• Biodegradation Of Petroleum And Alternative Fuel Hydrocarbons In Moderate To Cold Climate

      Horel, Agota Anna (2009)
      Microbial degradation of hydrocarbon fuels contaminating soil in the Arctic and subarctic environment is a relatively slow process. Nevertheless, due to transportation and logistical limitations in rural Alaska, biodegradation might be the best and cheapest contaminant removal option. The aim of this thesis was to investigate the environmental effects on biodegradation by naturally occurring microorganisms for some innovative hydrocarbon fuels and to determine the overall fate of hydrocarbons in soil, including degradation by fungi and bacteria, volatilization, and transport in the soil. Three major types of fuels were investigated in small scale microcosms and larger soil columns: conventional diesel as a control substance, synthetic diesel (arctic grade Syntroleum) and different types of fish oil based biodiesel. The environmental conditions investigated included different soil types (sand and gravel), different temperatures (constant 6�C, 20�C, and fluctuating between 6 and 20�C), moisture levels (from 2% to 12% GWC), fuel concentrations (from 500 to 20,000 mg fuel/kg soil) and nutrient dosages (0 or 300 mg N/kg soil). Microbial response times and growth phases were also investigated for different inoculum types. Conditions of 20�C, 300 mg N/kg soil, sand, ?4000 mg of fuel/kg soil and ?4% GWC were favorable for bioremediation, with a short lag phase lasting from one day to less than a week, and pronounced peaks of daily CO 2 production between week 2 and 3. At suboptimal conditions, all phases were extended and slow, however at low temperatures steady metabolization continued over a longer time. The relative importance of fungal and bacterial remediation varied between fuel types. Diesel fuel degradation was mainly due to bacterial activities while fish biodiesel degradation occurred largely by mycoremediation. For Syntroleum both bacterial and fungal remediation played key roles. Volatilization contributed up to 13% to overall contaminant removal. In soil columns, degradation was slower than in microcosms, due to an uneven concentration profile of contaminants, nutrients and oxygen with depth. In general, biodegradation showed promising results for soil remediation and the alternate fuel types were more biodegradable compared with conventional diesel fuel.
    • Experimental Study Of Adsorbed Cation Effects On The Frost Susceptibility Of Natural Soils

      Darrow, Margaret Marie; Huang, Scott; Shur, Yuri (2007)
      Frost heaving is ubiquitous throughout cold regions, causing damage to building foundations, roads, airfields, railways, utilities, and pipelines. Out of the voluminous body of research conducted over the last 80 years, few studies investigated the mineral surface effects on frost heaving. These previous studies were conducted nearly 50 years ago with rudimentary equipment and on homogeneous and artificial soils that have limited applicability to actual field conditions. The purpose of the research presented here is to investigate the adsorbed cation effects on the frost susceptibility of natural soils through experimental testing. A comprehensive suite of laboratory experiments was conducted on five natural heterogeneous soils, including the preparation of divalent and monovalent cation-treated samples. Experimental testing included measurements of engineering index properties, chemical properties, clay content and mineralogy, soil-moisture characteristic curves, unfrozen water content, zeta potential, and frost heave testing. Frost heave tests were conducted using a state-of-the-art laboratory system that demonstrates high repeatability. Soil-moisture characteristic---soil freezing characteristic (SMC-SFC) relations were developed for the five natural soils over an unprecedented range of measurements and using a new approach, which can be related to the Clausius-Clapeyron equation. The SMC-SFC relations yield a new variable, eta, which describes the water retention properties of soil at increasing matric potentials and decreasing temperatures. The five untreated soils demonstrated significantly different frost heave ratios, ranging from 0.7 percent to 49.2 percent. Statistical analysis indicates that the frost susceptibility of the five untreated soils is most dependent on adsorbed cations, eta, amount of microaggregates smaller than 2 mum, and clay content. For the entire body of untreated and cation-treated samples, statistical analysis indicates that the frost susceptibility is most dependent on adsorbed cations, unfrozen water content, and amount of smectite, kaolinite, and chlorite present in the soil. The results from each cation treatment indicate that the frost susceptibility of (1) Ca2+-saturated soil is most dependent on zeta potential and unfrozen water content; (2) Mg2+-saturated soil is most dependent on zeta potential and amount of chlorite; and (3) Na +-saturated soil is most dependent on zeta potential, unfrozen water content, and amount of chlorite.
    • Improved Membrane Filtration For Water And Wastewater Using Air Sparging And Backflushing

      Psoch, Christian (2005)
      The goal of this research was to investigate methods and techniques that enhance mass transfer through the membranes. Two general types of fluids were investigated: synthetic wastewater treated in a membrane bioreactor (MBR) and natural and simulated river water. For both fluids, a wide range of solid concentrations (up to 18 g/L) were tested. The membranes investigated were all tubular modules at pilot scale between 0.75 and 1.20 m length, with tubular diameters of 5.5--6.3 mm, 0.2 mum pore size, and membrane surface areas of 0.036--0.1 m2. For flux enhancement, two techniques were applied: air sparging (AS), and backflushing (BF). Both techniques were compared with the sponge ball cleaning method. The experimental temperature ranged between 10 and 30�C, cross-flow velocities (CFV) ranged between 0.5 and 5.2 m/s, and transmembrane pressure (TMP) ranged between 30 and 350 kPa. Research results showed, that AS was able to enhance the conventional flux over weeks to months up to factor of 4.5 for river water and a factor of 3 for wastewater. At modest CFV of 1.5--2 m/s, AS was as successful as BF. If higher CFV (up to 5.2 m/s) were supplied for BF, this technique could enhance the wastewater flux by factor 4.5. The supply of AS and BF combined was superior to the single application even at moderate CFV. The major finding of this research was that cake thickness on the membrane surface was decreased by AS, contrary to research by other authors. AS can be used as substitute aeration in MBRs, without impairing the degradation performance. The combination of AS and BF generated the least filter cake, but the lowest fouling was observed for AS. An empirical equation was proposed to calculate the viscosity in a sidestream MBR depending on reactor temperature and mixed liquor suspended solids (MLSS).
    • Modeling Biosorption Of Cadmium, Zinc And Lead Onto Native And Immobilized Citrus Peels In Batch And Fixed Bed Reactors

      Chatterjee, Abhijit; Schiewer, Silke; Barnes, Dave; Johnson, Ron; Tainor, Tom (2012)
      Biosorption, i.e., the passive uptake of pollutants (heavy metals, dyes) from aqueous phase by biosorbents, obtained cheaply from natural sources or industrial/agricultural waste, can be a cost-effective alternative to conventional metal removal methods. Conventional methods such as chemical precipitation, membrane filtration or ion exchange are not suitable to treat large volumes of dilute discharge, such as mining effluent. This study is a continuation of previous research utilizing citrus peels for metal removal in batch reactors. Since fixed bed reactors feature better mass transfer and are typically used in water or waste water treatment using ion-exchange resins, this thesis focuses on packed bed columns. A number of fixed bed experiments were conducted by varying Cd inlet concentration (5-15 mg/L), bed height (24-75 cm) and flow rate (2-15.5 ml/min). Breakthrough and saturation uptake ranged between 14-29 mg/g and 42-45 mg/g respectively. An empty bed contact time of 10 minutes was required for optimum column operation. Breakthrough curves were described by mathematical models, whereby three popular models were shown to be mathematically identical. Citrus peels were immobilized within an alginate matrix to produce uniform granules with higher uptake capacity than raw peels. All breakthrough curves of native and immobilized peels were predicted using external and intra-particle mass transfer resistances from correlations and batch experiments, respectively. Several analogous mathematical models were identified; other frequently used models were shown to be the approximate derivatives of a single parent model. To determine the influence of competing metals, batch and fixed bed experiments were conducted in different binary combinations of Pb, Cd, Zn and Ca. Equilibrium data were analyzed by applying competitive, uncompetitive and partially competitive models. In column applications, high affinity Pb replaced previously bound Zn and Cd in Pb-Zn and Pb-Cd systems, respectively. However, the Cd-Zn system did not show any overshoot. Calcium, which is weakly bound, did not affect target metal binding as much as other metals. Saturated columns were desorbed with 0.1 N nitric acid to recover the metal, achieving concentration factors of 34-129. Finally, 5 g of citrus peels purified 5.40 L mining wastewater.
    • Phytoremediation strategies for recalcitrant chlorinated organics

      Schnabel, William Edwin; White, Daniel (2000)
      The purpose of the research was to investigate novel strategies for the phytoremediation of recalcitrant chlorinated organic soil contaminants. The recalcitrance of many chlorinated organics is related to chemical stability and bioavailability. Mycorrhizal fungi have the potential to enhance the degradation of such compounds through the action of lignolytic enzyme systems, and to increase the bioavailability of such compounds through increased root surface area and reach. Furthermore, the addition of surfactants has the potential to increase compound bioavailability via increased solubility. The organochlorine pesticide aldrin, and the polychlorinated biphenyl 3,3'4,4 '-tetrachlorobiphenyl (TCB) were chosen as representative recalcitrant contaminants. Feltleaf willow (Salix alaxensis) and balsain poplar (Populus balsamifera) were chosen as vegetative species likely to be useful for phytoremediation in sub-arctic ecosystems. Mixed-culture mycorrhizal fungi were first shown to be capable of taking up the hydrophobic contaminants in vitro. In the same experiments, surfactant addition increased the level of contaminant uptake. In subsequent vegetative uptake studies, mycorrhizal infection was highly correlated with the uptake of aldrin and TCB in the willow systems. In the poplar systems, this correlation was not as strong. Once taken up into the vegetative matrix of either species, most of the carbon originating from the chlorinated compounds existed as bound transformation products. Additionally, water-soluble transformation products of aldrin were formed in all of the soils tested, and such transformations were enhanced in the presence of vegetation. TCB transformation products were not detected in any of the soils tested. Surfactant addition did not impact the fate of either contaminant in the vegetative uptake studies. The surfactants, in the concentrations added, did not sufficiently solubilize the contaminants into the soil solution. The results of these studies indicated that the phytoremediation of recalcitrant chlorinated organics such as aldrin and TCB could be enhanced through the action of mycorrhizal fungi, and that surfactant addition has the potential to increase mycorrhizal uptake. Field studies were recommended, involving the use of specific degradative fungal species and effective surfactants.
    • Using Geophysical Constraints To Determine Groundwater Travel Times, Seafloor Arrival Locations, And Saltwater Concentrations For Transition Zone Depths At Underground Nuclear Detonations On Amchitka Island

      Wagner, Anna M.; Barnes, David (2007)
      There is a great amount of radioactive material in the subsurface of Amchitka Island as a result from underground nuclear testing performed between 1965 and 1971. It is unknown how long it will take for the radionuclides to travel to the seafloor and the marine environment or where possible seepage zones will occur. The contaminant transport is greatly affected by the location of the transition zone (TZ) and the effective porosity, which were both determined by magnetotellurics (MT) in 2004. The hypothesis of this study was as follows: the groundwater travel times and seafloor arrival locations, can be estimated through groundwater modeling, with the location of the transition zone being estimated by magnetotellurics. An additional hypothesis is as follows: saltwater concentration for a TZ and the general subsurface characteristics can be quantified with groundwater modeling, using geophysical constraints in combination with saltwater and hydraulic head measurements. The groundwater travel times were estimated with groundwater modeling using the transition zone location as determined by MT. Shortest groundwater travel times are 1,200 and 2,100 years, at Long Shot and Cannikin respectively. At Long Shot, a decreased groundwater travel time of up to 55% could be seen when an enhanced hydraulic conductivity was included at the location of an assumed andesite sill layer. The seafloor arrival locations can be up to 1,000 and 2,100 m offshore at Long Shot and Cannikin respectively but will most likely occur closer to shore. This study was also successful at establishing the general characteristics of the subsurface by using geophysical constraints in combination with saltwater and hydraulic head measurements. The subsurface at Long Shot is isotropic or has mild anisotropy ratio of 1:2, which confirms the study by Fenske (1972). As represented in this study, this method has been shown to be valuable in determining the saltwater concentration of the TZ as determined by MT and can thus be used in further studies of islands and coastal areas.