groundwater in September 2007. The historical data collected between1992 to 2006 showed the degradation of the VOC plume in Layer 5 was controlled by the availability of electron acceptors and redox conditions in the fracture bedrock aquifer. This pattern and the extension of the VOC plume were linked to different DNALP pumping events in the source zone and the operation of a Hydraulic Barrier System. The current geochemical and isotope study showed a different pattern of biodegradation of chlorinated compounds in different parts of the plume. The cis-DCE tend to accumulate in the area from the source to the middle of the plume and around 80 % of biodegradation of 1,1,1-TCA to 1,1-DCA was observed in this area. The fringes of the plume were characterized by a dominant presence of TCE and 1,1,1 TCA. These patterns were linked to different redox conditions and amount of electron acceptors. The cis-DCE dominated area is characterized by anaerobic conditions and the presence of relative high amount of BTEX. The TCE-dominated area is under aerobic condition and no BTEX was found in this area. The operation of the Hydraulic Barrier System seems to have change redox condition which influenced the extent of degradation in the plume, especially in the area between the extraction wells. The formation of large amounts of VC in Layer 2 and the more reducing (at least sulfate reducing and maybe methanogenic conditions) of the groundwater in this Layer compared to Layer 5 confirmed the extent of VOC biodegradation is linked to the availability of electron donors. This study provides information about the current degree of the biodegradation of chlorinated compounds at a fracture rock site. This information is very valuable for the evaluation of natural attenuation as strategy for long term plume management or for future remediation strategies such as biostimulation or bioaugmentation at the site. This study also shows the present and long term behavior of the chlorinated compounds (degradation history) in the most contaminated hydrogeologic unit (Layer 5), has mainly been controlled by plume management strategies including DNAPL pumping in the source and the creation of a Hydraulic Barrier System. The ketones and BTEX, that acted as electron donors and carbon substrate for the microbial community responsible for the dechlorination of chlorinated compounds were shown to have controlled the past and current redox conditions and thus the degree and potential of biodegradation of chlorinated ethenes and chlorinated ethanes at the study site.

Isotopic methods have been developed over the last 10 years as a method for determining chemical interactions of chlorinated solvents. These methods are especially promising for. This study attempts to employ and develop compound specific isotopic analyses of TCE and cDCE, along with chemical data, to characterize the degradation of TCE in a fractured bedrock aquifers. The Smithville site is a contaminated field site with extremely high levels of TCE contamination that is currently undergoing monitored remediation. From December 2008 until April 2010 extended samples were collected from the site to provide additional data analyses including isotopic data. The redox conditions at the site are anoxic to reducing, with sulfate reduction and methanogenesis as dominant terminal electron accepting processes. Redox data indicates that well electrochemical conditions are highly variable within the site, including areas near the source zone that not very reducing. Documented changes in groundwater conditions to much more reducing environments indicate that oxidation of organic matter is occurring at the Smithville site in select wells. Chemical analyses of TCE, DCE, VC, ethene and ethane are employed determine whether reductive dechlorination was occurring at the site. Results of field testing indicate that many wells on site, especially in the proximity of the source zone, dechlorination products were found. The isotopic data had a high range in both carbon and chlorine isotopes. Chlorine isotopic data ranges from a δ37Cl(TCE) of 1.39 to 4.69, a δ37Cl(cDCE) of 3.57 to 13.86, a δ13C(TCE) of -28.9 to -20.7, and a δ13C(cDCE) of -26.5 to -11.82. The range in values indicate varying degrees of degradation throughout the site, with the same wells grouping together. Combined chemical, redox and isotopic data shows that degradation seems to be a removal process for TCE at the Smithville site. Concentrations of chemicals created as a result of TCE degradation verify degradation, especially in wells 15S9, R7 and 17S9. Historically production of DCE in significant amounts, above 1.0 ppb, was observed to only occur after 2003. In addition to this, DCE data shows that the percentage of DCE made up of cDCE is above 96%. This indicates that microbes most likely mediate the processes that formed DCE from TCE. The linear regression of the delta-delta plot for isotopic TCE data shows line that is likely a direct function of the carbon and chlorine isotopic fractionation imparted upon the original TCE released. The slope found is consistent with data collected from other studies though cannot be applied to determining the process directly given the range of variability in isotopic field data.

The main objective of this study was to evaluate the feasibility of using nanoscale zero-valent iron (nZVI) as the source of hydrogen to enhance in situ anaerobic biodegradation of trichloroethylene (TCE). In the first part of this study, microcosms were constructed to evaluate the effects of different controlling factors [e.g., different redox conditions (aerobic and anaerobic conditions), different microorganisms (in situ microorganisms, activated sludge, and anaerobic sludge), and different sources of substrates and electron donors (phenol, cane molasses, hydrogen, and nZVI)] on TCE biodegradation. In the second part of this study, batch experiments were conducted to evaluate the feasibility of hydrogen production by nZVI and bimetallic particles. Results from the microcosm study indicate that in-situ microorganisms were capable of degrading TCE under aerobic and anaerobic conditions. Results also show that TCE removal was more effective by activated sludge and anaerobic sludge. Aerobic biodegradation of TCE was enhanced by the addition of phenol and cane molasses. Under anaerobic conditions, TCE removal could be improved when cane molasses and hydrogen were supplied. In addition, anaerobic TCE degradation was more effective with the presence of hydrogen. Results of microcosms conducted with the addition of nZVI reveal that TCE was degraded completely in both live and autoclaved microcosms. This indicates that chemical reductive dechlorination seemed to dominate the removal of TCE in microcosms. Therefore, further studies with higher TCE concentrations or lower nZVI doses need to be conducted to determine the effects of the produced hydrogen on TCE biodegradation. Results from the hydrogen production experiments indicate that efficiency of hydrogen production by nZVI ranged from 30% to 76%. Higher dose of nZVI addition resulted in higher amount of hydrogen production. The total amounts of hydrogen production were correlated with the doses of nZVI. In addition, rates and efficiency of hydrogen production by bimetallic particles were better than those of nZVI. Results of the batch experiments reveal that nZVI and bimetallic particles had good efficiency on hydrogen production. This indicates that nZVI and bimetallic particles have high potential to be used as hydrogen producers. In this study, a simple system consisted of only water and nZVI or bimetallic particles was applied to produce hydrogen. Although TCE in microcosms with nZVI addition was totally consumed by nZVI, results of microcosms with hydrogen addition demonstrated that hydrogen was able to improve the efficiency of anaerobic TCE biodegradation. Thus, it may be feasible to use nZVI as the source of hydrogen to enhance in situ anaerobic biodegradation of TCE. The advantages of using nZVI as the source of hydrogen include: (1) rapid removal of significant contaminant concentrations in the early stage of nZVI injection; (2) creation of a more reducing environment; (3) safer than liquid hydrogen, which is stored in steel containers; and (4) direct hydrogen supply without transfer of biological mechanisms compared to commercial hydrogen release compounds and other organic substrates. Results of this study suggest that biological reductive dechlorination of TCE can be enhanced if proper doses of nZVI are supplied in situ. Knowledge and comprehension obtained in this study will be helpful in designing an enhanced in situ anaerobic bioremediation system for a TCE-contaminated site.