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Articles 1 - 13 of 13
Full-Text Articles in Engineering
Experimental And Modeling Studies For Optimizing Flocculant-Aided Sediment Retention Ponds, Byung Joon Lee
Experimental And Modeling Studies For Optimizing Flocculant-Aided Sediment Retention Ponds, Byung Joon Lee
All Dissertations
Attempts to control sediment-containing runoff and associated water quality problems have involved the establishment of many small to medium sediment retention ponds and the injection of nonionic and anionic polyacrylamide (PAM) flocculants to enhance colloid removal. However, to date use has been driven more by practicing engineers and trial-and-error approaches than by logical and consistent design approaches. Therefore, the purpose of this research was to optimize colloidal clay removal in PAM-aided sediment retention ponds by applying experimental and theoretical methodologies.
Initially, simple measurement techniques for the molecular weight (MW) and charge density (CD) of various PAMs were tested and their …
Effect Of Nitrification On Lead Corrosion In Chloraminated Distribution Systems, Michael Shade
Effect Of Nitrification On Lead Corrosion In Chloraminated Distribution Systems, Michael Shade
All Theses
Water treatment facilities have been shifting from using chlorination to chloramination as a primary disinfectant since 2004, when the EPA enacted the Disinfectants/Disinfection By-Products (D/DBP) Rule mandating the decrease of DBPs. After the switch to chloramination, an unexpected lead concentration increase was detected in the Washington, D. C., and Greenville, NC water systems. These increases may be associated with the switch from chlorination to chloramination. Decomposition of chloramines results in higher ammonia loading to drinking water distribution systems, which may increase nitrification. Nitrifying bacteria may facilitate lead corrosion via two mechanisms: use of nitrite or nitrate as an alternative electron …
Laboratory Evaluation Of Polycyclic Aromatic Hydrocarbon Biodegradation At A Former Tar Plant Site, Mihika Baruah
Laboratory Evaluation Of Polycyclic Aromatic Hydrocarbon Biodegradation At A Former Tar Plant Site, Mihika Baruah
All Theses
A former tar plant site in the southeastern
U.S. is one of hundreds across the country that is contaminated with polycyclic
aromatic hydrocarbons (PAHs). The 2007
CERCLA Priority List of Hazardous Substances ranks PAHs as the eighth most
prominent hazardous substance at National Priority List sites. However, benzo(a)pyrene
is the only PAH that is regulated under the Safe Drinking Water Act, with a maximum
contaminant level of 0.2 µg/l. As with most sites, monitored natural
attenuation was the preferred bioremediation approach for this site, assuming
it could be shown that the PAHs were undergoing biodegradation. Field data from the site …
Spatial Variability Of Radionuclide Distribution Coefficients At The Savannah River Site And The Sub-Surface Transport Implications, Kelly Grogan
All Theses
Distribution coefficients, Kd, were measured for a suite of gamma-emitting radionuclides in uncontaminated soils from the E-Area burial grounds at the Savannah River Site. The objectives of the study were to (1) characterize the spatial variability of Kd, (2) evaluate the effect of spatial variability on vadose zone transport, and (3) develop statistical models for predicting Kd from physical or chemical characteristics.
Equilibrium batch sorption tests were performed on 27 soil samples collected from depths ranging from 11 ft to 100 ft from the BGO-3A core with 241Am, 109Cd, 139Ce, 137Cs, 57Co, 60Co, 203Hg, 85Sr, and 88Y. Distribution coefficients were …
Exploration Of A Carbon Nanotube Anode Gas-Filled Radiation Detector, Landon Pruitt
Exploration Of A Carbon Nanotube Anode Gas-Filled Radiation Detector, Landon Pruitt
All Theses
The primary objective of this study was to design, test, and model the electrostatic field in a gas-filled radiation detector constructed with either a carbon nanotube (CNT) or a CNT array as the anode. Tungsten anodes of 500 to 4μm diameters were used to observe the gradual decrease in operating voltage with a decreasing anode diameter and estimate efficiencies of CNT anodes in a coaxial design. An electrostatic model (Maxwell 3D/2D) was used to model the resulting electric field associated with a single CNT in the coaxial configuration as well as to optimize the pitch (distance between individual CNTs in …
Scale-Up And Characterization Of An Enrichment Culture For Bioaugmentation Of The P-Area Chlorinated Ethene Plume At The Savannah River Site, Ashley Eaddy
All Theses
Bioaugmentation has become an increasingly popular remediation strategy for groundwater sites contaminated with chlorinated solvents. When biostimulation is not an option due to the lack of necessary microorganisms required for dechlorination of the contaminants, bioaugmentation is an attractive option for remediation. The P-Area groundwater plumes at the Savannah River Site (SRS) are just such a case. The P-Area site is contaminated with tetrachloroethene (PCE), trichloroethene (TCE), and cis-dichloroethene (cDCE), and no dechlorination past cDCE is occurring. A similar site, the C-Area site, is near one of the P-Area site's source zones but displays complete reduction of TCE to ethene. …
Microcosm Evaluation Of Vinyl Chloride Bio-Oxidation Under Anaerobic Conditions, Jessica High
Microcosm Evaluation Of Vinyl Chloride Bio-Oxidation Under Anaerobic Conditions, Jessica High
All Theses
The vast majority of hazardous waste sites in the US have groundwater contaminated with halogenated organic solvents, primarily tetrachloroethene (PCE) and trichloroethene (TCE). Because the cost to remediate these sites is projected to exceed hundreds of billions of dollars, there is considerable interest in utilizing bioremediation as a low-cost remedy. Under anaerobic conditions, the best characterized biodegradation pathway for chlorinated ethenes is reductive dechlorination, whereby an electron donor such as hydrogen provides the reducing equivalents needed to replace chlorine atoms with hydrogen atoms. The ultimate daughter products from chlorinated ethenes are non-hazardous ethene and ethane, a process easily documented with …
Fecal Coliform Source Identification Using Chemical Tracers, Nicole Fahrenfeld
Fecal Coliform Source Identification Using Chemical Tracers, Nicole Fahrenfeld
All Theses
Fecal sterols and fluorinated whitening agents (FWA) were used as chemical tracers for fecal coliform source tracking in Cane and Little Cane creeks in Walhalla, SC. Fecal sterols were quantifiable in both stream sediments and suspended particulates using an extraction, clean-up, and analytical method modified from Isobe et al. (2002) with a N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization scheme. Only human sterol source identification ratios were able to be calculated using the chosen sterol suite. Human fecal signatures were seen in both the sediment and the water column at various points along both creeks, indicating human fecal pollution is contributing to the fecal …
Development Of A Colorimetric Test For Quantification Of Uranium In Drinking Water, Amy Ratliff
Development Of A Colorimetric Test For Quantification Of Uranium In Drinking Water, Amy Ratliff
All Theses
A new method was developed for the determination of uranium in groundwater above 30µg/L (30ppb). This concentration is the maximum contaminant level (MCL) for uranium in drinking water, which was set in December 2003 by the US EPA under the provisions of the Safe Drinking Water Act. The method is rapid and requires little technical training to conduct, allowing it to be used by consumers, in the laboratory, or in the field. The two-step technique involves preconcentrating uranium using a U/TEVA-2 extraction chromatographic resin followed by complexation with a pyridylazo indicator dye, Br-PADAP. At neutral pH, a counter ion is …
Anaerobic Biodegradation Of Ethylene Dibromide And 1,2-Dichloroethane In The Presence Of Fuel Hydrocarbons, James Henderson
Anaerobic Biodegradation Of Ethylene Dibromide And 1,2-Dichloroethane In The Presence Of Fuel Hydrocarbons, James Henderson
All Dissertations
Field evidence from underground storage tank (UST) sites where leaded gasoline leaked indicates the lead scavengers 1,2-dibromoethane (ethylene dibromide, or EDB) and 1,2-dichloroethane (1,2-DCA) may be present in groundwater at levels that pose unacceptable risk. These compounds are seldom tested for at UST sites. Although dehalogenation of EDB and 1,2-DCA is known to occur, the effect of fuel hydrocarbons on their biodegradability under anaerobic conditions is poorly understood. Microcosms (2 L glass bottles) were prepared with soil and groundwater from a UST site in Clemson, South Carolina, using samples collected from the source (containing residual fuel) and less contaminated downgradient …
The Formation Of Halonitromethanes In Wastewater Treatment Plant Effluents, Jesse Addison
The Formation Of Halonitromethanes In Wastewater Treatment Plant Effluents, Jesse Addison
All Theses
Disinfection by-products (DBPs) have been a water treatment concern since their discovery in the 1970's. Today, only eleven drinking water DBPs are regulated by the Environmental Protection Agency (EPA). However, over 500 DBPs have been identified in drinking waters with advances in analytical methods within the last two decades. Halonitromethanes (HNMs) were among the fifty-plus unregulated high-priority DBPs that were monitored for and detected in drinking waters in a recent nationwide occurrence study funded by EPA. The toxicology studies conducted in recent years showed that HNMs are one of the most cytotoxic and genotoxic classes among the emerging DBPs, and …
Storm Water Export Of Nitrogen, Phosphorous, And Carbon From Developing Catchments In The Upper Piedmont Physiographic Province, Laura Reid
All Theses
Impacts on water quality caused by land use change from forests and pastures to housing subdivisions were evaluated in catchments undergoing active development in the upper Piedmont physiographic province of South Carolina. Specific attention was focused on the export of nitrogen, phosphorus and carbon from these catchments during storm events. Three catchments with varying stages of development were compared to categorize the effects of land disturbance. Storm events occurring within a four year period of 2004 through 2007 were studied for changes in water quality within catchment streams. Due to the potential large input of surface runoff to streams following …
Laboratory Evaluation Of Chlorinated Ethene Transformation Processes In Fractured Sandstone, Ramona Darlington
Laboratory Evaluation Of Chlorinated Ethene Transformation Processes In Fractured Sandstone, Ramona Darlington
All Dissertations
A fractured sandstone aquifer at an industrial site in southern California is contaminated with trichloroethene (TCE) to depths in excess of 244 m. Field monitoring data suggest that TCE is undergoing reduction to cis-DCE and that additional attenuation is occurring. However, vinyl chloride (VC) and ethene have not been detected in significant amounts, so that if transformation is occurring, a process other than reductive dechlorination must be responsible. The overall objective of this study was to evaluate the occurrence of biotic and abiotic transformation processes at this site for TCE, cis-DCE and VC. Anaerobic microcosms were constructed with site groundwater …