Laboratory microcosm experiments were conducted to assess the potential for biostimulation and bioaugmentation as source reduction measures in support of a monitored natural attenuation remedial strategy at Naval Amphibious Base (NAB) Little Creek. Previous work with laboratory microcosms conducted under simulated natural (unamended) conditions has demonstrated that indigenous dehalorespirators were capable of partial dechlorination of tetrachloroethene (PCE) to cis-dichloroethene (cis-DCE). This study attempts to achieve complete reductive dechlorination with amendments to static microcosms to test the hypotheses that nutrient-limited or microorganism-limited conditions exist in aquifer sediments obtained from the site. The enhanced bioremediation experiments were comprised of nutrient-amended microcosms receiving additions of electron donors, mineral medium, or anaerobic digester supernatant, and dechlorinating culture-amended microcosms were inoculated with a culture capable of transforming PCE to ethene. Reductive dechlorination in the nutrient-amended microcosms proceeded to cis-DCE over a 260-day study period, at slightly higher rates than in experiments conducted with aquifer sediments from the same location under natural conditions. Inoculation of aquifer sediments with a small amount of dechlorinating culture initiated rapid transformation of PCE to vinyl chloride (VC) by day 18 of the study. Zero-order rates of PCE dechlorination in unamended, propionate-, formate-, mineral medium-, digester supernatant-, and dechlorinating culture-amended microcosms were 0.24, 0.750, 1.30, 0.339, 0.177, and 1.75 µM/day, respectively. The results of this study suggest that an engineered biostimulation approach alone may not be as beneficial for PCE source reduction at NAB Little Creek, than bioaugmentation with competent dehalorespirators, along with the inclusion of supplemental nutrients which would be available to stimulate dechlorination activity of both indigenous and introduced microorganisms. / Master of Science

No description available.

Doctor of Philosophy / Department of Chemical Engineering / Larry E. Erickson / Chlorinated solvents are the second most ubiquitous contaminants, next to petroleum hydrocarbons, and many are carcinogens. Tetrachloroethylene or perchloroethene (PCE) has been employed extensively in the dry cleaning industry and carbon tetrachloride (CT) has been used as a fumigant in grain storage facilities. In this work, remediation feasibility studies were conducted by mesocosm experiments; a chamber was divided into six channels and filled with soil, and plants were grown on top. Each channel was fed with contaminated water near the bottom and collected at the outlet, simulating groundwater flow conditions. The contaminants were introduced starting from March 12, 2004. PCE was introduced at a concentration of about 2 mg/L ([similar to]12 [Mu]moles/L) in three channels, two of them with alfalfa plants and the other with grass. CT was introduced at a concentration of about 2 mg/L ([similar to]13 [Mu]moles/L) in the other three channels, two of them with alfalfa plants and the other with grass. After the system had attained steady state, the concentrations of PCE and CT at inlet and outlet were monitored and the amount of PCE and CT disappearing in the saturated zone was studied. Since no degradation products were found at the outlet after about 100 days, one channel-each for PCE and CT (with alfalfa) was made anaerobic by adding one liter of 0.2 % glucose solution. The glucose solution was fed once every month starting from July 1, 2004 and continued until February 2005. From October 1, 2004, one liter of 0.1 % emulsified soy oil methyl esters (SOME) was fed to two other channels (with alfalfa), one exposed to PCE and another exposed to CT. The SOME addition dates were the same as that for glucose. The outlet liquid of the channel fed with PCE and SOME started to contain some of the degradation compounds of PCE; however, the extent of degradation was not as great as that of the glucose fed channel. No degradation compounds were observed in the outlet solution of the channel (grass grown on top) in which no carbon and energy supplements were added. Similar trend was observed in the CT fed channels also. KB-1, a commercially available microbial culture (a consortium of dehalococcoides) that degrades dichloroethene (DCE), was added through the inlet of the PCE fed channels, but this did not lead to sufficient conversion of DCE. Addition of KB-1 at well 3, located approximately in the middle of the channel, had a greater impact in the degradation of DCE, in both glucose and SOME amended channels, compared to addition at the inlet. KB-1 culture added to the channel was active even 155 days later, suggesting that there is sustainable growth of KB-1 when provided with suitable conditions and substrates. A pilot field study was conducted for remediation of a tetrachloroethylene (PCE) contaminated site at Manhattan, KS. The aquifer in the pilot study area has two distinct zones, termed shallow zone and deep zone, with groundwater velocities of about 0.3 m/day and 0.1 m/day. Prior to the pilot study, PCE concentration in groundwater at the pilot study area was about 15 mg/L (ppm) in the deep zone and 1 mg/L in the shallow zone. Nutrient solution comprising soy oil methyl esters (SOME), lactate, yeast extract and glucose was added in the pilot study area for biostimulation, on August 18, 2005. Potassium bromide (KBr) was added to the nutrient solution as a tracer. PCE was converted to DCE under these conditions. To carry out complete degradation of PCE, KB-1, a consortium of Dehalococcoides, and a second dose of nutrient solution were added on October 13, 2005. After addition of KB-1, both PCE and DCE concentrations decreased. Nutrients were again injected on March 3, 2006 (with KBr) and on August 1, 2006. The total chlorinated ethenes (CEs) have decreased by about 80 % in the pilot study area due to bioremediation. Biodegradation of CEs continued for a long time (several months) after the addition of nutrients. The insoluble SOME may be retained at the feeding area and provide a long time source of electron donors. Biostimulation and bioaugmentation of PCE contaminated soil and groundwater was evaluated in the laboratory and this technique was implemented successfully in the pilot field study. Modeling of the tracer study was performed using an advection-dispersion equation (ADE) and traditional residence time distribution (RTD) methods. The dispersion coefficient, groundwater velocity and hydraulic conductivity were estimated from the experimental data. The groundwater velocities vary from 1.5 cm/d to 10 cm/d in the deep zone and 15 cm/d to 40 cm/d in the shallow zone. The velocities estimated from the 2004 tracer study and 2005 tracer study were higher compared to the velocity estimated from the 2006 tracer study, most likely because of microbial growth and product formation that reduced the hydraulic conductivity. Based on data collected from several wells the hydrologic parameter values obtained from tracer studies appear to vary spatially.

<p>Soil bottles and soil slurry experiments were conducted to investigate the effect of some additives on the aerobic and anaerobic biodegradation of chlorinated aliphatic hydrocarbons; tetrachloroethylene (PCE), trichloroethylene (TCE) and dichloroethylene (DCE) in a contaminated soil from Startvätten AB Linköping Sweden. For the aerobic degradation study the soil sample was divided into two groups, one was fertilised. The two groups of soil in the experimental bottles were treated to varying amount of methane in pairs. DCE and TCE were added to all samples while PCE was found in the contaminated soil. Both aerobic and anaerobic experiments were conducted. For aerobic study air was added to all bottles to serve as electron acceptor (oxygen). It was observed that all the samples showed a very small amount of methane consumption while the fertilised soil samples showed more oxygen consumption. For the chlorinated compounds the expected degradation could not be ascertained since the control and experimental set up were more or less the same.</p><p>For the anaerobic biodegradation study soil slurry was made with different media i.e. basic mineral medium (BM), BM and an organic compound (lactate), water and sulphide, phosphate buffer and sulphide and phosphate buffer, sulphide and ammonia. To assure anaerobic conditions, the headspace in the experimental bottles was changed to N2/CO2. As for the aerobic study all the samples were added DCE and TCE while PCE was found in the contaminated soil. The sample without the soil i.e. the control was also given PCE. It was observed that there was no clear decrease in the GC peak area of the pollutants in the different media. The decrease in GC peak area of the pollutants could not be seen, this may be so because more susceptible microorganisms are required, stringent addition of nutrients and to lower the risk of the high concentration of PCE and petroleum products in the soil from Startvätten AB.</p>

Soil bottles and soil slurry experiments were conducted to investigate the effect of some additives on the aerobic and anaerobic biodegradation of chlorinated aliphatic hydrocarbons; tetrachloroethylene (PCE), trichloroethylene (TCE) and dichloroethylene (DCE) in a contaminated soil from Startvätten AB Linköping Sweden. For the aerobic degradation study the soil sample was divided into two groups, one was fertilised. The two groups of soil in the experimental bottles were treated to varying amount of methane in pairs. DCE and TCE were added to all samples while PCE was found in the contaminated soil. Both aerobic and anaerobic experiments were conducted. For aerobic study air was added to all bottles to serve as electron acceptor (oxygen). It was observed that all the samples showed a very small amount of methane consumption while the fertilised soil samples showed more oxygen consumption. For the chlorinated compounds the expected degradation could not be ascertained since the control and experimental set up were more or less the same. For the anaerobic biodegradation study soil slurry was made with different media i.e. basic mineral medium (BM), BM and an organic compound (lactate), water and sulphide, phosphate buffer and sulphide and phosphate buffer, sulphide and ammonia. To assure anaerobic conditions, the headspace in the experimental bottles was changed to N2/CO2. As for the aerobic study all the samples were added DCE and TCE while PCE was found in the contaminated soil. The sample without the soil i.e. the control was also given PCE. It was observed that there was no clear decrease in the GC peak area of the pollutants in the different media. The decrease in GC peak area of the pollutants could not be seen, this may be so because more susceptible microorganisms are required, stringent addition of nutrients and to lower the risk of the high concentration of PCE and petroleum products in the soil from Startvätten AB.