Showing papers in "Environmental Progress in 1993"
TL;DR: In this article, the authors used a cell in which the anode and cathode compartments were separated by a cation exchange membrane and showed that over 95 percent recovery of both EDTA and lead could be achieved by electrolysis.
Abstract: Removal of toxic heavy metals from a soil matrix by the addition of ethylenediamine tetraacetic acid (EDTA) is an effective means of remediation The liquid stream containing the metal and chelating agent is amenable to further treatment by electrolysis in which the metal can be separated from the chelating agent This provides a separated metal that can be removed for reuse or treated for final disposal by conventional technologies and a reclaimed EDTA stream that can be used again for treatment of contaminated soil
Under the diffusion controlled conditions of polarography or voltammetry, we observed reduction of cadmium, copper and lead ions and their protonated EDTA complexes (MHY−), but not of the non-protonated EDTA complexes (MY2−) Potentials applicable for metal deposition and, consequently, regeneration of the EDTA were established To prevent electrochemical oxidation of EDTA during electrolysis we used a cell in which the anode and cathode compartments were separated by a cation exchange membrane Tests with Pb-EDTA demonstrated that over 95 percent recovery of both EDTA and lead could be achieved by electrolysis The lead that was deposited onto a copper electrode was a mixture of hydrolysis products and salts and the lead could be recovered by dissolution in acid EDTA was equilibrated with soil before addition of lead When electrolyzed, this sample released EDTA and deposited Pb to approximately the same extent as did the samples that had not been equilibrated with soil
144 citations
TL;DR: The modular solvent concentrator (MSC) as mentioned in this paper was 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.
Abstract: 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
93 citations
TL;DR: In this article, 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.
Abstract: 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. 22 refs., 8 figs., 5 tabs.
75 citations
TL;DR: The Solar Detoxification Field Experiment as mentioned in this paper was designed to investigate the photocatalytic decomposition of organic contaminants in groundwater at a Superfund site at Lawrence Livermore National Laboratory.
Abstract: The Solar Detoxification Field Experiment was designed to investigate the photocatalytic decomposition of organic contaminants in groundwater at a Superfund site at Lawrence Livermore National Laboratory. The process uses ultraviolet (UV) energy available in sunlight in conjunction with a photocatalyst, titanium dioxide, to decompose organic chemicals into nontoxic compounds. The destruction mechanism, as in many other advanced oxidation processes, involves hydroxyl radicals. The field experiment was developed by three federal laboratories: The National Renewable Energy Laboratory, Sandia National Laboratory, and Lawrence Livermore National Laboratory. The United States Department of Energy funded the experiment. Groundwater at the test site was contaminated with trichloroethylene (TCE). A factorial test series examined four separate process variables: pH, catalyst loading, flow velocity, and solar intensity. Lowering the pH from pH 7 to pH 5 had the largest single effect, presumably by minimizing interference by bicarbonate. The catalyst was found to operate more efficiently at low, e.g. ambient sunlight, UV light levels. Information from these field tests suggest that treatment costs for the solar process would be similar to those for more conventional technologies. 8 refs., 10 figs., 4 tabs.
63 citations
TL;DR: In this article, a comparison is made of the characteristics of precipitation and sorption barriers, and a comparison of the properties of these two types of barriers is made on the extraction of uranium and molybdenum.
Abstract: Chemical barriers are being explored as a low-cost means of controlling groundwater contamination. The barrier can intercept a contaminant plume and prevent migration by transferring contaminants from the groundwater to immobile solids. A chemical barrier can be emplaced in a landfill liner or in an aquifer cutoff wall or can be injected into a contaminant plume. Chemical barriers can be classified as either precipitation barriers or sorption barriers depending upon the dominant mode of contaminant extraction. In a precipitation barrier, contaminants are bound in the structures of newly formed phases; whereas, in a sorption barrier, contaminants attach to the surfaces of preexisting solids by adsorption or some other surface mechanism. Sorption of contaminants is pH dependent. A precipitation barrier can control the pH of the system, but alkaline groundwater may dominate the pH in a sorption barrier. A comparison is made of the characteristics of precipitation and sorption barriers. Experimental data on the extraction of uranium and molybdenum from simulated groundwater are used to demonstrate these concepts. 10 refs., 9 figs., 1 tab.
51 citations
TL;DR: In this article, the kinetics of the catalytic hydrodechlorination (HDCl) process in the liquid phase of 1,2,3-trichlorobenzene was studied.
Abstract: 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[degrees]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. The authors 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. 29 refs., 6 figs., 2 tabs.
47 citations
TL;DR: Ceramic alumina microfiltration membranes were evaluated for treatment of 3 aqueous streams containing heavy metals, oils, and solids at petrochemical manufacturing facilities in this paper.
Abstract: Ceramic alumina microfiltration membranes were evaluated for treatment of 3 aqueous streams containing heavy metals, oils, and solids at petrochemical manufacturing facilities. To the best of the author's knowledge, this is the first reported use of ceramic alumina membranes for process water and wastewater treatment in a US petrochemical plant. In a pilot test at a vinyl chloride monomer (VCM) plant, precipitated heavy metal solids were filtered with the membranes. On another stream at that site, the ceramic membrane pilot system successfully treated emulsions of 1,2-dichloroethane (EDC), water, and solids. Membrane filtration of a linear alkyl benzene (LAB) oily wastewater stream produced water with less than 5 ppmw oil and grease, after pretreatment with HCl and ferric chloride. A preliminary financial analysis shows that the installed system cost for a ceramic membrane unit is comparable to other membrane technologies, while operating costs are anticipated to be lower. Specific process conditions that are particularly amenable to treatment by ceramic membrane microfiltration are also given in the paper. 10 refs., 11 figs., 7 tabs.
43 citations
TL;DR: In this article, 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 gas velocity.
Abstract: 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.
38 citations
TL;DR: A bioremediation treatability protocol for soil is presented which can provide feasibility study and remedial action engineers maximum information with respect to the viability and efficiency of biodemediation.
Abstract: A bioremediation treatability protocol for soil is presented which can provide feasibility study and remedial action engineers maximum information with respect to the viability and efficiency of bioremediation. The protocol, divided into two main phases, progressively evaluates the viability of biodegradation and the requirements for optimization of the process once implemented. Chemical and microbiological baseline conditions and the potential for contaminant degradation are assessed during Phase I screening. During Phase II the endpoint achievable and kinetics of the biodegradation reactions can be established with pan and slurry reactor tests for ex-situ systems or column tests for in-situ systems. Models are reviewed which can predict the rate of removal of organic constituents, and these data in conjunction with the Phase I and II may be used to estimate the potential time required to achieve cleanup standards, assess the relative importance of biological versus chemical removal mechanisms, and compare expected performance of alternative bioremediation methods. 45 refs., 4 figs., 4 tabs.
37 citations
TL;DR: In this article, a simulated vegetative buffer zone over a shallow aquifer was used to investigate the effects of rainfall, evapotranspiration and atrazine uptake by plants.
Abstract: 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.
37 citations
TL;DR: A bench-scale study was conducted to assess the feasibility of bioremediating phthalate contaminated soil from a polyvinyl chloride manufacturing operation in New Jersey as mentioned in this paper, where approximately 50 to 60% of the carbon in BEHP was mineralized directly to CO 2 by indigenous microbial flora, while the remaining 40 to 50% was converted into cell mass.
Abstract: 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 14 C-labeled bis-(2-ethylhexyl) phthalate (BEHP) demonstrated that approximately 50 to 60% of the carbon in BEHP was mineralized directly to CO 2 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)
TL;DR: In this paper, the kinetics of limestone dissolution in wet type flue gas desulfurization (FGD) processes were studied and a predictive model was developed based on mass transfer mechanisms.
Abstract: 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 distributions. A predictive model was developed based on mass transfer mechanisms. It was in good agreement with experimental data. Moreover, the rate of dissolution for 25 limestones of different compositions and size distributions were measured in apparatus with a sulfur dioxide absorber which simulated FGD processes. The model was also in good agreement with these results. 11 refs., 8 figs., 2 tabs.
TL;DR: In this paper, a hybrid method incorporating selective polymeric binding and membrane separation was used for the removal of arsenic from contaminated groundwater, where two types of polymers, polyethylenimine (PEI) and poly-diallyl dimethyl ammonium chloride (DADMAC) and an ultrafiltration membrane were used at various concentrations and pH.
Abstract: A hybrid method incorporating selective polymeric binding and membrane separation was used for the removal of arsenic from contaminated groundwater. Two types of polymers, polyethylenimine (PEI) and poly-diallyl dimethyl ammonium chloride (DADMAC) and an ultrafiltration membrane were used at various concentrations and pH. Bench-scale tests demonstrated a high degree of arsenic removal. The retention of arsenic was also determined in the presence of various background salts such as NaCl, NaNO3, Na2SO4, Na2CO3. Retention was found to depend on the concentration and type of anion present in solution.
TL;DR: A low-temperature process employing activated carbon-based catalysts and operating downstream of the electrostatic precipitator (ESP) is being developed jointly by Research Triangle Institute (RTI) and the University of Waterloo (Waterloo) as discussed by the authors.
Abstract: A low-temperature process employing activated carbon-based catalysts and operating downstream of the electrostatic precipitator (ESP) is being developed jointly by Research Triangle Institute (RTI) and the University of Waterloo (Waterloo). The RTI-Waterloo process is capable of removing more than 95% SO[sub 2] and 75% NO[sub x] from coal combustion flue gas. The flue gas leaving the ESP is first cooled to approximately 100[degrees]C. The SO[sub 2] is then catalytically oxidized to SO[sub 3] which is removed as medium-strength sulfuric acid in a series of periodically flushed trickle-bed reactors containing an activated carbon-based catalyst. The SO[sub 2]-free gas is then reheated to approximately 150[degrees]C and NH[sub 3] is injected into the gas stream. It is then passed over a fixed bed of a different promoted activated carbon-based catalyst to reduce the NO[sub x] to N[sub 2] and H[sub 2]O. The clean flue gas is then vented to the stack. The feasibility of the process has been demonstrated in laboratory-scale experiments using simulated flue gas. Catalysts have been identified which gave the required performance for SO[sub 2] and NO[sub x] removal with less than 25 ppm NH[sub 3] slip. Potential for producing greater than 10N H[sub 2]SO[sub 4] by periodically flushing themore » SO[sub 2] removal reactor was also demonstrated. Cost for the RTI-Waterloo process was competitive with conventional selective catalytic reduction (SCR)-flue gas desulfurization (FGD) process and other emerging combined SO[sub 2]/NO[sub x] removal processes. 4 refs., 7 figs., 4 tabs.« less
TL;DR: In this article, the authors developed a recycling process for the hydroprocessing catalysts used in oil refineries (NiMo, CoMo, NiW on alumina or mixed alumina silica).
Abstract: Disposal of spent catalysts is a growing concern for all refiners. Environmental regulations are becoming stricter and stricter and state recommendations are to develop disposal routes which would emphasize recycling as much as possible, and processing the wastes as near as possible to the production center. In this context, EURECAT has developed a recycling process for the hydroprocessing catalysts used in oil refineries (NiMo, CoMo, NiW on alumina or mixed alumina silica). The process starts with a regeneration of the catalyst to eliminate hydrocarbons, carbon and sulfur. After a caustic roasting, the material is leached to obtain a solution containing mainly molybdenum (or tungsten) and vanadium and a solid containing essentially alumina, cobalt and/or nickel. Molybdenum and vanadium are separated by an ion exchange resin technique. The solid is processed in an arc furnace to separate the alumina. Nickel and cobalt are separated by conventional solvent extraction to obtain pure metal. Alumina is disposed of as an inert slag. The strength of the process lies in the combination of proven technologies applied by companies whose reliability in their respective field is well known. The aspects concerning spent catalyst handling, packaging and transport are also discussed. 13 refs., 2 figs., 1more » tab.« less
TL;DR: In this paper, the authors proposed a semi-empirical simplified model 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 gases as well as from the impurities contained in the used raw material limestone itself.
Abstract: 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 supplemented with a single salt of CaCl[sub 2], MgCl[sub 2], NaCl, Na[sub 2]SO[sub 4] and MgSO[sub 4] 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. 9 refs., 8 figs., 1 tab.
TL;DR: The first pilot-scale study described the performance of a UV/oxidation system, developed by Ultrox International of Santa Ana, California, in treating groundwater contaminated with volatile organic compounds (VOCs) as mentioned in this paper.
Abstract: This paper presents information useful in evaluating the applicability of UV/oxidation treatment technologies for groundwater contaminated with organics. The information presented includes a description of the technologies, factors affecting the technologies, and results from two pilot-scale studies of UV/oxidation treatment system applications. The first pilot-scale study describes the performance of a UV/oxidation system, developed by Ultrox International of Santa Ana, California, in treating groundwater contaminated with volatile organic compounds (VOCs). At the optimum operating conditions, the Ultrox system achieved total VOC removals of greater than 90 percent
TL;DR: In this paper, the ability of supercritical CO 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.
Abstract: 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 CO[sub 2] 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 fixed-site 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 cents/lb (23 cents/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,more » which reduces carbon replacement costs and significantly decreases the need for carbon disposal by landfill or incineration. 25 refs., 13 figs., 3 tabs.« less
TL;DR: The results of an initial feasibility study on the bioremediation of sludge are presented in this paper, where the results show limited effectiveness of biological treatment at conditions employing indigenous bacteria and low (2%) sludge concentraticws in Bushnell-Haas media.
Abstract: The results of an initial feasibility study on the bioremediation of sludge are presented. The sludge used in the study was taken from a site containing waste produced during the refining of lubricant oils to which sulfuric acid had been added. The effectiveness of bioremediation was examined using shake flask experiments with indigenous and other bacteria sources and nutrient supplementation. The initial results show limited effectiveness of biological treatment at conditions employing indigenous bacteria and low (2%) sludge concentraticws in Bushnell-Haas media. In addition, the indigenous bacteria were seen to degrade the polycyclic aromatic hydrocarbons naphthalene, penanthrene and pyrene which are present at some locations at the site. No apparent degradution of material was seen using conditions of high (30%) sludge concentrations in Bushnell-Haas medium under a variety of conditions. In addition, nutrients were rapidly depleted at these sludge concentrations, with the exception of sulfates which were produced when high sludge concentrations were used.
TL;DR: The NOXSO process as discussed by the authors uses a regenerable sorbent that removes SO[sub 2] and NO[sub x] simultaneously from flue gas, which is a [gamma] alumina bead impregnated with sodium carbonate.
Abstract: The NOXSO process uses a regenerable sorbent that removes SO[sub 2] and NO[sub x] simultaneously from flue gas. The sorbent is a [gamma] alumina bead impregnated with sodium carbonate. The process was successfully tested at three different scales, equivalent to 0.017, 0.06 and 0.75 MW of flue gas generated from a coal-fired power plant. The Proof-of-Concept (POC) Test is the last test prior to a full-scale demonstration. A slip stream of flue gas equivalent to a 5 MW coal-fired power plant was used for the POC test. This paper summarizes the NOXSO POC process and its current test results. 7 refs., 8 figs., 2 tabs.
TL;DR: In this paper, the authors describe the results of initial feasibility studies, sensitivity analyses and conceptual design work of a biocatalyst-based desulfurization process for refining of crude oil and middle distillates.
Abstract: Biocatalytic Desulfurization (BDS) represents an alternative approach to the reduction of sulfur in fossil fuels The objective is to use bacteria to selectively remove sulfur from petroleum and middle distillate fractions, without the concomitant release of carbon Recently, bacteria have been developed which have the ability to desulfurize dibenzothiophene (DBT) and other organosulfur molecules These bacteria are being developed for use in a biocatalyst-based desulfurization process Analysis of preliminary conceptual engineering designs has shown that this process has the potential to complement conventional technology as a method to temper the sulfur levels in crude oil, or remove the recalcitrant sulfur in middle distillates to achieve the deep desulfurization mandated by State and Federal regulations This paper describes the results of initial feasibility studies, sensitivity analyses and conceptual design work Feasibility studies with various crude oils and middle distillates achieved unoptimized desulfurization levels of 40-80% Sensitivity analyses indicate that total desulfurization costs of about $300 per barrel for crude oil and less than $200 per barrel for diesel are possible Key criteria for commercial success of the process include the cost and half-life of the biocatalyst, residence time in the reactor, oil/water ratios required to extract the sulfur and the dispositionmore » of the separated sulfur products 9 refs, 3 figs« less
TL;DR: In this paper, the effect of catalytic deactivation on fuel costs and hence total operating costs is investigated using an example of the oxidation of a VOC-containing gas stream over a commercial hopcalite catalyst.
Abstract: 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. 8 refs., 4 figs., 2 tabs.
TL;DR: In this paper, EER is developing a control process with potential to reduce NO[sub x] emissions from coal-fired utility boilers by up to 85% under contract with the US Department of Energy.
Abstract: Under contract with the Department of Energy, EER is developing a NO[sub x] control process with potential to reduce NO[sub x] emissions from coal-fired utility boilers by up to 85%. CombiNO[sub x] is a family of NO[sub x] 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 NO[sub x] reduction in a given boiler. Integration of these processes may be site-specific depending on boiler configuration and required emission limits. 3 refs., 8 figs.
TL;DR: In this article, a pilot-scale rotary kiln simulator was used to make experimental measurements of the thermal response of solids charged onto a preexisting bed of hot solids material.
Abstract: 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 heal transfer to the fresh charge of solids.
TL;DR: Based on prior quenching and polarization studies, this finding suggests that micelle maturation may occur over the time scale of days, resulting in increased sequestering of naphthalene in the micellar phase.
Abstract: Polycyclic Aromatic Hydrocarbons (PAH) are ubiquitous environmental pollutants that are suspected to be carcinogenic. Because some PAHs can undergo metabolic degradation, an interest has emerged in bioremediating contaminated sites and incorporating surfactants into treatment processes because the release of slowing desorbing, soil-bound PAH may be promoted. The authors employed fluorescence spectroscopy and quenching experiments to investigate micelle-naphthalene interaction and the dynamics of biodegradation in the presence and absence of micelles. These experiments were envisioned to provide some molecular-level insights as well as constitute the basis for subsequent work where realistic model systems will be investigated in a noninvasive manner. In the absence of micelles, naphthalene was observed to be degraded within three days and intermediates were detected. Micelles protected naphthalene against copper quenching and also suppressed biodegradation. Additionally, the emission spectrum of the naphthalene associated with the micelles changed over the course of days. Based on prior quenching and polarization studies, this finding suggests that micelle maturation may occur over the time scale of days, resulting in increased sequestering of naphthalene in the micellar phase. 12 refs., 7 figs.
TL;DR: The MX-2500 as mentioned in this paper is an electrically heated dryer system that recovers virtually all of the hydrocarbon value of refinery wastes and secondary materials, while producing a solid residue meeting EPA Land Disposal Restriction (LDR) treatment levels which allows the refinery to land dispose of the solids, thereby realizing waste minimization and oil recovery/recycling.
Abstract: Separation and Recovery Systems, Inc. (SRS) of Irvine, California is the market leader in supplying hazardous waste and secondary material dewatering and drying services to the petroleum refining industry. In late 1991, SRS introduced the new generation of dryer technology, the MX-2500. The MX-2500 is an electrically heated dryer system that recovers virtually all of the hydrocarbon value of refinery wastes and secondary materials, while producing a solid residue meeting EPA Land Disposal Restriction (LDR) treatment levels which allows the refinery to land dispose of the solids, thereby realizing two objectives: waste minimization and oil recovery/recycling. 2 figs., 3 tabs.
TL;DR: The Societe Suisse de Microbiologie, 52eme Assemblee Annuelle, Montreux, 11-12 mars 1993 Reference LBE-POSTER-1993-002 Record created on 2005-03-02, modified on 2016-08-08.
Abstract: Note: Abstracts: Societe Suisse de Microbiologie, 52eme Assemblee Annuelle, Montreux, 11-12 mars 1993 Reference LBE-POSTER-1993-002 Record created on 2005-03-02, modified on 2016-08-08
TL;DR: In this paper, the initial progress of an ongoing laboratory investigation is described in which phenol and aniline were mixed into a slightly organic, loamy soil and various aqueous solutions used to attempt to extract these organic contaminants.
Abstract: The initial progress of an ongoing laboratory investigation is described in which phenol and aniline were mixed into a slightly organic, loamy soil and various aqueous solutions used to attempt to extract these organic contaminants. Extraction compounds consisted of deionized water, hydrogen peroxide at varying concentration and sodium hydroxide at varying pH. Two methods were used to affect desorption. The first method, which is simple and quick, has been termed the “successive reverse isotherm” (SRI) method, and the second method, which is very labor intensive and time-consuming, but which represents better the conditions that exist in an in situ extraction operation, was the permeation method. The SRI method indicated that an aqueous solution of hydrogen peroxide in concentration of 200 to 500 mg/L extracted about 45% of the phenol, while an aqueous solution of sodium hydroxide at a pH of 10 extracted in excess of 70% of the phenol. On the other hand, none of the solutions extracted more than 25% of the aniline. Further tests conducted in permeameters indicated that approximately 80% of phenol was recovered by permeation with either hydrogen peroxide or sodium hydroxide and that both were measurably more effective than deionized water. Neither the phenol nor any of the decontaminants had any major effect on hydraulic conductivity or physical index properties of the soil. From the results of the tests to date, the SRI test appears to provide a viable method of predicting whether permeameter tests will yield productive results.
TL;DR: In this paper, a wet oxidation process was developed to treat waste water from an organic nitration process, which contained a number of priority pollutants including dinitrotoluene, 2-nitrophenol, 4-nitro-ortho-cresol and phenol.
Abstract: 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.
TL;DR: Results from model calculations indicate that the bio-remediation rate increases and approaches a limiting value when one of the rates becomes controlling, which means that the rate controlling step of the bioremediation site may be identified quickly and steps to improve the biowaste rate can be recommended.
Abstract: A mathematical model of bio-remediation of hydrocarbons in a soil matrix has been developed to predict the rate controlling step and the remediation rate during the bioremediation of a contaminated soil. The model is based on mass transfer of oxygen and oil into the aqueous solution in the soil matrix and the biodegradation of the hydrocarbons in the aqueous solution. Monod's equation was used to describe the biodegradation rate in aqueous solution while the mass transfer equations were used to describe the mass transfer rates of oxygen and oil in the soil matrix. Results from model calculations indicate that the bio-remediation rate increases and approaches a limiting value when one of the rates becomes controlling. When the parameters of the site soil samples are measured and the solubilities of oxygen and oil in aqueous solution are obtained, the bioremediation rate can be predicted by this model. The rate controlling step of the bioremediation site may be identified quickly and steps to improve the bioremediation rate can be recommended. 8 refs., 7 figs.