bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heavy metal soil remediation: The effects of attrition scrubbing on a wet gravity concentration process
Authors: Marino Michael A. , Brica R. Mark , Neale C. Nelson 
Published: February 2007

AbstractThe US military has historically conducted activities which have either directly or indirectly contributed to environmental contamination. Metal contaminated soil at military sites has resulted from operations such as weapons production, small arms training activities, metal cleaning, and metal plating activities.Soil washing is an effective approach to the treatment of contaminated soils employing both physical and chemical separation techniques. Physical separation methods encompass many different unit operations including screening, grinding, flotation, hydroclassification, attrition scrubbing and gravity concentration such as tabling and spiraling. The primary focus of this paper will be to address the effects of attrition scrubbing (an abrasive soil particle to soil particle interaction in a high solids environment), on a gravity concentration process.Soil from an Army small arms training range with lead contamination in the bulk soil at approximately 40,000 mg/kg, was evaluated using a WEMCO® Laboratory Attrition Scrubber in conjunction with a Wilfley® Laboratory Wet Shaking Table. Results indicate attrition scrubbing enhanced the physical separation process on the wet shaker table by liberating the Pb contamination from the bulk soil, which resulted in a large volume of clean soil while simultaneously producing a small volume of Pb concentrated soil. Laboratory tests indicate over 96% of the contamination could be concentrated on 20% of the original soil mass.
A simplified approach for preliminary design and process performance modeling of soil vapor extraction systems
Authors: Staudinger Jeff , Roberts Paul V. , Hartley James D. 
Published: February 2007

AbstractWhile soil vapor extraction has been widely utilized as a remedial action technology over the past decade, design and associated process performance modeling of full‐scale systems continues to be frequently based on the results of pilot‐scale treatability tests. To aid engineers in conducting preliminary scoping studies without the benefit of such treatability data, a relatively simple approach, consisting of linked design and process performance elements, was developed and subsequently incorporated into a spreadsheet format for rapid project evaluation purposes. Under this approach, a preliminary design is specified via a set of baseline values which vary based on the predominant soil type encountered at a particular site. Process performance is then mathematically modeled by a semi‐empirical relation accounting for non‐equilibrium (mass transfer) effects via use of a lumped parameter, the venting efficiency factor (η). Values for η vary based on characterization of soil heterogeneity. The low values cited for η (on the order of 0.02–0.20) reflect the relative inefficiency of field venting operations (due to inherent mass transfer limitations) when compared to idealized conditions. Validation results, considering two case studies reported in the literature, indicate that the approach developed provides reasonably accurate predictions. Evaluation of a hypothetical case study reveals that the number of extraction vents required as well as the number of pore volumes of soil vapor that must be extracted for effective remediation can vary by an order of magnitude depending upon the particular soil matrix encountered.
Remediation of polychlorinated biphenyl contaminated soils/sediments by supercritical fluid extraction
Authors: Chen P. , Zhou W. , Tavlarides L. L. 
Published: February 2007

AbstractStudies of polychlorinated biphenyl (PCB) desorption from soils have been conducted in a laboratory scale supercritical fluid extraction (SEF) unit to provide information for soil remediation. The results demonstrate the effectiveness of SFE as a promising technology for the clean up of PCB contaminated soils/sediments. After 30 minutes of extraction at 40°Cand 100 atm, more than 86% of PCBs in real world Hudson River sediment and 92% in St. Lawrence River sediment were removed. The extraction of PCBs from spiked samples showed even higher efficiencies. Various effects such as temperature, pressure, cosolvent, sample water content, and soil/sediment type on PCB desorption have been investigated. The sample water content and the presence of cosolvent were shown to be the most important factors affecting desorption of PCBs. The results show that PCBs in real world samples are more tightly bound than in spiked samples. The desorption behavior of individual PCB congeners in various samples has been investigated. The results demonstrate no relative accumulation of the most environmentally threatening PCB congeners throughout the extraction process.
Application of design for environment concepts to the semiconductor industry
Authors: Beu Laurie , Mendicino Laura 
Published: February 2007

AbstractMotorola has traditionally focused on cost, yield, performance, and logistics as primary drivers for decision‐making. In the semiconductor industry, environmental issues have resulted in major modifications of tools and process steps because they are not routinely considered when making process design and manufacturing choices, nor is their impact on cost, yield, and cycle time. Certain business driving forces, such as cost, sustainability of processes/tools, time to market, market access, and market share, are leading Motorola to a cultural change in which environmental impacts must be considered during product and process design; however, design and process engineers have not been able to adequately address these impacts. Motorola's Advanced Process Research and Development Laboratory (APRDL) in the Semiconductor Product Sector (SPS) has recognized this and has established its own environmental group (separate from the site environmental compliance group) to implement a Design for Environmental (DFE) strategy. This group works with several project teams to address environmental issues in process development. To empower engineers to consider the environmental impacts of their materials and processes at the earliest possible stage, the APRDL environmental group has also developed a DFE training course. This web‐based course targets semiconductor design and process engineers and is available through Motorola University, the corporate training institution.In the broadest terms, DFE is a systematic management approach for evaluating and mitigating environmental concerns at the earliest possible stages of process design or product life cycle. It includes ongoing evaluation during the product life cycle, while optimizing the balance between environmental priorities and factors such as cost, yield, cycle time, performance, etc. This optimization requires that Motorola make value judgments based on the best information available. The course is designed to provide semiconductor engineers with the neccesary background to understand the concepts of DFE and the tools to incorporate consideration for environmental impacts into their daily routine with‐qut adding a significant burden to their workload.
Evaluating acids and chelating agents for removing heavy metals from contaminated soils
Authors: Neale C. Nelson , Bricka R. Y , Chao Allen C. 
Published: February 2007

AbstractThe prevalence of heavy metal soil contamination at Army facilities poses a serious threat to human health and the environment. To address this problem, the US Army Engineer Waterways Experiment Station in Vicksburg MS is developing a mobile piot‐scale soil washing treatment facility that can be used to remove metals from the contaminated soils. To support this project, laboratory studies were conducted on both acids and chelating agents to evaluate their ability in extracting heavy metals from contaminated soils. Eight soils contaminated with lead, cadmium, and chromium were selected for use in this study. Contaminant concentrations in the various soils ranged from 4,000–30,000 mg/kg lead, 40–1,000 mg/kg cadmium, and 500–2,000 mg/kg chromium.The results indicated that, before a full‐scale clean‐up is initiated, a preliminary investigation is needed to determine principal contaminants of concern, their concentrations, and soil type followed by treatability studies to determine optimal reagent and concentrations of reagents for cleanup. Specific results from this study also indicated that Cd was the easiest metal to remove from soils followed by Pb and Cr. The results also suggested that the strong acids and chelating agents were both effective extracting agents, and the latter group of compounds may be more useful in soil washing because they are less harmful to the soil environment. Finally, higher initial concentrations of metal contaminants in the soil resulted in greater metal removal efficiencies using the reagents.
Calcium sulfite hemihydrate: Crystal growth rate and crystal habit
Authors: Tseng Philip C. , Rochelle Gary T. 
Published: February 2007

AbstractThe crystal growth rate of CaSO3 · 1/2H2O was measured by a pH‐stat method in aqueous solution with pH 3.5 to 6.5, 1 to 25 mM dissolved sulfite, 0.01 to 0.3 M Ca++, and 0 to 25 mM sulfate. The growth rate was a strong function of relative supersaturation and was strongly inhibited by dissolved sulfate. The growth rate per unit BET surface area, R' (mole/cm2‐min), is given by: 9.7 × 10−4 exp (−10250/RT) × (RSCaSO3−1)2 × RSCaSO4−1, where RSCaSO3 and RSCaSO4 are the relative saturations with respect to calcium sulfite and gypsum, respectively. Scanning electron microscopy and IR spectroscopy demonstrated that solids generated in the presence of dissolved sulfate contained solid solution sulfate and crystallized as agglomerates of very thin platelets. In the absence of solid or dissolved sulfate the solids were agglomerates of well‐informed columnar, hexagonal crystals.
Modeling the transport of 2,3,7,8‐TCDD and other low volatility chemicals in soils
Authors: Freeman Raymond A. , Schroy Jerry M. 
Published: February 2007

AbstractA model has been developed to describe the transport of low volatility organic chemicals in a column of soil. The mathematical model calculates the rate of movement through the soil by solving the dynamic material and energy balances around the soil column. The model is used to make predictions on the transport of 2,3,7,8‐tetrachlorodibenzop‐dioxin (TCDD) at the Eglin Air Force Base Agent Orange biodegradation test plots. The model predicts a vertical movement of TCDD, buried in 1972, through the soil column. Soil column profile data confirm the vertical movement of TCDD.
Dissolution rate of calcium sulfite hemihydrate in flue gas desulfurization processes
Authors: Teseng Philip C. , Rochelle Gary T. 
Published: February 2007

AbstractThe rate of calcium sulfite dissolution in slurry scrubbers and hold tanks for flue gas desulfurization affects SO2 absorption, limestone utilization and sulfite oxidation. The dissolution rates of calcium sulfite were measured by the pH‐state method. A mass transfer model was developed assuming that calcium sulfite particles behave as spheres in an infinite stagnant solution. The model combined with the Bechtel‐modified Radian solution equilibrium program successfully predicts calcium sulfite dissolution rates at pH 3.5 – 5.5, 23 and 55°C, 0.001 – 0.3 M Ca++ and 2 – 25 mM dissolved sulfite. The effects of sulfate content in solids and liquids and particle size/shape were also studied.At conditions typical of flue gas desulfurization processes calcium sulfite dissolution was controlled by mass transfer, not surface reaction kinetics. Dissolution was fast at low pH and slowed near the equilibrium pH determined by dissolved Ca++ and SO3= concentrations in the aqueous solutions, Ksp of the CaSO3 · 1/2H2O solids, and temperature. The presence of dissolved Mg++ increased the equilibrium pH and enhanced the disolution rate. The presence of dissolved sulfate reduced the dissolution rate and the equilibrium pH. The effect of sulfate was not adequately described by the mass transfer model.
Health risk comparison between groundwater transport models and field data
Authors: Hwang Seong T. 
Published: February 2007

AbstractThe potential of ground water contamination is one of the major concerns over land disposal of hazardous waste. Risk assessment requires information on groundwater concentrations of contaminants at the exposure location. Results are presented of case studies comparing health risk assessment and plume delineation based on state‐of‐the‐modeling and monitoring data.
Economics of membrane treatment of wastewaters containing firefighting foam
Authors: Chan Deh Bin , Chian Edward S. K. 
Published: February 2007

AbstractAqueous Film Forming Foam (AFFF) is the most effective fuel/oil fire fighting agent. Wastewater generated from firefighting training facilities contains mixtures of AFFF, residual free fuel oil, emulsified fuel oil, gasoline, purple K (PKP), and miscellaneous combustion products. Membrane treatment of these wastewaters by a two stage ultrafiltration (UF) and reverse osmosis (RO) process appearas economically attractive. Cost effectiveness of the membrane process is compared with a rotating biological contactor (RBC) and a carbon adsorption system.
The effect of weak chelating agents on the removal of heavy metals by precipitation processes
Authors: Ku Young , Peters Robert W. 
Published: February 2007

AbstractParticle size distributions and heavy metal removals are presented for hydroxide precipitations and heavy metal removals are presented for hydroxide precipitation and sulfide precipitation of zinc and cadmium in the presence of several weak complexing agents, namely citrate, tartrate, and ammonia. The pH was held constant at pH 10.0 in these experiments. The presence of these weak complexing agents had little effect on the chemical equilibrium for both the hydroxide and sulfide systems due to their weak complexing ability with metal ions. The presence of the complexing agents does affect the particle size distribution, generally forming smaller particles. Particle size distributions are presented for the Zn(OH)2, ZnS, Cd(OH)2, and CdS systems (at pH 10.0) in the presence of the chelating agents citrate, tartrate, and ammonia. Sulfide precipitation exhibits a better particle size distribution and settling characteristics than the corresponding metal hydroxide precipitation for both zinc and cadmium.
Application of aluminas in water treatment
Authors: Fleming Hubert L. 
Published: February 2007

AbstractRemoval of contaminants from process and waste water by adsorption with transition aluminas is receiving increased attention. As separation requirements become more stringent, the advent of controlled surface chemistry and pore morphology in adsorbent processing has resulted in innovative application of these materials to water treatment. This paper reviews current technology and examines emerging processes utilizing these versatile materials.
Utilization of residuals from flue gas desulfurization
Authors: Kappe J. , Ellison William 
Published: February 2007

AbstractDiverse large‐scale sources of FGD gypsum, the plentiful waste by‐product from SO2 emissions cleanup in major industrial countries, are characterized in terms of properties including crystal form and contained impurities that affect commercial usability. New technology to expand FGD gypsum usage by economical conversion to alpha hemihydrate of calcium sulfate is detailed.
Evaluation of air emission release rate model predictions of hazardous organics from land treatment facilities
Authors: Ryan Dupont R. 
Published: February 2007

AbstractThe Thibodeaux‐Hwang Air Emission Release Rate (AERR) model for volatile emissions from land treatment systems was evaluated on a constituent specific basis utilizing API Separator Sludge and a Slop Oil Emulsion Solids waste stream applied to laboratory sand and soil microcosms. Literature correlation equations were used for estimating air:oil partition coefficients necessary for model input. Measured data suggested that vapor partitioning and retardation by soil organic matter are of minor importance in the overall vapor soil transport process, and that volatile organic vapor soil diffusion can be adequately described simply by the physical environment through which the vapor is traveling.Subsurface waste application produced a two‐ to ten‐fold decrease in emission rates as predicted from the Thibodeaux‐Hwang AERR model compared with surface application conditions. Measured data followed the predicted linear relationship of flux rate versus 1/t1/2 indicating the diffusional nature of soil vapor movement. The Thibodeaux‐Hwang AERR model and the parameter estimation approach consistently overestimated flux rates for the pure constituents by only a factor of approximately 2 to 10, and consequently appear quite effective for the estimation of volatile organic emissions from complex waste/soil systems.
Fly ash recycle in dry scrubbing
Authors: Jozewicz Wojciech , Rochelle Gary T. 
Published: February 2007

AbstractPrevious workers have shown that the recycle of product solids improves the utilization of slaked lime [Ca(OH)2] for SO2 removal by spray dryers with bag filters. In laboratory‐scale experiments with a packed bed reactor, utilization was increased several‐fold when the Ca(OH)2 was first slurried with one of several different fly ashes. The enhancement increased with the higher loading of fly ash [g fly ash/g Ca(OH)2]. Much higher Ca(OH)2 utilization was achieved when silicic acid was used instead of fly ash. Scanning electron microscopy supports the explanation that Ca(OH)2 and silica dissolve and reprecipitate as a more reactive calcium silicate. Other major constituents of fly ash have less or no effect at all on Ca(OH)2 utilization. The amount of calcium in the fly ash did not affect the overall SO2 removal after Ca(OH)2 was added. Slurrying for longer than 2 hours at higher than 60°C can improve the utilization of Ca(OH)2 slurried with fly ash.
The electric utility sulfuric acid plant
Authors: Aragon F. G. , Taylor H. S. , Petrie J. C. 
Published: February 2007

AbstractSan Juan Generating Station is a coal‐fired power plant utilizing the Wellman‐Lord SO2 recovery process for meeting SO2 compliance regulations. A sulfuric acid plant was designed and built for reliably producing a saleable product from the recovered SO2. Criteria are presented to describe some of the features incorporated into the plant design to meet this unique application.
Process simulation of the fluidized‐bed copper oxide process sulfation reaction
Authors: Yeh James T. , Drummond Charles J. , Joubert James I. 
Published: February 2007

AbstractThe Fluidized‐Bed Copper Oxide Process is a regenerative process for the simultaneous removal of both sulfur dioxide (SO2) and nitrogen oxides (NOX) from the flue gas of coal‐fired boilers. An ideal‐flow reactor model for SO2 removal was formulated based on a sulfation reaction kinetics model developed using data from a microbalance reactor. Experimental data obtained from a fluidized‐bed reactor having a cross section measuring 1.02 m by 1.22 m (40 in. by 48 in.) were used to validate the model. The variables in the model were systematically varied to predict reactor performance under different operating conditions. The process variables studies were (1) sorbent copper content, (2) reactor bed depth, and (3) reaction temperature. The reactor performance predictions showed that increasing the copper content of the sorbent from 5 percent to 7 percent would lower the required sorbent recirculation rate by 30 percent. The expanded‐bed depth in the reactor was also an important parameter. Effective performance of the process can be obtained with lower sorbent recirculation rates if the expanded‐bed depth in the reactor is increased.
Stabilization of cadmium and lead in portland cement paste using a synthetic seawater leachant
Authors: Campbell Kristine Melchinger , El‐Korchi Tahar , Gress David , Bishop Paul 
Published: February 2007

AbstractThe seawater leachability of cadmium and lead sludges solidified in portland cement paste was investigated. The leachates of the wastes containing cadmium and lead were analyzed for metal contents using flame atomic absorption spectrophotometry (AAS) as well as pH and alkalinity. A control sample containing only portland cement paste was also leached to serve as a comparison. Results show that the total cadmium leached from the stabilized waste over a 50‐day period was about 1.0% of the total cadmium added to the paste. Lead was not detected in the leachate, however, this could be due to physical and analytical interferences associated with lead. The pH and alkalinity data show that initially, hydroxide is leached from the waste and calcium carbonates are formed on the particle surfaces. After a 50‐day period, the pH and alkalinity of the waste leachates approach that of the seawater leachant.The microstructure of the waste samples was investigated using scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDXA) and powder X‐ray diffraction (XRD). The presence of lead did not appear to have an effect on the hydrated structure of the portland cement paste, whereas cadmium seemed to create a more porous microstructure with abundant colloidal ettringite (a calcium sulfoaluminate compound often found in hydrated portland cement paste). Results show that the fixation of cadmium in portland cement paste accelerates sulfate attack on the paste by seawater, which in turn leads to destructive cracking of the paste. It appears that cadmium release is related to the physical destruction of the portland cement paste.
Development of a data base for modelling adsorption of inorganics on iron and aluminum oxides
Authors: Dzombak David A. , Morel François M. M. 
Published: February 2007

AbstractAlthough there is an abundance of data for equilibrium adsorption of inorganic ions on hydrous oxides and surface complexation models are capable of fitting the data with only a few adjustable parameters, these models have not been used in practice because of the lack of consensus as to the “best” model and the lack of a coherent compendium of equilibrium adsorption constants. To remedy this situation, a thermodynamic data base for inorganic adsorption is being developed from original data using a simple yet widely applicable model. The resulting data base can be included in general chemical equilibrium computer programs and used to predict adsorption (outside as well as within the range of calibrating data) in aqueous systems containing oxide surfaces. Both the model and the parameter extraction procedure are presented, and results for adsorption of some cations on hydrous ferric oxide are reported and discussed.
Controlling acid deposition by seasonal gas substitution in coal‐ and oil‐fired power plants
Authors: Galeucia Gary , Golomb Dan , Fay James A. 
Published: February 2007

AbstractBased on evidence that the rate of wet sulfate deposition in eastern North America is higher in the summer half of the year than in the winter half, seasonal control of emissions is proposed as a means of minimizing acid deposition control costs. This paper evaluates the proposal that natural gas be substituted for coal and oil in electric power plants during April through September. A model is presented that simulates the substitution of natural gas for coal and oil in power plants in the eastern 31 state region, so as to minimize total costs with respect to deposition reductions at an Adirondack receptor. The results of the model show: 1) the increased effectiveness of seasonal versus year‐round controls; 2) changes in fuel consumption levels as a result of substitution; and 3) the costs of achieving various levels of deposition reduction at an Adirondack receptor. The costs of seasonal gas substitution are compared to cost estimates for other proposed control methods. The conclusion is that seasonal gas substitution is cost‐competitive with other control methods, at least in some plants and states.