VTechWorks Repository :: Browsing by Author "Michelsen, Donald L."

Browsing by Author "Michelsen, Donald L."

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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.
An analysis of microbial film fermentor system for production of secondary metabolites
Park, Young Hoon (Virginia Polytechnic Institute and State University, 1983)
Performance of a three-phase fluidized-bed biofilm fermenter system, which is used for the production of a secondary metabolite, is analyzed through computer simulation techniques. Penicillin fermentation was chosen for the model system. From the steady-state analysis, it was found that a complete-mixed contacting pattern is superior to a plug flow pattern in terms of productivity, since less inhibitory effect of the substrate is pronounced in that configuration. Optimum biofilm thickness for the fermenter system was found to be a function of various operating parameters, and should be determined from information on the interactions between fermenter productivity and the operating conditions. The dynamic analysis has shown that for a given constant oxygen transfer rate in bulk phase, there exist operating conditions optimal for maximizing the volumetric productivity of the fermenter system. When a constant oxygen transfer rate with a k.e.a of 300 hr 1 was used with a complete-mixed contacting pattern, the optimum inlet substrate con- centration and mean residence time were found to be 20 (g glucose/liter) and 10 (hours), respectively. Production phase could be extended by increasing the substrate concentration in the feed stream, but the optimum increasing rate and initiation time of increase are functions of other operating parameters, such as initial inlet substrate concentration, mean residence time, and oxygen transfer rate in the fermentor. An increasing rate of 0.6 g glucose/liter/hr with the initiation time t 0 = 51 was found to be the optimal, for the operating conditions found in the dynamic analysis. The result has also shown that a high total biomass concentration and a high oxygen transfer rate in the fermentor are the most important factors to achieve a high productivity.
Application of oxygen microbubbles for in situ biodegradation of p-xylene contaminated ground water in a soil column
Jenkins, Kristen Buch (Virginia Tech, 1992-01-05)
In situ biodegradation of p-xylene was studied in a 2.75 inch diameter column using oxygen microbubbles to supply the electron acceptor. One objective was to demonstrate that pxylene can be biodegraded in the soil column and to follow the degradation and pressure drops as a function of time. The next objective was to demonstrate the potential for biodegradation of p-xylene in the presence of ferrous iron and to follow bioremediation and anticipated pressure drops as a function of time. Then, an air sparging section was added prior to the biodegradation section to determine if the ferrous iron could be removed in this section. The air sparging section would then be flushed with air and/or water to determine if the ferrous could be removed from the sand matrix and alleviate the expected plugging. The bacteria degraded p-xylene to below detectable limits until the oxygen supply was exhausted. The pressure drops over this time showed a slight increase over the first few days and then a gradual decline, which shows promise for in situ biodegradation as the microorganisms were thought to cause plugging. The next run which studied the simultaneous biodegradation of xylene and ferrous oxidation showed no interference from the ferrous iron. The microorganisms seemed to store the oxygen that they needed before the ferrous could oxidize. The pressure drops showed no general trend, therefore the ferric precipitate did not cause an appreciable amount of plugging as expected. The air sparging section resulted in volatilization of xylene with very little ferrous oxidation. To flush the ferric precipitate from this zone, either a combination of air sparging and backwashing or backwashing at the fluidization velocity was needed to remove the ferric iron.
Break-in behavior of a tungsten oxide on silica catalyst during propylene disproportionation
Fathi-Kalajahi, Jamshid (Virginia Tech, 1978-04-05)
This investigation consisted of a study of the break-in behavior of a tungsten oxide on silica catalyst during propylene disproportionation. A catalyst of 10 percent WO3 on silica gel (223 square meters per gram B.E.T. surface area) was used in a microcatalytic reactor. During the initial contacting of freshly activated samples of this catalyst with propylene, significant increases in disproportionation activity were observed for periods of up to 20 hours. The object of this study was to investigate the phenomena responsible for this break-in. The rate of approach to steady-state activity data were obtained using catalyst samples which were first saturated with each of the three gases involved in this reaction (propylene, ethylene, and 2-butene) by pulsing at .94 and 2.7 atmospheres before.starting the propylene flow. Effects of each gas on the break-in behavior of the catalyst were determined. A material balance around the reactor was made for each gas by pulse reactor techniques.
Colloidal gas aphrons: generation, flow characterization and application in soil and groundwater decontamination
Longe, Timothy A. (Virginia Polytechnic Institute and State University, 1989)
This study examines the fundamental properties of Colloidal Gas Aphrons, CGA, relevant to its application in soil and groundwater decontamination. It also presents the results of laboratory experiments on the applicability of CGA in treating soils contaminated with organic chemicals. CGA is a collection of spherical, 10 to 100 micron-sized gas bubbles dispersed in an aqueous surfactant solution with a volumetric gas fraction (quality) of at most 0.74. It is characterized by its quality, bubble size, stability and apparent viscosity. The stability can be described by the half life, the time needed for 50% of its liquid phase to separate by gravitational drainage. CGA is a non-Newtonian fluid. The apparent viscosity is higher than that of its liquid or gas phase and increases with increase in quality. At quality above 0.6, CGA is a pseudoplastic fluid and can be modelled by the power law. In this quality range, apparent viscosity decreases with increase in shear rate. Measured apparent viscosity can be as high as 25 centipoise at low shear rates for a CGA quality of 0.72. But at low quality, CGA is best described by the Bingham fluid model. CGA flow through porous media follows the discontinuous fluid flow model with the liquid phase advancing faster than the gas phase. The presence of CGA bubbles causes considerable reduction of effective mobility compared to water flow. The bubbles act to reduce the effective flow area by first blocking the wider pores and re-directing flow to narrower pores. The tenacity of the bubbles in the presence of adequate surfactant molecules account for its flow characteristics in porous media. CGA is more effective in flushing hydrophobic organics from saturated sand-packed columns compared with surfactant flushing. CGA provides the surface active agent needed to lower the interfacial tension of the non-wetting phase and at the same time creates enough viscous force to mobilize any trapped fluid. Its ability to preferentially block large pores in a heterogeneous media and direct fluid flow to smaller pores also contributes to the demonstrated effectiveness as a soil flushing agent.
Color removal in textile dye wastewaters by means of coagulation
Inge, Thomas Benjamin (Virginia Tech, 1996-07-14)
In textile mill wastewater effluent, highly colored and stable dyes are formidable and somewhat insusceptible to removal treatment processes. Recent governmental regulations have made it necessary to remove most color before discharging the treated wastewater to surface waters. Chemical coagulation is successful in some cases at reducing wastewater color to acceptable levels. Also anaerobic biological treatment is usually successful in destroying the dyes and color in the wastewater. Aerobic biological treatment often does not degrade the dyes or remove significant color, but aerobic treatment, unlike anaerobic treatment, removes a large amount of organics. This thesis explored the color removal in two textile dye wastewaters by means of coagulation in conjunction to the following treatments: no prior treatment, aerobic treatment, anaerobic treatment, and anaerobic-aerobic treatment. In the first industry, a reactive azo dye washwater (or rinsewater) was evaluated, and the influent into the municipal treatment facility that receives the azo dyes was also evaluated. Polymer coagulation proved to be successful following anaerobic-aerobic treatment in reducing color, solids, and organics. Color removals were most favorable at low pHs of 3 to 5 when using polymer dosages less than 100 mg/L in the washwater and less than 25 mg/L in the municipal wastewater. At higher amounts of coagulant over 100 mg/L in the washwater and 25 mg/L in the municipal wastewater, color removals were similar at pHs 3 to 8. The second industry uses many dyes that include acid and disperse dyes. Alum addition of 300 to 400 m/L at pH 5 compared favorably to the polymers presently added by the industry. Both the currently used polymers and alum were successful in removing color when utilizing proper settling techniques.
Enhanced petroleum-contaminated soil bioremediation by plants
Al-Ghazzawi, Ziad D. (Virginia Tech, 1995-07-16)
A petroleum-contaminated soil remediation study was conducted in a greenhouse. The system consisted of 36 pots, 12 were vegetated with squash, 12 were vegetated with fescue grass and the last 12 units served as unvegetated controls. For each group, three treatments were applied, 1) the addition of single dose of nutrients, 2) the addition of double dose of nutrients and 3) the addition of double dose of nutrients and acclimated bacteria to the irrigation water. The two plants were selected to represent extremely different species in terms of transpiration potential and root density in order to better understand the mechanisms involved in phytoremediation. Clay sandy soil (3: 1, by weight) was spiked with Fuel oil No.2 and allowed to weather for 1 week before it was placed in the pots. Under all study treatments, units vegetated with fescue grass had significantly less TPH concentration than the unvegetated controls after 10 weeks. Units vegetated with squash had significantly less TPH concentration than the un vegetated controls after 10 weeks only under treatment 3. Squash significantly accumulated TPH in the shoot under all treatments while grass shoot accumulated TPH significantly only under treatment 1. The mechanisms most important in phytoremediation seemed to include plant uptake of TPH, desorption and enhanced bioavailability by transpiration-induced water movement in the rhizosphere and root stimulation of microbial degradation.
Influence of organic matter on the sorption and bioavailability of 2,4,6-trichloro-(¹⁴C)-phenol
Robinson, Kevin G. (Virginia Tech, 1990)
Hydrophobic organic contaminants released into the subsurface can become sorbed to the soil matrix. The sorbed compounds may slowly leach into the groundwater, providing a long-term source of contamination. Bioremediation has been cited as a potential clean-up strategy for residual organics in soils. At present, factors which control biological utilization and retention of organic contaminants in the subsurface are poorly understood. The purpose of this study was to investigate how the adsorption/desorption and biodegradation processes interact to control the distribution and biological fate of subsurface contaminants. Batch soil microcosms were used to evaluate the sorption of a chlorinated aromatic compound [2,4,6-trichlorophenol (TCP)] to mineral soils, organic soils, and dissolved macromolecules (humic acid). Microbial utilization of 2,4,6-TCP was then evaluated after addition of a bacterial culture previously acclimated to the substrate. Biodegradation was evaluated by production of ¹⁴CO₂ and disappearance of 2,4,6-TCP from the sorbed and solution phases. Size exclusion chromatography was used to distinguish between free 2,4,6-TCP in solution and 2,4,6-TCP bound to humic acid in solution. Sorption of 2,4,6-TCP to mineral surfaces was rapid but sorption to organic soils varied with contact time. Most 2,4,6-TCP sorption to organic soils occurred during the first few days of contact with the soil. However, the sorption rate gradually decreased with time and 2,4,6-TCP continued to sorb for weeks at a reduced rate. The amount of 2,4,6-TCP which sorbed at the slower rate was dependent upon the organic matter content of the soil. Desorption of 2,4,6-TCP from organic soils was similar to adsorption; however, it appeared that slow desorption took longer than slow adsorption. Humic acid in solution formed an additional phase to which 2,4,6-TCP sorbed. The sorption capacity of dissolved humic acid was a function of the humic acid concentration. Higher concentrations of humic acid had lower sorption capacities when normalized for total organic carbon content. The mineralization rate of 2,4,6-TCP by Pseudomonas aeruginosa was dependent upon the initial substrate concentration. Total mineralization of 2,4,6-TCP by P. aeruginosa decreased in the presence of organic soils. However, mineralization rates were elevated in organic soils compared to mineral soils after 5 days of incubation. This was attributed to an influx of substrate into solution from an initially sorbed state. Total mineralization of 2,4,6-TCP in humic-containing solutions was reduced by 5-10 % over humic-free solutions. The bioavailability of 2,4,6-TCP was greatly reduced in the sorbed state. Biodegradation of unbound 2,4,6-TCP in solution was very rapid while biodegradation of 2,4,6-TCP sorbed to organic soil or to dissolved humic acid was much reduced. Desorption of most 2,4,6-TCP from soil was rapid, thereby becoming available to acclimated bacteria. However, a small quantity of 2,4,6-TCP desorbed from organic soil and dissolved humic acid very slowly and became available for biodegradation at a rate limited by desorption.
Iron oxidation coupled with biodegradation of organic contaminants in a simulated ground water system
Achanta, Srinivasa G. (Virginia Tech, 1991-05-22)
Aerobic degradation of hydrocarbon contaminants in anaerobic ground water would be enhanced by oxygenating the water. However, when a contaminated ground water contains high concentrations of reduced iron, competition for oxygen may occur. This study was designed to study this competition. The oxidation of iron and biodegradation of organics was studied in a 12 in X 2.5 in soil column by injecting either oxygen microbubbles or hydrogen peroxide into the soil matrix to provide a source of oxygen. The effluent concentrations of organic and inorganic constituents and the head losses were monitored after injecting oxygen. First, iron oxidation alone was studied. Second, biodegradation of the organic compound was studied. Finally, the simultaneous iron oxidation and biodegradation of organic compound was carried out. The effect of different Fe2+ concentrations in water on the biodegradation of the organic contaminants was evaluated. It was intended to determine whether iron oxidation or biodegradation of organic compound would cause more plugging in soil. The oxidation efficiencies using oxygen microbubbles and peroxide were compared. It was concluded that at high concentrations of Fe2+ in water, iron is rapidly oxidized utilizing most of the available oxygen. At low Fe2+ concentrations, biodegradation efficiency was high. Oxygen microbubbles were found to be slightly more effective than hydrogen peroxide in transferring oxygen to ground water and oxidizing iron or biodegrading organic contaminants. Soil plugging was found to occur regardless of the method of oxygen delivery. The use of coarse media removal system seemed to solve the problem.
The Microbubble Assisted Bioremediation of Chlorinated Ethenes
Kaiser, Philip Marc Jr. (Virginia Tech, 1998-04-13)
This work focused on using a microbubble dispersion to deliver hydrogen and carbon dioxide to anaerobic consortia to stimulate their ability to reductively dehalogenate tetrachloroethylene all the way to ethene and ethane. A continuous flow system, consisting of six anaerobic soil column bioreactors, inoculated with sediments from Virginia Tech's Duck Pond, was used for this study. Two columns received microbubbles containing hydrogen and carbon dioxide, two received sodium propionate, and two were not fed a substrate. A 30 micromolar PCE solution was delivered to the consortia at 3 ml/min. Microbubbles containing a mixture of 90% hydrogen and 10% carbon dioxide were effectively produced in a closed spinning disk generator, and were acceptable for delivering the gases to the columns. After the biodegradation study was completed, the microbubbles were found to have a pH of 4.4, due to the carbon dioxide. Microbubbles amended with NaOH to 0.01 molar yielded pH neutral microbubbles with improved stability. Methane was measured in all six columns throughout the experiment, verifying that methanogens were present. Methane levels were highest in the propionate columns, showing the the methanogens there were more active. Methane levels in the microbubble columns were similar to those in the control columns. Propionate and acetate were not detected in the columns where propionate was fed, showing that proton reducers and acetoclastic methanogens were both active. Recovery of PCE and the degradation products was almost 90% in the microbubble and control columns where most of the PCE was recovered in the effluent. The predominant product in both systems was TCE, although some ethene was detected in all four columns. The control consortia produced TCE averaging about five micromolar while the microbubble columns averaged about two micromolar TCE. One of the components of the microbubbles probably caused the lowered amounts of PCE reduction. That some ethene was seen in the microbubble columns suggests different conditions can be found to stimulate the further reduction of PCE with hydrogen and carbon dioxide microbubbles. The product recovery in the propionate columns was about 64%. Over half of the injected PCE was dechlorinated to ethene and ethane.
Microbubble generator
(United States Patent and Trademark Office, 1994-05-24)
Means are provided for supplying a liquid surfactant solution, for supplying a gas under pressure, for mixing the liquid surfactant solution and the pressurized gas to form a liquid coarse dispersion of relatively large gas bubbles, and for receiving the liquid coarse dispersion to generate a liquid fine dispersion of relatively small micron-size gas bubbles. The fine dispersion generator mean generally comprises a cylindrical chamber having an inlet for admitting the liquid coarse dispersion into the chamber, and an outlet for discharging a liquid fine dispersion of relatively small micron-size gas bubbles from the chamber; a cylindrical rotor which is mounted within the chamber and has an outer side surface which is provided with means for imparting axial motion components in opposite directions to various portions of the liquid dispersion adjacent to rotor; and a plurality of baffles located between the rotor outer side surface and the chamber inner side wall surface which are spaced apart around the rotor and where each baffle has an inner longitudinal edge which faces the rotor outer side surface and is separated therefrom by a first gap within which the large gas bubbles are sheared into small micron-size gas bubbles.
A multiattribute evaluation model for environmental compliance of existing metal hydroxide precipitation systems in the electroplating industry
Brown, Neil J. (Virginia Tech, 1991-08-09)
The electroplating industry has not evolved substantially over the years. Typically, the industry relies on experience as well as the common sense of its personnel to produce parts and to deal with any waste products that the plating process produces. With the heightened environmental awareness of the 1990s, past practices which produced acceptable treatment levels are no longer good enough. There are numerous methods for meeting the environmental laws of the 1990's. Technology can range from the simple to the complex. Several established methods for the electroplating industry are ion exchange, reverse osmosis, electrodialysis, ion flotation, sulfide precipitation and activated carbon. Internal waste reduction programs, discharging to publicly owned treatment works and zero discharge are as well viable options for the industry. With the combination of regulations and compliance scenarios facing today's eltectroplating operations, it is necessary to define a protocol or methodology which will enable them to make economically feasible decisions as to what compliance option best fits with their corporate strategy. By doing so, the decision will allow them to continue to operate into the 21st century. The selection process must be flexible enough so that state of the art technologies are not the only solution. It must allow for multiperson evaluation of systems with multiattributes. This report represents the development and application of a methodology for evaluating different environmental compliance scenarios for the electroplating industry. The methodology was developed using the analytical hierarchy process, AHP. The strength of AHP lies in its ability to incorporate complex, multiattribute systems into a single decision making process which is robust enough to allow for multiperson evaluation.
Optimization of metal dependent antibodies for chromatography
Madurawe, Rapti D. (Virginia Tech, 1990-04-05)
This study focuses on the utilization of metal-dependent monoclonal antibodies for large-scale chromatography and addresses an aspect that has been cited to lower immunosorbent performance, namely "orientation" of antibodies on matrices. The antibodies used in this study, the "EDTAdependent" 7D7BlO and the "Ca²⁺ -dependent" HPC4 are directed against human Protein C (PC). The 7D7BI0 antibody was characterized in terms of its metaldependency and specificity. The region of PC (epitope) recognized by 7D7BlO was identified as the first 15 residues in the NH₂-terminal. Immunosorbents made with 7D7BI0 provided highly pure and functional PC. The "orientation" of the antibodies on matrices was addressed in two ways. In the first approach, performance of immunosorbents coupled through carbohydrate moieties were compared with immunosorbents coupled through peptide regions. Coupling via carbohydrate linkages, which is generally believed to be Fc-directed, did not have any advantage in terms of efficiency and recovery over coupling via peptide.
Pilot-scale study on anaerobic/aerobic treatment of a textile dye wastewater
Boe, Randall William (Virginia Tech, 1993-09-14)
A pilot-scale system was constructed at the Martinsville Publicly Owned Treatment Works (POTW) in Martinsville, Virginia, to evaluate an anaerobic/aerobic treatment scheme for removal of color from textile dye waste waters mixed with municipal sewage. Treatments were evaluated with and without addition of a reducing agent (thiourea dioxide) after anaerobic treatment utilizing 6 and 12 hour anaerobic hydraulic retention times (HRT). Polymer treatment of the aerobic effluents and toxicity of the wastewaters to Ceriodaphnia dubia and Pimephales promelas were studied. In addition, the benefits of polymer treatment of anaerobic effluent, prior to aerobic treatment, were evaluated in a lab-scale system utilizing continuous flow biological reactors (CFBRs). Wastewater samples were collected throughout the treatment schemes and analyzed for: color, total organic carbon (TOC), 5-day biochemical oxygen demand (BODs), chemical oxygen demand (COD), total phosphorus, sulfide, sulfate, total Kjeldahl nitrogen (TKN), ammonia, nitrate, chloride and oxidation-reduction potential (ORP). Nearly 50% color removal was observed during anaerobic treatment with a 12 hour HRT, with a total system color removal, including subsequent aerobic treatment, of about 53%.
Predispersed solvent extraction
Rodarte, Alma Isabel Marín (Virginia Tech, 1988-05-15)
A new solvent extraction method has been developed for the extraction of metal and organic ions from very dilute aqueous solutions. The new method, which has been named Predispersed Solvent Extraction (POSE), is based on the principle that 1 there is no need to comminute both phases. All that is necessary is to comminute the solvent phase prior to contacting it with the feed. This is done by converting the solvent into aphrons, which are micron-sized globules encapsulated in a soapy film. Since the aphrons are so small, it takes a long time for the solvent to rise to the surface under the influence of gravity alone. Therefore, the separation is expedited by piggy-back flotation of the aphrons on specially prepared gas bubbles, which are somewhat larger than aphrons and are called colloidal gas aphrons (CGA). Copper, uranium and chromium ions, and alizarin yellow were extracted from very dilute aqueous solutions using PDSE. Tests were performed in a vertical glass column in both batch and continuous modes, and in a continuous horizontal trough. The new solvent extraction procedure worked very efficiently and very quickly under laboratory conditions. Higher than 99% extraction was achieved in many of the tests performed.
Predispersed solvent extraction of copper from dilute aqueous solution
Rodarte, Alma Isabel MarÃn (Virginia Tech, 1991-09-20)
Predispersed Solvent Extraction (POSE) was used to extract copper ions from dilute acidic aqueous solution. POSE is based on the principle that there is no need to comminute both phases. All that is necessary is to comminute the solvent phase prior to contacting it with the feed. This is done by converting the solvent into aphrons. which are micron-sized globules encapsulated in a soapy film. Since the aphrons are so small, it takes a long time for the solvent to rise to the surface under the influence of gravity alone. Therefore, the separation is expedited by piggy-back flotation of the aphrons on especially prepared gas bubbles, which are somewhat larger than aphrons and are called colloidal gas aphrons (CGA). Polyaphrons of various types were studied extensively. The apparatus used to generate the polyaphrons was upgraded. The residence time distribution of a liquid in the polyaphron generator was determined. The particle size distribution of polyaphrons was determined using photo-microscopy and sedimentation among other methods. Batch tests were done using both conventional and POSE. Results showed that POSE approaches equilibrium much faster than conventional extraction. Equilibrium isotherms were drawn and empirical equilibrium relationships were developed. The dynamics of the kinetics of the extraction was modeled using film theory. Equipment for the POSE process was built. Experiments were carried out in continuous mode and the process was optimized. An empirical statistical equation was developed for the extraction process in continuous mode. Depending on the aqueous to solvent ration, more than 99% copper can be extracted.
Process and reactor design study of lignin propoxylation
Barbero, Ana Maria (Virginia Tech, 1991-09-16)
Lignin, the second most abundant biopolymer on earth following cellulose, can be described as a million-ton, low cost, under-utilized resource. The use of lignin in polymeric products adds the highest value to the raw material. Production of engineering plastics from lignin is an attractive approach to the utilization of lignin. The use of lignin in structural materials is limited by its insolubility and its failure to undergo melt flow. A promising method to overcome the limitations is to chemically modify lignin by reaction with a low modulus substance, like an aliphatic ether. The reaction of lignin with propylene oxide (PO) produces a copolymer, hydroxypropyl lignin (HPL). Extensive studies have been directed toward the understanding of the chemistry and properties of HPL. A study of the process design is necessary to examine the economics of lignin propoxylation. This work includes the chemical and kinetic analysis of the lignin propoxylation reaction as well as the modelling of a semibatch polymerization process; the design of a lignin propoxylation pilot plant; and a preliminary study of an industrial plant. Two models for the lignin propoxylation reaction are proposed and analyzed to produce a mathematical description of the reaction process. The design of the pilot plant involves (a) the process design, which includes a material balance, a flow sheet, and a listing of the equipment; and (b) the economic analysis in which estimates of capital cost and operating costs are discussed. The scale-up to industrial production gives an estimate of the characteristics of a continuous process. This study constitutes a substantial contribution to the development of a new technology dealing with Engineering Plastics from Lignin.
Removal of soluble mercury from waste water by complexing techniques
Michelsen, Donald L.; Gideon, James A., 1947-; Griffith, Gerald P.; Pace, John E., 1948-; Kutat, Hidayet L., 1947- (Water Resources Research Center, Virginia Polytechnic Institute and State University, 1975)
Soil washing and post-wash biological treatment of petroleum hydrocarbon contaminated soils
Bhandari, Alok (Virginia Tech, 1992-07-05)
A laboratory scale study was conducted to investigate the treatability of petroleum contaminated soils by soil washing and subsequent biological treatment of the different soil fractions. In addition to soils obtained from contaminated sites, studies were also performed on soils contaminated in the laboratory. Soil washing was performed using a bench-scale soil washing system. Washing was carried out with simultaneous fractionation of the bulk soil into sand, silt and clay fractions. Cleaning efficiencies due to soil washing ranged from 60 to 81% for different soils. After washing, the finer soil particles (silts and clays) were found to possess higher concentrations of adsorbed hydrocarbons, thus requiring further treatment. Distribution of n-alkanes was studied to obtain a better understanding of contaminant redistribution and mass transfer during washing.
A system for the segregation of aqueous particulate-laden streams
Brady, Thomas A. (Virginia Tech, 1995-05-07)
A system is under development which can automatically draw a sample from a solids-containing aqueous stream, rapidly filter and analyze the sample using a number of possible technologies, and act on the results of that analysis. The action time for this process can be on the order of one to three seconds, although this is dependent on the time required before the stream sampled must be acted upon. For example, if it takes the sampled stream three seconds from when it is first sampled to reach the diverting valve, the system must respond within that time. Note that this time can be extended with an optional reservoir prior to the diverting valve, as shown in Figure 1.

Browsing by Author "Michelsen, Donald L."

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