bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detoxification of chlorinated organic compounds using hydrodechlorination on sulfided NiO‐MoO3/γ‐Al2O3 catalyst. Kinetic analysis and effect of temperature
Authors: Murena Fabio , Famiglietti Vittorio , Gioia Francesco 
Published: February 2007

AbstractThe kinetics of the catalytic hydrodechlorination (HDCl) process in the liquid phase of 1,2,3‐trichlorobenzene was studied. A commercial Ni‐Mo type catalyst, previously sulfided, was used. Experiments were run in the temperature range 280–350°C in a stirred tank reactor under a hydrogen pressure of approximately 100 bar. The reaction network was identified and the kinetic constants have been evaluated using Arrhenius' law and a hypothesis of first order kinetics. The data obtained have been compared with those from an earlier experiment carried out using the same catalyst in unsulfided form. We observed that the sulfidation treatment notably increased the activity of the catalyst. The results have also been reported in terms of the degree of detoxification. The possibility of reaching detoxification efficiency levels, even in mild operating conditions, comparable with those required by legislation for incineration of chlorinated organic compounds, have been demonstrated.
Effects of particle size distribution on limestone dissolution in wet FGD process applications
Authors: Ukawa Naohiko , Takashina Toru , Shinoda Naoharu , Shimizu Taku 
Published: February 2007

AbstractThe kinetics of limestone dissolution in the wet type flue gas desulfurization (FGD) processes has been studied. The rates of dissolution and particle size reduction were measured in both batch and continuous reaction systems for limestone of different size distribution. A predictive model was developed based on mass transfer mechanism. It was in good agreement with experimental data. Moreover, the rate of dissolution for 25 limestones of different composition and size distribution were measured in apparatus with a sulfur dioxide absorber which simulated FGD processes. The model was also in good agreement with these results.
The use of a secondary catalyst bed to increase incinerator destruction efficiency
Authors: Erb Jeff 
Published: February 2007

AbstractMany incinerators in Texas and the USA are required to achieve 95–99% destruction efficiency. Over time incinerator efficiency may drop due to leaks developing in older equipment, resulting in bypass of catalyst beds or heat exchangers. The use of an additional catalyst bed on the incinerator exhaust stack is an economical way to boost the efficiency back to acceptable levels. The secondary catalyst bed is also efficient in converting CO to CO2 and oxidizing other products of incomplete combustion (PICs).Following is a case history of a 12 year old incinerator at IBM‐Austin which was retrofitted with a secondary catalyst bed and successfully achieved 99% destruction in VOCs and reduction in PICs by an order of magnitude.
Use of sedimentation ponds for removal of metals from ash transport waters
Authors: Lagnese Kathleen M. , Dzombak David A. 
Published: February 2007

AbstractThis study investigated the feasibility of using existing ash sedimentation ponds at coal‐fired power plants as treatment reactors to reduce concentrations of metals in bottom ash and fly ash transport waters by precipitation and/or adsorption onto iron oxyhydroxide. Intrapond treatment offers economic advantages over construction of a plant for treatment of ash pond effluent. Bench‐scale experiments were conducted with bottom ash and fly ash suspensions to investigate pH control and removals of aluminum, manganese, and arsenic under different chemical conditions, including addition of ferric chloride to promote adsoption on iron oxyhydroxide. The effects of pH and iron addition on ash‐water partitioning of the metals of interest were studied via batch experiments. In addition, the ability to control pH and promote removal of manganese in an intrapond treatment process was investigated using semi‐continuous, bench‐scale, pond‐simulation reactors. Results of the reactor experiments indicated that the pH could be maintained in range of 8 to 8.5 by dosing the influent with the proper amount of base as determined by batch titration, and that by doing so the influent manganese concentration of 2ppm could be consistently lowered to less than 0.2 ppm. The effects of accumulation of settled ash were examined in the reactor studies and with the use of a coupled hydraulic/sedimentation model for ash ponds. Overall, results of this study suggest that concentrations of most metals of interest in ash pond water can be kept low with control of pH, in situ precipitation of iron oxyhydroxide, and effective sedimentation of particles. Further examination of the intrapond treatment approach is warranted.
Developing strategies for compliance with OCPSF regulations
Authors: Stephenson Ralph L. , Kikta Annette J. , Clark Gary L. , Gomaa Hassan M. 
Published: February 2007

AbstractThis paper presents a brief summary of the Organic Chemical, Plastics, and Synthetic Fibers (OCPSF) regulations and a 10 point plan for compliance with the regulations. Several practical examples are discussed concerning the application of this plan to actual facilities with emphasis placed on waste minimization methods.
Wet oxidation system—process concept to design
Authors: Sawicki John E. , Casas Baldomero 
Published: February 2007

AbstractA wet oxidation process was developed to treat waste water from an organic nitration process. The waste water contained EPA listed priority pollutants including dinitrotoluene, 2‐nitrophenol, 4‐nitrophenol, 2,4‐dinitrophenol, 4,6‐dinitro‐ortho‐cresol and phenol. The process design was based on experimental data generated in both batch and continuous laboratory and pilot scale reactors and in cooperation with university researchers, a private development company and an engineering company. Process variables included temperatures between 250 and 500 C, pressures in the 23,000–28,000 kPa (3,450–4,000 psi) range and residence times between 1 and 7 minutes.The final design was a tubular reactor operating at temperatures slightly below the critical temperature for water and short residence times. Destruction efficiencies for most of the priority pollutants were greater than 99% and final concentrations were below those specified by EPA regulations.
Effects of salts on limestone dissolution rate in wet limestone flue gas desulfurization
Authors: Ukawa Naohiko , Takashina Toru , Oshima Michio , Oishi Tsuyoshi 
Published: February 2007

AbstractTo understand how the dissolution rate of limestone used for absorbent in a wet flue gas desulfurization plant is affected by the soluble salts formed from hydrogen chloride gas in flue gas as well as from the impurities contained in the used raw material limestone itself, various limestone slurries each added with a single salt of CaCl2, MgCl2, NaCl, Na2SO4 and MgSO4 were titrated with sulfuric acid. From the titration results the dissolution rate was found to vary greatly with the kind and the concentration of the salts with a general tendency to decrease in chloride solution but to increase in sulfate solutions.Based on this finding, the authors proposed a semi‐empirical simplified model. The evaluated results using this model closely agreed with the measured values of the limestone dissolution rate both in single‐salt solutions and mixed salt solutions.
The effect of equilibration time on desorption rate measurements with chlorinated alkenes and aquifer particles
Authors: Harmon Thomas C. , Roberts Paul V. 
Published: February 2007

AbstractSorption and desorption phenomena affect the uptake and release of contaminants from aquifer solids, and can play an important role in determining the duration of an aquifer remediation effort. Independent estimates of desorption rates are useful in evaluating various cleanup strategies (e.g., pump‐and‐treat, in situ biorestoration). In this study, two type of aquifer solids, a weakly sorbing sand (Borden) and a relatively strongly sorbing solids fraction (Moffett), were equilibrated for periods of one day and greater than 190 days with tetrachloroethane (PCE) and trichloroethene (TCE), respectively. The samples were subjected to an intermittent purging technique, and the resulting contaminant release curves were analyzed using a radial pore diffusion model which incorporated the effects of equilibrium partitioning. Failure to account for the insufficient equilibrium conditions led to a moderate underestimation of the effective pore diffusion coefficient value (Dp) for the Borden under‐equilibrated sample (one day), and a substantial overestimation of the Dp value for the Moffett under‐equilibrated system. A second set of simulations, was used to find the Dp value that best fit the observed release data while accounting for the nonequilibrium initial conditions. Given these adjustments, the Borden/PCE under‐equilibrated system provided approximately the same desorption rate value (effective pore diffusion coefficient, Dp) as its long‐term sample. For the Moffett/TCE under‐equilibrated sample, accounting for the insufficient equilibration time led to a significantly greater Dp value than was obtained for the long‐term sample. The results for the two solute/sorbent systems are discussed with respect to the pore diffusion mechanism, and the prospect of short‐term parameter estimation methods.
Sorption and desorption of contaminants from different host matrices
Authors: El‐Shoubary Youssef , Woodmansee Donald E. , Shilling Norman Z. 
Published: February 2007

AbstractThermogravimetric studies were run in air and nitrogen atmospheres, on sand/oil and sand/PCB mixtures, to determine the effect of surface area on the contaminant sorption and desorption. The contaminant sorption is dependent on the surface area. As the surface area increases, the contaminant concentration increases.In the case of desorption, the onset temperature decreases as the surface area increases. However, this phenomenon was reversed when the surface area included pore structure. An Arrhenius‐type kinetic model was used to describe the surface area effects of contaminants with no pore structures on desorption. The model shows that the desorption does not depend on the type of gas (air or nitrogen), but does depend on surface area and contaminant concentration. In addition, the model showed two reaction regions for the desorption of contaminants from materials with pore structure. It was believed that the first region was volatilization of free contaminant at the host matrix surface. The second region is believed to be diffusion controlled, i.e., it is controlled by how fast the contaminant diffuses through the pores to reach the surface and is consequently stripped or volatilized.
Effect of clay minerals present in aquifer soils on the adsorption and desorption of hydrophobic organic compounds
Authors: Ghosh Deepak R. , Keinath Thomas M. 
Published: February 2007

AbstractAdsorption of hydrophobic organic compounds (HOCs) onto clay minerals and organic matter present in soils results in retarding their mobility. To study the impact of clay minerals on HOC sorption, kinetic and equilibrium studies were performed using naphthalene as a test surrogate contaminant. The results of these studies indicated that expandable clay minerals (clays that expand and expose large internal surface area on wetting), such as montmorillonite and vermiculite, had a significant impact on naphthalene partitioning. A mathematical model was developed from the equilibrium data which related clay mineral concentrations with the naphthalene partition coefficient. Equilibrium desorption studies were also performed by adding a micellar solution of a surfactant mixture (50:50) of Tween 20 and Aerosol AY‐65 to mobilize the adsorbed naphthalene. The surfactant mixture was generally unable to mobilize the sorbed contaminant due to sorption irreversibility and adsorption hysteresis.
Content and fractionation of heavy metals in soils of two contaminated sites in Taiwan
Authors: Shu G. Y. , Liu J. C. 
Published: February 2007

AbstractThe rice paddies near Taoyuan County, Taiwan, were contaminated with trace metals by the effluent from two plasticizer plants in the seventies. A study was conducted to: (i) determine the total metal contents, (ii) compare the extraction strength of different solutions, and (iii) investigate the metal speciation. Total soil metals at site 1 ranged from: lead = 201 to 1955 mg Kg−1; cadmium = 18 to 205 mg Kg−1; and zinc = 131 to 282 mg Kg−1. Total soil metals at site 2 ranged from: lead = 80 to 148 mg Kg−1; cadmium = 8 to 82 mg Kg−1; and zinc = 55 to 65 mg Kg−1. Five different extractants (4 N HNO3, aqua regia, 0.1 N HCl, 0.002 M EDTA, and 0.002 M NTA) were utilized and compared. Sequential extraction was conducted to assess the metal speciation in soil systems. Lead was found to be predominantly organic‐bound or oxide‐bound. The exchangeable fraction was the dominant form of cadmium in both sites. Zinc was mostly oxide‐bound. The potential impacts on groundwater quality by cadmium were assessed.
Biological vapor‐phase treatment using biofilter and biotrickling filter reactors: Practical operating regimes
Authors: Togna A. Paul , Singh Manjari 
Published: February 2007

AbstractThe biological treatment of volatile organic compounds (VOCs) and air toxics has received increased attention in recent years. Biotreatment of air‐borne contaminants offers an inexpensive alternative to conventional air treatment technologies such as carbon adsorption and incineration. Most biological air treatment technologies commercially available are fixed‐film systems that rely on growth of a biofilm layer on an inert organic support such as compost or peat (biofilters), or an inorganic support such as ceramic or plastic (biotrickling filters). If designed properly, these systems combine the advantages of high biomass concentration with high specific surface area for mass transfer.At economically viable vapor residence times (1 to 1.5 minutes), biofilters can be used for treating vapor streams containing up to approximately 1500 μg/L of readily biodegradable compounds. Biotrickling filters may offer greater performance than biofilters at high contaminant loadings, possibly due to higher internal biomass concentrations. Both systems are best suited for treating vapor streams containing one or two major compounds. If designed properly, biofilters are especially well suited for treating streams that vary in concentration from minute to minute.
Modelling the fate of chlorinated phenols in wastewater treatment plants
Authors: Parker W. J. , Bell J. P. , Melcer H. 
Published: February 2007

AbstractThe behavior of 2‐chlorophenol, 2,4,6‐trichlorophenol and pentachlorophenol in activated sludge wastewater treatment plants was investigated at pilot scale. Batch sorption studies along with steady state and dynamic continuous flow experiments were performed to determine partitioning between the liquid and solid phases and biodegradation rate coefficients. A mechanistic mass balance based model was employed as a framework with which sorption and biodegradation coefficients were estimated by model fitting of experimental data for each compound.Pentachlorophenol was adsorbed to the greatest extent and biodegraded the least with values for the sorption and biodegradation coefficients ranging from 0.6‐9.6 L/g and 0.021‐0.058 L/g · hr respectively. There was evidence of a dependence of biodegradation rate upon sludge age for pentachlorophenol. The sorption and biodegradation coefficients for 2,4,6‐trichlorophenol were estimated in the range 0.11‐0.71 L/g and 0.041‐0.042 L/g · hr respectively. 2‐Chlorophenol was sorbed the least and biodegraded to the greatest extent with sorption and biodegradation coefficients of 0.06 L/g and 0.23 L/g · hr respectively.
Measurement of gas‐liquid mass transfer coefficients for volatile organic compounds in sewers
Authors: Whitmore Arlene , Corsi Richard L. 
Published: February 2007

AbstractField experiments were completed to determine gas‐liquid mass transfer coefficients for VOCs in sewers characterized by uniform flow conditions. Both deuterated chloroform and 1,1,1‐trichloroethane were used as surrogate volatile tracers during four experiments in two operating sanitary sewers. Experimental mass transfer coefficients were in good agreement with those predicted using a diffusivity‐adjusted oxygen transfer model. The experimental methodology provides a protocol for future studies of VOC mass transfer in municipal and on‐site industrial sewers.
Biofilter treatment of ethanol vapors
Authors: Hodge Douglas S. , Devinny Joseph S. 
Published: February 2007

AbstractBench scale experiments and a numerical model were used to test the effectiveness of biofiltration in treating air contaminated with ethanol vapors. Three packing materials, granular activated carbon, compost, and a mixture of compost and diatomaceous earth were tested. The GAC material supported the highest elimination rates, ranging from 53 to 219 grams/m3‐hr for a range of loading rates. Partitioning coefficients for the contaminant on the biofilter packing material had a strong effect on the efficiency of the biofilters.
PCB cleanup using an oxygen/fuel‐fired mobile incinerator
Authors: Baukal C. E. , Schafer L. L. , Papadelis E. P. 
Published: February 2007

AbstractA trial burn was recently conducted at a hazardous waste site containing soil contaminated with PCBs. Simulated soils containing 1 percent PCB and oils containing up to 40 percent PCBs were incinerated. The test results showed that >99.9999 percent of the PCBs were destroyed in a newly commissioned mobile incinerator incorporating an oxygen‐fuel burner in the primary combustion chamber. In addition to the high destruction efficiency, particulates, HCl and CO were all well below the regulatory limits.
Final disposal of VOCs from industrial wastewaters
Authors: Ying Wei‐Chi , Bonk Robert R. , Hannam Shennen C. , Li Qi‐Dong 
Published: February 2007

AbstractVapor phase carbon adsorption followed by spent carbon regeneration and catalytic oxidation where evaluated as methods for disposal of volatile organic compounds (VOCs) released from industrial wastewaters during treatment operations such as aeration, air‐stripping and aerobic biodegradation.Adsorptive capacities and breakthrough characteristics for eight VOCs found in many hazardous landfill leachates and contaminated groundwater were compared for selection of the best adsorbent and optimum treatment conditions. Coconut shell‐based activated carbons exhibited higher VOC loading capacities than coal‐based carbons, fiber carbon, molecular sieve and zeolite. Steam and hot nitrogen were both effective for regeneration of the spent carbon. A small quantity of adsorbates left in the regenerated carbon did not result in immediate VOC breakthrough in the next cycle adsorption treatment. Catalytic oxidation was found to be an attractive alternative for VOC disposal. Using a new commercial catalyst developed for destruction of halogenated organic compounds, even stable VOCs such as trichloroethylene and tetrachloroethylene were completely destroyed at <350°C when oxidation was conducted at a space velocity of 17000/hr.
Operating characteristics and commercial operating experience with high temperature SCR NOx catalyst
Authors: Heck R. M. , Chen J. M. , Speronello B. K. 
Published: February 2007

AbstractSelective catalytic reduction of NOx has been recognized as a very effective method to achieve low NOx emissions. A family of versatile catalyst technologies has been developed by Engelhard to control NOx emissions over a wide range of operating temperatures, 177 to 593°C (350 to 1100°F). Reaction mechanisms are different for the catalysts used over this broad temperature range. The catalyst designed for high temperature operation is zeolite based and operates in the 454 to 593°C range (850 to 1100°F). Performance characteristics of this high temperature SCR NOx catalyst are presented. The reaction mechanism for the high temperature catalyst is contrasted with the low and medium temperature catalyst. Commercial operating data on this ZNX™ catalyst are presented for installations on a reciprocating engine and a gas turbine.
Using vegetation to enhance in situ bioremediation
Authors: Erickson L. E. , Banks M. K. , Davis L. C. , Schwab A. P. , Muralidharan N. , Reilley K. , Tracy J. C. 
Published: February 2007

AbstractVegetation can enhance in situ bioremediation processes in many applications. Microbial transformations occur in the soil external to the plant roots. Organic contaminants also enter vegetation and are transformed within plants. Research progress is reviewed with emphasis on recent experimental results and mathematical models of contaminant fate in systems where vegetation is present. Evapotranspiration provides a solar driven pump‐and‐treat system which helps bring contaminants to the rhizosphere and helps contain them on the site.
Semi‐continuous evaporation model for leachate treatment process evaluation
Authors: Marks A. Leigh , Luthy Richard G. , Diwekar Urmila M. 
Published: February 2007

AbstractThe use of evaporation for treatment of landfill leachate may be effective at removing contaminants in one principal unit operation. A semi‐continuous evaporation treatment process model, Reaction EQuilibrium Evaporation Model (REQEM), was developed for engineering assessment to: i) simulate different batch flash vaporization processes, ii) predict the effluent stream compositions and quantities, and iii) compute the energy requirements. The model integrates previously separate features into a composite chemical equilibrium and dynamic process simulation model.Simulations have shown that multi‐stage flash with recirculation and condensation heat recovery maximizes the amount of evaporate produced and minimizes the steam and pumping energy requirements. Leachate with low volatile organic acids may need only acidic evaporation to efficiently treat the leachate. Leachate with high concentrations of both ammonia and volatile organic acids may require a two‐step, pH‐adjustment evaporation process. If nonionic volatile organic compounds are present in leachate, then pretreatment such as air stripping may be necessary to obtain adequate evaporate quality. Adjustments of the initial leachate pH value will have no direct effect on the product‐to‐feed ratio, the performance ratio, or the evaporate quality with respect to nonvolatile compounds such as metals. Landfill gas may provide sufficient energy for leachate vaporization in many instances for modern landfills, and semi‐continuous operations may be the most practical treatment mode.
Migration and sorption of jet fuel cycloalkane and aromatic vapors in unsaturated soil
Authors: Li Chiayang , Voudrias Evangelos A. 
Published: February 2007

AbstractMulticomponent vapor transport experiments were conducted in large (10.5 cm × 100 cm) columns packed with dry sand and wet soil to evaluate the effect of vapor phase adsorption on the migration of jet fuel cycloalkane and aromatic components. A diffusion model accounting for sorption at the gas‐soil and water‐soil interface and vapor partitioning into the soil moisture was fitted to experimental concentration versus time profiles in order to determine the overall diffusion coefficients, D, which combine the effects of both diffusion and sorption. With the exception of benzene, an excellent agreement was observed between model calculations and experimental data for all cycloalkane and aromatic vapors studied. A poor model fit resulted for benzene in wet soil, due to possible biodegradation. The soil tortuosity was determined using the experimental data of n‐butane (a conservative gas tracer). Retardation factors, R, were computed for each vapor using the respective D values. R values increased with decreasing solubility of the vapor and were higher for wet soil than for the dry sand.