bluuebunny/crossref_metadata_2025 huggingface dataset:
Effectiveness of supplemental aeration and an enlarged first‐stage in improving RBC performance
Authors: Surampalli Rao Y. , Robert Baumann E.
Published: February 2007

A full‐scale RBC plant having two parallel trains and treating combined municipal and industrial dairy waste was used to investigate the effectiveness of supplemental aeration and an enlarged first‐stage in improving RBC performance. Enlarged first‐stage was created by removing the baffles between the first two stages. One RBC train was used as a control and the other train was used to evaluate the combined effectiveness of supplemental aeration and an enlarged first‐stage. Composite wastewater samples were collected from influent and effluent of each RBC stage in both trains. Samples were analyzed for soluble COD and BOD5, ammonia nitrogen, and suspended solids. Wastewater temperature, pH and dissolved oxygen levels were measured in each stage. The study results indicate that it is possible to achieve higher organic loading rates and removal rates when RBC units are provided with supplemental aeration and enlarged first‐stage.
The fate of BDAT polynuclear aromatic compounds during biotreatment of refinery API oil separator sludge
Authors: Huesemann Michael H. , Moore K. O. , Johnson R. N.
Published: February 2007

A 16 week laboratory study was conducted to assess the biotreatability of regulated (BDAT list) polynuclear aromatic compounds (PNA) in refinery API oil separator sludge. The three different treatments consisted of a biotic, nutrient amended, inoculated aerated slurry reactor, a second biotic oxygen‐sparged reactor, and a sterile, nitrogen‐sparged control. Naphthalene, anthracene, phenanthrene, and benzo (a) pyrene were completely biodegraded in the first 4 weeks in both biotic treatments. Chrysene disappeared within 4 weeks in the aerated bio‐reactor, whereas it required 16 weeks to degrade in the oxygen‐sparged reactor. Pyrene degraded only 30% in the aerated bioreactor and did not exhibit any significant concentration changes in the oxygen‐sparged reactor. Phenanthrene, chrysene, and pyrene concentration levels did not change significantly during the 16 week treatment period in the nitrogen‐sparged control reactor indicating the absence of stripping losses for these PNAs. By contrast, naphthalene, anthracene, and benzo (a) pyrene levels remained constant during the first 2‐4 weeks in the control but decreased to below detection limits (5 mg/kg) at the end of the treatment. It is not clear whether the disappearance of these compounds is due to stripping, irreversible sorption or some anaerobic/aerobic biodegradation processes. In conclusion, the aerobic biotreatment of refinery API oil separator sludge was successful in removing most BDAT PNA compounds. The reduced biodegradability of pyrene may be explained in terms of either the inherently low biodegradation rate of this compound or the limited bioavailability in the weathered oily sludge system.
Bioremediation of soils contaminated with bis‐(2‐ethylhexyl) phthalate (BEHP)in a soil slurry‐sequencing batch reactor
Authors: Irvine R. L. , Earley J. P. , Kehrberger George J. , Tod Delaney B.
Published: February 2007

A bench‐scale study was conducted to assess the feasibility of bioremediating phthalate contaminated soil from a polyvinyl chloride manufacturing operation in New Jersey. A bench‐scale slurry reactor study which utilized l4C‐labeled bis‐(2‐ethylhexyl) phthalate (BEHP) demonstrated that approximately 50 to 60% of the carbon in BEHP was mineralized directly to CO2 by indigenous microbial flora, while the remaining 40 to 50% was converted into cell mass. Additional bench‐scale studies were conducted in Soil Slurry‐Sequencing Batch Reactors (SS‐SBR) to evaluate the impact of basic biotreatability parameters (e.g., nutrient requirements and seed acclimation) on the bioremediation of soil contaminated with high levels of BEHP and total petroleum hydrocarbons (TPH). Treatment efficiencies of greater than 96% for both BEHP and TPH were observed in slurry reactors supplemented with nutrients (e.g., 1.4 to 2.0 g N per kg dry soil and 0.16 to 0.4 g P per kg dry soil). BEHP concentrations were reduced from initial levels as high as 24,000 mg/kg to less than 230 mg/kg and TPH concentrations, from 8,000 mg/kg to 160 mg/kg.
Fundamentals of bioventing applied to fuel contaminated sites
Authors: Dupont R. Ryan
Published: February 2007

Bioventing entails the use of soil vapor extraction (SVE) systems for the transport of oxygen to the subsurface, where indigenous organisms are stimulated to aerobically metabolize fuel components. Bioventing systems are designed and configured to optimize oxygen transfer and oxygen utilization efficiency, and are operated at much lower flow rates and with configurations much different than those of conventional SVE systems. Bioventing system applications and design are contrasted to those of conventional SVE systems, and the two key elements of bioventing system design evaluation, i.e., in situ microbial activity and air permeability determinations, are highlighted in this paper. The application of bioventing to vadose zone bioremediation was reviewed with particular emphasis on its advantages over aqueous based bioremediation systems in terms of its superior oxygen transfer efficiency. Finally, the application of bioventing and bioventing design concepts are illustrated through a case study of JP‐4 jet fuel contaminated soil remediation at Hill AFB, Utah.
Limitations and practical use of a mass transfer model for predicting air stripper performance
Authors: Thom James E. , Byers William D.
Published: February 2007

The Onda Mass Transfer Model is widely used for predicting air stripper performance, yet reports of its reliability vary significantly. Researchers, who generally pay close attention to all aspects of a stripping column's design, construction, and operation, report results closely aligning with model predictions (± 30 percent). In practice, however, where design and construction details vary, much wider variations between field performance and model predictions are reported.

This paper discusses design and construction issues that can contribute to performance problems in practice and lead to field deviations from model predictions. The design and construction issues of greatest importance include: liquid distribution, packing material, and adherence to the limitations and restrictions of the air stripping model used, in this case the Onda Model. Some less common problematic areas are also discussed, including: Henry's Law data, fouling, chemical reactions, and end effects.
Modeling the effects of plants on the bioremediation of contaminated soil and ground water
Authors: Davis L. C. , Erickson L. E. , Lee E. , Shimp J. F. , Tracy J. C.
Published: February 2007

Plants have the potential for aiding in situ remediation of contaminated soil and groundwater by promoting microbial growth in the rhizosphere. Microbial populations vary in response to the presence of oxygen, water and metabolizable carbon sources. Plants are able to provide a favorable environment for microbe growth by providing a plant pathway for oxygen transfer to the soil, transferring water from saturated to unsaturated soil, and supplying supplemental substrate in the form of root exudates and decaying root hairs. Models of the physical, chemical, and biological relationships in the rhizosphere are reported. Simulation results are presented for a hypothetical vegetative buffer zone over a shallow aquifer. The fate of atrazine is simulated in order to investigate the effects of rainfall, evapotranspiration, atrazine uptake by plants, and atrazine adsorption to root surfaces on atrazine concentration at the downstream edge of the vegetative buffer zone.
Bed mixing and heat transfer in a batch loaded rotary kiln
Authors: Leger Christopher B. , Cook Charles A. , Cundy Vic A. , Sterling Arthur M. , Deng Xiao‐Xue , Lighty Joann S.
Published: February 2007

A pilot‐scale rotary kiln simulator has been used to make experimental measurements of the thermal response of solids charged onto a preexisting bed of hot solids material. The measurements clearly show that the bed is not thermally uniform. Time constants for bulk heating and mixing were extracted from the measurements. A simple model is developed that correlates the time constant for mixing to bed turnover rate, allowing the thermal history of a charge of solids to be predicted based on measurable parameters of the kiln and bed. The measured and predicted thermal histories show that mixture greatly augments the initial rate of heat transfer to the fresh charge of solids. This is important because rapid heating of a fresh charge of solids could result in rapid evolution of volatile species.
Simultaneous removal of NO and SO2 in packed scrubbers or spray towers
Authors: Harriott Peter , Smith Kevin , Benson Lewis B.
Published: February 2007

Nitric oxide and sulfur dioxide can be removed from flue gas by scrubbing with a lime slurry containing ferrous EDTA. Tests in a 0.90m diameter column with several commercial packings gave 99 to 99.9 percent SO2 removal and 10 to 60 percent NO removal. The absorption of NO is controlled by the liquid‐film resistance, and the number of transfer units varies with the square root of the ferrous EDTA concentration, the 0.4 to 0.6 power of the liquid rate, and the − 1.0 power of the gas velocity, in agreement with predictions. The height of a transfer unit for NO absorption, corrected for end effects, was 10 to 15m, about 30 times the estimated values for SO2 absorption, which is gas‐film controlled. The spray tower gave lower removal rates for both gases, but the ratio of transfer units was about the same as for the packed columns.
Development of bacterial cultures which can metabolize structural analogs of dioxin
Authors: Rugge Carol D. , Ahlert Robert C. , O'Connor Owen A.
Published: February 2007

Widely present in the environment, the highly‐toxic compound 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) has been found to resist microbial biodegradation. To develop an anaerobic biodegradation approach for soils and sediments contaminated with TCDD, methanogenic and denitrifying cultures were established on a variety of chloroaromatic substrates, including 2‐chlorophenol, 3‐chlorophenol, 4‐chlorophenol, 2,3‐dichlorophenol, 3,4‐dichlorophenol, 4,5‐dichlorocatechol and catechol, using an inoculum from Newtown Creek (New York, NY). Dehalogenation was observed, with monochlorophenols producing phenol and dichlorophenols producing monochlorinated phenols and phenol. Based on gas production, the chlorinated catechol did not appear to undergo biodegradation under any condition, while catechol was degraded under methanogenic conditions. Select cultures amended with a mixture of chloroaromatics and n‐butanol, a solubilizing agent, exhibited depressed gas production under both anaerobic conditions. Biodegradation of TCDD adsorbed onto particles of gallium oxide is under investigation with an amalgamation of the active single‐substrate methanogenic cultures.
Advanced coolside desulfurization process
Authors: Stouffer M. R. , Rosenhoover W. A. , Withum J. A.
Published: February 2007

This paper describes a dry sorbent injection SO2 abatement process with the potential to significantly enhance desulfurization performance over that of existing in‐duct injection technology such as the Coolside process. The Advanced Coolside process was developed by CONSOL Inc. and is being tested in a pilotscale project, partially funded by the U.S. Department of Energy (DOE). The goals of this process development effort are to increase the applicability of sorbent injection technology as a compliance option for coal‐fired boilers for the 1990 Clean Air Act Amendments and to reduce total process SO2 control costs. Specific performance objectives are to achieve 90% SO2 removal and 60% sorbent utilization efficiency, while retaining the low‐capital cost and retrofit advantages inherent to in‐duct sorbent injection technology. The Advanced Coolside process concept involves flue gas humidification to near the adiabatic saturation point combined with fly ash removal using a gas/liquid contacting device, followed by injection of a sorbent (e.g., Ca(OH)2) into the highly humid flue gas with collection by the existing particulate collector. High SO2 removal and sorbent utilization efficiency are possible with hydrated lime when the flue gas is nearly saturated with moisture. Sorbent utilization is further improved by recycle, and the potential for improvement by the use of recycle is increased with removal of the fly ash before sorbent injection. Further, testing indicates that pre‐treatment of the recycle sorbent before reinjection can improve process performance. Because flue gas is humidified completely before sorbent injection, the existing duct configuration may not limit process retrofit potential. The heat of reaction between SO2 and Ca(OH)2 heats the flue gas before the existing particulate collector. Current pilot test data indicate that the Advanced Coolside process performance objectives are achievable. On‐going process development work includes design optimization for the contacting device, improving efficiency of sorbent recycle, and optimization of sorbent performance.
Evaluation of the CombiNOx process at pilot scale
Authors: Newhall Pont J. , Evans A. B. , England G. C. , Lyon R. K. , Seeker W. R.
Published: February 2007

Under contract with the Deparment of Energy, EER is developing a NOx control process with potential to reduce NOx emissions from coal fired utility boilers by up to 85%. CombiNOx is a family of NOx reduction processes which involves the synergistic application of combinations of technologies such as staged combustion, reburning, selective non‐catalytic reduction (SNCR), and methanol injection. Any combination of these technologies can be applied to achieve a desired NOx reduction in a given boiler. Integration of these processes may be site‐specific depending on boiler configuration and required emission limits.
Economic effects of catalyst deactivation during VOC oxidation
Authors: Agarwal Sanjay K. , Spivey James J.
Published: February 2007

Catalytic oxidation of volatile organic compounds (VOCs) is widely used for air pollution control. While catalytic oxidation offers several advantages over alternative processes, the catalyst can deactivate over time, resulting in changes in activity and selectivity with time‐on‐stream. To maintain constant catalyst activity, required for environmental regulations, the temperature is generally increased gradually to compensate for catalyst deactivation. This results in an increase in fuel consumption with time. Since the fuel costs can account for 50 to 70 percent of the total operating costs, the effect of catalyst deactivation on fuel costs and hence total operating costs should be considered. This paper shows how the catalyst deactivation affects the total operating costs using an example of the oxidation of a VOC‐containing gas stream over a commercial hopcalite catalyst.
Pilot scale study and design of a granular activated carbon regeneration process using supercritical fluids
Authors: Tomasko David L. , James Hay K. , Leman Gregory W. , Eckert Charles A.
Published: February 2007

A technology which has great potential for environmental control and waste remediation is contaminant removal and separation with supercritical fluids (SCF's) or supercritical fluid extraction (SFE). Pressure tuning of solvent power allows SCF processes to adapt to a wide variety of small batch oriented separations typified by environmental cleanup operations.

The ability of supercritical CO2 to extract model contaminant compounds from GAC and subsequently drop out most of the contaminant in a liquid phase has been investigated in a pilot scale apparatus. Typical desorption profiles indicate an 85% removal of the compound from the carbon which allows for reuse. The desorption results have been interpreted with a generalized desorption‐mass transfer model.

The results of the pilot plant studies have been applied to the design of a fixedsite GAC regeneration unit consisting of a three‐element desorber with two‐stage flash separation. Optimization of the process centers around minimizing the cost of recycling the SCF through an efficient recompression scheme and cycle configuration in the desorber unit. An economic evaluation shows a processing cost of 10.6¢/lb (23¢/kg) GAC which compares favorably with thermal regeneration and incineration. This non‐destructive process allows re‐use of the GAC while maintaining a high adsorbate capacity, which reduces carbon replacement costs and significantly decreases the need for carbon disposal by landfill or incineration.
Hazardous waste source‐reduction study with treated groundwater recycling
Authors: Chang Li‐Yang , McCoy Benjamin J.
Published: February 2007

A feasibility study is presented for modifying electroplating processes for source reduction. Ion exchange and reverse osmosis units are suggested to allow reclaiming and recycling of metal solutions. A particular example of water conservation in an electroplating shop is presented for the treatment and utilization of groundwater contaminated by hydrocarbon chemicals, including volatile organic compounds (VOCs) and gasoline products. Granular carbon adsorption, UV oxidation, and demineralization steps and alkalinity control measures for the groundwater are discussed. Engineering and economic analyses provide a basis for comparing alternative designs. An integrated scheme, including groundwater remediation and source reduction, is feasible for the plating shop. The removal of VOCs and demineralization of the polluted groundwater are important steps. With the integrated plan, 90% removal or recovery of heavy metals can be achieved, and water usage and wastewater can be reduced by 90%. Thus, it is feasible to prevent water pollution at the source and to recycle treated groundwater and wastewater for the manufacturing process.
Hydrophobic zeolite adsorbent: A proven advancement in solvent separation technology
Authors: Blocki Stephen W.
Published: February 2007

With the passage of the Clean Air Act Amendment (CAAA) of 1990, solvent emission regulations continue to become ever more stringent. An ongoing and increasingly strong incentive exists to develop and apply to the solvent emission control industry more efficient and cost effective control technologies.

This paper presents a new technology used for solvent separation and concentration, hydrophobic zeolite adsorbent. Because of its unique physical properties, solvent control systems using hydrophobic zeolite may exhibit separation capacity equal to or better than systems using activated carbon without requiring much of the support equipment. Though activated carbon remains the adsorbent of choice for many applications, hydrophobic zeolite represents an efficient alternative for many niche applications. Extensive tests have proven its capabilities and the results are presented here.

Also presented is the modular solvent concentrator (MSC) designed to handle up to 50,000 scfm (79,000 Nm3/h)—up to 50% more air flow as current concentrators—in the same area. The MSC is flexible enough to handle any currently available adsorbent. Several case studies are presented to illustrate use of hydrophobic zeolite as well as the MSC.
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

The 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

The 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

Many 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

This 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

This 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

A 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

To 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

Sorption 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

Thermogravimetric 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

Adsorption 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

The 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

The 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

The 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

Field 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

Bench 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

A 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

Vapor 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

Selective 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

Vegetation 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

The 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

Multicomponent 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.
Design concepts for biological treatment of industrial wastewater
Authors: Capps Ronald W. , Mantelli Guy N. , Bradford Michael L.
Published: February 2007

Wastewater treatment systems have an operating envelope bounded by upper and lower operating limits. The design criteria should therefore include upper and lower operating limits. Upper limits are generally dictated by the effluent permit, whereas lower limits are the result of design. The design challenge for an industrial wastewater treatment system is to create a process which is capable of responding to extreme variations in flow and pollutant concentration, yet maintain the effluent within permit limitations. Industrial wastewater is contaminated with oil, aromatics, ammonia, phenols, sulfide, and heavy metals. Because the operating loads (flow, pollutant concentration, toxics, pH, and salinity) are largely unpredictable, maximum flexibility and controllability should be incorporated into the design. Since the heart of the wastewater treating system is the biological oxidation process, particular attention should be given to its specifications. A biological oxidation system that is too large can cause as many problems as one that is too small. This paper focuses on design considerations for the activated sludge process for industrial wastewater.

Case Study 1 is an example of how to design a grass roots wastewater treatment plant for a new refinery. This design provides for the maximum efficiency and operability within permit limits. However, Case Study 2 is an example of how not to design an industrial wastewater treatment plant. Typically wastewater treatment systems like Case Study 2 are over‐designed, which causes many operability problems that lead to permit excursions.
New advanced solids/oil/water separator
Authors: Woinsky Samuel G.
Published: February 2007

ACS Industries, Inc. recently commercialized proprietary advanced oil/water separation technology which separates heavy oils (up to 50,000 centistokes). The separation efficiency of ACS' unit is exceptional (down to less than 2 mg/l oil in water in field trials). During emergency situations, the unit can produce effluent water containing less than 15 mg/l of oil (with up to 50% oil in the feed).

The system is commercially proven with 32 units built for the Marine Spill Response Corporation (MSRC), plus units processing waste water at three power plants. These units are mounted on a single skid in capacities up to 2 cubic meters/minute (528 GPM), and they are fully automated.

ACS has also been providing CPI separators to the Process Industries for seven years. ACS is now integrating its CPI separator know‐how with its proprietary oil/water separation technology to provide higher quality water effluents at a lower cost than can be achieved by any other technology.

The history of the development, proprietary improvements, design details, commercial data, factors affecting the extent of separation and a competitive comparison are discussed.
Demonstration of an innovative heavy metals removal process
Authors: McLaughlin R. James , Danzberger A. H. , McLaughlin Richard E.
Published: February 2007

A new process, subsequently patented, has been developed for and used successfully at a large Superfund site for three years at flow rates up to 400 gpm.
Development of emissions inventories for evaluation of eulerian acid deposition models
Authors: Kaplan Norman , Dewaters Jan E. , Ryan Ronald , Novak Joan H.
Published: February 2007

During the past decade, acid deposition has been a primary environmental problem of concern for the governments of the United States and Canada. In order to better evaluate and study the problem, these governments and other organizations have developed and used Eulerian mathematical models to bring together the sciences of chemistry, physics, and meteorology. Since these models use emissions of acid rain precursors as input, it is important that these emissions estimates be as accurate as possible. A paper, entitled “The Eulerian Model Evaluation Field Study” (EMEFS) [1], gives an overview of the activities of a binational (U.S./Canadian) group organized to conduct an extensive field study to evaluate two Eulerian models. That group appointed and directs the activities of four teams: diagnostic measurements, operational (surface) measurements, model evaluation, and emissions inventory. This paper describes the emissions inventory that was developed by the emissions inventory team (EIT) and is being used as input to the Eulerian models discussed in the above referenced paper.