VTechWorks Repository :: Browsing by Author "Dietrich, Andrea M."

Browsing by Author "Dietrich, Andrea M."

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Acute toxicity of ammonia and nitrite to Pacific White Shrimp (Litopenaeus vannamei) at low salinities
Schuler, Dominic (Virginia Tech, 2008-04-30)
The Pacific white leg shrimp, Litopenaeus vannamei, is a potential species for low salinity inland aquaculture. Due to several independent variables, such as species, age, size, salinity and pH, that must be taken into account, there are gaps in the literature pertaining to the toxicity of ammonia and nitrite to shrimp. This study was conducted to investigate the individual and combined effects of ammonia and nitrite on L. vannamei postlarvae (25-45 days old) at 10 ppt salinity, 28 C and a pH of 7.8. The independent variables were salinity, total ammonia as nitrogen (TAN) and nitrite-N (NO₂-N), separately and combined. The TAN experiments were conducted at 18 and 10 ppt salinity while the NO₂-N test was conducted at 10 ppt salinity. Combined TAN and NO2 tests were also conducted at 10 ppt salinity. The LC50 values for TAN at 18 ppt salinity, TAN at 10 ppt salinity, and NO2-N at 10 ppt were observed to be 42.92, 39.72 mg/L (2.26 and 2.09 mg/L unionized ammonia-N), and 153.75 mg/L, respectively. When NO₂- N was adjusted to the LOEC level and TAN concentrations were varied, synergistic effects were observed, with an LC50 calculated to be 28.2 mg/L TAN (1.49 mg/L unionized ammonia-N). However, when the ammonia level was adjusted to the LOEC and nitrite was varied, antagonistic effects were observed with an LC50 calculated to be 163.3 mg/L NO₂-N. The results suggest that further investigations into the combined effects of ammonia and nitrite at varying concentrations and lower salinities will be important in developing "standard operating procedures" for the shrimp industry.
Advanced Applications of Raman Spectroscopy for Environmental Analyses
Lahr, Rebecca Halvorson (Virginia Tech, 2014-01-09)
Due to an ever-increasing global population and limited resource availability, there is a constant need for detection of both natural and anthropogenic hazards in water, air, food, and material goods. Traditionally a different instrument would be used to detect each class of contaminant, often after a concentration or separation protocol to extract the analyte from its matrix. Raman spectroscopy is unique in its ability to detect organic or inorganic, airborne or waterborne, and embedded or adsorbed analytes within environmental systems. This ability comes from the inherent abilities of the Raman spectrometer combined with concentration, separation, and signal enhancement provided by drop coating deposition Raman (DCDR) and surface-enhanced Raman spectroscopy (SERS). Herein the capacity of DCDR to differentiate between cyanotoxin variants in aqueous solutions was demonstrated using principal component analysis (PCA) to statistically demonstrate spectral differentiation. A set of rules was outlined based on Raman peak ratios to allow an inexperienced user to determine the toxin variant identity from its Raman spectrum. DCDR was also employed for microcystin-LR (MC-LR) detection in environmental waters at environmentally relevant concentrations, after pre-concentration with solid-phase extraction (SPE). In a cellulose matrix, SERS and normal Raman spectral imaging revealed nanoparticle transport and deposition patterns, illustrating that nanoparticle surface coating dictated the observed transport properties. Both SERS spectral imaging and insight into analyte transport in wax-printed paper microfluidic channels will ultimately be useful for microfluidic paper-based analytical device (𝜇PAD) development. Within algal cells, SERS produced 3D cellular images in the presence of intracellularly biosynthesized gold nanoparticles (AuNP), documenting in detail the molecular vibrations of biomolecules at the AuNP surfaces. Molecules involved in nanoparticle biosynthesis were identified at AuNP surfaces within algal cells, thus aiding in mechanism elucidation. The capabilities of Raman spectroscopy are endless, especially in light of SERS tag design, coordinating detection of analytes that do not inherently produce strong Raman vibrations. The increase in portable Raman spectrometer availability will only facilitate cheaper, more frequent application of Raman spectrometry both in the field and the lab. The tremendous detection power of the Raman spectrometer cannot be ignored.
Advancing Forward Osmosis for Energy-efficient Wastewater Treatment towards Enhanced Water Reuse and Resource Recovery
Zou, Shiqiang (Virginia Tech, 2019-05-30)
Current treatment of wastewater can effectively remove the contaminants; however, the effluent is still not widely reused because of some undesired substances like pathogens and trace organic chemicals. To promote water reuse, membrane-based technologies have emerged as a robust and more efficient alternative to current treatment practice. Among these membrane processes, forward osmosis (FO) utilizes an osmotic pressure gradient across a semi-permeable membrane to reclaim high-quality water. Still, several key challenges remain to be addressed towards broader FO application, including energy-intensive draw regeneration to yield product water and salinity buildup in the feed solution. To bypass energy-intensive draw regeneration, commercial solid fertilizers was utilized as a regeneration-free draw solute (DS), harvesting fresh water towards direct agricultural irrigation. However, using nutrient-rich fertilizers as DS resulted in an elevated reverse solute flux (RSF). This RSF, known as the cross-membrane diffusion of DS to the feed solution, led to deteriorated solute buildup on the feed side, reduced osmotic driving force, increased fouling propensity, and higher operation cost. To effectively mitigate solute buildup while achieving energy-efficient water reclamation, a parallel electrodialysis (ED) device was integrated to FO for DS recovery in the feed solution. The salinity in the feed solution was consistently controlled below 1 mS cm-1 via the hybrid FO-ED system. Considering solute buildup is merely a consequence of RSF, direct control of RSF was further investigated via operational strategy (i.e., an electrolysis-assisted FO) and membrane modification (i.e., surface coating of zwitterion-functionalized carbon nanotubes). Significantly reduced RSF (> 50% reduction) was obtained in both approaches with minor energy/material investment. With two major bottlenecks being properly addressed for energy-efficient water reclamation, FO was further integrated with a microbial electrolysis cell (MEC) to achieve integrated nutrient-energy-water recovery from high-strength wastewater (i.e., the digestor centrate). The abovementioned research projects are among the earliest efforts to address multiple key challenges of FO during practical application, serving as a cornerstone to facilitate the transformation of current water/wastewater treatment plant to resource recovery hub in order to ensure global food-energy-water security.
Advancing Potable Water Infrastructure through an Improved Understanding of Polymer Pipe Oxidation, Polymer–Contaminant Interactions, and Consumer Perception of Taste
Whelton, Andrew James (Virginia Tech, 2009-04-02)
While more than 100 years of research has focused on removing acute and chronic health threats from water, substantially less study has focused on potable water infrastructure and water quality deterioration, monitoring technologies, and relationships between water taste and consumer health. These knowledge–gaps have left infrastructure users, owners, regulators, and public health professionals largely unaware of how premise and buried polymer water pipes deteriorate and sorb/ desorb organic contaminants during normal operations and following water contamination events. These knowledge–gaps also prevent infrastructure managers from producing drinking water that optimizes mineral content for both water taste and health benefits, and employing a monitoring tool capable of immediately detecting water contamination or equipment failures. Research was conducted to address these challenges using analytical chemistry, environmental engineering, food science, polymer chemistry, public health, and material science principles. This work was enhanced by collaborations with sixteen American water utilities and the National Institute for Standards and Technology. These efforts were funded by the National Science Foundation, American Water Works Association, and the Water Research Foundation. Research results are unique and provide important scientific contributions to the public health, potable water, and material science industries. Particular achievements include the: (1) Evaluation of linkages between minerals, water palatability, and health useful for water production and public health decisions; (2) Creation of a novel infrastructure and water quality surveillance tool that has begun water utility implementation in the USA; (3) Development of an accelerated chlorinated water aging method with stable water pH, free chlorine, and alkalinity concentration that enables interpretation of polymer pipe surface and bulk characteristic changes; (4) Discovery that polar compounds are 2–193% more soluble in PEX than HDPE water pipes; (5) Finding that several polymer and contaminant properties can be used to predict contaminant diffusivity and solubility during sorption and desorption in new, lab aged, and water utility PE pipes; and the (6) Discovery that chlorinated water exposure of HDPE and PEX pipes increases polar contaminant diffusivity during sorption by 50–162% and decreases diffusivity during desorption as much as 211%. Outcomes of this work have domestic and global significance, and if engaged, can greatly improve public health protection, potable water infrastructure operations, water quality, sustainability, and regulation.
Aerosolization of Drinking Water Metals to Indoor Air and Assessment of Human Taste and Visual Thresholds for Manganese
Sain, Amanda Elizabeth (Virginia Tech, 2013-04-17)
Exposure to excess manganese via drinking water raises concerns due to potential for adverse neurological impacts, particularly in children. Manganese is ubiquitous in US groundwaters above the SMCL = 0.05 mg/L. Manganese is an essential nutrient, but exposures to elevated manganese have neurotoxic effects. Chapter 2 focuses on human senses\' ability to detect manganese in drinking water. Findings indicate human senses cannot be relied upon to detect excess Mn(II) in drinking water. Mn(IV) is easily visually detected, but cannot be tasted at 10 times the SMCL. Chapter 3 is an assessment the ability of an ultrasonic humidifier to expel drinking water impurities in aerosols. The quality of the water used to charge the humidifier reservoir affects the composition of elements in the aerosols and condensate. Findings indicate condensed humidifier aerosols contain 85% of elements present in the reservoir water for a variety of water types if there is no precipitation. Waters with high concentration of hardness or iron formed precipitates that decreased the concentrations of these metals in the aerosols causing variable results for other elements that were initially present at < 1mg/L in the charge water. This indicates that humidifiers could be a source of inhalation exposure for source water contaminants.
Aging and Copper Corrosion By-Product Release: Role of Common Anions, Impact of Silica and Chlorine, and Mitigating Release in New Pipe
Powers, Kimberly Alice (Virginia Tech, 2000-12-15)
It is desirable to reduce leaching of copper from home plumbing because of environmental concerns and to comply with stringent regulation of copper in wastewater and drinking water. The solubility of the scale (oxidized copper rust layer) on the copper pipe wall, which directly contacts drinking water, is a key factor controlling the maximum soluble copper release. Gradual replacement of soluble Cu(OH)2 scale to less soluble scale is desirable and occurs through a process known as "aging. The presence of sulfate, bicarbonate and orthophosphate in water can quickly convert Cu(OH)2 to less soluble solids. In some cases, this produces a desirable short-term reduction in copper solubility, but over longer time periods formation of these solids can be detrimental because they interfere with formation of very low solubility tenorite (CuO)or malachite phases. Likewise, silica present in water can sorb to Cu(OH)2 and hinder aging to low solubility tenorite, while the presence of chlorine can hasten aging by a chemical reaction with cupric species that has never been previously observed in the drinking water field. Mild chemical treatments that might be used to accelerate aging, and which could be applied to reduce environmental impacts of newly installed copper pipe, were successfully tested. Chemical pretreatments using lime, caustic, soda ash or chlorine reduced copper release by as much as 84% compared to new pipes without pretreatment.
Anaerobic/aerobic degradation of a textile dye wastewater
Loyd, Chapman Kemper (Virginia Tech, 1992-03-05)
Consumer demands have led to the development of new, more stable textile dyes. These dyes, many of the azo type, are often incompletely degraded/removed in wastewater treatment plants, leading to the discharge of highly colored effluents to rivers and streams. Concerns by downstream users of that water have led to enactment of effluent color and toxicity standards for plants that treat textile dye wastewater. Both anaerobic and aerobic biological degradation of azo dyes have been reported in the literature; the rate and extent of degradation is often quite dye-specific. This research utilized laboratory-scale reactors to investigate the effectiveness of those treatments, both singly and in combination, on two azo dye wastewaters: a textile dyeing and finishing process water and a municipal wastewater consisting predominately of textile dyeing and finishing mill effluents.
Analysis of Organic and Inorganic Parameters in Southern Virginia Rivers Following a Coal ash Spill
Waggener, Keegan Edward (Virginia Tech, 2018-01-23)
In February 2014, a coal ash spill on Duke Energy's Dan River Plant in Eden, NC released approximately 39,000 tons of coal ash into the Dan River. It took approximately one week to stop the spill. Starting in February 2015, drinking water utilities using the Dan River experienced a series of taste and odor (TandO) events described as "earthy" or "musty". Similar TandO events were not documented before the coal ash spill. This research attempted to understand causes of the TandO events and if the coal ash spill was connected. A variety of water quality analyses were performed on twelve sites from August 2016 to September 2017 on the Dan and Smith Rivers. The Smith River served as the control. From concentrations of coal ash indicators (particularly Ba, Sr, As, V, and Br-), there was a signature of coal ash on the Dan River that was not present on the Smith River. The signature could not be attributed to the coal ash spill, as the signature was present upstream of the spill. Chronic ecosystem toxicity due to metals was low and not significantly different between the Dan and Smith Rivers. No substantial TandO events occurred during the period of this study. All monitored odorants were detected with varying frequencies in both the Dan and Smith Rivers. No significant change in odorant concentration was found above and below the location of the coal ash spill.
Analysis of salivary fluid and chemosensory functions in patients treated for primary malignant brain tumors
Mirlohi, Susan; Duncan, Susan E.; Harmon, M.; Case, D.; Lesser, G.; Dietrich, Andrea M. (Springer, 2015-01-01)
Objectives The frequency and causes of chemosensory (taste and smell) disorders in cancer patients remain under-reported. This study examined the impact of cancer therapy on taste/ smell functions and salivary constituents in brain tumor patients. Materials and methods Twenty-two newly diagnosed patients with primary malignant gliomas underwent 6 weeks of combined modality treatment (CMD) with radiation and temozolomide followed by six monthly cycles of temozolomide. Chemosensory functions were assessed at 0, 3, 6, 10, 18, and 30 weeks with paired samples of saliva collected before and after an oral rinse with ferrous-spiked water. Iron (Fe)- induced oxidative stress was measured by salivary lipid oxidation (SLO); salivary proteins, electrolytes, and metals were determined. Parallel salivary analyses were performed on 22 healthy subjects. Results Chemosensory complaints of cancer patients increased significantly during treatment (p=0.04) except at 30 weeks. Fe-induced SLO increased at 10 and 18 weeks. When compared with healthy subjects, SLO, total protein, Na, K, Cu, P, S, and Mg levels, as averaged across all times, were significantly higher (p<0.05), whereas salivary Zn, Fe, and oral pH levels were significantly lower in cancer patients (p<0.05). Neither time nor treatment had a significant impact on these salivary parameters in cancer patients. Conclusions Impact of CMT treatment on chemosensory functions can range from minimal to moderate impairment. Analysis of SLO, metals, and total protein do not provide for reliable measures of chemosensory dysfunctions over time. Clinical relevance Taste and smell functions are relevant in health and diseases; study of salivary constituents may provide clues on the causes of their dysfunctions.
Application of Automated Facial Expression Analysis and Qualitative Analysis to Assess Consumer Perception and Acceptability of Beverages and Water
Crist, Courtney Alissa (Virginia Tech, 2016-04-27)
Sensory and consumer sciences aim to understand the influences of product acceptability and purchase decisions. The food industry measures product acceptability through hedonic testing but often does not assess implicit or qualitative response. Incorporation of qualitative research and automated facial expression analysis (AFEA) may supplement hedonic acceptability testing to provide product insights. The purpose of this research was to assess the application of AFEA and qualitative analysis to understand consumer experience and response. In two studies, AFEA was applied to elucidate consumers emotional response to dairy (n=42) and water (n=46) beverages. For dairy, unflavored milk (x=6.6±1.8) and vanilla syrup flavored milk (x=5.9±2.2) (p>0.05) were acceptably rated (1=dislike extremely; 9=like extremely) while salty flavored milk (x=2.3±1.3) was least acceptable (p<0.05). Vanilla syrup flavored milk generated emotions with surprised intermittently present over time (10 sec) (p<0.025) compared to unflavored milk. Salty flavored milk created an intense disgust response among other emotions compared to unflavored milk (p<0.025). Using a bitter solutions model in water, an inverse relationship existed with acceptability as bitter intensity increased (rs=-0.90; p<0.0001). Facial expressions characterized as disgust and happy emotion increased in duration as bitter intensity increased while neutral remained similar across bitter intensities compared to the control (p<0.025). In a mixed methods analysis to enumerate microbial populations, assess water quality, and qualitatively gain consumer insights regarding water fountains and water filling stations, results inferred that water quality differences did not exist between water fountains and water filling stations (metals, pH, chlorine, and microbial) (p>0.05). However, the exterior of water fountains were microbially (8.8 CFU/cm^2) and visually cleaner than filling stations (10.4x10^3 CFU/cm^2) (p<0.05). Qualitative analysis contradicted quantitative findings as participants preferred water filling stations because they felt they were cleaner and delivered higher quality water. Lastly, The Theory of Planned Behavior was able to assist in understanding undergraduates' reusable water bottle behavior and revealed 11 categories (attitudes n=6; subjective norms n=2; perceived behavioral control n=2; intentions n=1). Collectively, the use of AFEA and qualitative analysis provided additional insight to consumer-product interaction and acceptability; however, additional research should include improving the sensitivity of AFEA to consumer product evaluation.
Applications of Sensory Analysis for Water Quality Assessment
Byrd, Julia Frances (Virginia Tech, 2018-01-30)
In recent years, communities that source raw water from the Dan River experienced two severe and unprecedented outbreaks of unpleasant tastes and odors in their drinking water. During both TandO events strong 'earthy', 'musty' odors were reported, but the source was not identified. The first TandO event began in early February, 2015 and coincided with an algal bloom in the Dan River. The algal bloom was thought to be the cause, but after the bloom dissipated, odors persisted until May 2015. The second TandO in October, 2015 did not coincide with observed algal blooms. On February 2, 2014 approximately 39,000 tons of coal ash from a Duke Energy coal ash pond was spilled into the Dan River near Eden, NC. As there were no documented TandO events before the spill, there is concern the coal ash adversely impacted water quality and biological communities in the Dan River leading to the TandO events. In addition to the coal ash spill, years of industrial and agricultural activity in the Dan River area may have contributed to the TandO events. The purpose of this research was to elucidate causes of the two TandO events and provide guidance to prevent future problems. Monthly water samples were collected from August, 2016 to September, 2017 from twelve sites along the Dan and Smith Rivers. Multivariate analyses were applied to look for underlying factors, spatial or temporal trends in the data. There were no reported TandO events during the project but sensory analysis, Flavor Profile Analysis, characterized earthy/musty odors present. No temporal or spatial trends of odors were observed. Seven earthy/musty odorants commonly associated with TandO events were detected. Odor intensity was mainly driven by geosmin, but no relationship between strong odors and odorants was observed.
Assessing Human Exposure to Emissions from Ultrasonic Humidifiers
Yao, Wenchuo (Virginia Tech, 2021-09-14)
Portable ultrasonic humidifiers add moisture into room air, but they simultaneously add exposure risks of aerosolized metals from drinking water used as fill water. The inhalation exposure from emitted metals can be overlooked, and thus, co-exposure of inhalation and ingestion and co-exposure to multiple inorganic metals is investigated. The objectives of this work are: 1) predict airborne metal concentrations and particle sizes in four realistic room scenarios (33 m3 small or 72 m3 large, with varying ventilation rates from 0.2/hr -1.5/hr), and the investigated metals are arsenic, cadmium, chromium, copper, lead, and manganese; 2) characterize exposure doses and consequent risks for adults and 0.25, 1, 2.5, and 6 yr old children, when using identical drinking water ingested and as fill water, including inhalation of fine, respirable particles generated at the frequency of 8 hrs/day (equals 121.67 days/yr) and daily ingestion, under four realistic room scenarios. The risk assessment includes non-cancer [calculation of average daily dose (ADD) and hazard quotient (HQ)] and cancer risk evaluation; 3) quantify deposition fraction and deposited doses of multiple metals in human adult's and children's respiratory tract, using multi-path particle dosimetry (MPPD) model. Results show airborne-particle-bound metal concentrations increase proportionally with water metals, and a poorly ventilated room causes greater exposure. Ingestion ADDs are 2 magnitudes higher than inhalation ADD, at identical water metal concentrations and daily exposure frequency. However, in the worse-case scenario of 33 m3 small room with low air exchange rate, the consequent inhalation HQs are all greater than 1 for children and adults, except for lead, indicating significant non-cancer risks when exposed to humidifier particles under the worse-case scenario. The cancer risks for arsenic, cadmium, chromium, and lead metals reveal are greater than acceptable one case in a million population (1E-6) produced from inhalation of the humidifier emitted metal-containing particles only. The MPPD model results indicate inhaled metal-containing airborne particles deposit primarily in head and pulmonary regions, and a greater dose (unit in µg/kg body weight/day) deposits in children than adults. Inhalation of ultrasonic humidifier aerosolized metals results in additional, and potentially greater risks (indicated by HQinhalation >1, and greater deposited dose) than ingestion at the same aqueous metal concentration, especially for children. Room conditions (i.e. volume and ventilation) influence risks. Both inhalation and ingestion exposures require consideration for eliminating multiple metal exposures and health-based environmental policy making. Consumers should be aware that they may be degrading their indoor air quality by using ultrasonic humidifiers even when filling with acceptable water quality for drinking.
An assessment of factors controlling the biodegradation of benzene in the subsurface environment
Poor, Noreen D. (Virginia Tech, 1996)
The objectives of this research were to correlate benzene biodegradation with soil physical, chemical and biological properties, to determine if biodegradation could be predicted based on measured or observed soil properties, and to investigate the role of nutrients on benzene biodegradation in soil. Benzene disappearance over time was measured in aerobic active and control (autoclaved) microcosms prepared with previously-uncontaminated subsurface soils. Soil microcosm experiments were prepared with initial benzene concentrations of 1, 10 and 50 mg/L. For each soil, logistic, zero-, first-, and 3/2- order kinetic models were fit to benzene disappearance versus time data by regression analysis. The logistic and 3/2-order models fit the data better than zero- and first-order models for experiments prepared with initial benzene concentrations of 1 and 10 mg/L. For an initial benzene concentration of 50 mg/L, experimental data were often better fit by zero- or first-order kinetic models. To obtain predictive equations, logistic kinetic model rate constants were related to soil properties using multiple linear regression (MLR). The “best” MLR models and their regression coefficient estimates were statistically significant at p<0.05. For experiments prepared with an initial benzene concentration of 1 mg/L, the resulting predictive equation contained soil phosphorus concentration and cation exchange capacity (CEC). For experiments prepared with an initial benzene concentration of 10 mg/L, the predictive equation contained soil copper, nitrate-N and phosphorus concentrations, CEC, and % sand. A comparison was made between benzene biodegradation in unamended soil microcosms and soil microcosms amended with ammonium and potassium phosphates (11 mM nitrogen, 6 mM phosphorus and 0.6 mM potassium). Benzene disappearance over time in soil microcosms was stimulated by nutrient addition in one (11%), 6 (50%), and 5 (45%) soils at initial benzene concentrations of 1, 10 and 50 mg/L, respectively. In general, nutrient addition had the greatest affect on benzene biodegradation in low pH soils.
Benthic Macroinvertebrate Susceptibility to Trout Farm Effluents
Roberts, Lenn Darrell (Virginia Tech, 2005-08-30)
The direct effects of a Virginia trout farm on benthic macroinvertebrates were examined using multiple approaches. Static laboratory tests with the amphipod, Hyallela azteca, were conducted with exposures to water taken from a spring, effluent above a sedimentation basin, and effluent below a sedimentation basin. On-site mesocosms were constructed to expose previously colonized artificial substrates to the same treatments as the laboratory tests. Flat-headed mayflies were also collected from a nearby stream and transported to the mesocosms for a 10 day exposure. There was no significant difference between treatments in the laboratory tests after 20 days, but after 28 days the control was significantly lower than the above sedimentation basin treatment in one test. In the multispecies field tests, a clear decrease in total invertebrate abundance and EPT abundance was seen in the effluent treatments compared to the spring water treatments, with a slight improvement in survival in the treatment below the sedimentation basin. However, only total invertebrate abundance after 21 days produced statistically significant differences. A significant difference was detected between the effluent and the spring treatments in the flat-headed mayfly field test. We suggest that the effects seen in this study do not explain the lack of taxa richness in the receiving stream. The main cause of mortality from trout effluents appears to be solids accumulating upon the organisms, and sedimentation basins should be effective best management practices for protecting macroinvertebrates.
Biological and Membrane Treatment Applications for the Reduction of Specific Conductivity and Total Dissolved Solids in Coal Mine Waters
Kemak, Zachary Eric (Virginia Tech, 2017-01-25)
Specific conductivity (SC) and total dissolved solids (TDS) are increasingly being used as a parameter used to judge the aquatic health of streams that are impacted by coal mining operations in the Appalachian region of the United States. Due to this, government environmental regulatory bodies have been considering issuing a regulation on SC for all mining operation outfalls. Sulfate typically has the greatest dissolved ion presence in coal mine waters. In literature examining the treatment of mine waters, SC and TDS analysis is typically not reported. The technologies examined in this study were nanofiltration membrane technology and biological sulfate reducing bioreactors. In the nanofiltration study, three different nanofiltration membranes were evaluated for SC reduction: NF270, DK, and NFX. The DK and NFX nanofilters were able to reduce SC levels by an average of 84 percent for both mine waters tested and were able to reach SC levels below the proposed limit of 500 S/cm. The SC levels achieved by the NF270 nanofilters were observed to have much higher variability. The inclusion of microfiltration and simulated-sand filtration were also introduced as a pre-treatment stage in order to determine whether or not nanofiltration performance would improve in terms of SC reduction. In the biological sulfate reducing bioreactor study, multiple bioreactors were established to identify the optimal organic mixture to foster both SC and sulfate reduction. Sulfate reduction began to occur approximately 20 days after the establishment of each bioreactor. SC levels were greater than 13,000 S/cm in each of the bioreactors sampled by the fortieth day of sampling. The probable cause of the increase SC was identified to be the manure/compost used in the study. Future testing should incorporate more sampling in the early phases of experimentation in order to ensure the ability to monitor changes in water quality.
Biological treatment schemes for preventing oxime inhibition of nitrification
Lubkowitz, Erika M. (Virginia Tech, 1996-05-05)
The purpose of this research was to develop a single sludge multi-environment anoxic/aerobic biological treatment scheme that could achieve oxime degradation and nitrification in the same treatment process. Aerobic and anoxic batch experiments were initially performed to determine degrees of nitrification inhibition caused by three oximes, acetaldehyde oxime (AAO), aldicarb oxime (ADO), and methyl ethyl ketoxime (MEKO), and to investigate the fate of these oximes under anoxic, denitrifying conditions. Results from aerobic batch studies showed that MEKO was the only oxime which caused significant nitrification inhibition at concentrations expected in the industrial client's waste streams. Nitrification rates were reduced by 31% at MEKO concentrations as low as 2 mg/L and were almost completely inhibited above 9 mg/L. Results from anoxic batch studies demonstrated that MEKO was biologically degraded under nitrate limiting conditions, although the microorganism( s) responsible were not explicitly identified. Similar degradation trends were seen for AAO, but at significantly lower rates. ADO, however, appeared to be stable under all anoxic conditions examined. Results from batch studies were utilized to determine operational conditions for a single sludge multi-environment anoxic/anaerobic/aerobic sequencing batch reactor supplied with a synthetic organic wastewater containing up to 40 mgIL MEKO and 56 mgIL AAO. The system was able to achieve complete oxime degradation and nitrification when operated on a one day cycle with a twelve hour anoxic/anaerobic reaction phase and a nitrate:carbon ratio below 0.15 mg N0₃-N/mg TOC.
Biomarkers of Lipid Oxidation in the Oral Cavity
Vereb, Heather A. (Virginia Tech, 2011-10-14)
Measuring lipid oxidation is useful as a means of monitoring oxidative stress, such as that induced by clinical conditions or environmental exposure. Characteristic volatile compounds, often with low threshold odors, are secondary products of lipid oxidation reactions. Metallic flavor in food and beverages has been linked with oxidation of lipids in the oral cavity. Breath, an emerging medium for analysis of internal condition, is one means of measuring the metal-induced lipid oxidation responsible for this flavor. This project analyzes the breath of human subjects, as well as lipid oxidation of in vitro samples to identify compounds responsible for producing metallic flavor, which result from the oxidation of lipids in the oral cavity. Because these analytes are found at extremely low (picomolar to nanomolar) concentrations, preconcentration of samples prior to gas chromatography-mass spectrometry analysis is crucial. This study utilizes both solid phase microextraction (SPME) and micromachined silicon micropreconcentrators to concentrate compounds in breath to optimize analysis.
Changes in flavor volatile composition of oolong tea after panning during tea processing
Sheibani, E.; Duncan, Susan E.; Kuhn, D. D.; Dietrich, Andrea M.; Newkirk, J. J.; O'Keefe, Sean F. (2016-05)
Panning is a processing step used in manufacturing of some varieties of oolong tea. There is limited information available on effects of panning on oolong tea flavors. The goal of this study was to determine effects of panning on flavor volatile compositions of oolong using Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O). SDE and SPME techniques were applied for extraction of volatiles in panned and unpanned teas. A total of 190 volatiles were identified from SDE and SPME extractions using GC-MS and GC-O. There were no significant differences (P > 0.05) in aldehyde or terpene contents of unpanned and panned tea. However, alcohols, ketones, acids and esters contents were significantly reduced by panning. Among 12 major volatiles previously used for identification and quality assessment of oolong tea, trans nerolidol, 2- hexenal, benzaldehyde, indole, gernaiol, and benzenacetaldehyde contents were significantly decreased (P < 0.05) by panning. Panning increased (P < 0.05) contents of linalool oxide, cis jasmone, and methyl salicylate. The GC-O study also showed an increase of aroma active compounds with sweet descriptions and decrease of aroma active compounds with fruity and smoky descriptions after panning. Panning significantly changes the volatile compositions of the tea and created new aroma active compounds. Results from this study can be used in quality assessment of panned oolong tea.
Characterization of a Creosote-Contaminated Tie Yard Site and the Effects of Phytoremediation
Fetterolf, Glendon J. IV (Virginia Tech, 1998-06-15)
A creosote treatment facility was active during the 1950’s and 1960’s at a railroad tie yard site. In 1990, creosote contamination was discovered along a creek bank at the site. Phytoremediation was selected as the remedial technology and hybrid poplar trees were planted at the site in 1997. A research project was designed to: 1) characterize the site through collection of soil and ground water samples; 2) assess phytoremediation effects of 3 grasses, clover, fescue and rye, in creosote-contaminated surface soils; 3) perform assessment of the hybrid poplar tree phytoremediation system; 4) develop a hybrid poplar tree evapotranspiration model. This thesis is focused on the first and second items on the research agenda. Soil and ground water samples were collected and analyzed for 6 polycyclic aromatic hydrocarbons (PAHs), acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene and chrysene. Site characterization revealed multiple creosote sources. Areal subsurface bedrock DNAPL distribution, approximately 6500 ft², was much greater than previously reported. Total PAHs (Σ 6 PAHs) in the soil and ground water ranged from below detection limits (BDL) to 8,276 mg/kg and BDL to 1.58 mg/L, respectively. Aqueous phase PAHs should be available for hybrid poplar tree and microbial uptake. Dissolution and diffusion of PAH constituents from the free product phase to the aqueous and soil phases contaminated both matrices. PAH cosolvency effects were also evident. The presence of more soluble PAHs in the aqueous phase enhanced the solubility of two hydrophobic PAHs, chrysene and benzo(b)fluoranthene. Phytoremediation effects of fescue, rye, and clover grasses were assessed in creosote-contaminated surface soils. Over the 9 month period, clover grass growth was very poor. Clover data was not used in comparative analyses. Rye and fescue grasses exhibited acceptable growth. In planted and control (unplanted-amended) plots, acenaphthene, fluorene, phenanthrene, fluoranthene, and pyrene soil concentrations were reduced 72, 50, 73, 55 and 49 percent, respectively. Chrysene reduction was not statistically significant. During the first 4 months of the study, dry site conditions limited grass growth and subsurface biological activity. The site received approximately 16 inches of precipitation during the last 3 months of the study, including multiple, intense precipitation events. The subsurface was saturated for prolonged periods of time and oxygen transfer to indigenous microorganisms was likely limited. The root structures of fescue and rye grasses were neither dense nor complex enough to promote phytoremediation effects. PAH reductions were generally greater for constituents with higher aqueous solubilities. It is thought that PAH losses were primarily due to solubilization and/or microbial uptake.
Characterization of Metallic Flavor in Drinking Water: An Interdisciplinary Exploration through Sensory Science, Medicine, Health, and the Environment
Mirlohi, Susan (Virginia Tech, 2012-02-22)
Scientific explorations can lead to life changing discoveries or light the path for new discoveries as scientists continue to carry or pass on the torch of knowledge to current and future generations. This torch of knowledge radiates in many directions, as the path of discovery often demands a multidimensional perspective. This research explored the many aspects of metallic flavor in drinking water through applications of sensory science, medicine, health, and the environment. Humans interact with their environment through the five senses and are often exposed to contaminants through multiple routes; oral intake of trace metal contaminants through drinking water is a likely source. The biochemical mechanism by which humans are able to detect the flavor of strongly metallic agents such as iron has been previously elucidated, but little is known about population variability in the ability to sense metallic flavors. This research evaluated sensory thresholds and biochemical indicators of metallic flavor perception in healthy adults for ferrous iron in drinking water; 61 subjects aged 19 – 84 years, participated. The findings demonstrated an age-dependent sensitivity to iron indicating as people age they are less sensitive to metallic perception; impairment of olfactory functions is a contributing factor. Unlike in healthy adults, where human senses are often protective of overexposure to contaminants, and supportive of sensations of everyday life's pleasures, cancer patients often suffer from chemosensory dysfunctions. Metallic phantom taste is a commonly experienced sensation, yet very little studied aspect of this debilitating disorder. Impact of cancer therapy on chemosensory functions of patients with malignant brain tumors undergoing combined modality treatment (CMT) was explored. The results indicated that chemosensory dysfunctions of the patients can range from minimal to moderate impairment with maximum impairment developing during the 6-week CMT. Study of salivary constituents may provide clues on to the causes of chemosensory dysfunctions. On health aspects, implication of individual sensitivity to metallic flavor on beverage choices and overall water consumption was assessed in 33 healthy adults through self-reported beverage questionnaire. The results indicated that among the elderly reduced intake of drinking water coincided with reduced sensitivity to metallic flavor. The findings have important health implications in terms of hydration status and beverage choices. Finally, with environmental exposure relevance, preliminary findings on sensory properties of zerovalent iron nanoparticles (nZVI) indicated that oral exposure to nZVI may induce sensory properties different from that of ferrous iron, likely predictive of a diminished detection of metallic flavor by humans. Further research is warranted in this area.

Browsing by Author "Dietrich, Andrea M."

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