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Sample records for spouted bed reactor

  1. EMERGING TECHNOLOGY BULLETIN: SPOUTED BED REACTOR

    EPA Science Inventory

    The Spouted Bed Reactor (SBR) technology utilizes the unique attributes of the "spouting " fluidization regime, which can provide heat transfer rates comparable to traditional fluid beds, while providing robust circulation of highly heterogeneous solids, concurrent with very agg...

  2. Fast pyrolysis of eucalyptus waste in a conical spouted bed reactor.

    PubMed

    Amutio, Maider; Lopez, Gartzen; Alvarez, Jon; Olazar, Martin; Bilbao, Javier

    2015-10-01

    The fast pyrolysis of a forestry sector waste composed of Eucalyptus globulus wood, bark and leaves has been studied in a continuous bench-scale conical spouted bed reactor plant at 500°C. A high bio-oil yield of 75.4 wt.% has been obtained, which is explained by the suitable features of this reactor for biomass fast pyrolysis. Gas and bio-oil compositions have been determined by chromatographic techniques, and the char has also been characterized. The bio-oil has a water content of 35 wt.%, and phenols and ketones are the main organic compounds, with a concentration of 26 and 10 wt.%, respectively. In addition, a kinetic study has been carried out in thermobalance using a model of three independent and parallel reactions that allows quantifying this forestry waste's content of hemicellulose, cellulose and lignin.

  3. Fast pyrolysis of eucalyptus waste in a conical spouted bed reactor.

    PubMed

    Amutio, Maider; Lopez, Gartzen; Alvarez, Jon; Olazar, Martin; Bilbao, Javier

    2015-10-01

    The fast pyrolysis of a forestry sector waste composed of Eucalyptus globulus wood, bark and leaves has been studied in a continuous bench-scale conical spouted bed reactor plant at 500°C. A high bio-oil yield of 75.4 wt.% has been obtained, which is explained by the suitable features of this reactor for biomass fast pyrolysis. Gas and bio-oil compositions have been determined by chromatographic techniques, and the char has also been characterized. The bio-oil has a water content of 35 wt.%, and phenols and ketones are the main organic compounds, with a concentration of 26 and 10 wt.%, respectively. In addition, a kinetic study has been carried out in thermobalance using a model of three independent and parallel reactions that allows quantifying this forestry waste's content of hemicellulose, cellulose and lignin. PMID:26203554

  4. Fluorocarbon waste plasma destruction with a high temperature spouted-bed reactor: Kinetics, GC/MS analysis, chemical and mass balance for CF{sub 4}/H{sub 2}/O{sub 2}CaO systems

    SciTech Connect

    Al Ayoubi, S.; Amouroux, J.; Renou-Gonnord, M.F.

    1995-12-31

    The design of a plasma process for removing organic and hazardous substances has to account for pollutant emission by effluent gases. In order to evaluate the feasibility of using a plasma spouted-bed reactor for waste destruction, an efficient analytical procedure has been developed. CF{sub 4} has been chosen as a model molecule in both experimental work and in kinetic calculations.

  5. Spouted bed electrowinning of zinc: Part II. Investigations of the dynamics of particles in large thin spouted beds

    NASA Astrophysics Data System (ADS)

    Verma, A.; Evans, J. W.; Salas-Morales, Juan Carlos

    1997-02-01

    The behavior of particles in thin spouted beds, mostly equipped with draft tubes, has been investigated. Three apparatuses have been used: a laboratory-scale cylindrical bed, a 2-m-tall “flat” (rectangular cross section) bed and a 2-m-wide flat bed, the last equipped with multiple draft tubes. Most of the results were obtained on the tall bed. Minimum spouting flow rate, pressure distribution, particle velocities, and solid circulation rates were determined as a function of bed geometry (including draft tube dimensions and position). Observations were made of the direction of liquid flow in the bed outside the draft tube and of the occurrence of zones in the bed where the particles appeared stationary. The wide bed was used to determine that there is a maximum separation between draft tubes beyond which particles cannot be kept in motion across the whole width of the bed.

  6. Hydrodynamic characteristics of a novel annular spouted bed with multiple air nozzles

    SciTech Connect

    Gong, X.W.; Hu, G.X.; Li, Y.H.

    2006-06-21

    A novel spouted bed, namely, an annular spouted bed with multiple air nozzles, has been proposed for drying, pyrolysis, and gasification of coal particulates. It consists of two homocentric upright cylinders with some annularly located spouting air nozzles between inner and outer cylinders. Experiments have been performed to study hydrodynamic characteristics of this device. The test materials studied are ash particle, soy bean, and black bean. Three distinct spouting stages have been examined and outlined with the hold-ups increase. In the fully developed spouting stage, three flow behaviors of particles have been observed and delimited. The effects of nozzle mode and spouting velocity on the maximum spouting height of the dense-phase region, spoutable static bed height, and spouting pressure drop in the bed have been investigated experimentally.

  7. Electrically recharged battery employing a packed/spouted bed metal particle electrode

    DOEpatents

    Siu, Stanley C.; Evans, James W.; Salas-Morales, Juan

    1995-01-01

    A secondary metal air cell, employing a spouted/packed metal particle bed and an air electrode. More specifically a zinc air cell well suited for use in electric vehicles which is capable of being either electrically or hydraulically recharged.

  8. A New Dry Flue Gas Desulfurization Process-Underfeed Circulating Spouted Bed

    NASA Astrophysics Data System (ADS)

    Tao, M.; Jin, B. S.; Yang, Y. P.

    Applying an underfeed system, the underfeed circulating spouted bed was designed as a desulfurization reactor. The main objective of the technology is to improve the mixing effect and distribution uniformity of solid particles, and therefore to advance the desulfurization efficiency and calcium utility. In this article, a series of experimental studies were conducted to investigate the fluidization behavior of the solid-gas two-phase flow in the riser. The results show that the technology can distinctly improve the distribution of gas velocity and particle flux on sections compared with the facefeed style. Analysis of pressure fluctuation signals indicates that the operation parameters have significant influence on the flow field in the reaction bed. The existence of injecting flow near the underfeed nozzle has an evident effect on strengthening the particle mixing.

  9. Production of cellulase in a spouted bed fermentor using cells immobilized in biomass support particles

    SciTech Connect

    Webb, C.; Fukuda, H.; Atkinson, B.

    1986-01-01

    Continuous cellulase production by Trichoderma viride QM 9123, immobilized in 6 mm diameter, spherical, stainless steel biomass support particles, has been achieved using a medium containing glucose as the main carbon source. Experiments were carried out in a 10-L spouted bed fermentor. In this type of reactor recycled broth is used to create a jet at the base of a bed of particles, causing the particles to spout and circulate. During the circulation, particles pass through a region of high shear near the jet inlet. This effectively prevents a buildup of excess biomass and thus enables steady-state conditions to be achieved during continuous operation. Continuous production of cellulase was achieved at significantly higher yield and productivity than in conventional systems. At a dilution rate of 0.15 h/sup -1/ (nominal washout rate for freely suspended cells is 0.012 h/sup -1/), the yield of cellulase on glucose was 31% higher than that measured during batch operation, while the volumetric productivity (31.5 FPA U/L x h) was 53% greater than in the batch system. The specific cellulase productivity of the immobilized cells was more than 3 times that of freely suspended cells, showing that diffusional limitations can be beneficial. This offers significant opportunity for the further development of biomass support particles and associated bioreactors.

  10. SPOUTED BED ELECTRODES (SBE) FOR DIRECT UTILIZATION OF CARBON IN FUEL CELLS

    SciTech Connect

    J.M. Calo

    2004-12-01

    This Phase I project was focused on an investigation of spouted bed particulate electrodes for the direct utilization of solid carbon in fuel cells. This approach involves the use of a circulating carbon particle/molten carbonate slurry in the cell that provides a few critical functions: it (1) fuels the cell continuously with entrained carbon particles; (2) brings particles to the anode surfaces hydrodynamically; (3) removes ash from the anode surfaces and the cell hydrodynamically; (4) provides a facile means of cell temperature control due to its large thermal capacitance; (5) provides for electrolyte maintenance and control in the electrode separator(s); and (6) can (potentially) improve carbon conversion rates by ''pre-activating'' carbon particle surfaces via formation of intermediate oxygen surface complexes in the bulk molten carbonate. The approach of this scoping project was twofold: (1) adaptation and application of a CFD code, originally developed to simulate particle circulation in spouted bed electrolytic reactors, to carbon particle circulation in DCFC systems; and (2) experimental investigation of the hydrodynamics of carbon slurry circulation in DCFC systems using simulated slurry mixtures. The CFD model results demonstrated that slurry recirculation can be used to hydrodynamically feed carbon particles to anode surfaces. Variations of internal configurations were investigated in order to explore effects on contacting. It was shown that good contacting with inclined surfaces could be achieved even when the particles are of the same density as the molten carbonate. The use of CO{sub 2} product gas from the fuel cell as a ''lift-gas'' to circulate the slurry was also investigated with the model. The results showed that this is an effective method of slurry circulation; it entrains carbon particles more effectively in the draft duct and produces a somewhat slower recirculation rate, and thus higher residence times on anode surfaces, and can be

  11. II. Electrodeposition/removal of nickel in a spouted electrochemical reactor

    PubMed Central

    Grimshaw, Pengpeng; Calo, Joseph M.; Shirvanian, Pezhman A.; Hradil, George

    2011-01-01

    An investigation is presented of nickel electrodeposition from acidic solutions in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on nickel removal/recovery rate, current efficiency, and corrosion rate of deposited nickel on the cathodic particles were explored under galvanostatic operation. Nitrogen sparging was used to decrease the dissolved oxygen concentration in the electrolyte in order to reduce the nickel corrosion rate, thereby increasing the nickel electrowinning rate and current efficiency. A numerical model of electrodeposition, including corrosion and mass transfer in the particulate cathode moving bed, is presented that describes the behavior of the experimental net nickel electrodeposition data quite well. PMID:22039317

  12. II. Electrodeposition/removal of nickel in a spouted electrochemical reactor.

    PubMed

    Grimshaw, Pengpeng; Calo, Joseph M; Shirvanian, Pezhman A; Hradil, George

    2011-08-17

    An investigation is presented of nickel electrodeposition from acidic solutions in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on nickel removal/recovery rate, current efficiency, and corrosion rate of deposited nickel on the cathodic particles were explored under galvanostatic operation. Nitrogen sparging was used to decrease the dissolved oxygen concentration in the electrolyte in order to reduce the nickel corrosion rate, thereby increasing the nickel electrowinning rate and current efficiency. A numerical model of electrodeposition, including corrosion and mass transfer in the particulate cathode moving bed, is presented that describes the behavior of the experimental net nickel electrodeposition data quite well. PMID:22039317

  13. II. Electrodeposition/removal of nickel in a spouted electrochemical reactor.

    PubMed

    Grimshaw, Pengpeng; Calo, Joseph M; Shirvanian, Pezhman A; Hradil, George

    2011-08-17

    An investigation is presented of nickel electrodeposition from acidic solutions in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on nickel removal/recovery rate, current efficiency, and corrosion rate of deposited nickel on the cathodic particles were explored under galvanostatic operation. Nitrogen sparging was used to decrease the dissolved oxygen concentration in the electrolyte in order to reduce the nickel corrosion rate, thereby increasing the nickel electrowinning rate and current efficiency. A numerical model of electrodeposition, including corrosion and mass transfer in the particulate cathode moving bed, is presented that describes the behavior of the experimental net nickel electrodeposition data quite well.

  14. Innovative Method Using Magnetic Particle Tracking to Measure Solids Circulation in a Spouted Bed

    SciTech Connect

    Patterson, Ms. Emily; Halow, John; Daw, C Stuart

    2010-01-01

    We describe an innovative method for measuring particle motion inside spouted fluidized beds. The method uses a magnetic tracer particle, which follows the bulk particle flow and is continuously tracked by multiple magnetic field detectors located outside the bed. We analyze signals from the detectors to determine the tracer position at each instant in time. From statistical analysis of the tracer trajectory, characteristic measures of the bulk particle flow, such as the average recirculation frequency, can be determined as a function of operating conditions. For experiments with a range of particle sizes and densities in a 3.9-cm-diameter spouted bed, we find that average solids recirculation rates correlate with excess velocity (superficial minus minimum spouting velocity), particle density, and bed depth.

  15. Recovery of valuable materials from spent NIMH batteries using spouted bed elutriation.

    PubMed

    Tanabe, Eduardo H; Schlemmer, Diego F; Aguiar, Mônica L; Dotto, Guilherme L; Bertuol, Daniel A

    2016-04-15

    In recent years, a great increase in the generation of spent batteries occurred. Then, efficient recycling ways and correct disposal of hazardous wastes are necessary. An alternative to recover the valuable materials from spent NiMH batteries is the spouted bed elutriation. The aim of this study was to apply the mechanical processing (grinding and sieving) followed by spouted bed elutriation to separate the valuable materials present in spent NiMH batteries. The results of the manual characterization showed that about 62 wt.% of the batteries are composed by positive and negative electrodes. After the mechanical separation processes (grinding, sieving and spouted bed elutriation), three different fractions were obtained: 24.21 wt.% of metals, 28.20 wt.% of polymers and 42.00 wt.% of powder (the positive and negative electrodes). It was demonstrated that the different materials present in the spent NiMH batteries can be efficiently separated using a simple and inexpensive mechanical processing.

  16. Packed Bed Reactor Experiment

    NASA Video Gallery

    The purpose of the Packed Bed Reactor Experiment in low gravity is to determine how a mixture of gas and liquid flows through a packed bed in reduced gravity. A packed bed consists of a metal pipe ...

  17. Electrically recharged battery employing a packed/spouted bed metal particle electrode

    DOEpatents

    Siu, S.C.; Evans, J.W.; Salas-Morales, J.

    1995-08-15

    A secondary metal air cell, employing a spouted/packed metal particle bed and an air electrode, is described. More specifically a zinc air cell well suited for use in electric vehicles which is capable of being either electrically or hydraulically recharged. 5 figs.

  18. Arsenic removal via ZVI in a hybrid spouted vessel/fixed bed filter system

    PubMed Central

    Calo, Joseph M.; Madhavan, Lakshmi; Kirchner, Johannes; Bain, Euan J.

    2012-01-01

    The description and operation of a novel, hybrid spouted vessel/fixed bed filter system for the removal of arsenic from water are presented. The system utilizes zero-valent iron (ZVI) particles circulating in a spouted vessel that continuously generates active colloidal iron corrosion products via the “self-polishing” action between ZVI source particles rolling in the moving bed that forms on the conical bottom of the spouted vessel. This action also serves as a “surface renewal” mechanism for the particles that provides for maximum utilization of the ZVI material. (Results of batch experiments conducted to examine this mechanism are also presented.) The colloidal material produced in this fashion is continuously captured and concentrated in a fixed bed filter located within the spouted vessel reservoir wherein arsenic complexation occurs. It is demonstrated that this system is very effective for arsenic removal in the microgram per liter arsenic concentration (i.e., drinking water treatment) range, reducing 100 μg/L of arsenic to below detectable levels (≪10 μg/L) in less than an hour. A mechanistic analysis of arsenic behavior in the system is presented, identifying the principal components of the population of active colloidal material for arsenic removal that explains the experimental observations and working principles of the system. It is concluded that the apparent kinetic behavior of arsenic in systems where colloidal (i.e., micro/nano) iron corrosion products are dominant can be complex and may not be explained by simple first or zeroth order kinetics. PMID:22539917

  19. Properties of Spent Active Coke Particles Analysed via Comminution in Spouted Bed

    PubMed Central

    Buczek, Bronislaw

    2013-01-01

    Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals) through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases. PMID:24459454

  20. Experimental investigation of a draft tube spouted bed for effects of geometric parameters on operation

    NASA Astrophysics Data System (ADS)

    Azizaddini, Seyednezamaddin; Lin, Weigang; Dam-Johansen, Kim

    2016-06-01

    Experiments are performed in a draft tube spouted bed (DTSB) to investigate effects of the operating conditions and the geometric parameters on the hydrodynamics. Geometry parameters, such as heights of the entrained zone, draft tube inner diameter, inner angle of the conical section were studied. Increasing the draft tube inner diameter, sharper inner angle of the conical section and higher height of entrained zone increase the internal solid circulation rate and the pressure drop. Even though, for all different configurations, higher gas feeding rate leads to higher internal solid circulation rate considering a maximum value.

  1. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, J.

    1996-03-19

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

  2. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, Juhani

    1996-01-01

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

  3. Technical aspects of the production of dried extract of Maytenus ilicifolia leaves by jet spouted bed drying.

    PubMed

    Cordeiro, Daniel S; Oliveira, Wanderley P

    2005-08-11

    This work presents an evaluation of the performance of jet spouted bed with inert particles for production of dried extracts of Maytenus ilicifolia leaves. The development of the extraction procedure was carried-out with the aid of three factors and three levels Box-Behnken design. The effects of the extraction variables, temperature (Text); stirring time (theta); and the ratio of the plant to solvent mass (m(p)/m(s)) on the extraction yield were investigated. The drying performance and product properties were evaluated through the measurement of the product size distribution, loss on drying (Up), flavonoid degradation (D) and, process thermal efficiency (eta). These parameters were measured as a function of the inlet temperature of the spouting gas (Tgi), the feed mass flow rate of the concentrated extract relative to mass flow rate of the spouting gas (Ws/Wg), the ratio between the feed flow rate of spouting gas relative to feed flow rate at a minimum spouting condition (Q/Qms) and the static bed height (H0). A powder product with a low degradation of active substances and good physical properties were obtained for selected operating conditions. These results indicate the feasibility of this drying equipment for the production of dried extracts of M. ilicifolia Martius ex Reiss leaves.

  4. Computational fluid dynamics modeling of coal gasification in a pressurized spout-fluid bed

    SciTech Connect

    Zhongyi Deng; Rui Xiao; Baosheng Jin; He Huang; Laihong Shen; Qilei Song; Qianjun Li

    2008-05-15

    Computational fluid dynamics (CFD) modeling, which has recently proven to be an effective means of analysis and optimization of energy-conversion processes, has been extended to coal gasification in this paper. A 3D mathematical model has been developed to simulate the coal gasification process in a pressurized spout-fluid bed. This CFD model is composed of gas-solid hydrodynamics, coal pyrolysis, char gasification, and gas phase reaction submodels. The rates of heterogeneous reactions are determined by combining Arrhenius rate and diffusion rate. The homogeneous reactions of gas phase can be treated as secondary reactions. A comparison of the calculated and experimental data shows that most gasification performance parameters can be predicted accurately. This good agreement indicates that CFD modeling can be used for complex fluidized beds coal gasification processes. 37 refs., 7 figs., 5 tabs.

  5. Particle bed reactor modeling

    NASA Technical Reports Server (NTRS)

    Sapyta, Joe; Reid, Hank; Walton, Lew

    1993-01-01

    The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

  6. Dynamic bed reactor

    SciTech Connect

    Stormo, K.E.

    1996-07-02

    A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix. 27 figs.

  7. Dynamic bed reactor

    DOEpatents

    Stormo, Keith E.

    1996-07-02

    A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix.

  8. Biparticle fluidized bed reactor

    DOEpatents

    Scott, Charles D.; Marasco, Joseph A.

    1996-01-01

    A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary and tertiary particulate phases, continuously introduced and removed simultaneously in the cocurrent and countercurrent mode, act in a role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Means for introducing and removing the sorbent phases include feed screw mechanisms and multivane slurry valves.

  9. Biparticle fluidized bed reactor

    DOEpatents

    Scott, Charles D.

    1993-01-01

    A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves.

  10. Biparticle fluidized bed reactor

    DOEpatents

    Scott, Charles D.; Marasco, Joseph A.

    1995-01-01

    A fluidized bed reactor system utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves.

  11. Biparticle fluidized bed reactor

    DOEpatents

    Scott, C.D.

    1993-12-14

    A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase is described. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves. 3 figures.

  12. Biparticle fluidized bed reactor

    DOEpatents

    Scott, C.D.; Marasco, J.A.

    1996-02-27

    A fluidized bed reactor system is described which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary and tertiary particulate phases, continuously introduced and removed simultaneously in the cocurrent and countercurrent mode, act in a role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Means for introducing and removing the sorbent phases include feed screw mechanisms and multivane slurry valves. 3 figs.

  13. Biparticle fluidized bed reactor

    DOEpatents

    Scott, C.D.; Marasco, J.A.

    1995-04-25

    A fluidized bed reactor system utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves. 3 figs.

  14. Spouted bed electrowinning of zinc: Part I. Laboratory-scale electrowinning experiments

    NASA Astrophysics Data System (ADS)

    Salas-Morales, Juan Carlos; Evans, J. W.; Newman, O. M. G.; Adcock, P. A.

    1997-02-01

    Two types of laboratory cells have been constructed to electrowin zinc from sulfate electrolytes: one cell was cylindrical while the other had a rectangular (flat) geometry. Cells were operated on industrial or synthetic electrolytes to electrodeposit zinc onto a spouted bed of zinc particles in the range of 0.75 to 1.45 mm. Current efficiencies and cell voltages have been measured during the course of batch experiments, enabling the calculation of the energy consumption per kilogram of zinc deposited. Electrolyte samples have been analyzed. Current densities (current per unit of cell cross-sectional area) were in the range of 1380 to 6200 A/m2. Most catholytes were initially neutral and contained on the order of 150 g/L of zinc. Final acid contents were in the range of 39 to 114 g/L of sulfuric acid. The performance of the cells (particularly with respect to current efficiency) was superior to prior work on fluidized bed electrowinning from similar electrolytes. The flat cell was superior to the cylindrical cell and showed energy consumptions of less than 3 kWh/kg zinc at current densities up to 3500 A/m2 when used to take the zinc content from 150 to 100 g/L zinc. Current efficiencies in this application ranged from 91 to 92 pct.

  15. III. Co-electrodeposition/removal of copper and nickel in a spouted electrochemical reactor

    PubMed Central

    Grimshaw, Pengpeng; Calo, Joseph M.; Hradil, George

    2011-01-01

    Results are presented of an investigation of co-electrodeposition of copper and nickel from acidic solution mixtures in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on metal removal/recovery rate, current efficiency, and corrosion of the deposited metals from the cathodic particles were examined under galvanostatic operation. The quantitative and qualitative behavior of co-electrodeposition of the two metals from their mixtures differs significantly from that of the individual single metal solutions. This is primarily attributed to the metal displacement reaction between Ni0 and Cu2+. This reaction effectively reduces copper corrosion, and amplifies that for nickel (at least at high concentrations). It also amplifies the separation of the deposition regimes of the two metals in time, which indicates that the recovery of each metal as a relatively pure deposit from the mixture is possible. It was also shown that nitrogen sparging considerably increases the observed net electrodeposition rates for both metals – considerably more so than from solutions with just the single metals alone. A numerical model of co-electrodeposition, corrosion, metal displacement, and mass transfer in the cylindrical spouted electrochemical reactor is presented that describes the behavior of the experimental copper and nickel removal data quite well. PMID:21874093

  16. III. Co-electrodeposition/removal of copper and nickel in a spouted electrochemical reactor.

    PubMed

    Grimshaw, Pengpeng; Calo, Joseph M; Hradil, George

    2011-07-11

    Results are presented of an investigation of co-electrodeposition of copper and nickel from acidic solution mixtures in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on metal removal/recovery rate, current efficiency, and corrosion of the deposited metals from the cathodic particles were examined under galvanostatic operation. The quantitative and qualitative behavior of co-electrodeposition of the two metals from their mixtures differs significantly from that of the individual single metal solutions. This is primarily attributed to the metal displacement reaction between Ni(0) and Cu(2+). This reaction effectively reduces copper corrosion, and amplifies that for nickel (at least at high concentrations). It also amplifies the separation of the deposition regimes of the two metals in time, which indicates that the recovery of each metal as a relatively pure deposit from the mixture is possible. It was also shown that nitrogen sparging considerably increases the observed net electrodeposition rates for both metals - considerably more so than from solutions with just the single metals alone. A numerical model of co-electrodeposition, corrosion, metal displacement, and mass transfer in the cylindrical spouted electrochemical reactor is presented that describes the behavior of the experimental copper and nickel removal data quite well.

  17. Plasma-catalytic hybrid system using spouted bed with a gliding arc discharge: CH4 reforming as a model reaction

    NASA Astrophysics Data System (ADS)

    Lee, H.; Sekiguchi, H.

    2011-07-01

    A combination of a gliding arc discharge and a spouted catalytic bed was used to investigate a plasma-catalytic hybrid system using CH4 reforming as a model reaction. Alumina-supported catalysts that contained 0.5 wt% of Pt, Pd, Rh, and Ru (denoted as Pt/Al2O3, Pd/Al2O3, Rh/Al2O3 and Ru/Al2O3, respectively) were used. For comparison, active Al2O3 particles were also examined. The conversion of CH4 and the selectivity of the product were investigated by changing the feed flow rate and reaction time. The production of C2H2, H2 and soot was observed in the gliding arc discharge without a catalyst. Using Pt/Al2O3 and Pd/Al2O3with the gliding arc discharge, C2H4, C2H6 and C2H2 were produced. It is considered that C2H4 and C2H6 were formed by the hydrogenation of C2H2 on the active site of Pt/Al2O3 and Pd/Al2O3. A stronger resistance to deactivation was shown in the presence of Pd/Al2O3 than in the presence of Pt/Al2O3, whereas the selectivity of hydrocarbon using Rh/Al2O3 and Ru/Al2O3 showed a tendency similar to that in active Al2O3 and non-catalytic experiments. The proposed reactor has a potential to improve the selectivity of the plasma process.

  18. Evaluating of scale-up methodologies of gas-solid spouted beds for coating TRISO nuclear fuel particles using advanced measurement techniques

    NASA Astrophysics Data System (ADS)

    Ali, Neven Y.

    The work focuses on implementing for the first time advanced non-invasive measurement techniques to evaluate the scale-up methodology of gas-solid spouted beds for hydrodynamics similarity that has been reported in the literature based on matching dimensionless groups and the new mechanistic scale up methodology that has been developed in our laboratory based on matching the radial profile of gas holdup since the gas dynamics dictate the hydrodynamics of the gas-solid spouted beds. These techniques are gamma-ray computed tomography (CT) to measure the cross-sectional distribution of the phases' holdups and their radial profiles along the bed height and radioactive particle tracking (RPT) to measure in three-dimension (3D) solids velocity and their turbulent parameters. The measured local parameters and the analysis of the results obtained in this work validate our new methodology of scale up of gas-solid spouted beds by comparing for the similarity the phases' holdups and the dimensionless solids velocities and their turbulent parameters that are non-dimensionalized using the minimum spouting superficial gas velocity. However, the scale-up methodology of gas-solid spouted beds that is based on matching dimensionless groups has not been validated for hydrodynamics similarity with respect to the local parameters such as phases' holdups and dimensionless solids velocities and their turbulent parameters. Unfortunately, this method was validated in the literature by only measuring the global parameters. Thus, this work confirms that validation of the scale-up methods of gas-solid spouted beds for hydrodynamics similarity should reside on measuring and analyzing the local hydrodynamics parameters.

  19. A mathematical model for constant and intermittent batch drying of grains in a novel rotating jet spouted bed

    SciTech Connect

    Jumah, R.Y.; Mujumdar, A.S.; Raghavan, G.S.V.

    1996-05-01

    A diffusion-based mathematical model is presented for batch drying of corn in a novel rotating jet spouted bed device under constant as well as intermittent drying conditions. Such a device is suited for drying of large particles (e.g. grains, beans, seeds, etc.) for which internal heat and mass transfer rates control the drying kinetics. Based on literature data for moisture diffusivities the model predictions are compared with experimental data for both continuous and time-dependent air supply and/or heat input. Effects of relevant parameters are evaluated and discussed in the light of potential practical applications. 44 refs.

  20. Fluidized bed coal combustion reactor

    NASA Technical Reports Server (NTRS)

    Moynihan, P. I.; Young, D. L. (Inventor)

    1981-01-01

    A fluidized bed coal reactor includes a combination nozzle-injector ash-removal unit formed by a grid of closely spaced open channels, each containing a worm screw conveyor, which function as continuous ash removal troughs. A pressurized air-coal mixture is introduced below the unit and is injected through the elongated nozzles formed by the spaces between the channels. The ash build-up in the troughs protects the worm screw conveyors as does the cooling action of the injected mixture. The ash layer and the pressure from the injectors support a fluidized flame combustion zone above the grid which heats water in boiler tubes disposed within and/or above the combustion zone and/or within the walls of the reactor.

  1. Fluidized bed coal combustion reactor

    SciTech Connect

    Moynihan, P.I.; Young, D.L.

    1981-09-01

    A fluidized bed coal reactor includes a combination nozzle-injector ash-removal unit formed by a grid of closely spaced open channels, each containing a worm screw conveyor, which function as continuous ash removal troughs. A pressurized air-coal mixture is introduced below the unit and is injected through the elongated nozzles formed by the spaces between the channels. The ash build-up in the troughs protects the worm screw conveyors as does the cooling action of the injected mixture. The ash layer and the pressure from the injectors support a fluidized flame combustion zone above the grid which heats water in boiler tubes disposed within and/or above the combustion zone and/or within the walls of the reactor. Official Gazette of the U.S. Patent and Trademark Office

  2. Packed fluidized bed blanket for fusion reactor

    DOEpatents

    Chi, John W. H.

    1984-01-01

    A packed fluidized bed blanket for a fusion reactor providing for efficient radiation absorption for energy recovery, efficient neutron absorption for nuclear transformations, ease of blanket removal, processing and replacement, and on-line fueling/refueling. The blanket of the reactor contains a bed of stationary particles during reactor operation, cooled by a radial flow of coolant. During fueling/refueling, an axial flow is introduced into the bed in stages at various axial locations to fluidize the bed. When desired, the fluidization flow can be used to remove particles from the blanket.

  3. Fluidized-Bed Reactor With Zone Heating

    NASA Technical Reports Server (NTRS)

    Iya, Sridhar K.

    1989-01-01

    Deposition of silicon on wall suppressed. In new fluidized bed, silicon seed particles heated in uppermost zone of reactor. Hot particles gradually mix with lower particles and descend through fluidized bed. Lower wall of vessel kept relatively cool. Because silane enters at bottom and circulates through reactor pyrolized to silicon at high temperatures, silicon deposited on particles in preference wall. Design of fluidized bed for production of silicon greatly reduces tendency of silicon to deposit on wall of reaction vessel.

  4. Fluidized-Bed Silane-Decomposition Reactor

    NASA Technical Reports Server (NTRS)

    Iya, Sridhar K.

    1991-01-01

    Fluidized-bed pyrolysis reactor produces high-purity polycrystalline silicon from silane or halosilane via efficient heterogeneous deposition of silicon on silicon seed particles. Formation of silicon dust via homogeneous decomposition of silane minimized, and deposition of silicon on wall of reactor effectively eliminated. Silicon used to construct solar cells and other semiconductor products.

  5. Ultra high temperature particle bed reactor design

    NASA Technical Reports Server (NTRS)

    Lazareth, Otto; Ludewig, Hans; Perkins, K.; Powell, J.

    1990-01-01

    A direct nuclear propulsion engine which could be used for a mission to Mars is designed. The main features of this reactor design are high values for I(sub sp) and very efficient cooling. This particle bed reactor consists of 37 cylindrical fuel elements embedded in a cylinder of beryllium which acts as a moderator and reflector. The fuel consists of a packed bed of spherical fissionable fuel particles. Gaseous H2 passes over the fuel bed, removes the heat, and is exhausted out of the rocket. The design was found to be neutronically critical and to have tolerable heating rates. Therefore, this particle bed reactor design is suitable as a propulsion unit for this mission.

  6. Reactor for fluidized bed silane decomposition

    NASA Technical Reports Server (NTRS)

    Iya, Sridhar K. (Inventor)

    1989-01-01

    An improved heated fluidized bed reactor and method for the production of high purity polycrystalline silicon by silane pyrolysis wherein silicon seed particles are heated in an upper heating zone of the reactor and admixed with particles in a lower zone, in which zone a silane-containing gas stream, having passed through a lower cooled gas distribution zone not conducive to silane pyrolysis, contacts the heated seed particles whereon the silane is heterogeneously reduced to silicon.

  7. FBR and RBR particle bed space reactors

    SciTech Connect

    Powell, J.R.; Botts, T.E.

    1983-01-01

    Compact, high-performance nuclear reactor designs based on High-Temperature Gas Reactors (HTGRs) particulate fuel are investigated. The large surface area available with the small-diameter (approx. 500 microns) particulate fuel allows very high power densities (MW's/liter), small temperature differences between fuel and coolant (approx. 10/sup 0/K), high coolant-outlet temperatures (1500 to 3000/sup 0/K, depending on design), and fast reactor startup (approx. 2 to 3 seconds). Two reactor concepts are developed - the Fixed Bed Reactor (FBR), where the fuel particles are packed into a thin annular bed between two porous cylindrical drums, and the Rotating Bed Reactor (RBR), where the fuel particles are held inside a cold rotating (typically approx. 500 rpm) porous cylindrical drum. The FBR can operate steady-state in the closed-cycle He-cooled mode or in the open-cycle H/sub 2/-cooled mode. The RBR will operate only in the open-cycle H/sub 2/-cooled mode.

  8. Pebble Bed Reactor Dust Production Model

    SciTech Connect

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-09-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.

  9. A novel sorbent for transport reactors and fluidized bed reactors

    SciTech Connect

    Copeland, R.; Cesario, M.; Gershanovich, Y.; Sibold, J.; Windecker, B.

    1998-12-31

    Coal Fired Gasifier Combined Cycles (GCC) have both high efficiency and very low emissions. GCCs critically need a method of removing the H{sub 2}S produced from the sulfur in the coal from the hot gases. There has been extensive research on hot gas cleanup systems, focused on the use of a zinc oxide based sorbent (e.g., zinc titanate). TDA Research, Inc. (TDA) is developing a novel sorbent with improved attrition resistance for transport reactors and fluidized bed reactors. The authors are testing sorbents at conditions simulating the operating conditions of the Pinon Pine clean coal technology plant. TDA sulfided several different formulations at 538 C and found several that have high sulfur capacity when tested in a fluidized bed reactor. TDA initiated sorbent regeneration at 538 C. The sorbents retained chemical activity with multiple cycles. Additional tests will be conducted to evaluate the best sorbent formulation.

  10. Method and apparatus for a combination moving bed thermal treatment reactor and moving bed filter

    DOEpatents

    Badger, Phillip C.; Dunn, Jr., Kenneth J.

    2015-09-01

    A moving bed gasification/thermal treatment reactor includes a geometry in which moving bed reactor particles serve as both a moving bed filter and a heat carrier to provide thermal energy for thermal treatment reactions, such that the moving bed filter and the heat carrier are one and the same to remove solid particulates or droplets generated by thermal treatment processes or injected into the moving bed filter from other sources.

  11. Fermentation in a fluidized-bed reactor

    SciTech Connect

    Scott, C.D.

    1983-06-01

    A laboratory-scale fluidized-bed bioreactor system for the production of ethanol from a glucose solution using flocculating Zymomonas mobilis was studied. Although the results are preliminary, 2.5- to 3.8-cm-diameter systems were operated for more than 300 h using fluidized floc particles that are 1-2 mm in diameter. The ethanol production rate in the lower portion of the fluidized bed operating at 30/sup 0/C routinely exceeded 200 g/L x h and under some conditions was as high as 400 g/ L x h with a reactor residence time of a few minutes. This far surpasses the results obtained with a batch, stirred-tank reactor using yeast. Ethanol productivity based on the total reactor volume approached 100 g/L x h, and glucose conversion exceeded 95%. With continued research, even higher production rates will be possible as conditions are optimized and scale-up to larger systems will allow the establishment of technical feasibility.

  12. Silicon production in a fluidized bed reactor

    NASA Technical Reports Server (NTRS)

    Rohatgi, N. K.

    1986-01-01

    Part of the development effort of the JPL in-house technology involved in the Flat-Plate Solar Array (FSA) Project was the investigation of a low-cost process to produce semiconductor-grade silicon for terrestrial photovoltaic cell applications. The process selected was based on pyrolysis of silane in a fluidized-bed reactor (FBR). Following initial investigations involving 1- and 2-in. diameter reactors, a 6-in. diameter, engineering-scale FBR was constructed to establish reactor performance, mechanism of silicon deposition, product morphology, and product purity. The overall mass balance for all experiments indicates that more than 90% of the total silicon fed into the reactor is deposited on silicon seed particles and the remaining 10% becomes elutriated fines. Silicon production rates were demonstrated of 1.5 kg/h at 30% silane concentration and 3.5 kg/h at 80% silane concentration. The mechanism of silicon deposition is described by a six-path process: heterogeneous deposition, homogeneous decomposition, coalescence, coagulation, scavenging, and heterogeneous growth on fines. The bulk of the growth silicon layer appears to be made up of small diameter particles. This product morphology lends support to the concept of the scavenging of homogeneously nucleated silicon.

  13. A fluidized-bed reactor for silane pyrolysis

    NASA Technical Reports Server (NTRS)

    Iya, S.

    1984-01-01

    The silane decomposition in a fluidized bed reactor was studied. The process feasibility and operating windows were determined. Long duration tests were conducted and silicon purity was demonstrated. A high purity linear was installed in the fluid bed reactor; the FBR product was melted and single crystallized. Product purity improvements are noted.

  14. Evolution of Particle Bed Reactor Fuel

    NASA Astrophysics Data System (ADS)

    Jensen, Russell R.; Evans, Robert S.; Husser, Dewayne L.; Kerr, John M.

    1994-07-01

    To realize the potential performance advantages inherent in a particle bed reactor (PBR) for nuclear thermal propulsion (NTP) applications, high performance particle fuel is required. This fuel must operate safely and without failure at high temperature in high pressure, flowing hydrogen propellant. The mixed mean outlet temperature of the propellant is an important characteristic of PBR performance. This temperature is also a critical parameter for fuel particle design because it dictates the required maximum fuel operating temperature. In this paper, the evolution in PBR fuel form to achieve higher operating temperatures is discussed and the potential thermal performance of the different fuel types is evaluated. It is shown that the optimum fuel type for operation under the demanding conditions in a PBR is a coated, solid carbide particle.

  15. Hydraulic characteristics of packed bed reactors

    SciTech Connect

    Young, H.W.

    1986-01-01

    Tracer response tests were conducted to characterize the hydraulics of plastic crossflow filter media at Reynold's numbers less than 25. Sections of this media were cut to fit a laboratory scale reactor and radioactive tracer tests were conducted to measure the residence time distribution under different flow conditions. Introduction of gas and the use of agar coating were included to simulate the effect of biological solids formed within operating reactors. These tests were conducted for three different sizes of media providing a range of specific surface areas with flow rates typical of the residence times found in fixed-bed anaerobic processes. Tracer response curves were generated for these various conditions, and a computer program was developed to fit these curves based on a relatively simple hydraulic model. The best fit model parameters indicating the extent of plug flow and the hydraulic dead space were found to positively correlate with the Reynold's number within the range tested. An increase in the plug flow behavior of the system was associated with an increase in the specific surface area of the media. Gas was found to produce complete mixing regardless of media specific surface area while the simulated biological film had little effect on the tracer response.

  16. Multiscale Analysis of Pebble Bed Reactors

    SciTech Connect

    Hans Gougar; Woo Yoon; Abderrafi Ougouag

    2010-10-01

    – The PEBBED code was developed at the Idaho National Laboratory for design and analysis of pebble-bed high temperature reactors. The diffusion-depletion-pebble-mixing algorithm of the original PEBBED code was enhanced through coupling with the THERMIX-KONVEK code for thermal fluid analysis and by the COMBINE code for online cross section generation. The COMBINE code solves the B-1 or B-3 approximations to the transport equation for neutron slowing down and resonance interactions in a homogeneous medium with simple corrections for shadowing and thermal self-shielding. The number densities of materials within specified regions of the core are averaged and transferred to COMBINE from PEBBED for updating during the burnup iteration. The simple treatment of self-shielding in previous versions of COMBINE led to inaccurate results for cross sections and unsatisfactory core performance calculations. A new version of COMBINE has been developed that treats all levels of heterogeneity using the 1D transport code ANISN. In a 3-stage calculation, slowing down is performed in 167 groups for each homogeneous subregion (kernel, particle layers, graphite shell, control rod absorber annulus, etc.) Particles in a local average pebble are homogenized using ANISN then passed to the next (pebble) stage. A 1D transport solution is again performed over the pebble geometry and the homogenized pebble cross sections are passed to a 1-d radial model of a wedge of the pebble bed core. This wedge may also include homogeneous reflector regions and a control rod region composed of annuli of different absorbing regions. Radial leakage effects are therefore captured with discrete ordinates transport while axial and azimuthal effects are captured with a transverse buckling term. In this paper, results of various PBR models will be compared with comparable models from literature. Performance of the code will be assessed.

  17. Shielded fluid stream injector for particle bed reactor

    DOEpatents

    Notestein, John E.

    1993-01-01

    A shielded fluid-stream injector assembly is provided for particle bed reactors. The assembly includes a perforated pipe injector disposed across the particle bed region of the reactor and an inverted V-shaped shield placed over the pipe, overlapping it to prevent descending particles from coming into direct contact with the pipe. The pipe and shield are fixedly secured at one end to the reactor wall and slidably secured at the other end to compensate for thermal expansion. An axially extending housing aligned with the pipe and outside the reactor and an in-line reamer are provided for removing deposits from the inside of the pipe. The assembly enables fluid streams to be injected and distributed uniformly into the particle bed with minimized clogging of injector ports. The same design may also be used for extraction of fluid streams from particle bed reactors.

  18. COMPUTATIONAL MODELING OF CIRCULATING FLUIDIZED BED REACTORS

    SciTech Connect

    Ibrahim, Essam A

    2013-01-09

    Details of numerical simulations of two-phase gas-solid turbulent flow in the riser section of Circulating Fluidized Bed Reactor (CFBR) using Computational Fluid Dynamics (CFD) technique are reported. Two CFBR riser configurations are considered and modeled. Each of these two riser models consist of inlet, exit, connecting elbows and a main pipe. Both riser configurations are cylindrical and have the same diameter but differ in their inlet lengths and main pipe height to enable investigation of riser geometrical scaling effects. In addition, two types of solid particles are exploited in the solid phase of the two-phase gas-solid riser flow simulations to study the influence of solid loading ratio on flow patterns. The gaseous phase in the two-phase flow is represented by standard atmospheric air. The CFD-based FLUENT software is employed to obtain steady state and transient solutions for flow modulations in the riser. The physical dimensions, types and numbers of computation meshes, and solution methodology utilized in the present work are stated. Flow parameters, such as static and dynamic pressure, species velocity, and volume fractions are monitored and analyzed. The differences in the computational results between the two models, under steady and transient conditions, are compared, contrasted, and discussed.

  19. Use fluid bed reactor for maleic anhydride from butane

    SciTech Connect

    Arnold, S.C.; Neri, A.; Suciu, G.D.; Verde, L.

    1985-09-01

    A new process is described that incorporates three major improvements over the conventional air oxidation of benzene in a fixed-bed reactor system. The new ALMA Process was developed jointly by Alusuisse Italia and Lummus Crest. It includes the following process improvements: n-Butane feedstock, fluidized-bed reactor system, and a continuous maleic anhydride recovery system using an organic solvent. A summary of the process is given, as well as the steps in its development and its economic advantages.

  20. Deleterious Thermal Effects Due To Randomized Flow Paths in Pebble Bed, and Particle Bed Style Reactors

    NASA Technical Reports Server (NTRS)

    Moran, Robert P.

    2013-01-01

    A review of literature associated with Pebble Bed and Particle Bed reactor core research has revealed a systemic problem inherent to reactor core concepts which utilize randomized rather than structured coolant channel flow paths. For both the Pebble Bed and Particle Bed Reactor designs; case studies reveal that for indeterminate reasons, regions within the core would suffer from excessive heating leading to thermal runaway and localized fuel melting. A thermal Computational Fluid Dynamics model was utilized to verify that In both the Pebble Bed and Particle Bed Reactor concepts randomized coolant channel pathways combined with localized high temperature regions would work together to resist the flow of coolant diverting it away from where it is needed the most to cooler less resistive pathways where it is needed the least. In other words given the choice via randomized coolant pathways the reactor coolant will take the path of least resistance, and hot zones offer the highest resistance. Having identified the relationship between randomized coolant channel pathways and localized fuel melting it is now safe to assume that other reactor concepts that utilize randomized coolant pathways such as the foam core reactor are also susceptible to this phenomenon.

  1. Pebble Bed Reactor review update. Fiscal year 1979 annual report

    SciTech Connect

    Not Available

    1980-01-01

    Updated information is presented on the Pebble Bed Reactor (PBR) concept being developed in the Federal Republic of Germany for electricity generation and process heat applications. Information is presented concerning nuclear analysis and core performance, fuel cycle evaluation, reactor internals, and safety and availability.

  2. Packed bed reactor for photochemical .sup.196 Hg isotope separation

    DOEpatents

    Grossman, Mark W.; Speer, Richard

    1992-01-01

    Straight tubes and randomly oriented pieces of tubing having been employed in a photochemical mercury enrichment reactor and have been found to improve the enrichment factor (E) and utilization (U) compared to a non-packed reactor. One preferred embodiment of this system uses a moving bed (via gravity) for random packing.

  3. Perspectives for Fluidized Bed Nuclear Reactor Technology using Rotating Fluidized Beds in a Static Geometry

    NASA Astrophysics Data System (ADS)

    Broqueville, Axel De; Wilde, Juray De

    The new concept of a rotating fluidized bed in a static geometry opens perspectives for fluidized bed nuclear reactor technology and is experimentally and numerically investigated. With conventional fluidized bed technology, the maximum attainable power is rather limited and maximum at a certain fluidization gas flow rate. Using a rotating fluidized bed in a static geometry, the fluidization gas drives both the centrifugal force and the counteracting radial gas-solid drag force in a similar way. This allows operating the reactor at any chosen sufficiently high solids loading over a much wider fluidization gas flow rate range and in particular at much higher fluidization gas flow rates than with conventional fluidized bed reactor technology, offering increased flexibility with respect to cooling via the fluidization gas. Furthermore, the centrifugal force can be a multiple of earth gravity, allowing radial gas-solid slip velocities much higher than in conventional fluidized beds. The latter result in gas-solid heat transfer coefficients one or multiple orders of magnitude higher than in conventional fluidized beds. The combination of dense operation and high fluidization gas flow rates allows process intensification and a more compact reactor design.

  4. Computational fluid dynamic modeling of fluidized-bed polymerization reactors

    SciTech Connect

    Rokkam, Ram

    2012-01-01

    Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified using simple test cases, validated with experiments and applied to a pilot-scale polymerization fluidized-bed reactor. The CFD model reproduced qualitative trends in particle segregation and entrainment due to electrostatic charges observed in experiments. For the scale up of fluidized bed reactor, filtered models are developed and implemented on pilot scale reactor.

  5. Coal hydrogenation and deashing in ebullated bed catalytic reactor

    DOEpatents

    Huibers, Derk T. A.; Johanson, Edwin S.

    1983-01-01

    An improved process for hydrogenation of coal containing ash with agglomeration and removal of ash from an ebullated bed catalytic reactor to produce deashed hydrocarbon liquid and gas products. In the process, a flowable coal-oil slurry is reacted with hydrogen in an ebullated catalyst bed reaction zone at elevated temperature and pressure conditions. The upward velocity and viscosity of the reactor liquid are controlled so that a substantial portion of the ash released from the coal is agglomerated to form larger particles in the upper portion of the reactor above the catalyst bed, from which the agglomerated ash is separately withdrawn along with adhering reaction zone liquid. The resulting hydrogenated hydrocarbon effluent material product is phase separated to remove vapor fractions, after which any ash remaining in the liquid fraction can be removed to produce substantially ash-free coal-derived liquid products.

  6. Effect of bed characters on the direct synthesis of dimethyldichlorosilane in fluidized bed reactor.

    PubMed

    Zhang, Pan; Duan, Ji H; Chen, Guang H; Wang, Wei W

    2015-01-01

    This paper presents the numerical investigation of the effects of the general bed characteristics such as superficial gas velocities, bed temperature, bed heights and particle size, on the direct synthesis in a 3D fluidized bed reactor. A 3D model for the gas flow, heat transfer, and mass transfer was coupled to the direct synthesis reaction mechanism verified in the literature. The model was verified by comparing the simulated reaction rate and dimethyldichlorosilane (M2) selectivity with the experimental data in the open literature and real production data. Computed results indicate that superficial gas velocities, bed temperature, bed heights, and particle size have vital effect on the reaction rates and/or M2 selectivity.

  7. Effect of bed characters on the direct synthesis of dimethyldichlorosilane in fluidized bed reactor.

    PubMed

    Zhang, Pan; Duan, Ji H; Chen, Guang H; Wang, Wei W

    2015-01-01

    This paper presents the numerical investigation of the effects of the general bed characteristics such as superficial gas velocities, bed temperature, bed heights and particle size, on the direct synthesis in a 3D fluidized bed reactor. A 3D model for the gas flow, heat transfer, and mass transfer was coupled to the direct synthesis reaction mechanism verified in the literature. The model was verified by comparing the simulated reaction rate and dimethyldichlorosilane (M2) selectivity with the experimental data in the open literature and real production data. Computed results indicate that superficial gas velocities, bed temperature, bed heights, and particle size have vital effect on the reaction rates and/or M2 selectivity. PMID:25742729

  8. Effect of Bed Characters on the Direct Synthesis of Dimethyldichlorosilane in Fluidized Bed Reactor

    PubMed Central

    Zhang, Pan; Duan, Ji H.; Chen, Guang H.; Wang, Wei W.

    2015-01-01

    This paper presents the numerical investigation of the effects of the general bed characteristics such as superficial gas velocities, bed temperature, bed heights and particle size, on the direct synthesis in a 3D fluidized bed reactor. A 3D model for the gas flow, heat transfer, and mass transfer was coupled to the direct synthesis reaction mechanism verified in the literature. The model was verified by comparing the simulated reaction rate and dimethyldichlorosilane (M2) selectivity with the experimental data in the open literature and real production data. Computed results indicate that superficial gas velocities, bed temperature, bed heights, and particle size have vital effect on the reaction rates and/or M2 selectivity. PMID:25742729

  9. Flow instability in particle-bed nuclear reactors

    NASA Technical Reports Server (NTRS)

    Kerrebrock, Jack L.

    1993-01-01

    The particle-bed core offers mitigation of some of the problems of solid-core nuclear rocket reactors. Dividing the fuel elements into small spherical particles contained in a cylindrical bed through which the propellant flows radially, may reduce the thermal stress in the fuel elements, allowing higher propellant temperatures to be reached. The high temperature regions of the reactor are confined to the interior of cylindrical fuel assemblies, so most of the reactor can be relatively cool. This enables the use of structural and moderating materials which reduce the minimum critical size and mass of the reactor. One of the unresolved questions about this concept is whether the flow through the particle-bed will be well behaved, or will be subject to destructive flow instabilities. Most of the recent analyses of the stability of the particle-bed reactor have been extensions of the approach of Bussard and Delauer, where the bed is essentially treated as an array of parallel passages, so that the mass flow is continuous from inlet to outlet through any one passage. A more general three dimensional model of the bed is adopted, in which the fluid has mobility in three dimensions. Comparison of results of the earlier approach to the present one shows that the former does not accurately represent the stability at low Re. The more complete model presented should be capable of meeting this deficiency while accurately representing the effects of the cold and hot frits, and of heat conduction and radiation in the particle-bed. It can be extended to apply to the cylindrical geometry of particle-bed reactors without difficulty. From the exemplary calculations which were carried out, it can be concluded that a particle-bed without a cold frit would be subject to instability if operated at the high temperatures desired for nuclear rockets, and at power densities below about 4 megawatts per liter. Since the desired power density is about 40 megawatts per liter, it can be concluded

  10. Hydrodynamics of Packed Bed Reactor in Low Gravity

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Nahra, Henry K.; Balakotaiah, Vemuri

    2005-01-01

    Packed bed reactors are well known for their vast and diverse applications in the chemical industry; from gas absorption, to stripping, to catalytic conversion. Use of this type of reactor in terrestrial applications has been rather extensive because of its simplicity and relative ease of operation. Developing similar reactors for use in microgravity is critical to many space-based advanced life support systems. However, the hydrodynamics of two-phase flow packed bed reactors in this new environment and the effects of one physiochemical process on another has not been adequately assessed. Surface tension or capillary forces play a much greater role which results in a shifting in flow regime transitions and pressure drop. Results from low gravity experiments related to flow regimes and two-phase pressure drop models are presented in this paper along with a description of plans for a flight experiment on the International Space Station (ISS). Understanding the packed bed hydrodynamics and its effects on mass transfer processes in microgravity is crucial for the design of packed bed chemical or biological reactors to be used for water reclamation and other life support processes involving water purification.

  11. High power density reactors based on direct cooled particle beds

    NASA Astrophysics Data System (ADS)

    Powell, J. R.; Horn, F. L.

    Reactors based on direct cooled High Temperature Gas Cooled Reactor (HTGR) type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out along the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBRs) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed.

  12. Small particle bed reactors: Sensitivity to Brayton cycle parameters

    NASA Astrophysics Data System (ADS)

    Coiner, John R.; Short, Barry J.

    Relatively simple particle bed reactor (PBR) algorithms were developed for optimizing low power closed Brayton cycle (CBC) systems. These algorithms allow the system designer to understand the relationship among key system parameters as well as the sensitivity of the PBR size and mass (a major system component) to variations in these parameters. Thus, system optimization can be achieved.

  13. Operation of Packed-Bed Reactors Studied in Microgravity

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri

    2004-01-01

    The operation of a packed bed reactor (PBR) involves gas and liquid flowing simultaneously through a fixed-bed of solid particles. Depending on the application, the particles can be various shapes and sizes but are generally designed to force the two fluid phases through a tortuous route of narrow channels connecting the interstitial space. The PBR is the most common type of reactor in industry because it provides for intimate contact and high rates of transport between the phases needed to sustain chemical or biological reactions. The packing may also serve as either a catalyst or as a support for growing biological material. Furthermore, this type of reactor is relatively compact and requires minimal power to operate. This makes it an excellent candidate for unit operations in support of long-duration human space activities.

  14. Torrefaction of sawdust in a fluidized bed reactor.

    PubMed

    Li, Hui; Liu, Xinhua; Legros, Robert; Bi, Xiaotao T; Lim, C J; Sokhansanj, Shahab

    2012-01-01

    In the present work, stable fluidization of sawdust was achieved in a bench fluidized bed with an inclined orifice distributor without inert bed materials. A solids circulation pattern was established in the bed without the presence of slugging and channeling. The effects of treatment severity and weight loss on the solid product properties were identified. The decomposition of hemicelluloses was found to be responsible for the significant changes of chemical, physical and mechanical properties of the torrefied sawdust, including energy content, particle size distribution and moisture absorption capacity. The hydrophobicity of the torrefied sawdust was improved over the raw sawdust with a reduction of around 40 wt.% in saturated water uptake rate, and enhanced with increasing the treatment severity due to the decomposition of hemicelluloses which are rich in hydroxyl groups. The results in this study provided the basis for torrefaction in fluidized bed reactors.

  15. Heterogeneous decomposition of silane in a fixed bed reactor

    NASA Technical Reports Server (NTRS)

    Iya, S. K.; Flagella, R. N.; Dipaolo, F. S.

    1982-01-01

    Heterogeneous decomposition of silane in a fluidized bed offers an attractive route for the low-cost production of silicon for photovoltaic application. To obtain design data for a fluid bed silane pyrolysis reactor, deposition experiments were conducted in a small-scale fixed bed apparatus. Data on the decomposition mode, plating rate, and deposition morphology were obtained in the temperature range 600-900 C. Conditions favorable for heterogeneous decomposition with good deposition morphology were identified. The kinetic rate data showed the reaction to be first order with an activation energy of 38.8 kcal/mol, which agrees well with work done by others. The results are promising for the development of an economically attractive fluid bed process.

  16. Heterogeneous decomposition of silane in a fixed bed reactor

    NASA Technical Reports Server (NTRS)

    Iya, S. K.; Flagella, R. N.; Dipaolo, F. S.

    1981-01-01

    Heterogeneous decomposition of silane in a fluidized bed offers an attractive route for the low-cost production of silicon for photovoltaic application. To obtain design data for a fluid bed silane pyrolysis reactor, deposition experiments were conducted in a small-scale fixed bed apparatus. Data on the decomposition mode, plating rate, and deposition morphology were obtained in the temperature range 600 900 C. Conditions favorable for heterogenous decomposition with good deposition morphology were identified. The kinetic rate data showed the reaction to be first order with an activation energy of 38.8 kcal/mole, which agrees well with work done by others. The results are promising for the development of an economically attractive fluid bed process.

  17. Flow instability in particle-bed nuclear reactors

    NASA Technical Reports Server (NTRS)

    Kerrebrock, J. L.; Kalamas, J.

    1993-01-01

    A three-dimensional model of the stability of the particle-bed reactor is presented, in which the fluid has mobility in three dimensions. The model accurately represents the stability at low Re numbers as well as the effects of the cold and hot frits and of the heat conduction and radiation in the particle bed. The model can be easily extended to apply to the cylindrical geometry of particle-bed reactors. Exemplary calculations are carried out, showing that a particle bed without a cold frit would be subject to instability if operated at the high-temperature ratios used for nuclear rockets and at power densities below about 4 MW/l; since the desired power density for such a reactor is about 40 MW/l, the operation at design exit temperature but at reduced power could be hazardous. Calculations show however that it might be possible to remove the instability problem by appropriate combinations of cold and hot frits.

  18. Waste tyre pyrolysis: modelling of a moving bed reactor.

    PubMed

    Aylón, E; Fernández-Colino, A; Murillo, R; Grasa, G; Navarro, M V; García, T; Mastral, A M

    2010-12-01

    This paper describes the development of a new model for waste tyre pyrolysis in a moving bed reactor. This model comprises three different sub-models: a kinetic sub-model that predicts solid conversion in terms of reaction time and temperature, a heat transfer sub-model that calculates the temperature profile inside the particle and the energy flux from the surroundings to the tyre particles and, finally, a hydrodynamic model that predicts the solid flow pattern inside the reactor. These three sub-models have been integrated in order to develop a comprehensive reactor model. Experimental results were obtained in a continuous moving bed reactor and used to validate model predictions, with good approximation achieved between the experimental and simulated results. In addition, a parametric study of the model was carried out, which showed that tyre particle heating is clearly faster than average particle residence time inside the reactor. Therefore, this fast particle heating together with fast reaction kinetics enables total solid conversion to be achieved in this system in accordance with the predictive model.

  19. Maltodextrin hydrolysis in a fluidized-bed immobilized enzyme reactor

    SciTech Connect

    Vallat, I.; Monsan, P.; Riba, J.P.

    1986-02-01

    The present work deals with maltodextrin hydrolysis by glucoamylase immobilized onto corn stover in a fluidized bed reactor. An industrial enzyme preparation was convalently grafted onto corn stover, yielding an activity of up to 372 U/g and 1700 U/g for support particle sizes of 0.8 and 0.2 mm, respectively. A detailed kinetic study, using a differntial reactor, allowed the characterization of the influence of mass transfer resistance on the reaction catalyzed by immobilized glucoamylase. A simple and general mathematical model was then developed to describe the experimental conversion data and found to be vaild.

  20. Fixed Packed Bed Reactors in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro; McCready, Mark J.

    2004-01-01

    gravity cocurrent flow to determine the mass transfer enhancement and propose new mass transfer correlations for two-phase gas-liquid flows through packed beds in microgravity.

  1. Fixed Packed Bed Reactors in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro; McCready, Mark J.

    2004-01-01

    those in normal gravity cocurrent flow to determine the mass transfer enhancement and propose new mass transfer correlations for two-phase gas-liquid flows through packed beds in microgravity.

  2. Development of the Packed Bed Reactor ISS Flight Experiment

    NASA Technical Reports Server (NTRS)

    Patton, Martin O.; Bruzas, Anthony E.; Rame, Enrique; Motil, Brian J.

    2012-01-01

    Packed bed reactors are compact, require minimum power and maintenance to operate, and are highly reliable. These features make this technology a leading candidate as a potential unit operation in support of long duration human space exploration. On earth, this type of reactor accounts for approximately 80% of all the reactors used in the chemical process industry today. Development of this technology for space exploration is truly crosscutting with many other potential applications (e.g., in-situ chemical processing of planetary materials and transport of nutrients through soil). NASA is developing an ISS experiment to address this technology with particular focus on water reclamation and air revitalization. Earlier research and development efforts funded by NASA have resulted in two hydrodynamic models which require validation with appropriate instrumentation in an extended microgravity environment. The first model developed by Motil et al., (2003) is based on a modified Ergun equation. This model was demonstrated at moderate gas and liquid flow rates, but extension to the lower flow rates expected in many advanced life support systems must be validated. The other model, developed by Guo et al., (2004) is based on Darcy s (1856) law for two-phase flow. This model has been validated for a narrow range of flow parameters indirectly (without full instrumentation) and included test points where the flow was not fully developed. The flight experiment presented will be designed with removable test sections to test the hydrodynamic models. The experiment will provide flexibility to test additional beds with different types of packing in the future. One initial test bed is based on the VRA (Volatile Removal Assembly), a packed bed reactor currently on ISS whose behavior in micro-gravity is not fully understood. Improving the performance of this system through an accurate model will increase our ability to purify water in the space environment.

  3. Core Optimization of a Deep-Burn Pebble Bed Reactor

    SciTech Connect

    Brian Boer; Abderrafi M. Ougouag

    2010-06-01

    Achieving a high fuel burnup in the Deep-Burn (DB) pebble bed reactor design, while remaining within the limits for fuel temperature, power peaking and temperature reactivity feedback, is challenging. The high content of Pu and Minor Actinides in the Deep-Burn fuel significantly impacts the thermal neutron energy spectrum as compared to a ’standard’ UO2 fueled core. This can result in power and temperature peaking in the pebble bed core in locally thermalized regions near the graphite reflectors. Furthermore, the interplay of the Pu resonances of the neutron absorption cross sections at low-lying energies can lead to a positive temperature reactivity coefficient for the graphite moderator at certain operating conditions. The DB concept focuses on the destruction of spent fuel transuranics in TRISO coated particle fueled gas-cooled reactors with the aim of a fractional fuel burnup of 60-70% in fissions per initial metal atom (FIMA), using a single-pass, multi in-core fuel (re)cycling scheme. In principle, the DB pebble bed concept employs the same reactor designs as the present low enriched uranium core designs, i.e. the 400 MWth Pebble Bed Modular Reactor (PBMR-400). A Pu and Minor Actinide fueled PBMR-400 design serves as the starting point for a core optimization study. The fuel temperature, power peak, temperature reactivity coefficients, and burnup capabilities of the modified designs are analyzed with the PEBBED code. A code-to-code coupling with the PASTA code allows for the analysis of the TRISO fuel performance for both normal and Loss Of Forced Cooling conditions. An improved core design is sought, maximizing the fuel discharge burnup, while retaining negative temperature reactivity feedback coefficients for the entire temperature range and avoiding high fuel temperatures (fuel failure probabilities).

  4. Nuclear Safeguards Considerations For The Pebble Bed Modular Reactor (PBMR)

    SciTech Connect

    Phillip Casey Durst; David Beddingfield; Brian Boyer; Robert Bean; Michael Collins; Michael Ehinger; David Hanks; David L. Moses; Lee Refalo

    2009-10-01

    High temperature reactors (HTRs) have been considered since the 1940s, and have been constructed and demonstrated in the United Kingdom (Dragon), United States (Peach Bottom and Fort Saint Vrain), Japan (HTTR), Germany (AVR and THTR-300), and have been the subject of conceptual studies in Russia (VGM). The attraction to these reactors is that they can use a variety of reactor fuels, including abundant thorium, which upon reprocessing of the spent fuel can produce fissile U-233. Hence, they could extend the stocks of available uranium, provided the fuel is reprocessed. Another attractive attribute is that HTRs typically operate at a much higher temperature than conventional light water reactors (LWRs), because of the use of pyrolytic carbon and silicon carbide coated (TRISO) fuel particles embedded in ceramic graphite. Rather than simply discharge most of the unused heat from the working fluid in the power plant to the environment, engineers have been designing reactors for 40 years to recover this heat and make it available for district heating or chemical conversion plants. Demonstrating high-temperature nuclear energy conversion was the purpose behind Fort Saint Vrain in the United States, THTR-300 in Germany, HTTR in Japan, and HTR-10 and HTR-PM, being built in China. This resulted in nuclear reactors at least 30% or more thermodynamically efficient than conventional LWRs, especially if the waste heat can be effectively utilized in chemical processing plants. A modern variant of high temperature reactors is the Pebble Bed Modular Reactor (PBMR). Originally developed in the United States and Germany, it is now being redesigned and marketed by the Republic of South Africa and China. The team examined historical high temperature and high temperature gas reactors (HTR and HTGR) and reviewed safeguards considerations for this reactor. The following is a preliminary report on this topic prepared under the ASA-100 Advanced Safeguards Project in support of the NNSA Next

  5. Automated Design and Optimization of Pebble-bed Reactor Cores

    SciTech Connect

    Hans D. Gougar; Abderrafi M. Ougouag; William K. Terry

    2010-07-01

    We present a conceptual design approach for high-temperature gas-cooled reactors using recirculating pebble-bed cores. The design approach employs PEBBED, a reactor physics code specifically designed to solve for and analyze the asymptotic burnup state of pebble-bed reactors, in conjunction with a genetic algorithm to obtain a core that maximizes a fitness value that is a function of user-specified parameters. The uniqueness of the asymptotic core state and the small number of independent parameters that define it suggest that core geometry and fuel cycle can be efficiently optimized toward a specified objective. PEBBED exploits a novel representation of the distribution of pebbles that enables efficient coupling of the burnup and neutron diffusion solvers. With this method, even complex pebble recirculation schemes can be expressed in terms of a few parameters that are amenable to modern optimization techniques. With PEBBED, the user chooses the type and range of core physics parameters that represent the design space. A set of traits, each with acceptable and preferred values expressed by a simple fitness function, is used to evaluate the candidate reactor cores. The stochastic search algorithm automatically drives the generation of core parameters toward the optimal core as defined by the user. The optimized design can then be modeled and analyzed in greater detail using higher resolution and more computationally demanding tools to confirm the desired characteristics. For this study, the design of pebble-bed high temperature reactor concepts subjected to demanding physical constraints demonstrated the efficacy of the PEBBED algorithm.

  6. Biological perchlorate reduction in packed bed reactors using elemental sulfur.

    PubMed

    Sahu, Ashish K; Conneely, Teresa; Nüsslein, Klaus R; Ergas, Sarina J

    2009-06-15

    Sulfur-utilizing perchlorate (ClO4-)-reducing bacteria were enriched from a denitrifying wastewater seed with elemental sulfur (S0) as an electron donor. The enrichment was composed of a diverse microbial community, with the majority identified as members of the phylum Proteobacteria. Cultures were inoculated into bench-scale packed bed reactors (PBR) with S0 and crushed oyster shell packing media. High ClO4-concentrations (5-8 mg/L) were reduced to < 0.5 mg/L at an empty bed contact time (EBCT) of 13 h. Low C1O4- concentrations (60-120 microg/L), more typical of contaminated groundwater sites, were reduced to < 4 microg/L at an EBCT of 7.5 h. PBR performance decreased when effluent recirculation was applied or when smaller S0 particle sizes were used, indicating that mass transfer of ClO4- to the attached biofilm was not the limiting mechanism in this process, and that biofilm acclimation and growth were key factors in overall reactor performance. The presence of nitrate (6.5 mg N/L) inhibited ClO4- reduction. The microbial community composition was found to change with ClO4- availability from a majority of Beta-Proteobacteria near the influent end of the reactor to primarily sulfur-oxidizing bacteria near the effluent end of the reactor. PMID:19603663

  7. Investigation of Anaerobic Fluidized Bed Reactor/ Aerobic Moving Bed Bio Reactor (AFBR/MMBR) System for Treatment of Currant Wastewater

    PubMed Central

    JAFARI, Jalil; MESDAGHINIA, Alireza; NABIZADEH, Ramin; FARROKHI, Mehrdad; MAHVI, Amir Hossein

    2013-01-01

    Background: Anaerobic treatment methods are more suitable for the treatment of concentrated wastewater streams, offer lower operating costs, the production of usable biogas product. The aim of this study was to investigate the performance of an Anaerobic Fluidized Bed Reactor (AFBR)-Aerobic Moving Bed Bio Reactor (MBBR) in series arrangement to treat Currant wastewater. Methods: The bed materials of AFBR were cylindrical particles made of PVC with a diameter of 2–2.3 mm, particle density of 1250 kg/m3. The volume of all bed materials was 1.7 liter which expanded to 2.46 liters in fluidized situation. In MBBR, support media was composed of 1.5 liters Bee-Cell 2000 having porosity of 87% and specific surface area of 650m2/m3. Results: When system operated at 35 ºC, chemical oxygen demand (COD) removal efficiencies were achieved to 98% and 81.6% for organic loading rates (OLR) of 9.4 and 24.2 g COD/l.d, and hydraulic retention times (HRT) of 48 and 18 h, in average COD concentration feeding of 18.4 g/l, respectively. Conclusion: The contribution of AFBR in total COD removal efficiency at an organic loading rate (OLR) of 9.4 g COD/l.d was 95%, and gradually decreased to 76.5% in OLR of 24.2 g COD/l.d. Also with increasing in organic loading rate the contribution of aerobic reactor in removing COD gradually decreased. In this system, the anaerobic reactor played the most important role in the removal of COD, and the aerobic MBBR was actually needed to polish the anaerobic treated wastewater. PMID:26056640

  8. Tightly Coupled Multiphysics Algorithm for Pebble Bed Reactors

    SciTech Connect

    HyeongKae Park; Dana Knoll; Derek Gaston; Richard Martineau

    2010-10-01

    We have developed a tightly coupled multiphysics simulation tool for the pebble-bed reactor (PBR) concept, a type of Very High-Temperature gas-cooled Reactor (VHTR). The simulation tool, PRONGHORN, takes advantages of the Multiphysics Object-Oriented Simulation Environment library, and is capable of solving multidimensional thermal-fluid and neutronics problems implicitly with a Newton-based approach. Expensive Jacobian matrix formation is alleviated via the Jacobian-free Newton-Krylov method, and physics-based preconditioning is applied to minimize Krylov iterations. Motivation for the work is provided via analysis and numerical experiments on simpler multiphysics reactor models. We then provide detail of the physical models and numerical methods in PRONGHORN. Finally, PRONGHORN's algorithmic capability is demonstrated on a number of PBR test cases.

  9. Effect of calcium on moving-bed biofilm reactor biofilms.

    PubMed

    Goode, C; Allen, D G

    2011-03-01

    The effect of calcium concentration on the biofilm structure, microbiology, and treatment performance was evaluated in a moving-bed biofilm reactor. Three experiments were conducted in replicate laboratory-scale reactors to determine if wastewater calcium is an important variable for the design and optimization of these reactors. Biofilm structural properties, such as thickness, oxygen microprofiles, and the composition of extracellular polymeric substances (EPS) were affected by increasing calcium concentrations. Above a threshold concentration of calcium between 1 and 50 mg/L, biofilms became thicker and denser, with a shift toward increasingly proteinaceous EPS at higher calcium concentrations up to 200 mgCa2+/L. At 300 mgCa2+/L, biofilms were found to become primarily composed of inorganic calcium precipitates. Microbiology was assessed through microscopy, denaturing grade gel electrophoresis, and enumeration of higher organisms. Higher calcium concentrations were found to change the bacterial community and promote the abundant growth of filamentous organisms and various protazoa and metazoan populations. The chemical oxygen demand removal efficiency was improved for reactors at calcium concentrations of 50 mg/L and above. Reactor effluents for the lowest calcium concentration (1 mgCa2+/L) were found to be turbid (>50 NTU), as a result of the detachment of small and poorly settling planktonic biomass, whereas higher concentrations promoted settling of the suspended phase. In general, calcium was found to be an important variable causing significant changes in biofilm structure and reactor function.

  10. Completely stirred tank reactor behavior in an unmixed anaerobic digester: the induced bed reactor.

    PubMed

    Dustin, J Shaun; Hansen, Conly L

    2012-09-01

    The induced bed reactor (IBR) was developed to apply high-rate anaerobic digestion techniques to high suspended solids substrates (6 to 12% total solids). This technology has been implemented at multiple full-scale installations in the United States and Canada. Residence time distribution studies for 58-L laboratory-scale reactors operated at a 3.8-day hydraulic retention time were conducted at 35, 45, and 55 degrees C under control and active digestion conditions. Rhodamine WT and lithium ion were used as tracers. The results show that the IBR most closely approximated completely stirred tank reactor behavior when operated under the study conditions. Mixing was likely a result of a (1) combination of energy inputs from thermal gradients induced by heat flux through the reactors, and (2) shear induced by gas evolution in the sludge bed. PMID:23012770

  11. Pellet bed reactor for nuclear propelled vehicles: Part 1: Reactor technology

    NASA Technical Reports Server (NTRS)

    El-Genk, Mohamed S.

    1991-01-01

    The pellet bed reactor (PBR) for nuclear propelled vehicles is briefly discussed. Much of the information is given in viewgraph form. Viewgraphs include information on the layout for a Mars mission using a PBR nuclear thermal rocket, the rocket reactor layout, the fuel pellet design, materials compatibility, fuel microspheres, microsphere coating, melting points in quasibinary systems, stress analysis of microspheres, safety features, and advantages of the PBR concept.

  12. Chemical looping combustion in a rotating bed reactor--finding optimal process conditions for prototype reactor.

    PubMed

    Håkonsen, Silje Fosse; Blom, Richard

    2011-11-15

    A lab-scale rotating bed reactor for chemical looping combustion has been designed, constructed, and tested using a CuO/Al(2)O(3) oxygen carrier and methane as fuel. Process parameters such as bed rotating frequency, gas flows, and reactor temperature have been varied to find optimal performance of the prototype reactor. Around 90% CH(4) conversion and >90% CO(2) capture efficiency based on converted methane have been obtained. Stable operation has been accomplished over several hours, and also--stable operation can be regained after intentionally running into unstable conditions. Relatively high gas velocities are used to avoid fully reduced oxygen carrier in part of the bed. Potential CO(2) purity obtained is in the range 30 to 65%--mostly due to air slippage from the air sector--which seems to be the major drawback of the prototype reactor design. Considering the prototype nature of the first version of the rotating reactor setup, it is believed that significant improvements can be made to further avoid gas mixing in future modified and up-scaled reactor versions.

  13. Computational Fluid Dynamics Simulation of Fluidized Bed Polymerization Reactors

    SciTech Connect

    Fan, Rong

    2006-01-01

    Fluidized beds (FB) reactors are widely used in the polymerization industry due to their superior heat- and mass-transfer characteristics. Nevertheless, problems associated with local overheating of polymer particles and excessive agglomeration leading to FB reactors defluidization still persist and limit the range of operating temperatures that can be safely achieved in plant-scale reactors. Many people have been worked on the modeling of FB polymerization reactors, and quite a few models are available in the open literature, such as the well-mixed model developed by McAuley, Talbot, and Harris (1994), the constant bubble size model (Choi and Ray, 1985) and the heterogeneous three phase model (Fernandes and Lona, 2002). Most these research works focus on the kinetic aspects, but from industrial viewpoint, the behavior of FB reactors should be modeled by considering the particle and fluid dynamics in the reactor. Computational fluid dynamics (CFD) is a powerful tool for understanding the effect of fluid dynamics on chemical reactor performance. For single-phase flows, CFD models for turbulent reacting flows are now well understood and routinely applied to investigate complex flows with detailed chemistry. For multiphase flows, the state-of-the-art in CFD models is changing rapidly and it is now possible to predict reasonably well the flow characteristics of gas-solid FB reactors with mono-dispersed, non-cohesive solids. This thesis is organized into seven chapters. In Chapter 2, an overview of fluidized bed polymerization reactors is given, and a simplified two-site kinetic mechanism are discussed. Some basic theories used in our work are given in detail in Chapter 3. First, the governing equations and other constitutive equations for the multi-fluid model are summarized, and the kinetic theory for describing the solid stress tensor is discussed. The detailed derivation of DQMOM for the population balance equation is given as the second section. In this section

  14. Pellet bed reactor concept for nuclear electric propulsion

    NASA Astrophysics Data System (ADS)

    El-Genk, Mohamed S.; Morley, Nicholas J.; Juhasz, Albert

    1993-01-01

    For Nuclear Electric Propulsion (NEP) applications, gas cooled nuclear reactors with dynamic energy conversion systems offer high specific power and low total mass. This paper describes the Pellet Bed Reactor (PeBR) concept for potential NEP missions to Mars. The helium cooled, 75-80 MWt PeBR, consists of a single annular fuel region filled with a randomly packed bed of spherical fuel pellets, is designed for multiple starts, and offers unique safety and operation features. Each fuel pellet, about 8-10 mm in diameter, is composed of hundreds of TRISO type fuel microspheres embedded in a graphite matrix for a full retention of fission products. To eliminate the likelihood of a single-point failure, the annular core of the PeBR is divided into three 120° sectors. Each sector is self contained and separate and capable of operating and being cooled on its own and in cooperation with either one or two other sectors. Each sector is coupled to a separate, 5 MWe Closed Brayton Cycle (CBC) energy conversion unit and is subcritical for safe handling and launching. In the event of a failure of the cooling system of a core sector, the reactor power level may be reduced, allowing adjacent sectors to convect the heat away using their own cooling system, thus maintaining reactor operation. Also, due to the absence of an internal core structure in the PeBR core, fueling of the reactor can easily be performed either at the launch facility or in orbit, and refueling can be accomplished in orbit as needed to extend the power system lifetime

  15. PEBBED ANALYSIS OF HOT SPOTS IN PEBBLE-BED REACTORS

    SciTech Connect

    Abderrafi M. Ougouag; Hans D. Gougar; William K. Terry; Frederik Reitsma; Wessel Joubert

    2005-09-01

    The Idaho National Laboratory’s PEBBED code and simple probability considerations are used to estimate the likelihood and consequences of the accumulation of highly reactive pebbles in the region of peak power in a pebble-bed reactor. The PEBBED code is briefly described, and the logic of the probability calculations is presented in detail. The results of the calculations appear to show that hot-spot formation produces only moderate increases in peak accident temperatures, and no increases at all in normal operating temperatures.

  16. Critical Issues for Particle-Bed Reactor Fuels

    NASA Astrophysics Data System (ADS)

    Evans, Robert S.; Husser, Dewayne L.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    Particle-Bed Reactors (PBRs) potentially offer performance advantages for nuclear thermal propulsion, including very high power densities, thrust-to-weight ratios, and specific impulses. A key factor in achieving all of these is the development of a very-high-temperature fuel. The critical issues for all such PBR fuels are uranium loading, thermomechanical and thermochemical stability, compatibility with contacting materials, fission product retention, manufacturability, and operational tolerance for particle failures. Each issue is discussed with respect to its importance to PBR operation, its status among current fuels, and additional development needs. Mixed-carbide-based fuels are recommended for further development to support high-performance PBRs.

  17. Design and Cold Mode Experiment of Dual Bubbling Fluidized Bed Reactors for Multiple CCR Cycles

    NASA Astrophysics Data System (ADS)

    Fang, F.; Li, Z. S.; Cai, N. S.

    The dual fluidized bed reactors are the key technology to fulfill the multiple CCR (calcination/carbonation reactions) cycles for CO2 capture from the flue gases. Firstly, the dual bubbling fluidized bed reactors were selected in this work based on analyzing different types of dual fluidized bed reactors. Secondly, the design method of dual fluidized bed reactors for CO2 capture with CCR concept was proposed. Thirdly, with the designed results, a cold mode of the dual bubbling fluidized bed reactors was built. The long-term stable operation and the continuous solid circulation between two reactors could be achieved successfully. The experimental results indicated that the solid circulation rate was increased with an increase of bed height, diameter of solid injection nozzle, and diameter of holes on the solid injection nozzle.

  18. Upflow fixed bed bioelectrochemical reactor for wastewater treatment applications.

    PubMed

    González-Gutiérrez, Linda; Frontana, Carlos; Martínez, Eduardo

    2015-01-01

    A cylindrical Upflow Fixed Bed Reactor (UFB-BER) with granular activated carbon, steel mesh electrodes and anaerobic microorganisms, was constructed for analyzing how hydrodynamic parameters affect the reactions involved during wastewater treatment processes for azo dye degradation. Dye removal percentage was not compromised by decreasing HRTm (99-90% upon changing HRTm from 4 to 1h in single pass mode). Using the residence time distribution method for hydrodynamic characterization, it was found that a higher dispersion in the reactor occurs for HRTm=1h, than for HRTm=4h. A kinetic analysis suggests that this dispersion effect could be associated to a higher specific reaction rate dependent on the azo dye concentration. PMID:25465794

  19. Characterization of biofilm in 200W fluidized bed reactors

    SciTech Connect

    Lee, Michelle H.; Saurey, Sabrina D.; Lee, Brady D.; Parker, Kent E.; Eisenhauer, Emalee E. R.; Cordova, Elsa A.; Golovich, Elizabeth C.

    2014-09-29

    Contaminated groundwater beneath the 200 West Area at the Hanford Site in Southeast Washington is currently being treated using a pump and treat system to remove organics, inorganics, radionuclides, and metals. A granular activated carbon-based fluidized bed reactor (FBR) has been added to remove nitrate, hexavalent chromium and carbon tetrachloride. Initial analytical results indicated the microorganisms effectively reduced many of the contaminants to less than cleanup levels. However shortly thereafter operational upsets of the FBR include carbon carry over, over production of microbial extracellular polymeric substance (biofilm) materials, and over production of hydrogen sulfide. As a result detailed investigations were undertaken to understand the functional diversity and activity of the microbial community present in the FBR over time. Molecular analyses including terminal restriction fragment length polymorphism analysis, quantitative polymerase chain reaction and fluorescent in situ hybridization analyses were performed on the microbial community extracted from the biofilm within the bed and from the inoculum, to determine functional dynamics of the FBR bed over time and following operational changes. Findings from these analyses indicated: 1) the microbial community within the bed was completely different than community used for inoculation, and was likely from the groundwater; 2) analyses early in the testing showed an FBR community dominated by a few Curvibacter and Flavobacterium species; 3) the final sample taken indicated that the microbial community in the FBR bed had become more diverse; and 4) qPCR analyses indicated that bacteria involved in nitrogen cycling, including denitrifiers and anaerobic ammonia oxidizing bacteria, were dominant in the bed. These results indicate that molecular tools can be powerful for determining functional diversity within FBR type reactors. Coupled with micronutrient, influent and effluent chemistry

  20. Kinetics of thermophilic anaerobes in fixed-bed reactors.

    PubMed

    Perez, M; Romero, L I; Sales, D

    2001-08-01

    The main objective of this study is to estimate growth kinetic constants and the concentration of "active" attached biomass in two anaerobic thermophilic reactors which contain different initial sizes of immobilized anaerobic mixed cultures and decompose distillery wastewater. This paper studies the substrate decomposition in two lab-scale fixed-bed reactors operating at batch conditions with corrugated tubes as support media. It can be demonstrated that high micro-organisms-substrate ratios favor the degradation activity of the different anaerobic cultures, allowing the stable operation without lag-phases and giving better quality in effluent. The kinetic parameters obtained--maximum specific growth rates (mu(max)), non-biodegradable substrate (S(NB)) and "active or viable biomass" concentrations (X(V0))--were obtained by applying the Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz], with COD as substrate and methane (CH4) as the main product of the anaerobic process. This method is suitable to calculate and to differentiate the main kinetic parameters of both the total anaerobic mixed culture and the methanogenic population. Comparison of experimental measured concentration of volatile attached solids (VS(att)) in both reactors with the estimated "active" biomass concentrations obtained by applying Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz] shows that a large amount of inert matter is present in the fixed-bed reactor. PMID:11513409

  1. 6. Peavey Duluth Terminal Elevator spout floormayo spouts distribution floor ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Peavey Duluth Terminal Elevator spout floor-mayo spouts distribution floor looking roughly west to east. - Peavey Duluth Terminal Elevator, Workhouse, South side of first slip, north from outer end of Rice's Point, east of Garfield Avenue, Duluth, St. Louis County, MN

  2. Improving hydrolysis of food waste in a leach bed reactor

    SciTech Connect

    Browne, James D.; Allen, Eoin; Murphy, Jerry D.

    2013-11-15

    Highlights: • This paper assesses leaching of food waste in a two phase digestion system. • Leaching is assessed with and without an upflow anaerobic sludge blanket (UASB). • Without the UASB, low pH reduces hydrolysis, while increased flows increase leaching. • Inclusion of the UASB increases pH to optimal levels and greatly improves leaching. • The optimal conditions are suggested as low flow with connection to the UASB. - Abstract: This paper examines the rate of degradation of food waste in a leach bed reactor (LBR) under four different operating conditions. The effects of leachate recirculation at a low and high flow rate are examined with and without connection to an upflow anaerobic sludge blanket (UASB). Two dilution rates of the effective volume of the leach bed reactors were investigated: 1 and 6 dilutions per LBR per day. The increase in dilution rate from 1 to 6 improved the destruction of volatile solids without connection to the UASB. However connection to the UASB greatly improved the destruction of volatile solids (by almost 60%) at the low recirculation rate of 1 dilution per day. The increase in volatile solids destruction with connection to the UASB was attributed to an increase in leachate pH and buffering capacity provided by recirculated effluent from the UASB to the leach beds. The destruction of volatile solids for both the low and high dilution rates was similar with connection to the UASB, giving 82% and 88% volatile solids destruction respectively. This suggests that the most efficient leaching condition is 1 dilution per day with connection to the UASB.

  3. Countercurrent multistage fluidized bed reactor for immobilized biocatalysts: II. Operation of a laboratory-scale reactor.

    PubMed

    Vos, H J; Zomerdijk, M; Groen, D J; Luyben, K C

    1990-08-01

    In Part I of this series,(1) we derived a model and made simulations for a multistage fluidized bed reactor (MFBR). It was concluded that the MFBR can be an attractive alternative for a fixed bed reactor when operated with a deactivating biocatalyst. In Part II of this series, the design of a laboratory-scale MFBR and its evaluation to investigate the practical feasibility of this reactor type, will be described. Experiments with a duration as long as 10 days were carried out successfully using immobilized glucose isomerase as a model reaction system. The results predicted by the model are in good agreement with the measured glucose concentration and biocatalyst activity gradients, indicating perfect mixing of the particles in the reactor compartments.The diameters of the biocatalyst particles used in the experiments showed a large spread, with the largest being 1.7 times the smallest. Therefore, an additional check was carried out, to make sure that the particles were not segregating according to size. Particles withdrawn from the reactor compartments were investigated using an image analyzer. Histograms of particle size distribution do not indicate segregation and it is concluded that the particles used have been mixed completely within the compartments. As a result, transport of biocatalyst is nearly plug flow. PMID:18595091

  4. Catalytic Pyrolysis of Oak via Pyroprobe and Bench Scale, Packed Bed Pyrolysis Reactors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The pyrolytic conversion of oak sawdust at 500°C in flowing He over eight proprietary catalysts is described and compared to the control bed material, quartz sand. The reactions were conducted and compared in two reactors, an analytical, ug-scale pyroprobe reactor and a bench, g-scale packed bed re...

  5. Biological fluidized bed reactor (FBR): Emissionless groundwater treatment

    SciTech Connect

    Hines, R.D. Jr.; Laubacher, R.C.; Kunce, L.K.

    1996-12-31

    Groundwater treatment costs in the 1990`s have gone up significantly due to the air regulations that allow minimal or no VOC emissions. Treatment for air stripper off-gas has typically been vapor-phase carbon or catalytic oxidation. A more cost-effective alternative for groundwater treatment using a biological Granular Activated Carbon (GAC) Fluidized Bed Reactor (FBR) has been implemented successfully in remediating groundwater at two BP Distribution terminals. In the FBR system, GAC is the support media for biological growth, as well as a mechanism for organic adsorption. The FBR system predissolves self-generated pure oxygen to promote the aerobic degradation of dissolved hydrocarbons as they pass through the biofilm attached to the GAC. The use of predissolved pure oxygen prevents the air stripping action of conventional biological systems. Any hydrocarbons not rapidly broken down are adsorbed and subsequently degraded. The result is a high quality effluent without release of VOC air emissions. 4 refs., 3 figs.

  6. Proliferation resistant fuel for pebble bed modular reactors

    SciTech Connect

    Ronen, Y.; Aboudy, M.; Regev, D.; Gilad, E.

    2012-07-01

    We show that it is possible to denature the Plutonium produced in Pebble Bed Modular Reactors (PBMR) by doping the nuclear fuel with either 3050 ppm of {sup 237}Np or 2100 ppm of Am vector. A correct choice of these isotopes concentration yields denatured Plutonium with isotopic ratio {sup 238}Pu/Pu {>=} 6%, for the entire fuel burnup cycle. The penalty for introducing these isotopes into the nuclear fuel is a subsequent shortening of the fuel burnup cycle, with respect to a non-doped reference fuel, by 41.2 Full Power Days (FPDs) and 19.9 FPDs, respectively, which correspond to 4070 MWd/ton and 1965 MWd/ton reduction in fuel discharge burnup. (authors)

  7. Submerged bed versus unsaturated flow reactor: A pressurized hydrogenotrophic denitrification reactor as a case study.

    PubMed

    Epsztein, Razi; Beliavski, Michael; Tarre, Sheldon; Green, Michal

    2016-10-01

    The paper compares the main features of a submerged bed reactor (SuBR) with bubbling and recirculation of gas to those of an unsaturated flow reactor (uSFR) with liquid recirculation. A novel pressurized closed-headspace hydrogenotrophic denitrification system characterized by safe and economic utilization of H2 gas was used for the comparison. Under similar conditions, denitrification rates were lower in the SuBR as a result of a lower effective biofilm surface area and overall gas-liquid mass transfer coefficient kLa. Similar values of effluent DOC were achieved for both reactors, although effluent suspended solids concentration of the SuBR were substantially higher. On the other hand, the required cleaning frequency in the SuBR was 2.5 times lower. Moreover, the SuBR is expected to reduce the recirculation energy consumption by 0.35 kWh/m(3) treated. PMID:27424057

  8. Thermofluid effect on energy storage in fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Mahfoudi, Nadjiba; El Ganaoui, Mohammed; Moummi, Abdelhafid

    2016-05-01

    The development of innovative systems of heat storage is imperative to improve the efficiency of the existing systems used in the thermal solar energy applications. Several techniques were developed and realized in this context. The technology of the sand fluidized bed (sandTES) offers a promising alternative to the current state-of-the-art of the heat storage systems, such as fixed bed using a storage materials, as sand, ceramic, and stones, etc. Indeed, the use of the fluidization technique allows an effective heat transfer to the solid particles. With the sand, an important capacity of storage is obtained by an economic and ecological material [N. Mahfoudi, A. Moummi, M. El Ganaoui, Appl. Mech. Mater. 621, 214 (2014); N. Mahfoudi, A. Khachkouch, A. Moummi B. Benhaoua, M. El Ganaoui, Mech. Ind. 16, 411 (2015); N. Mahfoudi, A. Moummi, M. El Ganaoui, F. Mnasri, K.M. Aboudou, 3e Colloque internationale Francophone d"énergétique et mécanique, Comores, 2014, p. 91]. This paper presents a CFD simulation of the hydrodynamics and the thermal transient behavior of a fluidized bed reactor of sand, to determine the characteristics of storage. The simulation shows a symmetry breaking that occurs and gave way to chaotic transient generation of bubble formation after 3 s. Furthermore, the predicted average temperature of the solid phase (sand) increases gradually versus the time with a gain of 1 °C in an interval of 10 s. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  9. Moving bed biofilm reactor technology: process applications, design, and performance.

    PubMed

    McQuarrie, James P; Boltz, Joshua P

    2011-06-01

    The moving bed biofilm reactor (MBBR) can operate as a 2- (anoxic) or 3-(aerobic) phase system with buoyant free-moving plastic biofilm carriers. These systems can be used for municipal and industrial wastewater treatment, aquaculture, potable water denitrification, and, in roughing, secondary, tertiary, and sidestream applications. The system includes a submerged biofilm reactor and liquid-solids separation unit. The MBBR process benefits include the following: (1) capacity to meet treatment objectives similar to activated sludge systems with respect to carbon-oxidation and nitrogen removal, but requires a smaller tank volume than a clarifier-coupled activated sludge system; (2) biomass retention is clarifier-independent and solids loading to the liquid-solids separation unit is reduced significantly when compared with activated sludge systems; (3) the MBBR is a continuous-flow process that does not require a special operational cycle for biofilm thickness, L(F), control (e.g., biologically active filter backwashing); and (4) liquid-solids separation can be achieved with a variety of processes, including conventional and compact high-rate processes. Information related to system design is fragmented and poorly documented. This paper seeks to address this issue by summarizing state-of-the art MBBR design procedures and providing the reader with an overview of some commercially available systems and their components. PMID:21751715

  10. Moving bed biofilm reactor technology: process applications, design, and performance.

    PubMed

    McQuarrie, James P; Boltz, Joshua P

    2011-06-01

    The moving bed biofilm reactor (MBBR) can operate as a 2- (anoxic) or 3-(aerobic) phase system with buoyant free-moving plastic biofilm carriers. These systems can be used for municipal and industrial wastewater treatment, aquaculture, potable water denitrification, and, in roughing, secondary, tertiary, and sidestream applications. The system includes a submerged biofilm reactor and liquid-solids separation unit. The MBBR process benefits include the following: (1) capacity to meet treatment objectives similar to activated sludge systems with respect to carbon-oxidation and nitrogen removal, but requires a smaller tank volume than a clarifier-coupled activated sludge system; (2) biomass retention is clarifier-independent and solids loading to the liquid-solids separation unit is reduced significantly when compared with activated sludge systems; (3) the MBBR is a continuous-flow process that does not require a special operational cycle for biofilm thickness, L(F), control (e.g., biologically active filter backwashing); and (4) liquid-solids separation can be achieved with a variety of processes, including conventional and compact high-rate processes. Information related to system design is fragmented and poorly documented. This paper seeks to address this issue by summarizing state-of-the art MBBR design procedures and providing the reader with an overview of some commercially available systems and their components.

  11. Thermal modeling of microwave heated packed and fluidized bed catalytic reactors.

    PubMed

    Thomas, J R; Faucher, F

    2000-01-01

    Thermal models of small-scale, microwave-heated, packed-bed and fluidized-bed catalytic chemical reactors were developed to investigate the possibility of selectively heating the catalyst sites or the catalyst pellets with microwaves. Results indicate catalyst sites may be selectively heated under special conditions in a packed or fluidized bed, and catalyst pellets may be heated above the temperature of the cooling(and reacting) gas under certain conditions in a fluidized bed. PMID:11098441

  12. Nitrification of industrial and domestic saline wastewaters in moving bed biofilm reactor and sequencing batch reactor.

    PubMed

    Bassin, João P; Dezotti, Marcia; Sant'anna, Geraldo L

    2011-01-15

    Nitrification of saline wastewaters was investigated in bench-scale moving-bed biofilm reactors (MBBR). Wastewater from a chemical industry and domestic sewage, both treated by the activated sludge process, were fed to moving-bed reactors. The industrial wastewater contained 8000 mg Cl(-)/L and the salinity of the treated sewage was gradually increased until that level. Residual substances present in the treated industrial wastewater had a strong inhibitory effect on the nitrification process. Assays to determine inhibitory effects were performed with the industrial wastewater, which was submitted to ozonation and carbon adsorption pretreatments. The latter treatment was effective for dissolved organic carbon (DOC) removal and improved nitrification efficiency. Nitrification percentage of the treated domestic sewage was higher than 90% for all tested chloride concentrations up to 8000 mg/L. Results obtained in a sequencing batch reactor (SBR) were consistent with those attained in the MBBR systems, allowing tertiary nitrification and providing adequate conditions for adaptation of nitrifying microorganisms even under stressing and inhibitory conditions.

  13. Nitrification of industrial and domestic saline wastewaters in moving bed biofilm reactor and sequencing batch reactor.

    PubMed

    Bassin, João P; Dezotti, Marcia; Sant'anna, Geraldo L

    2011-01-15

    Nitrification of saline wastewaters was investigated in bench-scale moving-bed biofilm reactors (MBBR). Wastewater from a chemical industry and domestic sewage, both treated by the activated sludge process, were fed to moving-bed reactors. The industrial wastewater contained 8000 mg Cl(-)/L and the salinity of the treated sewage was gradually increased until that level. Residual substances present in the treated industrial wastewater had a strong inhibitory effect on the nitrification process. Assays to determine inhibitory effects were performed with the industrial wastewater, which was submitted to ozonation and carbon adsorption pretreatments. The latter treatment was effective for dissolved organic carbon (DOC) removal and improved nitrification efficiency. Nitrification percentage of the treated domestic sewage was higher than 90% for all tested chloride concentrations up to 8000 mg/L. Results obtained in a sequencing batch reactor (SBR) were consistent with those attained in the MBBR systems, allowing tertiary nitrification and providing adequate conditions for adaptation of nitrifying microorganisms even under stressing and inhibitory conditions. PMID:20933327

  14. Modular Pebble Bed Reactor Project, University Research Consortium Annual Report

    SciTech Connect

    Petti, David Andrew

    2000-07-01

    This project is developing a fundamental conceptual design for a gas-cooled, modular, pebble bed reactor. Key technology areas associated with this design are being investigated which intend to address issues concerning fuel performance, safety, core neutronics and proliferation resistance, economics and waste disposal. Research has been initiated in the following areas: · Improved fuel particle performance · Reactor physics · Economics · Proliferation resistance · Power conversion system modeling · Safety analysis · Regulatory and licensing strategy Recent accomplishments include: · Developed four conceptual models for fuel particle failures that are currently being evaluated by a series of ABAQUS analyses. Analytical fits to the results are being performed over a range of important parameters using statistical/factorial tools. The fits will be used in a Monte Carlo fuel performance code, which is under development. · A fracture mechanics approach has been used to develop a failure probability model for the fuel particle, which has resulted in significant improvement over earlier models. · Investigation of fuel particle physio-chemical behavior has been initiated which includes the development of a fission gas release model, particle temperature distributions, internal particle pressure, migration of fission products, and chemical attack of fuel particle layers. · A balance of plant, steady-state thermal hydraulics model has been developed to represent all major components of a MPBR. Component models are being refined to accurately reflect transient performance. · A comparison between air and helium for use in the energy-conversion cycle of the MPBR has been completed and formed the basis of a master’s degree thesis. · Safety issues associated with air ingress are being evaluated. · Post shutdown, reactor heat removal characteristics are being evaluated by the Heating-7 code. · PEBBED, a fast deterministic neutronic code package suitable for

  15. Biohydrogen production from tequila vinasses using a fixed bed reactor.

    PubMed

    Buitrón, Germán; Prato-Garcia, Dorian; Zhang, Axue

    2014-01-01

    In Mexico, the industrial production of tequila leads to the discharge of more than 31.2 million of m(3) of vinasse, which causes serious environmental issues because of its acidity, high organic load and the presence of recalcitrant compounds. The aim of this research was to study the feasibility of a fixed bed reactor for the production of biohydrogen by using tequila vinasse as substrate. The experiments were carried out in a continuous mode under mesophilic and acidic conditions. The maximum hydrogen yield and hydrogen production rate were 1.3 mol H2 mol/mol glucose and 72 ± 9 mL H2/(Lreactor h), respectively. Biogas consisted of carbon dioxide (36%) and hydrogen (64%); moreover methane was not observed. The electron-equivalent mass balance fitted satisfactorily (sink of electrons from 0.8 to 7.6%). For vinasses, hydrogen production accounted for 10.9% of the total available electron-equivalents. In the liquid phase, the principal metabolites identified were acetic, butyric and iso-butyric acids, which indicated a butyrate-acetate type fermentation. Tequila vinasses did not result in potential inhibition of the fermentative process. Considering the process as a water treatment system, only 20% of the original carbon was removed (as carbon dioxide and biomass) when the tequila vinasses are used. PMID:25521125

  16. Pressurised pyrolysis of Miscanthus using a fixed bed reactor.

    PubMed

    Melligan, F; Auccaise, R; Novotny, E H; Leahy, J J; Hayes, M H B; Kwapinski, W

    2011-02-01

    Miscanthus x giganteus was pyrolysed, in a fixed bed reactor in a constant flow of dinitrogen gas, at a rate of 13°C/min from ambient to 550°C, then held for 25 min at this temperature. The pressures employed ranged from atmospheric to 26 bar. The major compounds identified in the bio-oil were water, phenol, and phenol derivatives. The water contents impact on the usefulness of the bio-oil as a fuel. However, the phenols could provide useful platform chemicals and products. The properties of the char were determined using elemental analyses, surface area measurements using the Brunauer-Emmett-Teller equation, a calorimetric bomb, Scanning Electron Microscopy, and solid state (13)C NMR spectroscopy. The chars were highly carbonised, especially at the higher pressures, and provided thermally stable materials. Pressure impacted greatly on the surface area. Char formed at atmospheric pressure had a surface area of 162 m(2)/g, whereas that from the highest pressure applied was only 0.137 m(2)/g. PMID:21094043

  17. Biodenitrification of gaseous diffusion plant aqueous wastes: fluid bed reactor

    SciTech Connect

    Kowalchuk, M.

    1982-01-04

    Decontamination and uranium recovery operations at Portsmouth generate raffinates which contain nitrate. Nitrate discharges are now within EPA limits. However, more stringent limits go into effect on October 2, 1982. These limits cannot be met by present operating methods without seriously restricting decontamination and recovery operations. A biodentrification process will therefore be used at Portsmouth to reduce the nitrate concentration to acceptable levels. Pilot plant studies using a fluid bed reactor were carried out at ORNL. Process operating parameters were characterized and design criteria for the full-scale facility which is to be built at Portsmouth were devised. When operations were completed, the pilot plant, equipped with a 20-inch bioreactor, was shipped to Portsmouth. It will be installed during FY-1982, and will be operated until the full-scale facility is built. It will allow GAT to meet EPA limts and will accommodate 9000 liters of raffinate per month. The projected post CIP/CUP raffinate generation rate is 15,000 liters per month. Recovery operations will be limited to some extent until the fullscale biodenitrification facility is built.

  18. Biohydrogen production from tequila vinasses using a fixed bed reactor.

    PubMed

    Buitrón, Germán; Prato-Garcia, Dorian; Zhang, Axue

    2014-01-01

    In Mexico, the industrial production of tequila leads to the discharge of more than 31.2 million of m(3) of vinasse, which causes serious environmental issues because of its acidity, high organic load and the presence of recalcitrant compounds. The aim of this research was to study the feasibility of a fixed bed reactor for the production of biohydrogen by using tequila vinasse as substrate. The experiments were carried out in a continuous mode under mesophilic and acidic conditions. The maximum hydrogen yield and hydrogen production rate were 1.3 mol H2 mol/mol glucose and 72 ± 9 mL H2/(Lreactor h), respectively. Biogas consisted of carbon dioxide (36%) and hydrogen (64%); moreover methane was not observed. The electron-equivalent mass balance fitted satisfactorily (sink of electrons from 0.8 to 7.6%). For vinasses, hydrogen production accounted for 10.9% of the total available electron-equivalents. In the liquid phase, the principal metabolites identified were acetic, butyric and iso-butyric acids, which indicated a butyrate-acetate type fermentation. Tequila vinasses did not result in potential inhibition of the fermentative process. Considering the process as a water treatment system, only 20% of the original carbon was removed (as carbon dioxide and biomass) when the tequila vinasses are used.

  19. Treatment of semivolatile compounds in high strength wastes using an anaerobic expanded-bed GAC reactor

    EPA Science Inventory

    The potential of the anaerobic, expanded bed granular activated carbon (GAC) reactor in treating a high strength waste containing RCRA semivolatile organic compounds (VOCs) was studied. Six semivolatiles, orthochlorophenol, nitrobenzene, naphthalene, para-nitrophenol, lindane, a...

  20. TREATMENT OF VOCS IN HIGH STRENGTH WASTES USING AN ANAEROBIC EXPANDED-BED GAS REACTOR

    EPA Science Inventory

    The potential of the expanded-bed granular activated carbon (GAC) anaerobic reactor in treating a high strength waste containing RCRA volatile organic compounds (VOCs) was studied. A total of six VOCs, methylene chloride, chlorobenzene, carbon tetrachloride, chloroform, toluene ...

  1. A Kinetic and Mass Transfer Model for Glycerol Hydrogenolysis in a Trickle-Bed Reactor

    SciTech Connect

    Xi, Yaoyan; Holladay, Johnathan E.; Frye, John G.; Oberg, Aaron A.; Jackson, James E.; Miller, Dennis J.

    2010-11-15

    A detailed model of glycerol hydrogenolysis in a trickle-bed reactor is presented that includes a mechanistically based kinetic rate expression, energy transport, mass transport across the gas-liquid and liquid-solid interfaces, intraparticle catalyst mass transfer, and partial wetting of the bed. Optimal kinetic parameters for the glycerol hydrogenolysis rate expression were determined via nonlinear regression analysis on the basis of experiments conducted in a laboratory-scale trickle-bed reactor over a broad range of operating conditions. Model predictions agree well with experimental data and accurately predict trends in reactor performance with liquid flow rate, temperature, hydrogen pressure, and base promoter concentration. The model is thus a useful tool for predicting laboratory reactor performance and for design of commercial-scale trickle-bed systems.

  2. Catalytic fast pyrolysis of white oak wood in-situ using a bubbling fluidized bed reactor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Catalytic fast pyrolysis was performed on white oak wood using two zeolite-type catalysts as bed material in a bubbling fluidized bed reactor. The two catalysts chosen, based on a previous screening study, were Ca2+ exchanged Y54 (Ca-Y54) and a proprietary ß-zeolite type catalyst (catalyst M) both ...

  3. Anaerobic digestion of dairy wastewater by inverse fluidization: the inverse fluidized bed and the inverse turbulent bed reactors.

    PubMed

    Arnaiz, C; Buffiere, P; Elmaleh, S; Lebrato, J; Moletta, R

    2003-11-01

    This paper describes the application of the inverse fluidization technology to the anaerobic digestion of dairy wastewater. Two reactors were investigated: the inverse fluidized bed reactor and the inverse turbulent reactor. In these reactors, a granular floating solid is expanded by a down-flow current of effluent or an up-flow current of gas, respectively. The carrier particles (Extendospheres) were chosen for their large specific surface area (20,000 m2m(-3)) and their low energy requirements for fluidization (gas velocity of 1.5 mm s(-1), 5.4 m h(-1)). Organic load was increased stepwise by reducing hydraulic retention time from more than 60 days to 3 days, while maintaining constant the feed COD concentration. Both reactors achieved more than 90% of COD removal, at an organic loading rate of 10-12 kgCOD m(-3) d(-1), respectively. The performances observed were similar or even higher than that of other previously tested fluidized bed technologies treating the same wastewater. It was found that the main advantages of this system are: low energy requirement, because of the low fluidization velocities required; there is no need of a settling device, because solids accumulate at the bottom of the reactor, so they can be easily drawn out and particles with high-biomass content can be easily recovered. Lipid phosphate concentration has been revealed as a good method for biomass estimation in biofilms since it only includes living biomass.

  4. Discharge Characteristics of Series Surface/Packed-Bed Discharge Reactor Diven by Bipolar Pulsed Power

    NASA Astrophysics Data System (ADS)

    Hu, Jian; Jiang, Nan; Li, Jie; Shang, Kefeng; Lu, Na; Wu, Yan; Mizuno, Akira

    2016-03-01

    The discharge characteristics of the series surface/packed-bed discharge (SSPBD) reactor driven by bipolar pulse power were systemically investigated in this study. In order to evaluate the advantages of the SSPBD reactor, it was compared with traditional surface discharge (SD) reactor and packed-bed discharge (PBD) reactor in terms of the discharge voltage, discharge current, and ozone formation. The SSPBD reactor exhibited a faster rising time and lower tail voltage than the SD and PBD reactors. The distribution of the active species generated in different discharge regions of the SSPBD reactor was analyzed by optical emission spectra and ozone analysis. It was found that the packed-bed discharge region (3.5 mg/L), rather than the surface discharge region (1.3 mg/L) in the SSPBD reactor played a more important role in ozone generation. The optical emission spectroscopy analysis indicated that more intense peaks of the active species (e.g. N2 and OI) in the optical emission spectra were observed in the packed-bed region. supported by National Natural Science Foundation of China (No. 51177007), the Joint Funds of National Natural Science Foundation of China (No. U1462105), and Dalian University of Technology Fundamental Research Fund of China (No. DUT15RC(3)030)

  5. Production of activated carbon from coconut shell char in a fluidized bed reactor

    SciTech Connect

    Sai, P.M.S.; Ahmed, J.; Krishnaiah, K.

    1997-09-01

    Activated carbon is produced from coconut shell char using steam or carbon dioxide as the reacting gas in a 100 mm diameter fluidized bed reactor. The effect of process parameters such as reaction time, fluidizing velocity, particle size, static bed height, temperature of activation, fluidizing medium, and solid raw material on activation is studied. The product is characterized by determination of iodine number and BET surface area. The product obtained in the fluidized bed reactor is much superior in quality to the activated carbons produced by conventional processes. Based on the experimental observations, the optimum values of process parameters are identified.

  6. Designing reverse-flow packed bed reactors for stable treatment of volatile organic compounds.

    PubMed

    Chan, Fan Liang; Keith, Jason M

    2006-02-01

    Reverse-flow packed bed reactors can be used to treat gaseous pollutants from chemical plants. This article describes the design and operation of a modified reverse-flow reactor (MRFR) which has a recuperator on each end of the reactor and a reaction zone in the middle. The recuperators have low thermal dispersion and the reaction zone has a high thermal dispersion, obtained by placing metal inserts into the bed, parallel with the gas flow. Performance of the MRFR during extended lean and rich conditions is determined with analytical analysis and compares well with numerical simulations of CO oxidation; however, the theory is expected to be useful for any reaction kinetics. A major advantage of this MRFR design is an extended time for the reactor to extinguish during lean conditions. This work also describes MRFR performance with internal reactor cooling, which can be used as a control mechanism to maintain reactor temperature for proper removal of volatile organic compounds.

  7. Effects of reactor configuration on the performance of static-bed submerged media anaerobic reactors

    SciTech Connect

    Chiang, C.F.

    1988-01-01

    Three different configurations of cylindrical submerged media anaerobic reactors (SMARs) with packing volumes of 85 items were operated at 35 C for 415 days with COD loading rates varying from 1 to 12 g/l/d and three retention times of 0.5, 1, and 2 days. A synthetic waste consisting of a milk solution with a mineral supplement was used for the feed. Tracer studies on clean-bed and dirty-bed SMARs indicate that reactor configuration, biogas mixing, and biomass accumulation all have a significant effect on SMAR hydraulics and cause short-circuiting. Based on the isothermal energy dissipation theory, the higher hydrostatic pressures resulting from higher SMAR heights increases self-induced biogas mixing and improves the contact efficiency between substrate and organisms. Based on TCOD removal rate, the tallest SMAR performed slightly better at COD loading rates above 4/g/l/d. At COD loading rates equal to or below 4 g/l/d, there was little difference in TCOD removal rate between the three SMARs. The acetoclastic methanogenic activity (AMA) test developed in this study is reproducible with 6.5% at a mean of 0.39 l CH{sub 4} (STP)/gm VSS/d. For VSS less than 1 g/l, a higher AMA is associated with lower VSS concentrations. For VSS greater than 1 g/l, AMA varies within a narrow range of 0.1 to 0.2 l CH{sub 4} (STP)/gm VSS/d. Exit gas recycle at a ratio of 3.5-7.0% of exit gas flowrate resulted in a 5-13% increase in the methane content of the exit gas at a COD loading rate of about 10 g/l/d and a detention time of about 2 days. This suggest that, at high loading rates, hydrogen dissolution rate may be the rate-limiting step in anaerobic digestion.

  8. Development of a trickle bed reactor of electro-Fenton process for wastewater treatment.

    PubMed

    Lei, Yangming; Liu, Hong; Shen, Zhemin; Wang, Wenhua

    2013-10-15

    To avoid electrolyte leakage and gas bubbles in the electro-Fenton (E-Fenton) reactors using a gas diffusion cathode, we developed a trickle bed cathode by coating a layer composed of carbon black and polytetrafluoroethylene (C-PTFE) onto graphite chips instead of carbon cloth. The trickle bed cathode was optimized by single-factor and orthogonal experiments, in which carbon black, PTFE, and a surfactant were considered as the determinant of the performance of graphite chips. In the reactor assembled by the trickle bed cathode, H2O2 was generated with a current of 0.3A and a current efficiency of 60%. This performance was attributed to the fine distribution of electrolyte and air, as well as the effective oxygen transfer from the gas phase to the electrolyte-cathode interface. In terms of H2O2 generation and current efficiency, the developed trickle bed reactor had a performance comparable to that of the conventional E-Fenton reactor using a gas diffusion cathode. Further, 123 mg L(-1) of reactive brilliant red X-3B in aqueous solution was decomposed in the optimized trickle bed reactor as E-Fenton reactor. The decolorization ratio reached 97% within 20 min, and the mineralization reached 87% within 3h.

  9. Modeling for Anaerobic Fixed-Bed Biofilm Reactors

    SciTech Connect

    Liu, B. Y. M.; Pfeffer, J. T.

    1989-06-01

    The specific objectives of this research were: 1. to develop an equilibrium model for chemical aspects of anaerobic reactors; 2. to modify the equilibrium model for non-equilibrium conditions; 3. to incorporate the existing biofilm models into the models above to study the biological and chemical behavior of the fixed-film anaerobic reactors; 4. to experimentally verify the validity of these models; 5. to investigate the biomass-holding ability of difference packing materials for establishing reactor design criteria.

  10. Calculational approach and results of the safe shutdown earthquake event for the pebble bed modular reactor

    SciTech Connect

    Van Heerden, G.; Sen, S.; Reitsma, F.

    2006-07-01

    The Pebble Bed Modular Reactor (PBMR) concept can be described as a high-temperature helium-cooled, graphite-moderated pebble-bed reactor with a multi-pass fuelling scheme. The fuel is contained in 6 cm diameter graphite spheres containing carbon-based coated UO{sub 2} kernels. An online fuel reload scheme is applied with the fuel spheres being circulated through the reactor. The pebble-bed reactor core thus consists of fuel pebbles packed in the core cavity in a random way. The packing densities and pebble flow is well known through analysis and tests done in the German experimental and development program. The pebble-bed typically has a packing fraction of 0.61. In the event of an earthquake this packing fraction may increase with the effect that the core geometry and core reactivity will change. The Safe Shutdown Earthquake (SSE) analysis performed for the PBMR 400 MW design is described in this paper, and it specifically covers SSE-induced pebble-bed packing fractions of 0.62 and 0.64. The main effects governing the addition of reactivity in the SSE event are the changes in core neutronic leakage due to the decreased core size and the decreased effectiveness of the control rods as the pebble-bed height decreases. This paper describes the models, methods and tools used to analyse the event, the results obtained for the different approaches and the consequences and safety implications of such an event. (authors)

  11. Continuous biological waste gas treatment in stirred trickle-bed reactor with discontinuous removal of biomass

    SciTech Connect

    Laurenzis, A.; Heits, H.; Wuebker, S.M.; Heinze, U.; Friedrich, C.; Werner, U.

    1998-02-20

    A new reactor for biological waste gas treatment was developed to eliminate continuous solvents from waste gases. A trickle-bed reactor was chosen with discontinuous movement of the packed bed and intermittent percolation. The reactor was operated with toluene as the solvent and an optimum average biomass concentration of between 5 and 30 kg dry cell weight per cubic meter packed bed (m{sub pb}{sup 3}). This biomass concentration resulted in a high volumetric degradation rate. Reduction of surplus biomass by stirring and trickling caused a prolonged service life and prevented clogging of the trickle bed and a pressure drop increase. The pressure drop after biomass reduction was almost identical to the theoretical pressure drop as calculated for the irregular packed bed without biomass. The reduction in biomass and intermittent percolation of mineral medium resulted in high volumetric degradation rates of about 100 g of toluene m{sub pb}{sup {minus}3} h{sup {minus}1} at a load of 150 g of toluene m{sub pb}{sup {minus}3} h{sup {minus}1}. Such a removal rate with a trickle-bed reactor was not reported before.

  12. Pyrolysis of Uinta Basin Oil Sands in fluidized bed and rotary kiln reactors

    SciTech Connect

    Nagpal, S.; Fletcher, J.V.; Hanson, F.V.

    1995-12-31

    A pilot-scale fluidized bed reactor (FBR) was used to pyrolyze the mined and crushed ore from the PR Spring oil sands deposit which is located in the Uinta Basin of Utah. Liquid yields of approximately 80 wt% of the bitumen fed to the reactor were obtained. This compares to 55-70 wt% obtained from smaller laboratory scale fluidized bed reactors and a pilot-scale rotary kiln. The product yields and distributions exhibited no discernable trends with reactor temperature or solids retention time. The liquid products obtained from the pilot-scale fluidized bed reactor were upgraded compared to the bitumen in terms of volatility, viscosity, molecular weight, and metals (Ni and V) content. The nitrogen and sulphur contents of the total liquid products were also reduced relative to the bitumen. A comparison of oil sands pyrolysis yields from a pilot scale FBR and a rotary kiln of the same diameter (15.2 cm) was made. Under similar pyrolysis conditions, the rotary kiln produced a slightly more upgraded product but at lower total liquid yields. Kinetic modeling of the various reactors indicates that the pilot-scale FBR product distributions may be explained using a simplified two-reaction scheme. It is proposed that secondary cracking is suppressed in the large diameter FBR due to elimination of slugging and the superior quality of fluidization in the reactor. More experimental studies with the rotary kiln and an economic evaluation will be required before concluding which reactor is preferred for the thermal recovery process.

  13. Pebble bed reactor fiscal year 1980: review summary report

    SciTech Connect

    Not Available

    1980-07-01

    Information on high-temperature reactor development is presented concerning reactor operating experience; core performance assessment; core control and shutdown; reflector and core support; maintenance and availability; safety aspects of PBR and prismatic comparison; PCRV dimensions; and fuel reprocessing cost estimate.

  14. Pebble Bed Reactors Design Optimization Methods and their Application to the Pebble Bed Fluoride Salt Cooled High Temperature Reactor (PB-FHR)

    NASA Astrophysics Data System (ADS)

    Cisneros, Anselmo Tomas, Jr.

    The Fluoride salt cooled High temperature Reactor (FHR) is a class of advanced nuclear reactors that combine the robust coated particle fuel form from high temperature gas cooled reactors, direct reactor auxillary cooling system (DRACS) passive decay removal of liquid metal fast reactors, and the transparent, high volumetric heat capacitance liquid fluoride salt working fluids---flibe (33%7Li2F-67%BeF)---from molten salt reactors. This combination of fuel and coolant enables FHRs to operate in a high-temperature low-pressure design space that has beneficial safety and economic implications. In 2012, UC Berkeley was charged with developing a pre-conceptual design of a commercial prototype FHR---the Pebble Bed- Fluoride Salt Cooled High Temperature Reactor (PB-FHR)---as part of the Nuclear Energy University Programs' (NEUP) integrated research project. The Mark 1 design of the PB-FHR (Mk1 PB-FHR) is 236 MWt flibe cooled pebble bed nuclear heat source that drives an open-air Brayton combine-cycle power conversion system. The PB-FHR's pebble bed consists of a 19.8% enriched uranium fuel core surrounded by an inert graphite pebble reflector that shields the outer solid graphite reflector, core barrel and reactor vessel. The fuel reaches an average burnup of 178000 MWt-d/MT. The Mk1 PB-FHR exhibits strong negative temperature reactivity feedback from the fuel, graphite moderator and the flibe coolant but a small positive temperature reactivity feedback of the inner reflector and from the outer graphite pebble reflector. A novel neutronics and depletion methodology---the multiple burnup state methodology was developed for an accurate and efficient search for the equilibrium composition of an arbitrary continuously refueled pebble bed reactor core. The Burnup Equilibrium Analysis Utility (BEAU) computer program was developed to implement this methodology. BEAU was successfully benchmarked against published results generated with existing equilibrium depletion codes VSOP

  15. Treatment of oilfield wastewater in moving bed biofilm reactors using a novel suspended ceramic biocarrier.

    PubMed

    Dong, Zhiyong; Lu, Mang; Huang, Wenhui; Xu, Xiaochun

    2011-11-30

    In this study, a novel suspended ceramic carrier was prepared, which has high strength, optimum density (close to water), and high porosity. Two different carriers, unmodified and sepiolite-modified suspended ceramic carriers were used to feed two moving bed biofilm reactors (MBBRs) with a filling fraction of 50% to treat oilfield produced water. The hydraulic retention time (HRT) was varied from 36 to 10h. The results, during a monitoring period of 190 days, showed that removal efficiency of chemical oxygen demand was the highest in reactor 3 filled with the sepiolite-modified carriers, followed by reactor 2 filled with the unmodified carriers, with the lowest in reactor 1 (activated sludge reactor), at an HRT of 10h. Similar trends were found in the removal efficiencies of ammonia nitrogen and polycyclic aromatic hydrocarbons. Reactor 3 was more shock resistant than reactors 2 and 1. The results indicate that the suspended ceramic carrier is an excellent MBBR carrier.

  16. Very High Temperature Reactor (VHTR) Deep Burn Core and Fuel Analysis -- Complete Design Selection for the Pebble Bed Reactor

    SciTech Connect

    B. Boer; A. M. Ougouag

    2010-09-01

    The Deep-Burn (DB) concept focuses on the destruction of transuranic nuclides from used light water reactor fuel. These transuranic nuclides are incorporated into TRISO coated fuel particles and used in gas-cooled reactors with the aim of a fractional fuel burnup of 60 to 70% in fissions per initial metal atom (FIMA). This high performance is expected through the use of multiple recirculation passes of the fuel in pebble form without any physical or chemical changes between passes. In particular, the concept does not call for reprocessing of the fuel between passes. In principle, the DB pebble bed concept employs the same reactor designs as the presently envisioned low-enriched uranium core designs, such as the 400 MWth Pebble Bed Modular Reactor (PBMR-400). Although it has been shown in the previous Fiscal Year (2009) that a PuO2 fueled pebble bed reactor concept is viable, achieving a high fuel burnup, while remaining within safety-imposed prescribed operational limits for fuel temperature, power peaking and temperature reactivity feedback coefficients for the entire temperature range, is challenging. The presence of the isotopes 239-Pu, 240-Pu and 241-Pu that have resonances in the thermal energy range significantly modifies the neutron thermal energy spectrum as compared to a ”standard,” UO2-fueled core. Therefore, the DB pebble bed core exhibits a relatively hard neutron energy spectrum. However, regions within the pebble bed that are near the graphite reflectors experience a locally softer spectrum. This can lead to power and temperature peaking in these regions. Furthermore, a shift of the thermal energy spectrum with increasing temperature can lead to increased absorption in the resonances of the fissile Pu isotopes. This can lead to a positive temperature reactivity coefficient for the graphite moderator under certain operating conditions. The effort of this task in FY 2010 has focused on the optimization of the core to maximize the pebble discharge

  17. Rapid ignition of fluidized bed boiler

    DOEpatents

    Osborn, Liman D.

    1976-12-14

    A fluidized bed boiler is started up by directing into the static bed of inert and carbonaceous granules a downwardly angled burner so that the hot gases cause spouting. Air is introduced into the bed at a rate insufficient to fluidize the entire bed. Three regions are now formed in the bed, a region of lowest gas resistance, a fluidized region and a static region with a mobile region at the interface of the fluidized and static regions. Particles are transferred by the spouting action to form a conical heap with the carbonaceous granules concentrated at the top. The hot burner gases ignite the carbonaceous matter on the top of the bed which becomes distributed in the bed by the spouting action and bed movement. Thereafter the rate of air introduction is increased to fluidize the entire bed, the spouter/burner is shut off, and the entire fluidized bed is ignited.

  18. Microbial characterization and removal of anionic surfactant in an expanded granular sludge bed reactor.

    PubMed

    Delforno, T P; Okada, D Y; Polizel, J; Sakamoto, I K; Varesche, M B A

    2012-03-01

    This study evaluated linear alkylbenzene sulfonate removal in an expanded granular sludge bed reactor with hydraulic retention times of 26 h and 32 h. Sludge bed and separator phase biomass were phylogenetically characterized (sequencing 16S rRNA) and quantified (most probable number) to determine the total anaerobic bacteria and methanogenic Archaea. The reactor was fed with a mineral medium supplemented with 14 mg l(-1)LAS, ethanol and methanol. The stage I-32 h consisted of biomass adaptation (without LAS influent) until reactor stability was achieved (COD removal >97%). In stage II-32 h, LAS removal was 74% due to factors such as dilution, degradation and adsorption. Higher HRT values increased the LAS removal (stage III: 26 h - 48% and stage IV: 32 h - 64%), probably due to increased contact time between the biomass and LAS. The clone libraries were different between samples from the sludge bed (Synergitetes and Proteobacteria) and the separator phase (Firmicutes and Proteobacteria) biomass. PMID:22212695

  19. [Radiation transformation mechanism in a photocatalytic reactor of three-phase internal circulating fluidized bed].

    PubMed

    You, Hong; Luo, Wei-nan; Yao, Jie; Chen, Ping; Cai, Wei-min

    2005-01-01

    A novel three-phase internal circulating fluidized bed photocatalytic reactor was established and the radiation transformation in which was investigated. The experimental results indicate that with the interaction of gas and solid (gas flux > 0.3m3/h), the radiation transformation in the reactor along radial direction conforms to a definite exponential function, which agrees to formula Rose about the rules of light intensity distribution through evenly suspended particles. The value of radiation energy is affected by the initial light intensity, the concentration of photocatalyst and the thickness of liquid layer. The aerated gas amount only influence the state of the fluidized bed and has little effect on the distribution of light intensity along radical direction. Photocatalytic degradation of Rhodamine B indicate that the efficiency of three-phase internal circulating fluidized bed is much higher than slurry bed. The optimal catalyst concentration of this system is 10 - 12g/L.

  20. Modular Pebble-Bed Reactor Project: Laboratory-Directed Research and Development Program FY 2002 Annual Report

    SciTech Connect

    Petti, David Andrew; Dolan, Thomas James; Miller, Gregory Kent; Moore, Richard Leroy; Terry, William Knox; Ougouag, Abderrafi Mohammed-El-Ami; Oh, Chang H; Gougar, Hans D

    2002-11-01

    This report documents the results of our research in FY-02 on pebble-bed reactor technology under our Laboratory Directed Research and Development (LDRD) project entitled the Modular Pebble-Bed Reactor. The MPBR is an advanced reactor concept that can meet the energy and environmental needs of future generations under DOE’s Generation IV initiative. Our work is focused in three areas: neutronics, core design and fuel cycle; reactor safety and thermal hydraulics; and fuel performance.

  1. Deposition reactors for solar grade silicon: A comparative thermal analysis of a Siemens reactor and a fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Ramos, A.; Filtvedt, W. O.; Lindholm, D.; Ramachandran, P. A.; Rodríguez, A.; del Cañizo, C.

    2015-12-01

    Polysilicon production costs contribute approximately to 25-33% of the overall cost of the solar panels and a similar fraction of the total energy invested in their fabrication. Understanding the energy losses and the behaviour of process temperature is an essential requirement as one moves forward to design and build large scale polysilicon manufacturing plants. In this paper we present thermal models for two processes for poly production, viz., the Siemens process using trichlorosilane (TCS) as precursor and the fluid bed process using silane (monosilane, MS). We validate the models with some experimental measurements on prototype laboratory reactors relating the temperature profiles to product quality. A model sensitivity analysis is also performed, and the effects of some key parameters such as reactor wall emissivity and gas distributor temperature, on temperature distribution and product quality are examined. The information presented in this paper is useful for further understanding of the strengths and weaknesses of both deposition technologies, and will help in optimal temperature profiling of these systems aiming at lowering production costs without compromising the solar cell quality.

  2. Pressurized fluidized bed reactor and a method of operating the same

    DOEpatents

    Isaksson, J.

    1996-02-20

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

  3. Pressurized fluidized bed reactor and a method of operating the same

    DOEpatents

    Isaksson, Juhani

    1996-01-01

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

  4. Moving bed reactor for solar thermochemical fuel production

    SciTech Connect

    Ermanoski, Ivan

    2013-04-16

    Reactors and methods for solar thermochemical reactions are disclosed. Embodiments of reactors include at least two distinct reactor chambers between which there is at least a pressure differential. In embodiments, reactive particles are exchanged between chambers during a reaction cycle to thermally reduce the particles at first conditions and oxidize the particles at second conditions to produce chemical work from heat. In embodiments, chambers of a reactor are coupled to a heat exchanger to pre-heat the reactive particles prior to direct exposure to thermal energy with heat transferred from reduced reactive particles as the particles are oppositely conveyed between the thermal reduction chamber and the fuel production chamber. In an embodiment, particle conveyance is in part provided by an elevator which may further function as a heat exchanger.

  5. Solar-driven coal gasification in a thermally irradiated packed-bed reactor

    SciTech Connect

    Nicolas Piatkowski; Aldo Steinfeld

    2008-05-15

    Coal gasification for high-quality synthesis gas production is considered using concentrated solar energy as the source of high-temperature process heat. The solar reactor consists of two cavities separated by a radiant emitter plate, with the upper one serving as the solar absorber and the lower one containing the reacting packed bed that shrinks as the reaction progresses. A 5 kW prototype reactor with an 8 cm depth, 14.3 cm diameter cylindrical bed was fabricated and tested in a high-flux solar furnace, subjected to solar flux concentrations up to 2600 suns and packed-bed temperatures up to 1440 K. The reactor is modeled by formulating the 1D unsteady energy conservation equation that couples conductive-radiative heat transfer with the reaction kinetics and solving it by the finite volume technique for a transient shrinking domain. The overall reaction rate was determined experimentally by thermogravimetry, while the effective thermal conductivity was determined experimentally in a radial heat flow oven. Model validation was accomplished in terms of bed temperatures, gasified mass, and bed shrink rates measured in solar experiments conducted with beech charcoal. Heat transfer through the bed proved to be the rate-controlling mechanism, indicating an ablation regime. 31 refs., 18 figs.

  6. Performance of a magnetically stabilized bed reactor with immobilized yeast cells.

    PubMed

    Ivanova, V; Hristov, J; Dobreva, E; al-Hassan, Z; Penchev, I

    1996-05-01

    This paper is focused on the possibility to apply the magnetic stabilization technique in bioprocessing. The feasibility of a continuous ethanol fermentation process with immobilized Saccharomyces cerevisiae cells in a magnetically stabilized bed (MSB) was demonstrated. The fermentation processes were carried out in an external magnetic field, transverse to the fluid flow. The flexibility to change the bed expansion owing to the independent change of the fluid flow and the field intensity (the "magnetization FIRST" mode) permitted the creation of fixed beds with different particle arrangements, which affected the bed porosity, the effective fluid-particle contact area, and the mass transfer processes on the particle-fluid interface. As a result, higher ethanol concentration, ethanol production, and glucose uptake rates than in conventional packed bed reactor were reached.

  7. Treatment of cheese whey and soft drink bottling wastes in an anaerboic biological fluidized bed reactor

    SciTech Connect

    Hickey, R.; Owens, R.

    1982-11-01

    This report describes the development of an anaerobic system to produce combustible gas from cheese whey, soft drink bottling plant wastes, and other organic wastes. Experiments conducted using whey and soft drink wastes in a small scale reactor determined the optimum operating conditions to maximize combustible gas yield and minimize operating costs. Economic analyses are presented in the report which demonstrate that anaerobic treatment of these wastes in a fluidized bed reactor is a highly cost-effective process.

  8. Odor Removal Characteristics of a Laminated Film-Electrode Packed-Bed Nonthermal Plasma Reactor

    PubMed Central

    Kuwahara, Takuya; Okubo, Masaaki; Kuroki, Tomoyuki; Kametaka, Hideya; Yamamoto, Toshiaki

    2011-01-01

    Odor control has gained importance for ensuring a comfortable living environment. In this paper, the authors report the experimental results of a study on the detailed characteristics of a laminated film-electrode and a laminated film-electrode packed-bed nonthermal plasma reactor, which are types of dielectric barrier discharge (DBD) reactor used for odor control. These plasma reactors can be potentially used for the decomposition of volatile organic compounds (VOCs) and reduction of NOx. The reactor is driven by a low-cost 60-Hz neon transformer. Removal efficiencies under various experimental conditions are studied. The complete decomposition of the main odor component, namely, NH3, is achieved in a dry environment. The retention times are investigated for the complete removal of NH3 in the case of the film-electrode plasma reactor and the film-electrode packed-bed plasma reactor. The removal efficiency of the former reactor is lower than that of the latter reactor. Mixing another odor component such as CH3CHO in the gas stream has no significant effect on NH3 removal efficiency. PMID:22163912

  9. Odor removal characteristics of a laminated film-electrode packed-bed nonthermal plasma reactor.

    PubMed

    Kuwahara, Takuya; Okubo, Masaaki; Kuroki, Tomoyuki; Kametaka, Hideya; Yamamoto, Toshiaki

    2011-01-01

    Odor control has gained importance for ensuring a comfortable living environment. In this paper, the authors report the experimental results of a study on the detailed characteristics of a laminated film-electrode and a laminated film-electrode packed-bed nonthermal plasma reactor, which are types of dielectric barrier discharge (DBD) reactor used for odor control. These plasma reactors can be potentially used for the decomposition of volatile organic compounds (VOCs) and reduction of NO(x). The reactor is driven by a low-cost 60-Hz neon transformer. Removal efficiencies under various experimental conditions are studied. The complete decomposition of the main odor component, namely, NH(3), is achieved in a dry environment. The retention times are investigated for the complete removal of NH(3) in the case of the film-electrode plasma reactor and the film-electrode packed-bed plasma reactor. The removal efficiency of the former reactor is lower than that of the latter reactor. Mixing another odor component such as CH(3)CHO in the gas stream has no significant effect on NH(3) removal efficiency.

  10. Microbial community structure and dynamics in anaerobic fluidized‐bed and granular sludge‐bed reactors: influence of operational temperature and reactor configuration

    PubMed Central

    Bialek, Katarzyna; Kumar, Amit; Mahony, Thérèse; Lens, Piet N. L.; O' Flaherty, Vincent

    2012-01-01

    Summary Methanogenic community structure and dynamics were investigated in two different, replicated anaerobic wastewater treatment reactor configurations [inverted fluidized bed (IFB) and expanded granular sludge bed (EGSB)] treating synthetic dairy wastewater, during operating temperature transitions from 37°C to 25°C, and from 25°C to 15°C, over a 430‐day trial. Non‐metric multidimensional scaling (NMS) and moving‐window analyses, based on quantitative real‐time PCR data, along with denaturing gradient gel electrophoresis (DGGE) profiling, demonstrated that the methanogenic communities developed in a different manner in these reactor configurations. A comparable level of performance was recorded for both systems at 37°C and 25°C, but a more dynamic and diverse microbial community in the IFB reactors supported better stability and adaptative capacity towards low temperature operation. The emergence and maintenance of particular bacterial genotypes (phylum Firmicutes and Bacteroidetes) was associated with efficient protein hydrolysis in the IFB, while protein hydrolysis was inefficient in the EGSB. A significant community shift from a Methanobacteriales and Methanosaetaceae towards a Methanomicrobiales‐predominated community was demonstrated during operation at 15°C in both reactor configurations. PMID:22967313

  11. Ambient Laboratory Coater for Advanced Gas Reactor Fuel Development

    SciTech Connect

    Duane D. Bruns; Robert M. Counce; Irma D. Lima Rojas

    2010-06-09

    this research is targeted at developing improved experimentally-based scaling relationships for the hydrodynamics of shallow, gas-spouted beds of dense particles. The work is motivated by the need to more effctively scale up shallow spouted beds used in processes such as in the coating of nuclear fuel particles where precise control of solids and gas circulation is critically important. Experimental results reported here are for a 50 mm diameter spouted bed containing two different types of bed solids (alumina and zirconia) at different static bed depths and fluidized by air and helium. Measurements of multiple local average pressures, inlet gas pressure fluctuations, and spout height were used to characterize the bed hydrodynamics for each operating condition. Follow-on studies are planned that include additional variations in bed size, particle properties, and fluidizing gas. The ultimate objective is to identify the most important non-dimensional hydrodynamic scaling groups and possible spouted-bed design correlations based on these groups.

  12. Biomass growth restriction in a packed bed reactor

    DOEpatents

    Griffith, William L.; Compere, Alicia L.

    1978-01-01

    When carrying out continuous biologically catalyzed reactions with anaerobic microorganisms attached to a support in an upflow packed bed column, growth of the microorganisms is restricted to prevent the microorganisms from plugging the column by limiting the availability of an essential nutrient and/or by the presence of predatory protozoa which consume the anaerobic microorganisms. A membrane disruptive detergent may be provided in the column to lyse dead microorganisms to make them available as nutrients for live microorganisms.

  13. Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal.

    PubMed

    Makwana, J P; Joshi, Asim Kumar; Athawale, Gaurav; Singh, Dharminder; Mohanty, Pravakar

    2015-02-01

    An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210 mm diameter and 1600 mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750-850 °C, 25-31.3 kg/h, and 0.3-0.38, respectively. Flow rate of air was kept constant (37 m(3)/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ∼45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field. PMID:25446789

  14. Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal.

    PubMed

    Makwana, J P; Joshi, Asim Kumar; Athawale, Gaurav; Singh, Dharminder; Mohanty, Pravakar

    2015-02-01

    An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210 mm diameter and 1600 mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750-850 °C, 25-31.3 kg/h, and 0.3-0.38, respectively. Flow rate of air was kept constant (37 m(3)/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ∼45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field.

  15. Improved performance of parallel surface/packed-bed discharge reactor for indoor VOCs decomposition: optimization of the reactor structure

    NASA Astrophysics Data System (ADS)

    Jiang, Nan; Hui, Chun-Xue; Li, Jie; Lu, Na; Shang, Ke-Feng; Wu, Yan; Mizuno, Akira

    2015-10-01

    The purpose of this paper is to develop a high-efficiency air-cleaning system for volatile organic compounds (VOCs) existing in the workshop of a chemical factory. A novel parallel surface/packed-bed discharge (PSPBD) reactor, which utilized a combination of surface discharge (SD) plasma with packed-bed discharge (PBD) plasma, was designed and employed for VOCs removal in a closed vessel. In order to optimize the structure of the PSPBD reactor, the discharge characteristic, benzene removal efficiency, and energy yield were compared for different discharge lengths, quartz tube diameters, shapes of external high-voltage electrode, packed-bed discharge gaps, and packing pellet sizes, respectively. In the circulation test, 52.8% of benzene was removed and the energy yield achieved 0.79 mg kJ-1 after a 210 min discharge treatment in the PSPBD reactor, which was 10.3% and 0.18 mg kJ-1 higher, respectively, than in the SD reactor, 21.8% and 0.34 mg kJ-1 higher, respectively, than in the PBD reactor at 53 J l-1. The improved performance in benzene removal and energy yield can be attributed to the plasma chemistry effect of the sequential processing in the PSPBD reactor. The VOCs mineralization and organic intermediates generated during discharge treatment were followed by CO x selectivity and FT-IR analyses. The experimental results indicate that the PSPBD plasma process is an effective and energy-efficient approach for VOCs removal in an indoor environment.

  16. APPARATUS FOR SHORT TIME MEASUREMENTS IN A FIXED-BED, GAS/SOLID REACTOR

    EPA Science Inventory

    An apparatus for exposure of a solid to reactive process gas is described which makes possible short time (≥ 0.3 to 15 s) exposures in a fixed-bed reactor. Operating conditions for differential reaction with respect to the gas concentration and rapid quench for arresting hi...

  17. Large-Scale Simulations of Realistic Fluidized Bed Reactors using Novel Numerical Methods

    NASA Astrophysics Data System (ADS)

    Capecelatro, Jesse; Desjardins, Olivier; Pepiot, Perrine; National Renewable Energy Lab Collaboration

    2011-11-01

    Turbulent particle-laden flows in the form of fluidized bed reactors display good mixing properties, low pressure drops, and a fairly uniform temperature distribution. Understanding and predicting the flow dynamics within the reactor is necessary for improving the efficiency, and providing technologies for large-scale industrialization. A numerical strategy based on an Eulerian representation of the gas phase and Lagrangian tracking of the particles is developed in the framework of NGA, a high- order fully conservative parallel code tailored for turbulent flows. The particles are accounted for using a point-particle assumption. Once the gas-phase quantities are mapped to the particle location a conservative, implicit diffusion operation smoothes the field. Normal and tangential collisions are handled via soft-sphere model, modified to allow the bed to reach close packing at rest. The pressure drop across the bed is compared with theory to accurately predict the minimum fluidization velocity. 3D simulations of the National Renewable Energy Lab's 4-inch reactor are then conducted. Tens of millions of particles are tracked. The reactor's geometry is modeled using an immersed boundary scheme. Statistics for volume fraction, velocities, bed expansion, and bubble characteristics are analyzed and compared with experimental data.

  18. ANALYSIS OF AN AEROBIC FLUIDIZED BED REACTOR DEGRADING MTBE AND BTEX AT REDUCED EBCTS

    EPA Science Inventory

    The purpose of this study was to investigate the biodegradation of MTBE and BTEX using a fluidized bed reactor (FBR) with granular activated carbon (GAC) as a biological attachment medium. Batch experiments were run to analyze the MTBE and TBA degradation kinetics of the culture ...

  19. Computational and experimental prediction of dust production in pebble bed reactors, Part II

    SciTech Connect

    Mie Hiruta; Gannon Johnson; Maziar Rostamian; Gabriel P. Potirniche; Abderrafi M. Ougouag; Massimo Bertino; Louis Franzel; Akira Tokuhiro

    2013-10-01

    This paper is the continuation of Part I, which describes the high temperature and high pressure helium environment wear tests of graphite–graphite in frictional contact. In the present work, it has been attempted to simulate a Pebble Bed Reactor core environment as compared to Part I. The experimental apparatus, which is a custom-designed tribometer, is capable of performing wear tests at PBR relevant higher temperatures and pressures under a helium environment. This environment facilitates prediction of wear mass loss of graphite as dust particulates from the pebble bed. The experimental results of high temperature helium environment are used to anticipate the amount of wear mass produced in a pebble bed nuclear reactor.

  20. Modelling of turbulent flow in a radial reactor with fixed bed

    NASA Astrophysics Data System (ADS)

    Zhapbasbayev, U. K.; Ramazanova, G. I.; Kenzhaliev, O. B.

    2015-03-01

    The data of the computation of turbulent flow in the CF- π and CP- π configurations of the radial reactor with a fixed bed are presented. The Reynolds motion equations have been solved jointly with the k- ɛ turbulence model. To couple the parameters of flows at the interface free part-fixed bed the classical continuity equations were used. The computational data are obtained for the averaged and turbulent characteristics, and it is shown that the flow in the fixed bed causes the generation of the turbulence kinetic energy and its dissipation rate; the flow in the CF- π configuration is distributed more uniformly as compared to the CP- π configuration of the radial reactor. Computed data are compared with the experimental ones.

  1. Fluidized-bed atomic layer deposition reactor for the synthesis of core-shell nanoparticles

    SciTech Connect

    Didden, Arjen P.; Middelkoop, Joost; Krol, Roel van de; Besling, Wim F. A.; Nanu, Diana E.

    2014-01-15

    The design of a fluidized bed atomic layer deposition (ALD) reactor is described in detail. The reactor consists of three parts that have all been placed in one protective cabinet: precursor dosing, reactor, and residual gas treatment section. In the precursor dosing section, the chemicals needed for the ALD reaction are injected into the carrier gas using different methods for different precursors. The reactor section is designed in such a way that a homogeneous fluidized bed can be obtained with a constant, actively controlled, reactor pressure. Furthermore, no filters are required inside the reactor chamber, minimizing the risk of pressure increase due to fouling. The residual gas treatment section consists of a decomposition furnace to remove residual precursor and a particle filter and is installed to protect the pump. In order to demonstrate the performance of the reactor, SiO{sub 2} particles have been coated with TiO{sub 2} using tetrakis-dimethylamino titanium (TDMAT) and H{sub 2}O as precursors. Experiments with varying pulse times show that saturated growth can be obtained with TDMAT pulse times larger than 600 s. Analysis of the powder with High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) and energy dispersive X-ray spectroscopy confirmed that after 50 cycles, all SiO{sub 2} particles were coated with a 1.6 nm homogenous shell of TiO{sub 2}.

  2. Fluidized-bed atomic layer deposition reactor for the synthesis of core-shell nanoparticles.

    PubMed

    Didden, Arjen P; Middelkoop, Joost; Besling, Wim F A; Nanu, Diana E; van de Krol, Roel

    2014-01-01

    The design of a fluidized bed atomic layer deposition (ALD) reactor is described in detail. The reactor consists of three parts that have all been placed in one protective cabinet: precursor dosing, reactor, and residual gas treatment section. In the precursor dosing section, the chemicals needed for the ALD reaction are injected into the carrier gas using different methods for different precursors. The reactor section is designed in such a way that a homogeneous fluidized bed can be obtained with a constant, actively controlled, reactor pressure. Furthermore, no filters are required inside the reactor chamber, minimizing the risk of pressure increase due to fouling. The residual gas treatment section consists of a decomposition furnace to remove residual precursor and a particle filter and is installed to protect the pump. In order to demonstrate the performance of the reactor, SiO2 particles have been coated with TiO2 using tetrakis-dimethylamino titanium (TDMAT) and H2O as precursors. Experiments with varying pulse times show that saturated growth can be obtained with TDMAT pulse times larger than 600 s. Analysis of the powder with High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) and energy dispersive X-ray spectroscopy confirmed that after 50 cycles, all SiO2 particles were coated with a 1.6 nm homogenous shell of TiO2.

  3. Upgrading light olefin fuel gas and catalytic reformate in a turbulent fluidized bed catalyst reactor

    SciTech Connect

    Kushnerick, J.D.; Harandi, M.N.; Owen, H.

    1989-05-02

    A fluidized bed catalyst process is described for conversion of C/sub 4/- light olefinic gas feedstock to C/sub 5/+ hydrocarbons and for conversion of C/sub 6/ to C/sub 8/ aromatic feedstock to C/sub 7/ to C/sub 11/ aromatics. It consists of: maintaining a fluidized bed of zeolite catalyst particles in a turbulent reactor bed at a temperature of about 500/sup 0/ to 800/sup 0/F, the catalyst having an apparent particle density of about 0.9 to 1.6 g/cm/sup 3/ and a size range of about 1 to 150 microns, an average catalyst particle size of about 20 to 100 microns containing about 10 to 25 weight percent of fine particles having a particle size less than 32 microns; contacting the feedstocks and passing the feedstocks upwardly through the fluidized catalyst bed under turbulent flow conditions at reaction conditions sufficient to convert at least about 70% of the olefin feedstock and to convert at least 5% of the C/sub 6/ to C/sub 8/ aromatic feedstock; maintaining turbulent fluidized bed conditions through the reactor bed between transition velocity and transport velocity at a superficial fluid velocity of about 0.3 to 2 meters per second; and recovering hydrocarbon product containing C/sub 5/+ hydrocarbons C/sub 7/ to C/sub 11/ aromatic hydrocarbons.

  4. Chromate reduction by Arthrobacter CR47 in biofilm packed bed reactors.

    PubMed

    Córdoba, Andrés; Vargas, Paola; Dussan, Jenny

    2008-02-28

    Bacterial strain Cr47 was isolated from a landfarming process soil sample. It was identified, by 16s rDNA sequencing, as Arthrobacter sp. The time course of the Cr(VI) reduction was monitored in batch operated packed bed biofilm reactors (12 mL void volume) and in recirculating packed bed biofilm reactors (100 mL void volume) inoculated with bacterial strain Cr47. The reduction was evaluated with, 30 mg L(-1) Cr(VI) laboratory solutions prepared with K2Cr2O7 and enriched with glucose-minimal medium, and with 30 mg L(-1) Cr(VI) industrial model solutions prepared with chrome plating waste waters enriched with sucrose-minimal medium. Under batch mode the reduction reaction by the biofilm seemed to fit well an exponential-decay model with a first order kinetic parameter of 0.071 mg(L h)(-1) Cr(VI). In the recirculating reactor, monitored after 4 weeks from inoculation and fed with laboratory solutions the removal rate was 0.79 mg(L h)(-1). In the reactor fed with the industrial model solutions the maximum Cr(VI) removal rate attained was 0.49 mg(L h)(-1). Artrobacter sp. packed bed biofilm reactors achieved Cr(VI) reduction rates comparable to other aerobic and anaerobic fixed film bioreactors previously reported.

  5. Computational fluid dynamics modelling of biomass fast pyrolysis in fluidised bed reactors, focusing different kinetic schemes.

    PubMed

    Ranganathan, Panneerselvam; Gu, Sai

    2016-08-01

    The present work concerns with CFD modelling of biomass fast pyrolysis in a fluidised bed reactor. Initially, a study was conducted to understand the hydrodynamics of the fluidised bed reactor by investigating the particle density and size, and gas velocity effect. With the basic understanding of hydrodynamics, the study was further extended to investigate the different kinetic schemes for biomass fast pyrolysis process. The Eulerian-Eulerian approach was used to model the complex multiphase flows in the reactor. The yield of the products from the simulation was compared with the experimental data. A good comparison was obtained between the literature results and CFD simulation. It is also found that CFD prediction with the advanced kinetic scheme is better when compared to other schemes. With the confidence obtained from the CFD models, a parametric study was carried out to study the effect of biomass particle type and size and temperature on the yield of the products.

  6. The characteristics of gas-solid flow and wall heat transfer in a fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Choi, Hang Seok; Meier, Dietrich

    2012-09-01

    Numerical study using computational fluid dynamics has been carried out to investigate the heat transfer characteristics of a laboratory fluidized bed reactor. The fluidized bed reactor of vTI (Johann Heinrich von Thünen-Institute)-Institute of Wood Technology and Wood Biology is modeled. For the simulation of multiphase flow and thermal fields, an Eulerian-Eulerian approach is applied. The flow and thermal characteristics of the reactor are fully investigated for the wide range of superficial gas velocities and two different particle diameters. In particular, the contributions of the gas bubble and emulsion phase flows on the wall heat transfer are scrutinized. From the predicted results, it is fully elucidated that particular near-wall bubble motions mainly govern the wall heat transfer.

  7. Experimental and computational investigation of flow of pebbles in a pebble bed nuclear reactor

    NASA Astrophysics Data System (ADS)

    Khane, Vaibhav B.

    The Pebble Bed Reactor (PBR) is a 4th generation nuclear reactor which is conceptually similar to moving bed reactors used in the chemical and petrochemical industries. In a PBR core, nuclear fuel in the form of pebbles moves slowly under the influence of gravity. Due to the dynamic nature of the core, a thorough understanding about slow and dense granular flow of pebbles is required from both a reactor safety and performance evaluation point of view. In this dissertation, a new integrated experimental and computational study of granular flow in a PBR has been performed. Continuous pebble re-circulation experimental set-up, mimicking flow of pebbles in a PBR, is designed and developed. Experimental investigation of the flow of pebbles in a mimicked test reactor was carried out for the first time using non-invasive radioactive particle tracking (RPT) and residence time distribution (RTD) techniques to measure the pebble trajectory, velocity, overall/zonal residence times, flow patterns etc. The tracer trajectory length and overall/zonal residence time is found to increase with change in pebble's initial seeding position from the center towards the wall of the test reactor. Overall and zonal average velocities of pebbles are found to decrease from the center towards the wall. Discrete element method (DEM) based simulations of test reactor geometry were also carried out using commercial code EDEM(TM) and simulation results were validated using the obtained benchmark experimental data. In addition, EDEM(TM) based parametric sensitivity study of interaction properties was carried out which suggests that static friction characteristics play an important role from a packed/pebble beds structural characterization point of view. To make the RPT technique viable for practical applications and to enhance its accuracy, a novel and dynamic technique for RPT calibration was designed and developed. Preliminary feasibility results suggest that it can be implemented as a non

  8. Deleterious Thermal Effects due to Randomized Flow Paths in Pebble Bed, and Particle Bed Style Reactors

    NASA Technical Reports Server (NTRS)

    Moran, Robert P.

    2013-01-01

    Reactor fuel rod surface area that is perpendicular to coolant flow direction (+S) i.e. perpendicular to the P creates areas of coolant stagnation leading to increased coolant temperatures resulting in localized changes in fluid properties. Changes in coolant fluid properties caused by minor increases in temperature lead to localized reductions in coolant mass flow rates leading to localized thermal instabilities. Reductions in coolant mass flow rates result in further increases in local temperatures exacerbating changes to coolant fluid properties leading to localized thermal runaway. Unchecked localized thermal runaway leads to localized fuel melting. Reactor designs with randomized flow paths are vulnerable to localized thermal instabilities, localized thermal runaway, and localized fuel melting.

  9. CORE ANALYSIS, DESIGN AND OPTIMIZATION OF A DEEP-BURN PEBBLE BED REACTOR

    SciTech Connect

    B. Boer; A. M. Ougouag

    2010-05-01

    Achieving a high burnup in the Deep-Burn pebble bed reactor design, while remaining within the limits for fuel temperature, power peaking and temperature reactivity feedback, is challenging. The high content of Pu and Minor Actinides in the Deep-Burn fuel significantly impacts the thermal neutron energy spectrum. This can result in power and temperature peaking in the pebble bed core in locally thermalized regions near the graphite reflectors. Furthermore, the interplay of the Pu resonances of the neutron absorption cross sections at low-lying energies can lead to a positive temperature reactivity coefficient for the graphite moderator at certain operating conditions. To investigate the aforementioned effects a code system using existing codes has been developed for neutronic, thermal-hydraulic and fuel depletion analysis of Deep-Burn pebble bed reactors. A core analysis of a Deep-Burn Pebble Bed Modular Reactor (400 MWth) design has been performed for two Deep-Burn fuel types and possible improvements of the design with regard to power peaking and temperature reactivity feedback are identified.

  10. Continuous synthesis of hexanal by immobilized hydroperoxide lyase in packed-bed reactor.

    PubMed

    Liu, Qingqing; Hua, Yufei

    2015-12-01

    This study aimed to develop an optimal continuous procedure of immobilized hydroperoxide lyase (HPL)-catalyzed synthesis of hexanal. A central composite design was used to study the combined effect of substrate concentration and the residence time of the reactant on hexanal concentration. The optimum conditions for hexanal synthesis included a 13-HPOD concentration of 43.54 mM and a residence time of 60.99 min. The maximum hexanal concentration was 3560 ± 130 mg/L when 16 U of immobilized HPLwas used. Furthermore, the stability of immobilized HPL was significantly improved in the packed-bed reactor, as evidenced by the slowed enzyme inactivation and prolonged operation time. The immobilized HPL remained activity until 40 mL substrate solution flowed past the packed-bed reactor. The catalyst productivity of hexanal in the packed-bed reactor was 5.35 ± 0.34 mg/U, much higher than that in the batch stirred reactor. This study was greatly meaningful for providing a green method to the large-scale production of hexanal.

  11. Pebble Bed Reactors Design Optimization Methods and their Application to the Pebble Bed Fluoride Salt Cooled High Temperature Reactor (PB-FHR)

    NASA Astrophysics Data System (ADS)

    Cisneros, Anselmo Tomas, Jr.

    The Fluoride salt cooled High temperature Reactor (FHR) is a class of advanced nuclear reactors that combine the robust coated particle fuel form from high temperature gas cooled reactors, direct reactor auxillary cooling system (DRACS) passive decay removal of liquid metal fast reactors, and the transparent, high volumetric heat capacitance liquid fluoride salt working fluids---flibe (33%7Li2F-67%BeF)---from molten salt reactors. This combination of fuel and coolant enables FHRs to operate in a high-temperature low-pressure design space that has beneficial safety and economic implications. In 2012, UC Berkeley was charged with developing a pre-conceptual design of a commercial prototype FHR---the Pebble Bed- Fluoride Salt Cooled High Temperature Reactor (PB-FHR)---as part of the Nuclear Energy University Programs' (NEUP) integrated research project. The Mark 1 design of the PB-FHR (Mk1 PB-FHR) is 236 MWt flibe cooled pebble bed nuclear heat source that drives an open-air Brayton combine-cycle power conversion system. The PB-FHR's pebble bed consists of a 19.8% enriched uranium fuel core surrounded by an inert graphite pebble reflector that shields the outer solid graphite reflector, core barrel and reactor vessel. The fuel reaches an average burnup of 178000 MWt-d/MT. The Mk1 PB-FHR exhibits strong negative temperature reactivity feedback from the fuel, graphite moderator and the flibe coolant but a small positive temperature reactivity feedback of the inner reflector and from the outer graphite pebble reflector. A novel neutronics and depletion methodology---the multiple burnup state methodology was developed for an accurate and efficient search for the equilibrium composition of an arbitrary continuously refueled pebble bed reactor core. The Burnup Equilibrium Analysis Utility (BEAU) computer program was developed to implement this methodology. BEAU was successfully benchmarked against published results generated with existing equilibrium depletion codes VSOP

  12. Fluid dynamics of the freeboard in a fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Verloop, Willem Cornelis

    1994-05-01

    The present study focuses on the fluid dynamics of the gas-particle freeboard flow, whereas a subsequent study will cover the chemistry. The objective of the present thesis is to increase the insight in the physical processes that govern the freeboard particle flow. Special attention has to be paid to the lateral transport of particles and the often observed phenomenon of a downflowing wall layer of solids, which has not been explained satisfactorily up to now. In order to achieve this, detailed experiments have to be performed which provide data on the local flow structure. In addition, the freeboard flow has to be modeled at least two-dimensionally, incorporating the essential physical processes. The resulting model of the freeboard flow should firstly be capable of predicting the local properties of both the gas flow and the particle flow. This prediction has to serve as a basis for the subsequent modeling of the freeboard chemistry. Secondly, the model should serve as a basis for studying the consequences of the scaling up a fluidized bed installation from lab scale to industrial size.

  13. Synthesis of a nanosilica supported CO2 sorbent in a fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Soria-Hoyo, C.; Valverde, J. M.; van Ommen, J. R.; Sánchez-Jiménez, P. E.; Pérez-Maqueda, L. A.; Sayagués, M. J.

    2015-02-01

    CaO has been deposited on a nanosilica powder matrix by a procedure based on atomic layer deposition (ALD) in a fluidized bed reactor at atmospheric pressure following a potentially scalable process. In previous works ALD in gas fluidized bed has been mostly performed under reduced pressure, which hampers scaling-up the production technology. The material synthesized in the present work is tested as CO2 solid sorbent at calcium looping conditions. Multicyclic thermogravimetric analysis (TGA) shows that the nanosilica support stabilizes the capture capacity of CaO. EDX-STEM analysis illustrates the presence of Ca well distributed on the surface of the SiO2 nanoparticles.

  14. Apple juice clarification by immobilized pectolytic enzymes in packed or fluidized bed reactors.

    PubMed

    Diano, Nadia; Grimaldi, Tiziana; Bianco, Mariangela; Rossi, Sergio; Gabrovska, Katya; Yordanova, Galya; Godjevargova, Tzonka; Grano, Valentina; Nicolucci, Carla; Mita, Luigi; Bencivenga, Umberto; Canciglia, Paolo; Mita, Damiano G

    2008-12-10

    The catalytic behavior of a mixture of pectic enzymes, covalently immobilized on different supports (glass microspheres, nylon 6/6 pellets, and PAN beads), was analyzed with a pectin aqueous solution that simulates apple juice. The following parameters were investigated: the rate constant at which pectin hydrolysis is conducted, the time (tau(50)) in which the reduction of 50% of the initial viscosity is reached, and the time (tau(comp,dep)) required to obtain complete depectinization. The best catalytic system was proven to be PAN beads, and their pH and temperature behavior were determined. The yields of two bed reactors, packed or fluidized, using the catalytic PAN beads, were compared to the circulation flow rate of real apple juice. The experimental conditions were as follows: pH 4.0, T = 50 degrees C, and beads volume = 20 cm(3). The initial pectin concentration was the one that was present in our apple juice sample. No differences were observed at low circulation rates, while at higher recirculation rates, the time required to obtain complete pectin hydrolysis into the fluidized reactor was found to be 0.25 times smaller than in the packed bed reactor: 131 min for the packed reactors and 41 min for the fluidized reactors.

  15. Quantifying temperature and flow rate effects on the performance of a fixed-bed chromatographic reactor.

    PubMed

    Vu, Tien D; Seidel-Morgenstern, A

    2011-11-01

    Chromatographic reactors are based on coupling chemical reactions with chromatographic separation in fixed-beds. Temperature and flow rate are important parameters for the performance of such reactors. Temperature affects mainly adsorption, chemical equilibria, mass transfer and reaction kinetics, whereas flow rate influences residence time and dispersion. In order to evaluate the mentioned effects, the hydrolysis reactions of methyl formate (MF) and methyl acetate (MA) were chosen as case studies. These reactions were performed experimentally in a lab-scale fixed-bed chromatographic reactor packed with a strong acidic ion exchange resin. The chosen reactions can be considered to represent a relative fast (MF) and a relative slow (MA) reaction. The processes which take place inside the reactor were described and simulated using an isothermal equilibrium dispersive model. The essential model parameters were determined experimentally at different temperatures and flow rates. The performance of the chromatographic reactor was evaluated at several discrete constant temperature levels by quantifying product purity, productivity and yield. The work provides insight regarding the influence of temperature and flow rate on values of the model parameters and the performance criteria.

  16. Kinetics and fixed-bed reactor modeling of butane oxidation to maleic anhydride

    SciTech Connect

    Sharma, R.K.; Cresswell, D.L. ); Newson, E.J. )

    1991-01-01

    This paper reports on selective oxidation kinetics of n-butane to maleic anhydride in air studied over a commercial, fixed-bed vanadium-phosphor oxide catalyst. The temperature range was 573-653 K with butane concentrations up to 3 mol % in the feed, which is within flammability limits but below ignition temperatures. The rate data were modeled using power law kinetics with product inhibition and included total oxidation and decomposition reactions. Kinetic parameters were estimated using a multiresponse, nonlinear regression algorithm showing intercorrelation effects. The kinetics were combined with independent measurements of catalyst diffusivity and reactor heat transfer using a one- dimensional heterogeneous reactor model.

  17. Rotating-bed reactor as a power source for EM gun applications

    SciTech Connect

    Powell, J.; Botts, T.; Stickley, C.M.; Meth, S.

    1980-01-01

    Electromagnetic gun applications of the Rotating Bed Reactor (RBR) are examined. The RBR is a compact (approx. 1 m/sup 3/), (up to several thousand MW(th)), high-power reactor concept, capable of producing a high-temperature (up to approx. 300/sup 0/K) gas stream with a MHD generator coupled to it, the RBR can generate electric power (up to approx. 1000 MW(e)) in the pulsed or cw modes. Three EM gun applications are investigated: a rail gun thruster for orbit transfer, a rapid-fire EM gun for point defense, and a direct ground-to-space launch. The RBR appears suitable for all applications.

  18. Heat-transfer characteristics of flowing and stationary particle-bed-type fusion-reactor blankets

    SciTech Connect

    Nietert, R.E.

    1983-02-01

    The heat-transfer characteristics of flowing and stationary packed-particle beds have recently become of interest in connection with conceptual designs of fusion reactor blankets. A detailed literature survey has shown that the processes taking place in such beds are not fully understood despite their widespread use in the chemical industry and other engineering disciplines for more than five decades. In this study, two experimental investigations were pursued. In the first, a heat-transfer loop was constructed through which glass microspheres were allowed to flow by rgravity at controlled rates through an electrically heated stainless steel tubular test section. In the second, an annular packed bed was constructed in which heat was applied through the outer wall by electric heating of a stainless steel tube. Cooling occurred at the inner wall of the annular bed by flowing air through the central tube. A second air stream was allowed to flow through the voids of the packed bed. An error-minimization technique was utilized in order to obtain the two-dimensional one-parameter effective conductivity for the bed by comparing the experimental and theoretically predicted temperature profiles. Experiments were conducted for various modified Reynolds numbers less than ten.

  19. Results of theoretical and experimental studies of hydrodynamics of circulation loops in circulating fluidized bed reactors and systems with interconnected reactors

    NASA Astrophysics Data System (ADS)

    Ryabov, G. A.; Folomeev, O. M.; Sankin, D. A.; Melnikov, D. A.

    2015-02-01

    Problems of the calculation of circulation loops in circulating fluidized bed reactors and systems with interconnected reactors (polygeneration systems for the production of electricity, heat, and useful products and chemical cycles of combustion and gasification of solid fuels)are considered. A method has been developed for the calculation of circulation loop of fuel particles with respect to boilers with circulating fluidized bed (CFB) and systems with interconnected reactors with fluidized bed (FB) and CFB. New dependences for the connection between the fluidizing agent flow (air, gas, and steam) and performance of reactors and for the whole system (solids flow rate, furnace and cyclone pressure drops, and bed level in the riser) are important elements of this method. Experimental studies of hydrodynamics of circulation loops on the aerodynamic unit have been conducted. Experimental values of pressure drop of the horizontal part of the L-valve, which satisfy the calculated dependence, have been obtained.

  20. Microstructure of multicrystalline silicon seeded by polysilicon chips and fluidized bed reactor granules

    NASA Astrophysics Data System (ADS)

    Ekstrøm, K. E.; Stokkan, G.; Autruffe, A.; Søndenå, R.; Dalaker, H.; Arnberg, L.; Di Sabatino, M.

    2016-05-01

    Multicrystalline silicon displays a considerable smaller average grain size and reduced dislocation generation when being seeded by polycrystalline silicon chips or fluidized bed reactor silicon granules. A simple texture analysis shows how the initially random grain structure of the seeds develops a weak preference for near-<111> and near-<112> oriented grains upwards in the ingot. Closer investigations reveal a considerable coarsening of the initial microstructure of the seeds during the directional solidification process, especially for small fluidized bed reactor granules. The irregular shape of polysilicon chips allows for melt penetration into the seeding structure and potential indentation effects that may account for the increased dislocation generation observed in this case. The increased generation may, however, also be related to a higher ratio of ∑27 grain boundaries.

  1. Hydrogen sulfide removal from air by Acidithiobacillus thiooxidans in a trickle bed reactor.

    PubMed

    Ramirez, M; Gómez, J M; Cantero, D; Páca, J; Halecký, M; Kozliak, E I; Sobotka, M

    2009-09-01

    A strain of Acidithiobacillus thiooxidans immobilized in polyurethane foam was utilized for H(2)S removal in a bench-scale trickle-bed reactor, testing the limits of acidity and SO(4) (2-) accumulation. The use of this acidophilic strain resulted in remarkable stability in the performance of the system. The reactor maintained a >98-99 % H(2)S removal efficiency for c of up to 66 ppmv and empty bed residence time 98 % H(2)S was achieved under steady-state conditions, over the pH range of 0.44-7.30. Despite the accumulation of acidity and SO(4) (2-) (up to 97 g/L), the system operated without inhibition.

  2. Anaerobic treatment and biogas recovery for sago wastewater management using a fluidized bed reactor.

    PubMed

    Saravanane, R; Murthy, D V; Krishnaiah, K

    2001-01-01

    Starch manufacturing industrial units, such as sago mills, both at medium and large scale, suffer from inadequate treatment and disposal problems due to high concentration of suspended solid content present in the effluent. In order to investigate the viability of treatment of sago effluent, a laboratory scale study was conducted. The treatment of sago effluent was studied in a continuous flow anaerobic fluidized bed reactor. The start-up of the reactor was carried out using a mixture of digested supernatant sewage sludge and cow dung slurry in different proportions. The effect of operating variables such as COD of the effluent, bed expansion, minimum fluidization velocity on efficiency of treatment and recovery of biogas was investigated. The treated wastewater was analysed for recycling and reuse to ensure an alternative for sustainable water resourse management. The maximum efficiency of treatment was found to be 82% and the nitrogen enriched digested sludge was recommended for agricultural use.

  3. Cell retention by encapsulation for the cultivation of Jurkat cells in fixed and fluidized bed reactors.

    PubMed

    Kaiser, P; Werner, M; Jérôme, V; Hübner, H; Buchholz, R; Freitag, R

    2014-12-01

    Jurkat cells are accepted model cells for primary human T lymphocytes, for example, in medical research. Their growth to tissue-like cell densities (up to 100 × 10(6)  cells/mLcapsule ) in semi-permeable (molecular weight cut off <10,000 Da) sodium cellulose sulfate/poly(diallyldimethylammonium chloride) polyelectrolyte capsules has previously been shown by us [Werner et al. (2013). Use of the mitochondria toxicity assay for quantifying the viable cell density of microencapsulated jurkat cells. Biotechnol Prog 29(4): 986-993]. Herein, we demonstrate that encapsulation can be used to retain the cells in continuously operated bioreactors, which opens new possibilities for research, for example, the use of Jurkat cells in pulse response experiments under steady state conditions. Two reactor concepts are presented, a fluidized and a fixed bed reactor. A direct comparison of the growth kinetics in batch and repeated batch spinner cultivations, that is, under conditions where both encapsulated and non-encapsulated cells can be cultivated under otherwise identical conditions, showed that maximum specific growth rates were higher for the encapsulated than for the non-encapsulated cells. In the subsequent batch and repeated batch bioreactor experiments (only encapsulated cells), growth rates were similar, with the exception of the fixed bed batch reactor, where growth kinetics were significantly slower. Concomitantly, a significant fraction of the cells towards the bottom of the bed were no longer metabolically active, though apparently not dead. In the repeated batch fluidized bed reactor cellular division could be maintained for more than two weeks, albeit with a specific growth rate below the maximum one, leading to final cell densities of approximately 180 × 10(6)  cell/gcapsule . At the same time, the cell cycle distribution of the cells was shifted to the S and G2/M phases.

  4. Nuclear Thermal Propulsion engine based on Particle Bed Reactor using light water steam as a propellant

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Maise, G.

    1993-06-01

    In this paper the possibility of configuring a water cooled Nuclear Thermal Propulsion (NTP) rocket, based on a Particle Bed Reactor (PBR) is investigated. This rocket will be used to operate on water obtained from near earth objects. The conclusions reached in this paper indicate that it is possible to configure a PBR based NTP rocket to operate on water and meet the mission requirements envisioned for it. No insurmountable technology issues have been identified.

  5. PEBBLES: A COMPUTER CODE FOR MODELING PACKING, FLOW AND RECIRCULATIONOF PEBBLES IN A PEBBLE BED REACTOR

    SciTech Connect

    Joshua J. Cogliati; Abderrafi M. Ougouag

    2006-10-01

    A comprehensive, high fidelity model for pebble flow has been developed and embodied in the PEBBLES computer code. In this paper, a description of the physical artifacts included in the model is presented and some results from using the computer code for predicting the features of pebble flow and packing in a realistic pebble bed reactor design are shown. The sensitivity of models to various physical parameters is also discussed.

  6. Apparatus for high flux photocatalytic pollution control using a rotating fluidized bed reactor

    DOEpatents

    Tabatabaie-Raissi, Ali; Muradov, Nazim Z.; Martin, Eric

    2003-06-24

    An apparatus based on optimizing photoprocess energetics by decoupling of the process energy efficiency from the DRE for target contaminants. The technique is applicable to both low- and high-flux photoreactor design and scale-up. An apparatus for high-flux photocatalytic pollution control is based on the implementation of multifunctional metal oxide aerogels and other media in conjunction with a novel rotating fluidized particle bed reactor.

  7. A particle bed reactor based NTP in the 112,500 N thrust class

    SciTech Connect

    Ludewig, H.; Powell, J.R.; Lazareth, O.W. Jr.; Todosow, M.

    1993-04-01

    This paper discusses the application of a Particle bed Reactor (PBR) to a 112,500 N thrust Nuclear Thermal Propulsion (NTP) Engine. The method of analysis is described, followed by a presentation of the results. It is concluded that the PBR would result in a very competitive NTP engine. In addition, due to the high power densities possible with a PBR, high thrust/weight ratios are possible. This conclusion can be used to satisfy a variety of mission goals.

  8. Dual bed reactor for the study of catalytic biomass tars conversion

    SciTech Connect

    Ammendola, P.; Piriou, B.; Lisi, L.; Ruoppolo, G.; Chirone, R.; Russo, G.

    2010-04-15

    A dual fixed bed laboratory scale set up has been used to compare the activity of a novel Rh/LaCoO{sub 3}/Al{sub 2}O{sub 3} catalyst to that of dolomite, olivine and Ni/Al{sub 2}O{sub 3}, typical catalysts used in fluidized bed biomass gasification, to convert tars produced during biomass devolatilization stage. The experimental apparatus allows the catalyst to be operated under controlled conditions of temperature and with a real gas mixture obtained by the pyrolysis of the biomass carried out in a separate fixed bed reactor operated under a selected and controlled heating up rate. The proposed catalyst exhibits much better performances than conventional catalysts tested. It is able to completely convert tars and also to strongly decrease coke formation due to its good redox properties. (author)

  9. Advanced Core Design And Fuel Management For Pebble-Bed Reactors

    SciTech Connect

    Hans D. Gougar; Abderrafi M. Ougouag; William K. Terry

    2004-10-01

    A method for designing and optimizing recirculating pebble-bed reactor cores is presented. At the heart of the method is a new reactor physics computer code, PEBBED, which accurately and efficiently computes the neutronic and material properties of the asymptotic (equilibrium) fuel cycle. This core state is shown to be unique for a given core geometry, power level, discharge burnup, and fuel circulation policy. Fuel circulation in the pebble-bed can be described in terms of a few well?defined parameters and expressed as a recirculation matrix. The implementation of a few heat?transfer relations suitable for high-temperature gas-cooled reactors allows for the rapid estimation of thermal properties critical for safe operation. Thus, modeling and design optimization of a given pebble-bed core can be performed quickly and efficiently via the manipulation of a limited number key parameters. Automation of the optimization process is achieved by manipulation of these parameters using a genetic algorithm. The end result is an economical, passively safe, proliferation-resistant nuclear power plant.

  10. Comprehensive kinetic studies of acidic oil continuous esterification by cation-exchange resin in fixed bed reactors.

    PubMed

    Cheng, Yu; Feng, Yaohui; Ren, Yanbiao; Liu, Xuan; Gao, Aoran; He, Benqiao; Yan, Feng; Li, Jianxin

    2012-06-01

    Biodiesel produced by esterification from molar ratio of methanol to free fatty acid (FFA) as 25:1 in presence of triglyceride was carried out with cation-exchange resin as a heterogeneous catalyst in three different scales of fixed bed reactors from minireactor (6.8 mm × 110 mm) to pilot scale reactor (70 mm × 1260 mm) at 338 K. The kinetic study of esterification was undertaken in terms of pseudo-homogeneous mechanism and performed as a first order reaction with elimination of the solid-liquid internal and external mass transfer resistances. Moreover, a kinetic model of FFA esterification was developed to illustrate the relationship between the FFA conversion and the catalyst bed height of fixed bed reactor. The model was also suitable for various resins in fixed bed reactor. The theoretical predictions were in agreement with the experimental data with root mean square (RMS) errors <10.

  11. Use of a seeder reactor to manage crystal growth in the fluidized bed reactor for phosphorus recovery.

    PubMed

    Shimamura, Kazuaki; Ishikawa, Hideyuki; Tanaka, Toshihiro; Hirasawa, Izumi

    2007-04-01

    The authors have been engaged in the development of a phosphorus recovery system capable of maintaining high recovery efficiencies, with the chemical cost suppressed. This time, they conducted demonstration tests of a fluidized bed magnesium ammonium phosphate reactor provided with a seeder reactor for the supernatant from anaerobic digestion using a pilot experimental plant with a wastewater treatment capacity of 20 m3/d. For the digestion supernatant with a phosphorus concentration of approximately 300 mg/L, the treated water phosphorus concentration was 10 to 25 mg/L, and the phosphorus recovery efficiency was more than 90%. Relative to the chemical cost in the case of magnesium chloride, the chemical cost in the case of magnesium hydroxide is approximately 40%. Thus, with the new system, it was possible to reduce the running cost while maintaining high recovery efficiencies. PMID:17489275

  12. Racemization of undesired enantiomers: Immobilization of mandelate racemase and application in a fixed bed reactor.

    PubMed

    Wrzosek, Katarzyna; Rivera, Mariel A García; Bettenbrock, Katja; Seidel-Morgenstern, Andreas

    2016-03-01

    Production of optically pure products can be based on simple unselective synthesis of racemic mixtures combined with a subsequent separation of the enantiomers; however, this approach suffers from a 50% yield limitation which can be overcome by racemization of the undesired enantiomer and recycling. Application of biocatalyst for the racemization steps offers an attractive option for high-yield manufacturing of commercially valuable compounds. Our work focuses on exploiting the potential of racemization with immobilized mandelate racemase. Immobilization of crude mandelate racemase via covalent attachment was optimized for two supports: Eupergit(®) CM and CNBr-activated Sepharose 4 Fast Flow. To allow coupling of enzymatic reaction with enantioselective chromatography, a mobile phase composition compatible with both processes was used in enzymatic reactor. Kinetic parameters obtained analyzing experiments carried out in a batch reactor could be successfully used to predict fixed-bed reactor performance. The applicability of the immobilized enzyme and the determined kinetic parameters were validated in transient experiments recording responses to pulse injections of R-mandelic acid. The approach investigated can be used for futher design and optimization of high yield combined resolution processes. The characterized fixed-bed enzymatic reactor can be integrated e.g. with chromatographic single- or multicolumn steps in various configurations.

  13. Gas-Liquid Two-Phase Flows Through Packed Bed Reactors in Microgravity

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri

    2001-01-01

    The simultaneous flow of gas and liquid through a fixed bed of particles occurs in many unit operations of interest to the designers of space-based as well as terrestrial equipment. Examples include separation columns, gas-liquid reactors, humidification, drying, extraction, and leaching. These operations are critical to a wide variety of industries such as petroleum, pharmaceutical, mining, biological, and chemical. NASA recognizes that similar operations will need to be performed in space and on planetary bodies such as Mars if we are to achieve our goals of human exploration and the development of space. The goal of this research is to understand how to apply our current understanding of two-phase fluid flow through fixed-bed reactors to zero- or partial-gravity environments. Previous experiments by NASA have shown that reactors designed to work on Earth do not necessarily function in a similar manner in space. Two experiments, the Water Processor Assembly and the Volatile Removal Assembly have encountered difficulties in predicting and controlling the distribution of the phases (a crucial element in the operation of this type of reactor) as well as the overall pressure drop.

  14. Reactor Pressure Vessel Temperature Analysis for Prismatic and Pebble-Bed VHTR Designs

    SciTech Connect

    H. D. Gougar; C. B. Davis

    2006-04-01

    Analyses were performed to determine maximum temperatures in the reactor pressure vessel for two potential Very-High Temperature Reactor (VHTR) designs during normal operation and during a depressurized conduction cooldown accident. The purpose of the analyses was to aid in the determination of appropriate reactor vessel materials for the VHTR. The designs evaluated utilized both prismatic and pebble-bed cores that generated 600 MW of thermal power. Calculations were performed for fluid outlet temperatures of 900 and 950 °C, corresponding to the expected range for the VHTR. The analyses were performed using the RELAP5-3D and PEBBED-THERMIX computer codes. Results of the calculations were compared with preliminary temperature limits derived from the ASME pressure vessel code.

  15. Elimination of weapons grade plutonium via burning in a Particle Bed Reactor

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Maise, G.; Todosow, M.

    1993-08-01

    An initial assessment of a concept for burning weapons grade plutonium based on the Particle Bed Reactor (PBR) is described. The high power density/flux level achievable with the PBR make it an attractive candidate for this application. The PBR based plutonium burner concept also possesses a number of safety and economic benefits relative to other reactor based Pu-burner approaches including a safeguards advantages, a low inventory of radionuclides, and high integrity, coated fuel particles which can withstand extremely high temperatures while retaining virtually all fission products. In addition the reactor also possesses a number of ``engineered safety features,`` which, along with the use of high temperature capable materials further enhance its safety characteristics.

  16. Sequential UASB and dual media packed-bed reactors for domestic wastewater treatment - experiment and simulation.

    PubMed

    Rodríguez-Gómez, Raúl; Renman, Gunno

    2016-01-01

    A wastewater treatment system composed of an upflow anaerobic sludge blanket (UASB) reactor followed by a packed-bed reactor (PBR) filled with Sorbulite(®) and Polonite(®) filter material was tested in a laboratory bench-scale experiment. The system was operated for 50 weeks and achieved very efficient total phosphorus (P) removal (99%), 7-day biochemical oxygen demand removal (99%) and pathogenic bacteria reduction (99%). However, total nitrogen was only moderately reduced in the system (40%). A model focusing on simulation of organic material, solids and size of granules was then implemented and validated for the UASB reactor. Good agreement between the simulated and measured results demonstrated the capacity of the model to predict the behaviour of solids and chemical oxygen demand, which is critical for successful P removal and recovery in the PBR. PMID:27332842

  17. Investigation of Multiphase Flow in a Packed Bed Reactor Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Lian, Yongsheng; Motil, Brian; Rame, Enrique

    2016-01-01

    In this paper we study the two-phase flow phenomena in a packed bed reactor using an integrated experimental and numerical method. The cylindrical bed is filled with uniformly sized spheres. In the experiment water and air are injected into the bed simultaneously. The pressure distribution along the bed will be measured. The numerical simulation is based on a two-phase flow solver which solves the Navier-Stokes equations on Cartesian grids. A novel coupled level set and moment of fluid method is used to construct the interface. A sequential method is used to position spheres in the cylinder. Preliminary experimental results showed that the tested flow rates resulted in pulse flow. The numerical simulation revealed that air bubbles could merge into larger bubbles and also could break up into smaller bubbles to pass through the pores in the bed. Preliminary results showed that flow passed through regions where the porosity is high. Comparison between the experimental and numerical results in terms of pressure distributions at different flow injection rates will be conducted. Comparison of flow phenomena under terrestrial gravity and microgravity will be made.

  18. Fluidized bed coupled rotary reactor for nanoparticles coating via atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Duan, Chen-Long; Liu, Xiao; Shan, Bin; Chen, Rong

    2015-07-01

    A fluidized bed coupled rotary reactor has been designed for coating on nanoparticles (NPs) via atomic layer deposition. It consists of five major parts: reaction chamber, dosing and fluidizing section, pumping section, rotary manipulator components, as well as a double-layer cartridge for the storage of particles. In the deposition procedure, continuous fluidization of particles enlarges and homogenizes the void fraction in the particle bed, while rotation enhances the gas-solid interactions to stabilize fluidization. The particle cartridge presented here enables both the fluidization and rotation acting on the particle bed, demonstrated by the analysis of pressure drop. Moreover, enlarged interstitials and intense gas-solid contact under sufficient fluidizing velocity and proper rotation speed facilitate the precursor delivery throughout the particle bed and consequently provide a fast coating process. The cartridge can ensure precursors flowing through the particle bed exclusively to achieve high utilization without static exposure operation. By optimizing superficial gas velocities and rotation speeds, minimum pulse time for complete coating has been shortened in experiment, and in situ mass spectrometry showed the precursor usage can reach 90%. Inductively coupled plasma-optical emission spectroscopy results suggested a saturated growth of nanoscale Al2O3 films on spherical SiO2 NPs. Finally, the uniformity and composition of the shells were characterized by high angle annular dark field-transmission electron microscopy and energy dispersive X-ray spectroscopy.

  19. Fluidized bed coupled rotary reactor for nanoparticles coating via atomic layer deposition.

    PubMed

    Duan, Chen-Long; Liu, Xiao; Shan, Bin; Chen, Rong

    2015-07-01

    A fluidized bed coupled rotary reactor has been designed for coating on nanoparticles (NPs) via atomic layer deposition. It consists of five major parts: reaction chamber, dosing and fluidizing section, pumping section, rotary manipulator components, as well as a double-layer cartridge for the storage of particles. In the deposition procedure, continuous fluidization of particles enlarges and homogenizes the void fraction in the particle bed, while rotation enhances the gas-solid interactions to stabilize fluidization. The particle cartridge presented here enables both the fluidization and rotation acting on the particle bed, demonstrated by the analysis of pressure drop. Moreover, enlarged interstitials and intense gas-solid contact under sufficient fluidizing velocity and proper rotation speed facilitate the precursor delivery throughout the particle bed and consequently provide a fast coating process. The cartridge can ensure precursors flowing through the particle bed exclusively to achieve high utilization without static exposure operation. By optimizing superficial gas velocities and rotation speeds, minimum pulse time for complete coating has been shortened in experiment, and in situ mass spectrometry showed the precursor usage can reach 90%. Inductively coupled plasma-optical emission spectroscopy results suggested a saturated growth of nanoscale Al2O3 films on spherical SiO2 NPs. Finally, the uniformity and composition of the shells were characterized by high angle annular dark field-transmission electron microscopy and energy dispersive X-ray spectroscopy. PMID:26233411

  20. Fluidized bed coupled rotary reactor for nanoparticles coating via atomic layer deposition

    SciTech Connect

    Duan, Chen-Long; Liu, Xiao; Chen, Rong E-mail: bshan@mail.hust.edu.cn; Shan, Bin E-mail: bshan@mail.hust.edu.cn

    2015-07-15

    A fluidized bed coupled rotary reactor has been designed for coating on nanoparticles (NPs) via atomic layer deposition. It consists of five major parts: reaction chamber, dosing and fluidizing section, pumping section, rotary manipulator components, as well as a double-layer cartridge for the storage of particles. In the deposition procedure, continuous fluidization of particles enlarges and homogenizes the void fraction in the particle bed, while rotation enhances the gas-solid interactions to stabilize fluidization. The particle cartridge presented here enables both the fluidization and rotation acting on the particle bed, demonstrated by the analysis of pressure drop. Moreover, enlarged interstitials and intense gas–solid contact under sufficient fluidizing velocity and proper rotation speed facilitate the precursor delivery throughout the particle bed and consequently provide a fast coating process. The cartridge can ensure precursors flowing through the particle bed exclusively to achieve high utilization without static exposure operation. By optimizing superficial gas velocities and rotation speeds, minimum pulse time for complete coating has been shortened in experiment, and in situ mass spectrometry showed the precursor usage can reach 90%. Inductively coupled plasma-optical emission spectroscopy results suggested a saturated growth of nanoscale Al{sub 2}O{sub 3} films on spherical SiO{sub 2} NPs. Finally, the uniformity and composition of the shells were characterized by high angle annular dark field-transmission electron microscopy and energy dispersive X-ray spectroscopy.

  1. Plutonium and minor actinide utilisation in a pebble-bed high temperature reactor

    SciTech Connect

    Petrov, B. Y.; Kuijper, J. C.; Oppe, J.; De Haas, J. B. M.

    2012-07-01

    This paper contains results of the analysis of the pebble-bed high temperature gas-cooled PUMA reactor loaded with plutonium and minor actinide (Pu/MA) fuel. Starting from knowledge and experience gained in the Euratom FP5 projects HTR-N and HTR-N1, this study aims at demonstrating the potential of high temperature reactors to utilize or transmute Pu/MA fuel. The work has been performed within the Euratom FP6 project PUMA. A number of different fuel types and fuel configurations have been analyzed and compared with respect to incineration performance and safety-related reactor parameters. The results show the excellent plutonium and minor actinide burning capabilities of the high temperature reactor. The largest degree of incineration is attained in the case of an HTR fuelled by pure plutonium fuel as it remains critical at very deep burnup of the discharged pebbles. Addition of minor actinides to the fuel leads to decrease of the achievable discharge burnup and therefore smaller fraction of actinides incinerated during reactor operation. The inert-matrix fuel design improves the transmutation performance of the reactor, while the 'wallpaper' fuel does not have advantage over the standard fuel design in this respect. After 100 years of decay following the fuel discharge, the total amount of actinides remains almost unchanged for all of the fuel types considered. Among the plutonium isotopes, only the amount of Pu-241 is reduced significantly due to its relatively short half-life. (authors)

  2. [Flow model of internal-loop granular sludge bed nitrifying reactor].

    PubMed

    Lu, Gang; Zheng, Ping

    2003-11-01

    Internal-loop granular sludge bed nitrifying reactor is a new type of aerobic nitrifying equipment and has shown a good potential for nitrification. To study the flow pattern and construct the flow model, the tracer tests were performed using pulse stimulus-response technique. Based on the experimental results, the flow pattern in the settling section and the circulating section of reactor were analyzed by axial dispersion model and tank-in-series model, respectively. The dispersion number D/uL of 0.00148 in the settling section indicates that its flow pattern is similar to plug flow reactor (PFR), and the series number N of 1.021 in the circulating section indicates that its flow pattern is similar to continuously stirred tank reactor (CSTR). During steady state, the theoretic hydraulic retention time is 360 min, and the actual hydraulic retention time is 341.2 min. The percentage of dead space in the reactor is 5.22%, thereinto the dead space caused by biomass (db ) is 0.75 % and the hydraulic dead space (dh) is 4.47%, which shows that the structural performance of the reactor is excellent. Based on the experiments and analysis, a model of CSTR and PFR in series was constructed. The actual hydraulic retention time distribution of the reactor is in good agreement with the model predictions. Since the relative error between them is 8.56%, the model is accurate to describe the flow pattern. The results have laid a foundation for the kinetic model of the reactor and will be helpful for its design and operation.

  3. 8. Peavey Duluth Terminal Elevator spout floor with mayo distribution ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. Peavey Duluth Terminal Elevator spout floor with mayo distribution spouts from northeast corner. - Peavey Duluth Terminal Elevator, Workhouse, South side of first slip, north from outer end of Rice's Point, east of Garfield Avenue, Duluth, St. Louis County, MN

  4. Summary of particle bed reactor designs for the Space Nuclear Thermal Propulsion Program

    NASA Astrophysics Data System (ADS)

    Powell, J. R.; Ludewig, H.; Todosow, M.

    1993-09-01

    A summary report of the Particle Bed Reactor (PBR) designs considered for the space nuclear thermal propulsion program has been prepared. The first chapters outline the methods of analysis, and their validation. Monte Carlo methods are used for the physics analysis, several new algorithms are used for the fluid dynamics heat transfer and engine system analysis, and commercially available codes are used for the stress analysis. A critical experiment, prototypic of the PBR was used for the physics validation, and blowdown experiments using fuel beds of prototypic dimensions were used to validate the power extraction capabilities from particle beds. In all four different PBR rocket reactor designs were studied to varying degrees of detail. They varied in power from 400 MW to 2000 MW. These designs were all characterized by a negative prompt coefficient, due to Doppler feedback, and the feedback due to moderator heat up varied from slightly negative to slightly positive. In all practical cases, the coolant worth was positive, although core configurations with negative coolant worth could be designed. In all practical cases the thrust/weight ratio was greater than 20.

  5. Pebble bed modular reactor safeguards: developing new approaches and implementing safeguards by design

    SciTech Connect

    Beyer, Brian David; Beddingfield, David H; Durst, Philip; Bean, Robert

    2010-01-01

    The design of the Pebble Bed Modular Reactor (PBMR) does not fit or seem appropriate to the IAEA safeguards approach under the categories of light water reactor (LWR), on-load refueled reactor (OLR, i.e. CANDU), or Other (prismatic HTGR) because the fuel is in a bulk form, rather than discrete items. Because the nuclear fuel is a collection of nuclear material inserted in tennis-ball sized spheres containing structural and moderating material and a PBMR core will contain a bulk load on the order of 500,000 spheres, it could be classified as a 'Bulk-Fuel Reactor.' Hence, the IAEA should develop unique safeguards criteria. In a multi-lab DOE study, it was found that an optimized blend of: (i) developing techniques to verify the plutonium content in spent fuel pebbles, (ii) improving burn-up computer codes for PBMR spent fuel to provide better understanding of the core and spent fuel makeup, and (iii) utilizing bulk verification techniques for PBMR spent fuel storage bins should be combined with the historic IAEA and South African approaches of containment and surveillance to verify and maintain continuity of knowledge of PBMR fuel. For all of these techniques to work the design of the reactor will need to accommodate safeguards and material accountancy measures to a far greater extent than has thus far been the case. The implementation of Safeguards-by-Design as the PBMR design progresses provides an approach to meets these safeguards and accountancy needs.

  6. Effect of filling fraction on the performance of sponge-based moving bed biofilm reactor.

    PubMed

    Zhang, Xinbo; Chen, Xun; Zhang, Chunqing; Wen, Haitao; Guo, Wenshan; Ngo, Huu Hao

    2016-11-01

    Cubic-shaped polyurethane sponges (15×15×15mm) in the form of biofilm carriers were used in a moving bed biofilm reactor (MBBR) for treating synthetic domestic wastewater. Results indicated there was no significant difference in total organic carbon (TOC) and ammonia (NH4(+)-N) removal at different filling fractions. Three reactors exhibited high removal efficiencies of over 93% TOC and 95% NH4(+)-N on average at an HRT of 12h and aeration flow of 0.09m(3)/h. However, total nitrogen (TN) removal and simultaneous nitrification and denitrification (SND) increased with increasing the filling fraction. TN removal averaged at 77.2, 85.5% and 86.7% in 10%, 20% and 30% filling fraction reactor, respectively. Correspondingly, SND were 85.5±8.7%, 91.3±9.4% and 93.3±10.2%. Moreover, it was observed that sponge carriers in the 20% filling fraction reactor achieved the maximum biomass amount per gram sponge, followed by the 10% and 30% filling fraction reactors. PMID:27567965

  7. Effect of filling fraction on the performance of sponge-based moving bed biofilm reactor.

    PubMed

    Zhang, Xinbo; Chen, Xun; Zhang, Chunqing; Wen, Haitao; Guo, Wenshan; Ngo, Huu Hao

    2016-11-01

    Cubic-shaped polyurethane sponges (15×15×15mm) in the form of biofilm carriers were used in a moving bed biofilm reactor (MBBR) for treating synthetic domestic wastewater. Results indicated there was no significant difference in total organic carbon (TOC) and ammonia (NH4(+)-N) removal at different filling fractions. Three reactors exhibited high removal efficiencies of over 93% TOC and 95% NH4(+)-N on average at an HRT of 12h and aeration flow of 0.09m(3)/h. However, total nitrogen (TN) removal and simultaneous nitrification and denitrification (SND) increased with increasing the filling fraction. TN removal averaged at 77.2, 85.5% and 86.7% in 10%, 20% and 30% filling fraction reactor, respectively. Correspondingly, SND were 85.5±8.7%, 91.3±9.4% and 93.3±10.2%. Moreover, it was observed that sponge carriers in the 20% filling fraction reactor achieved the maximum biomass amount per gram sponge, followed by the 10% and 30% filling fraction reactors.

  8. Comparative evaluation of pebble-bed and prismatic fueled high-temperature gas-cooled reactors

    SciTech Connect

    Kasten, P.R.; Bartine, D.E.

    1981-01-01

    A comparative evaluation has been performed of the HTGR and the Federal Republic of Germany's Pebble Bed Reactor (PBR) for potential commercial applications in the US. The evaluation considered two reactor sizes (1000 and 3000 MW(t)) and three process applications (steam cycle, direct cycle, and process heat, with outlet coolant temperatures of 750, 850, and 950/sup 0/C, respectively). The primary criterion for the comparison was the levelized (15-year) cost of producing electricity or process heat. Emphasis was placed on the cost impact of differences between the prismatic-type HTGR core, which requires periodic refuelings during reactor shutdowns, and the pebble bed PBR core, which is refueled continuously during reactor operations. Detailed studies of key technical issues using reference HTGR and PBR designs revealed that two cost components contributing to the levelized power costs are higher for the PBR: capital costs and operation and maintenance costs. A third cost component, associated with nonavailability penalties, tended to be higher for the PBR except for the process heat application, for which there is a large uncertainty in the HTGR nonavailability penalty at the 950/sup 0/C outlet coolant temperature. A fourth cost component, fuel cycle costs, is lower for the PBR, but not sufficiently lower to offset the capital cost component. Thus the HTGR appears to be slightly superior to the PBR in economic performance. Because of the advanced development of the HTGR concept, large HTGRs could also be commercialized in the US with lower R and D costs and shorter lead times than could large PBRs. It is recommended that the US gas-cooled thermal reactor program continue giving primary support to the HTGR, while also maintaining its cooperative PBR program with FRG.

  9. A CFD model for biomass fast pyrolysis in fluidized-bed reactors

    NASA Astrophysics Data System (ADS)

    Xue, Qingluan; Heindel, T. J.; Fox, R. O.

    2010-11-01

    A numerical study is conducted to evaluate the performance and optimal operating conditions of fluidized-bed reactors for fast pyrolysis of biomass to bio-oil. A comprehensive CFD model, coupling a pyrolysis kinetic model with a detailed hydrodynamics model, is developed. A lumped kinetic model is applied to describe the pyrolysis of biomass particles. Variable particle porosity is used to account for the evolution of particle physical properties. The kinetic scheme includes primary decomposition and secondary cracking of tar. Biomass is composed of reference components: cellulose, hemicellulose, and lignin. Products are categorized into groups: gaseous, tar vapor, and solid char. The particle kinetic processes and their interaction with the reactive gas phase are modeled with a multi-fluid model derived from the kinetic theory of granular flow. The gas, sand and biomass constitute three continuum phases coupled by the interphase source terms. The model is applied to investigate the effect of operating conditions on the tar yield in a fluidized-bed reactor. The influence of various parameters on tar yield, including operating temperature and others are investigated. Predicted optimal conditions for tar yield and scale-up of the reactor are discussed.

  10. Degradation of Benzene by Using a Silent-Packed Bed Hybrid Discharge Plasma Reactor

    NASA Astrophysics Data System (ADS)

    Jiang, Nan; Lu, Na; Li, Jie; Wu, Yan

    2012-02-01

    In this work, a novel gas phase silent-packed bed hybrid discharge plasma reactor has been proposed, and its ability to control a simulative gas stream containing 240 ppm benzene is experimentally investigated. In order to optimize the geometry of the reactor, the benzene conversion rate and energy yield (EY) were compared for various inner electrode diameters and quartz tube shapes and sizes. In addition, benzene removal efficiency in different discharge regions was qualitatively analyzed and the gas parameter (space velocity) was systematically studied. It has been found that silent-packed bed hybrid discharge plasma reactor can effectively decompose benzene. Benzene removal proved to achieve an optimum value of 60% with a characteristic energy density of 255 J/L in this paper with a 6 mm bolt high-voltage electrode and a 13 mm quartz tube. The optimal space velocity was 188.1 h-1, which resulted in moderate energy yield and removal efficiency. Reaction by-products such as hydroquinone, heptanoic acid, 4-nitrocatechol, phenol and 4-phenoxy-phenol were identified by mean of GC-MS. In addition, based on these organic by-products, a benzene destruction pathway was proposed.

  11. Remediation of trichloroethylene by bio-precipitated and encapsulated palladium nanoparticles in a fixed bed reactor.

    PubMed

    Hennebel, Tom; Verhagen, Pieter; Simoen, Henri; De Gusseme, Bart; Vlaeminck, Siegfried E; Boon, Nico; Verstraete, Willy

    2009-08-01

    Trichloroethylene is a toxic and recalcitrant groundwater pollutant. Palladium nanoparticles bio-precipitated on Shewanella oneidensis were encapsulated in polyurethane, polyacrylamide, alginate, silica or coated on zeolites. The reactivity of these bio-Pd beads and zeolites was tested in batch experiments and trichloroethylene dechlorination followed first order reaction kinetics. The calculated k-values of the encapsulated catalysts were a factor of six lower compared to non-encapsulated bio-Pd. Bio-Pd, used as a catalyst, was able to dechlorinate 100 mgL(-1) trichloroethylene within a time period of 1h. The main reaction product was ethane; yet small levels of chlorinated intermediates were detected. Subsequently polyurethane cubes empowered with bio-Pd were implemented in a fixed bed reactor for the treatment of water containing trichloroethylene. The influent recycle configuration resulted in a cumulative removal of 98% after 22 h. The same reactor in a flow through configuration achieved removal rates up to 1059 mg trichloroethylene g Pd(-1)d(-1). This work showed that fixed bed reactors with bio-Pd polyurethane cubes can be instrumental for remediation of water contaminated with trichloroethylene. PMID:19560796

  12. Six years of operation of a fluidised bed reactor for denitrification.

    PubMed

    Harri, A; Bosander, J

    2004-01-01

    At Himmerfjärden wastewater treatment plant, a fluidised bed reactor for nitrogen removal has been operated since 1997. Despite its small footprint, the system enables a far-reaching nitrogen removal. The current nitrate reduction in the reactor is 95%. The reduction of total nitrogen at the wastewater treatment plant is 80-90% at normal operation. The concentration of nitrate in the effluent is easily controlled by changing the dose of carbon. As part of a series of full-scale experiments, the plant has, for the last two years, been operated without denitrification for a couple of months during spring/summer, in order to benefit a favourable N/P-ratio in the recipient and to counteract the growth of nitrogen fixing blue-green algae, When resuming the dosage of carbon, full denitrification was re-established in about two weeks. Important factors to take into consideration when operating the fluidised bed reactor are the abrasive characteristics of the carrier material (sand), the increased concentration of suspended solids in the effluent, and the importance of a suitable N/P-ratio in the influent, as lack of phosphorus might cause an uncontrolled microbiological growth. PMID:15553464

  13. [Synthesis of diacylglycerol using immoblized regiospecific lipase in continuously operated fixed bed reactors].

    PubMed

    Meng, Xiang-He; Sun, Pei-Long; Yang, Kai; He, Rong-Jun; Mao, Zhong-Gui

    2005-05-01

    Diacylglycerol, DAG, because of its multifunctional and nutritional properties, attracted considerable attention recently. Enzymatic synthesis of diacylglycerols from linoleic acid was investigated in a solvent-free reaction in a continuously operated fixed bed reactors containing Lipozyme RM IM. By appropriate manipulation of the fluid-residence time, the relative proportions of the various acylglycerols in the effluent stream can be controlled. In addition, the presence of excess glycerol is effective for the removal of water produced during the esterification reactions. Under the conditions of molar ratio of linoleic acid to glycerol of 0.5, the immoblized enzyme maintained high stability and allowed the reaction to continue for 10 days without significant deterioration in enzyme activity. It was determined that the conversion of fatty acid, content of 1,3-DAG and volume efficiency of reactor reached optima under the conditions: a packaged-bed reactor(with a ratio of packed length to inner diameter of 7.8), reacting temperature at 65 degrees C, molar ratio of linoleic acid to glycerol of 0.5, and feeding flow rate of 1.2 mL/min.

  14. Remediation of trichloroethylene by bio-precipitated and encapsulated palladium nanoparticles in a fixed bed reactor.

    PubMed

    Hennebel, Tom; Verhagen, Pieter; Simoen, Henri; De Gusseme, Bart; Vlaeminck, Siegfried E; Boon, Nico; Verstraete, Willy

    2009-08-01

    Trichloroethylene is a toxic and recalcitrant groundwater pollutant. Palladium nanoparticles bio-precipitated on Shewanella oneidensis were encapsulated in polyurethane, polyacrylamide, alginate, silica or coated on zeolites. The reactivity of these bio-Pd beads and zeolites was tested in batch experiments and trichloroethylene dechlorination followed first order reaction kinetics. The calculated k-values of the encapsulated catalysts were a factor of six lower compared to non-encapsulated bio-Pd. Bio-Pd, used as a catalyst, was able to dechlorinate 100 mgL(-1) trichloroethylene within a time period of 1h. The main reaction product was ethane; yet small levels of chlorinated intermediates were detected. Subsequently polyurethane cubes empowered with bio-Pd were implemented in a fixed bed reactor for the treatment of water containing trichloroethylene. The influent recycle configuration resulted in a cumulative removal of 98% after 22 h. The same reactor in a flow through configuration achieved removal rates up to 1059 mg trichloroethylene g Pd(-1)d(-1). This work showed that fixed bed reactors with bio-Pd polyurethane cubes can be instrumental for remediation of water contaminated with trichloroethylene.

  15. Production of polygalacturonases by Aspergillus section Nigri strains in a fixed bed reactor.

    PubMed

    Maciel, Marília; Ottoni, Cristiane; Santos, Cledir; Lima, Nelson; Moreira, Keila; Souza-Motta, Cristina

    2013-01-28

    Polygalacturonases (PG) are pectinolytic enzymes that have technological, functional and biological applications in food processing, fruit ripening and plant-fungus interactions, respectively. In the present, a microtitre plate methodology was used for rapid screening of 61 isolates of fungi from Aspergillus section Nigri to assess production of endo- and exo-PG. Studies of scale-up were carried out in a fixed bed reactor operated under different parameters using the best producer strain immobilised in orange peels. Four experiments were conducted under the following conditions: the immobilised cells without aeration; immobilised cells with aeration; immobilised cells with aeration and added pectin; and free cells with aeration. The fermentation was performed for 168 h with removal of sample every 24 h. Aspergillus niger strain URM 5162 showed the highest PG production. The results obtained indicated that the maximum endo- and exo-PG activities (1.18 U · mL-1 and 4.11 U · mL-1, respectively) were obtained when the reactor was operating without aeration. The microtitre plate method is a simple way to screen fungal isolates for PG activity detection. The fixed bed reactor with orange peel support and using A. niger URM 5162 is a promising process for PG production at the industrial level.

  16. Highly enantioselective esterification of racemic ibuprofen in a packed bed reactor using immobilised Rhizomucor miehei lipase.

    PubMed

    Sánchez; Valero; Lafuente; Solà

    2000-07-01

    A systematic study of the enantioselective resolution of ibuprofen by commercial Rhizomucor miehei lipase (Lipozyme(R) IM20) has been carried out using isooctane as solvent and butanol as esterificating agent. The main variables controlling the process (temperature, ibuprofen concentration, ratio butanol:ibuprofen) have been studied using an orthogonal full factorial experimental design, in which the selected objective function was enantioselectivity. This strategy has resulted in a polynomial function that describes the process. By optimizing this function, optimal conditions for carrying out the esterification of racemic ibuprofen have been determined. Under these conditions, enantiomeric excess and total conversion values were 93.8% and 49.9%, respectively, and the enantioselectivity was 113 after 112 h of reaction. These conditions have been considered in the design of a continuous reactor to scale up the process. The esterification of ibuprofen was properly described by pseudo first-order kinetics. Thus, a packed bed reactor operating as a plug-flow reactor (PFR) is the most appropriate in terms of minimizing the residence time compared with a continuous stirred tank reactor (CSTR) to achieve the same final conversion. This reactor shows a similar behavior in terms of enantioselectivity, enantiomeric excess, and conversion when compared with batch reactors. A residence-time distribution (RTD) shows that the flow model is essentially a plug flow with a slight nonsymmetrical axial dispersion (Peclet number = 43), which was also corroborated by the model of CSTR in series. The stability of the system (up to 100 h) and the possibility of reutilization of the enzyme (up to four times) lead to consider this reactor as a suitable configuration for scale up of the process.

  17. An Experimental Investigation of Sewage Sludge Gasification in a Fluidized Bed Reactor

    PubMed Central

    Calvo, L. F.; García, A. I.; Otero, M.

    2013-01-01

    The gasification of sewage sludge was carried out in a simple atmospheric fluidized bed gasifier. Flow and fuel feed rate were adjusted for experimentally obtaining an air mass : fuel mass ratio (A/F) of 0.2 < A/F < 0.4. Fuel characterization, mass and power balances, produced gas composition, gas phase alkali and ammonia, tar concentration, agglomeration tendencies, and gas efficiencies were assessed. Although accumulation of material inside the reactor was a main problem, this was avoided by removing and adding bed media along gasification. This allowed improving the process heat transfer and, therefore, gasification efficiency. The heating value of the produced gas was 8.4 MJ/Nm, attaining a hot gas efficiency of 70% and a cold gas efficiency of 57%. PMID:24453863

  18. Fluid modelling of a packed bed dielectric barrier discharge plasma reactor

    NASA Astrophysics Data System (ADS)

    Van Laer, Koen; Bogaerts, Annemie

    2016-02-01

    A packed bed dielectric barrier discharge plasma reactor is computationally studied with a fluid model. Two different complementary axisymmetric 2D geometries are used to mimic the intrinsic 3D problem. It is found that a packing enhances the electric field strength and electron temperature at the contact points of the dielectric material due to polarization of the beads by the applied potential. As a result, these contact points prove to be of direct importance to initiate the plasma. At low applied potential, the discharge stays at the contact points, and shows the properties of a Townsend discharge. When a high enough potential is applied, the plasma will be able to travel through the gaps in between the beads from wall to wall, forming a kind of glow discharge. Therefore, the inclusion of a so-called ‘channel of voids’ is indispensable in any type of packed bed modelling.

  19. Applicability of fluidized bed reactor in recalcitrant compound degradation through advanced oxidation processes: a review.

    PubMed

    Tisa, Farhana; Abdul Raman, Abdul Aziz; Wan Daud, Wan Mohd Ashri

    2014-12-15

    Treatment of industrial waste water (e.g. textile waste water, phenol waste water, pharmaceutical etc) faces limitation in conventional treatment procedures. Advanced oxidation processes (AOPs) do not suffer from the limits of conventional treatment processes and consequently degrade toxic pollutants more efficiently. Complexity is faced in eradicating the restrictions of AOPs such as sludge formation, toxic intermediates formation and high requirement for oxidants. Increased mass-transfer in AOPs is an alternate solution to this problem. AOPs combined with Fluidized bed reactor (FBR) can be a potential choice compared to fixed bed or moving bed reactor, as AOP catalysts life-span last for only maximum of 5-10 cycles. Hence, FBR-AOPs require lesser operational and maintenance cost by reducing material resources. The time required for AOP can be minimized using FBR and also treatable working volume can be increased. FBR-AOP can process from 1 to 10 L of volume which is 10 times more than simple batch reaction. The mass transfer is higher thus the reaction time is lesser. For having increased mass transfer sludge production can be successfully avoided. The review study suggests that, optimum particle size, catalyst to reactor volume ratio, catalyst diameter and liquid or gas velocity is required for efficient FBR-AOP systems. However, FBR-AOPs are still under lab-scale investigation and for industrial application cost study is needed. Cost of FBR-AOPs highly depends on energy density needed and the mechanism of degradation of the pollutant. The cost of waste water treatment containing azo dyes was found to be US$ 50 to US$ 500 per 1000 gallons where, the cost for treating phenol water was US$ 50 to US$ 800 per 1000 gallons. The analysis for FBR-AOP costs has been found to depend on the targeted pollutant, degradation mechanism (zero order, 1st order and 2nd order) and energy consumptions by the AOPs.

  20. Applicability of fluidized bed reactor in recalcitrant compound degradation through advanced oxidation processes: a review.

    PubMed

    Tisa, Farhana; Abdul Raman, Abdul Aziz; Wan Daud, Wan Mohd Ashri

    2014-12-15

    Treatment of industrial waste water (e.g. textile waste water, phenol waste water, pharmaceutical etc) faces limitation in conventional treatment procedures. Advanced oxidation processes (AOPs) do not suffer from the limits of conventional treatment processes and consequently degrade toxic pollutants more efficiently. Complexity is faced in eradicating the restrictions of AOPs such as sludge formation, toxic intermediates formation and high requirement for oxidants. Increased mass-transfer in AOPs is an alternate solution to this problem. AOPs combined with Fluidized bed reactor (FBR) can be a potential choice compared to fixed bed or moving bed reactor, as AOP catalysts life-span last for only maximum of 5-10 cycles. Hence, FBR-AOPs require lesser operational and maintenance cost by reducing material resources. The time required for AOP can be minimized using FBR and also treatable working volume can be increased. FBR-AOP can process from 1 to 10 L of volume which is 10 times more than simple batch reaction. The mass transfer is higher thus the reaction time is lesser. For having increased mass transfer sludge production can be successfully avoided. The review study suggests that, optimum particle size, catalyst to reactor volume ratio, catalyst diameter and liquid or gas velocity is required for efficient FBR-AOP systems. However, FBR-AOPs are still under lab-scale investigation and for industrial application cost study is needed. Cost of FBR-AOPs highly depends on energy density needed and the mechanism of degradation of the pollutant. The cost of waste water treatment containing azo dyes was found to be US$ 50 to US$ 500 per 1000 gallons where, the cost for treating phenol water was US$ 50 to US$ 800 per 1000 gallons. The analysis for FBR-AOP costs has been found to depend on the targeted pollutant, degradation mechanism (zero order, 1st order and 2nd order) and energy consumptions by the AOPs. PMID:25190594

  1. Multistage fluidized bed reactor performance characterization for adsorption of carbon dioxide

    SciTech Connect

    Roy, S.; Mohanty, C.R.; Meikap, B.C.

    2009-12-15

    Carbon dioxide and its different compounds are generated as primary greenhouse gases from the flue gases of coal-fired thermal power plants, boilers, and other stationary combustion processes. This greenhouse gas causes global warming after being emitted to the environment. To deal with this problem, a new dry scrubbing process was tested in this study. A three-stage countercurrent fluidized bed adsorber was developed, designed, and fabricated. It was used as a removal apparatus and operated in a continuous regime for the two-phase system. The height of each stage was 0.30 m, and the inner diameter was 0.10 m. The paper presents the removal of CO{sub 2} from gas mixtures by chemical sorption on porous granular calcium oxide particles in the reactor at ambient temperature. The advantages of a multistage fluidized bed reactor for high mass transfer and high gas-solid contact can enhance the removal of the gas when using a dry method. The effects of the operating parameters such as sorbent, superficial gas velocity, and the Weir height on CO{sub 2} removal efficiency in the multistage fluidized bed were investigated. The results indicate that the removal efficiency of the carbon dioxide was around 71% at a high solid flow rate corresponding to lower gas velocity at room temperature. In comparison with wet scrubbers, this dry process appears to have lower cost, less complicated configuration, and simpler disposal of used sorbent. The results in this study assume importance from the perspective of use of a multistage fluidized bed adsorber for control of gaseous pollutants at high temperature.

  2. Electrical Capacitance Volume Tomography for the Packed Bed Reactor ISS Flight Experiment

    NASA Technical Reports Server (NTRS)

    Marashdeh, Qussai; Motil, Brian; Wang, Aining; Liang-Shih, Fan

    2013-01-01

    Fixed packed bed reactors are compact, require minimum power and maintenance to operate, and are highly reliable. These features make this technology a highly desirable unit operation for long duration life support systems in space. NASA is developing an ISS experiment to address this technology with particular focus on water reclamation and air revitalization. Earlier research and development efforts funded by NASA have resulted in two hydrodynamic models which require validation with appropriate instrumentation in an extended microgravity environment. To validate these models, the instantaneous distribution of the gas and liquid phases must be measured.Electrical Capacitance Volume Tomography (ECVT) is a non-invasive imaging technology recently developed for multi-phase flow applications. It is based on distributing flexible capacitance plates on the peripheral of a flow column and collecting real-time measurements of inter-electrode capacitances. Capacitance measurements here are directly related to dielectric constant distribution, a physical property that is also related to material distribution in the imaging domain. Reconstruction algorithms are employed to map volume images of dielectric distribution in the imaging domain, which is in turn related to phase distribution. ECVT is suitable for imaging interacting materials of different dielectric constants, typical in multi-phase flow systems. ECVT is being used extensively for measuring flow variables in various gas-liquid and gas-solid flow systems. Recent application of ECVT include flows in risers and exit regions of circulating fluidized beds, gas-liquid and gas-solid bubble columns, trickle beds, and slurry bubble columns. ECVT is also used to validate flow models and CFD simulations. The technology is uniquely qualified for imaging phase concentrations in packed bed reactors for the ISS flight experiments as it exhibits favorable features of compact size, low profile sensors, high imaging speed, and

  3. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed Reactor

    SciTech Connect

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-15

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  4. Hot waste-to-energy flue gas treatment using an integrated fluidised bed reactor.

    PubMed

    Bianchini, A; Pellegrini, M; Saccani, C

    2009-04-01

    This paper describes an innovative process to increase superheated steam temperatures in waste-to-energy (WTE) plants. This solution is mainly characterised by a fluidised bed reactor in which hot flue gas is treated both chemically and mechanically. This approach, together with gas recirculation, increases the energy conversion efficiency, and raises the superheated steam temperature without decreasing the useful life of the superheater. This paper presents new experimental data obtained from the test facility installed at the Hera S.p.A. WTE plant in Forlì, Italy; discusses changes that can be implemented to increase the duration of experimental testing; offers suggestions for the design of an industrial solution.

  5. Degradation of mix hydrocarbons by immobilized cells of mix culture using a trickle fluidized bed reactor

    SciTech Connect

    Chapatwala, K.D.

    1993-01-01

    The microorganisms, capable of degrading mix hydrocarbons were isolated from the soil samples collected from the hydrocarbon contaminated sites. The mix cultures were immobilized in calcium alginate solution in the form of beads. A trickle fluidized bed air-uplift-type reactor designed to study the degradation of mix hydrocarbons was filled with 0.85% normal saline containing the immobilized cells of mix culture. The immobilized beads were aerated with CO[sub 2]-free air at 200 ml/min. The degradation of different concentrations of hydrocarbons in the presence/absence of commercially available fertilizers by the immobilized cells of mix culture is now in progress.

  6. PEBBLE: a two-dimensional steady-state pebble bed reactor thermal hydraulics code

    SciTech Connect

    Vondy, D.R.

    1981-09-01

    This report documents the local implementation of the PEBBLE code to treat the two-dimensional steady-state pebble bed reactor thermal hydraulics problem. This code is implemented as a module of a computation system used for reactor core history calculations. Given power density data, the geometric description in (RZ), and basic heat removal conditions and thermal properties, the coolant properties, flow conditions, and temperature distributions in the pebble fuel elements are predicted. The calculation is oriented to the continuous fueling, steady state condition with consideration of the effect of the high energy neutron flux exposure and temperature history on the thermal conductivity. The coolant flow conditions are calculated for the same geometry as used in the neutronics calculation, power density and fluence data being used directly, and temperature results are made available for subsequent use.

  7. Particle bed reactor propulsion vehicle performance and characteristics as an orbital transfer rocket

    SciTech Connect

    Horn, F.L.; Powell, J.R.; Lazareth, O.W.

    1986-01-01

    The particle bed reactor designed for 100 to 300 MW power output using hydrogen as a coolant is capable of specific impulses up to 1000 seconds as a nuclear rocket. A single space shuttle compatible vehicle can perform extensive missions from LEO to 3 times GEO and return with multi-ton payloads. The use of hydrogen to directly cool particulate reactor fuel results in a compact, lightweight rocket vehicle, whose duration of usefulness is dependent only upon hydrogen resupply availability. The LEO to GEO mission had a payload capability of 15.4 metric tons with 3.4 meters of shuttle bay. To increase the volume limitation of the shuttle bay, the use of ammonia in the initial boost phase from LEO is used to give greater payload volume with a small decrease in payload mass, 8.7 meters and 12.7 m-tons. 5 refs., 15 figs.

  8. Inhibition and recovery of nitrification in treating real coal gasification wastewater with moving bed biofilm reactor.

    PubMed

    Li, Huiqiang; Han, Hongjun; Du, Maoan; Wang, Wei

    2011-01-01

    Moving bed biofilm reactor (MBBR) was used to treat real coal gasification wastewater. Nitrification of the MBBR was inhibited almost completely during start-up period. Sudden increase of influent total NH3 concentration was the main factor inducing nitrification inhibition. Increasing DO concentration in the bulk liquid (from 2 to 3 mg/L) had little effect on nitrification recovery. Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days. Nitrification ratio of the MBBR achieved 65% within 12 days by increasing dilute ratio of the influent wastewater with tap water. The ratio of nitrification decreased to 25% when influent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70% for another 4 days.

  9. Countercurrent multistage fluidized bed reactor for immobilized biocatalysts: III. Hydrodynamic aspects.

    PubMed

    Vos, H J; van Houwelingen, C; Zomerdijk, M; Luyben, K C

    1990-08-01

    In Parts I and II of this series we described the modelling, design, and operation of a multistage fluidized bed reactor (MFBR) for immobilized biocatalysts. This article deals with those aspects of the MFBR which are different from single-stage fluidized beds which are operated in batch mode with respect to the solids. The semicontinuous transport of the particles requires perfect mixing of the particles in the reactor compartments, because particles are mainly transported from the bottom of these compartments. A large spread in the physical properties of the biocatalyst particles, especially of both size and density, may cause the particles to segregate into layers with different diameter and/or density. This affects the efficient use of the biocatalyst. The properties of the particles are dependent on the immobilization method. The suitability of different methods for possible future application in the MFBR is therefore compared. Because of segregation, successful use of a biofilm catalyst with a nonuniform thickness of the biofilm is doubtful. Experiments in a small scale reactor (+/- 0.1 m diameter) demonstrated that perfect particle mixing is possible using commercially available biocatalyst particles of uniform density. Co-immobilization of the biocatalyst with glass powder in a gel is a simple and effective method of increasing gel density. High density particles allow high liquid flow rates, and thus an improved external mass transfer can be achieved.The distributor plates, which separate the reactor compartments, must allow unhindered transport of particles. Therefore, the holes in these plates must have a diameter of at least 4.5 times that of the largest particles which are present in the particle mixture used. Furthermore, the plates must be designed such that, when scaling-up the reactor, a uniform liquid distribution over the cross-sectional area of the reactor occurs. Large-scale experiments were not carried out, but published correlations, indicate

  10. Catalytic stepwise nitrate hydrogenation in batch-recycle fixed-bed reactors.

    PubMed

    Pintar, Albin; Batista, Jurka

    2007-10-22

    Pd (1.0 wt.%)-Cu (0.3 wt.%) bimetallic and Pd (1.0 wt.%) monometallic catalysts were synthesized by means of incipient-wetness impregnation technique and deposited on alumina spheres (dp=1.7 mm). The prepared catalysts were tested at T=298 K and p(H2)=1.0 bar in the integrated process of catalytic liquid-phase hydrogenation of aqueous nitrate solutions, in which the denitration step was carried out consecutively in separate, single-flow fixed-bed reactor units operating in a batch-recycle mode. In the first reactor packed with a Pd-Cu bimetallic catalyst, nitrate ions were transformed to nitrites at pH 12.5 with a selectivity as high as 93%; the rest was found in the form of ammonium ions. Liquid-phase nitrite hydrogenation to nitrogen in the second reactor unit packed with a Pd monometallic catalyst was conducted at low pH values of 3.7 and 4.5, respectively. Although these values are well below the pHpzc of examined catalyst (6.1), which assured that the nitrite reduction was carried out over a positively charged catalyst surface, up to 15% (23% in the presence of 5.0 g/l NaCl in the solution) of initial nitrite content was converted to undesired ammonium ions. Since a negligible amount of these species (below 0.5mg/l) was produced at identical operating conditions over a powdered Pd/gamma-Al2O3 catalyst, it is believed that the enhanced production of ammonium ions observed in the second fixed-bed reactor is due to the build-up of pH gradients in liquid-filled pores of spherical catalyst particles. Both Pd-Cu bimetallic and Pd monometallic catalysts were chemically resistant in the investigated range of pH values. PMID:17478039

  11. Carbon and nutrient removal in a dual-media fluidized bed reactor.

    PubMed

    Safferman, Steven I; Mashingaidze, Ella M; McMackin, Stephanie A

    2003-09-01

    A dual-media fluidized bed is a unique reactor design containing two distinct media that results in two segregated treatment zones. By the strategic use of these two zones, this design has the potential to remove both BOD and nutrients (nitrogen and phosphorus) in a single compact reactor. Three operational strategies are conceivable. The first is to maintain a microbiological zone close to the influent to achieve BOD and nitrogen removal. The zone above would contain an exchange media to remove phosphorous. In another scenario, the lower zone would be kept aerobic and the higher zone anoxic. This would enhance denitrification. In the third scenario, the first two are combined by having the exchange media serve as the anoxic zone or including an independent third zone (aerobic, anoxic, and exchange). This scenario could result in the comprehensive treatment of BOD, nitrogen, and phosphorus removal. This proof-of-concept research primarily investigated the first scenario and provided preliminary data for the other two. A low-loaded operating strategy was used to minimize the inherent disadvantages of a fluidized bed reactor, primarily caused by excessive biofilm growth. The reactor was operated for approximately 1 year using sand and activated alumina as the two media. Good separation with minimum mixing at the interface resulted. BOD and phosphorus removal and nitrification were consistently very good during non-transitional periods. Denitrification varied depending on the influent concentration, dissolved oxygen, and oxidation/reduction potential. Preliminary data also indicated that when a low recirculation ratio is used, denitrification could be enhanced. There appears to be a potential difficulty, however, in exchanging phosphorous using activated alumina under low oxidation/reduction potential conditions.

  12. Analysis of granular flow in a pebble-bed nuclear reactor

    SciTech Connect

    Rycroft, C H; Grest, Gary S; Landry, James W; Bazant, Martin Z

    2006-04-17

    Pebble-bed nuclear reactor technology, which is currently being revived around the world, raises fundamental questions about dense granular flow in silos. A typical reactor core is composed of graphite fuel pebbles, which drain very slowly in a continuous refueling process. Pebble flow is poorly understood and not easily accessible to experiments, and yet it has a ma jor impact on reactor physics. To address this problem, we perform full-scale, discrete-element simulations in realistic geometries, with up to 440,000 frictional, viscoelastic 6cm-diameter spheres draining in a cylindrical vessel of diameter 3.5m and height 10m with bottom funnels angled at 30° or 60° . We also simulate a bidisperse core with a dynamic central column of smaller graphite moderator pebbles and show that little mixing occurs down to a 1:2 diameter ratio. We analyze the mean velocity, diffusion and mixing, local ordering and porosity (from Voronoi volumes), the residence-time distribution, and the effects of wall friction and discuss implications for reactor design and the basic physics of granular flow.

  13. Feasibility of Burning First- and Second-Generation Plutonium in Pebble Bed High-Temperature Reactors

    SciTech Connect

    Haas, J.B.M. de; Kuijper, J.C

    2005-08-15

    The core physics investigations at the Nuclear Research Consultancy Group in the Netherlands, as part of the activities within the HTR-N project of the European Fifth Framework Program, are focused on the incineration of pure (first- and second-generation) Pu fuels in the reference pebble bed high-temperature gas-cooled reactor (HTR) HTR-MODUL with a continuous reload [MEDUL, (MEhrfach DUrchLauf, multipass)] fueling strategy in which the spherical fuel elements, or pebbles, pass through the core a number of times before being permanently discharged. For pebbles fueled with different loadings of plutonium, the feasibility of a sustained fuel cycle under nominal reactor conditions was investigated by means of the reactivity and temperature coefficients of the reactor. The HTR-MODUL was found to be a very effective reactor to reduce the stockpile of first-generation plutonium. It reduces the amount of plutonium to about one-sixth of the original and reduces the risk of proliferation by denaturing the plutonium vector. For second-generation plutonium the incineration is less favorable, as the amount of plutonium is only halved.

  14. Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

    NASA Technical Reports Server (NTRS)

    Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

    1995-01-01

    Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

  15. A two-stage enzymatic ethanol-based biodiesel production in a packed bed reactor.

    PubMed

    Xu, Yuan; Nordblad, Mathias; Woodley, John M

    2012-12-31

    A two-stage enzymatic process for producing fatty acid ethyl ester (FAEE) in a packed bed reactor is reported. The process uses an experimental immobilized lipase (NS 88001) and Novozym 435 to catalyze transesterification (first stage) and esterification (second stage), respectively. Both stages were conducted in a simulated series of reactors by repeatedly passing the reaction mixture through a single reactor, with separation of the by-product glycerol and water between passes in the first and second stages, respectively. The second stage brought the major components of biodiesel to 'in-spec' levels according to the European biodiesel specifications for methanol-based biodiesel. The highest overall productivity achieved in the first stage was 2.52 kg FAEE(kg catalyst)⁻¹ h⁻¹ at a superficial velocity of 7.6 cm min⁻¹, close to the efficiency of a stirred tank reactor under similar conditions. The overall productivity of the proposed two-stage process was 1.56 kg FAEE(kg catalyst)⁻¹ h⁻¹. Based on this process model, the challenges of scale-up have been addressed and potential continuous process options have been proposed.

  16. Analysis of granular flow in a pebble-bed nuclear reactor.

    PubMed

    Rycroft, Chris H; Grest, Gary S; Landry, James W; Bazant, Martin Z

    2006-08-01

    Pebble-bed nuclear reactor technology, which is currently being revived around the world, raises fundamental questions about dense granular flow in silos. A typical reactor core is composed of graphite fuel pebbles, which drain very slowly in a continuous refueling process. Pebble flow is poorly understood and not easily accessible to experiments, and yet it has a major impact on reactor physics. To address this problem, we perform full-scale, discrete-element simulations in realistic geometries, with up to 440,000 frictional, viscoelastic 6-cm-diam spheres draining in a cylindrical vessel of diameter 3.5m and height 10 m with bottom funnels angled at 30 degrees or 60 degrees. We also simulate a bidisperse core with a dynamic central column of smaller graphite moderator pebbles and show that little mixing occurs down to a 1:2 diameter ratio. We analyze the mean velocity, diffusion and mixing, local ordering and porosity (from Voronoi volumes), the residence-time distribution, and the effects of wall friction and discuss implications for reactor design and the basic physics of granular flow.

  17. An investigation of moving bed biofilm reactor nitrification during long-term exposure to cold temperatures.

    PubMed

    Hoang, Valerie; Delatolla, Robert; Laflamme, Edith; Gadbois, Alain

    2014-01-01

    Biological treatment is the most common and economical means of ammonia removal in wastewater; however, nitrification rates can become completely impeded at cold temperatures. Attached growth processes and, specifically, moving bed biofilm reactors (MBBRs) have shown promise with respect to low-temperature nitrification. In this study, two laboratory MBBRs were used to investigate MBBR nitrification rates at 20, 5, and 1 degree C. Furthermore, the solids detached by the MBBR reactors were investigated and Arrhenius temperature correction models used to predict nitrification rates after long-term low-temperature exposure was evaluated. The nitrification rate at 5 degrees C was 66 +/- 3.9% and 64 +/- 3.7% compared to the rate measured at 20 degrees C for reactors 1 and 2, respectively. The nitrification rates at 1 degree C over a 4-month exposure period compared to the rate at 20 degrees C were 18.7 +/- 5.5% and 15.7 +/- 4.7% for the two reactors. The quantity of solids detached from the MBBR biocarriers was low and the mass of biofilm per carrier did not vary significantly at 20 degrees C compared to that after long-term exposure at 1 degree C. Lastly, a temperature correction model based on exposure time to cold temperatures showed a strong correlation to the calculated ammonia removal rates relative to 20 degrees C following a gradual acclimatization period to cold temperatures.

  18. Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

    NASA Astrophysics Data System (ADS)

    Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

    1995-03-01

    Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

  19. Adsorptive control of water in esterification with immobilized enzymes: II. fixed-bed reactor behavior.

    PubMed

    Mensah, P; Gainer, J L; Carta, G

    1998-11-20

    Experimental and theoretical studies are conducted to understand the dynamic behavior of a continuous-flow fixed-bed reactor in which an esterification is catalyzed by an immobilized enzyme in an organic solvent medium. The experimental system consists of a commercial immobilized lipase preparation known as Lipozyme as the biocatalyst, with propionic acid and isoamyl alcohol (dissolved in hexane) as the reaction substrates. A complex dynamic behavior is observed experimentally as a result of the simultaneous occurrence of reaction and adsorption phenomena. Both propionic acid and water are adsorbed by the biocatalyst resulting in lower reaction rates. In addition, an excessive accumulation of water in the reactor leads to a rapid irreversible inactivation of the enzyme. A model based on previously-obtained adsorption isotherms and kinetic expressions, as well as on adsorption rate measurements obtained in this work, is used to predict the concentration and thermodynamic activity of water along the reactor length. The model successfully predicts the dynamic behavior of the reactor and shows that a maximum thermodynamic activity of water occurs at a point at some distance from the reactor entrance. A cation exchange resin in sodium form, packed in the reactor as a selective water adsorbent together with the catalyst particles, is shown to be an effective means for preventing an excessive accumulation of water formed in the reaction. Its use results in longer cycle times and greater productivity. As predicted by the model, the experimental results show that the water adsorbed on the catalyst and on the ion exchange resin can be removed with isoamyl alcohol with no apparent loss in enzyme activity.

  20. Safeguards Challenges for Pebble-Bed Reactors (PBRs):Peoples Republic of China (PRC)

    SciTech Connect

    Forsberg, Charles W.; Moses, David Lewis

    2009-11-01

    The Peoples Republic of China (PRC) is operating the HTR-10 pebble-bed reactor (PBR) and is in the process of building a prototype PBR plant with two modular reactors (250-MW(t) per reactor) feeding steam to a single turbine-generator. It is likely to be the first modular hightemperature reactor to be ready for commercial deployment in the world because it is a highpriority project for the PRC. The plant design features multiple modular reactors feeding steam to a single turbine generator where the number of modules determines the plant output. The design and commercialization strategy are based on PRC strengths: (1) a rapidly growing electric market that will support low-cost mass production of modular reactor units and (2) a balance of plant system based on economics of scale that uses the same mass-produced turbine-generator systems used in PRC coal plants. If successful, in addition to supplying the PRC market, this strategy could enable China to be the leading exporter of nuclear reactors to developing countries. The modular characteristics of the reactor match much of the need elsewhere in the world. PBRs have major safety advantages and a radically different fuel. The fuel, not the plant systems, is the primary safety system to prevent and mitigate the release of radionuclides under accident conditions. The fuel consists of small (6-cm) pebbles (spheres) containing coatedparticle fuel in a graphitized carbon matrix. The fuel loading per pebble is small (~9 grams of low-enriched uranium) and hundreds of thousands of pebbles are required to fuel a nuclear plant. The uranium concentration in the fuel is an order of magnitude less than in traditional nuclear fuels. These characteristics make the fuel significantly less attractive for illicit use (weapons production or dirty bomb); but, its unusual physical form may require changes in the tools used for safeguards. This report describes PBRs, what is different, and the safeguards challenges. A series of

  1. High temperature CO2 capture using calcium oxide sorbent in a fixed-bed reactor.

    PubMed

    Dou, Binlin; Song, Yongchen; Liu, Yingguang; Feng, Cong

    2010-11-15

    The gas-solid reaction and breakthrough curve of CO(2) capture using calcium oxide sorbent at high temperature in a fixed-bed reactor are of great importance, and being influenced by a number of factors makes the characterization and prediction of these a difficult problem. In this study, the operating parameters on reaction between solid sorbent and CO(2) gas at high temperature were investigated. The results of the breakthrough curves showed that calcium oxide sorbent in the fixed-bed reactor was capable of reducing the CO(2) level to near zero level with the steam of 10 vol%, and the sorbent in CaO mixed with MgO of 40 wt% had extremely low capacity for CO(2) capture at 550°C. Calcium oxide sorbent after reaction can be easily regenerated at 900°C by pure N(2) flow. The experimental data were analyzed by shrinking core model, and the results showed reaction rates of both fresh and regeneration sorbents with CO(2) were controlled by a combination of the surface chemical reaction and diffusion of product layer.

  2. Biological treatment of textile dyes by agar-agar immobilized consortium in a packed bed reactor.

    PubMed

    Patel, Yogesh; Gupte, Akshaya

    2015-03-01

    The decolorization of Acid Maroon V was investigated using bacterial consortium EDPA containing Enterobacter dissolvens AGYP1 and Pseudomonas aeruginosa AGYP2 immobilized in different entrapment matrices. The consortium displayed 96% removal of dye (100 mg/l) within 6 h when immobilized in agar-agar. Under optimum concentrations of agar-agar (3.0% w/v) and cell biomass (0.9 g% w/v), the consortium displayed decolorization for 18 successive batches of Acid Maroon V and also decolorized 14 other different textile dyes. A packed bed reactor under batch mode showed 89% decolorization of dye after 56 repetitive cycles. Under continuous flow mode, maximum color removal was achieved with bed length of 36 cm, hydraulic retention time of 2.66 h, and dye concentration of 100 mg/l. Additionally, the reactor decolorized relatively higher concentrations (100-2000 mg/l) of dye. The synthetic dye wastewater containing five textile dyes was decolorized 92% with 62% COD reduction using an immobilized consortium.

  3. Algae-removal performance of a fluidized-bed biofilm reactor system for lake water treatment.

    PubMed

    Tanaka, T; Tsuzuki, K; Nishijima, N; Takagi, T

    2001-01-01

    The algae removal efficiency of a pilot plant--based on a fluidized-bed biofilm reactor system for treating--was investigated. This system does not require back-washing because the fluidized-bed suffers no clogging. Moreover, the system uses dissolved oxygen in the influent water for aerobic biological treatment without the need for additional aeration equipment. This, it is an easy-maintenance, low-energy system for purifying eutrophic lake water. The system was operated continuously at a flow rate of 1500 m3/d for nine months at Tsuchiura Port in Lake Kasumigaura. And concentrations of chlorophyll-a and dissolved oxygen in both the influent and effluent water were continuously monitored. In summer (August to September) when water bloom occurred, the average efficiency of chlorophyll-a removal was 64% at an average influent chlorophyll-a concentration of 137.8 micrograms/L. Over the entire experimental period of nine months, the average daily amount of removed chlorophyll-a was 40.3 g/d at an average influent chlorophyll-a concentration of 89.5 micrograms/L. By analyzing the relationship between the amount of removed chlorophyll-a and the consumption of dissolved oxygen, it was estimated that almost all of the algae trapped in the reactor was biologically degraded.

  4. Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

    PubMed

    Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

    2016-07-28

    To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas. PMID:27163861

  5. Production of volatile fatty acids from wastewater screenings using a leach-bed reactor.

    PubMed

    Cadavid-Rodríguez, Luz Stella; Horan, Nigel J

    2014-09-01

    Screenings recovered from the inlet works of wastewater treatment plants were digested without pre-treatment or dilution using a lab-scale, leach-bed reactor. Variations in recirculation ratio of the leachate of 4 and 8 l/lreactor/day and pH values of 5 and 6 were evaluated in order to determine the optimal operating conditions for maximum total volatile fatty acids (VFA) production. By increasing the recirculation ratio of the leachate from 4 to 8 l/lreactor/day it was possible to increase VFA production (11%) and soluble COD (17%) and thus generate up to 264 g VFA/kg-dry screenings. These VFA were predominantly acetic acid with some propionic and butyric acid. The optimum pH for VFA production was 6.0, when the methanogenic phase was inhibited. Below pH 5.0, acid-producing fermentation was inhibited and some alcohols were produced. Ammonia release during the hydrolysis of screenings provided adequate alkalinity; consequently, a digestion process without pH adjustment could be recommended. The leach-bed reactor was able to achieve rapid rates of screenings degradation with the production of valuable end-products that will reduce the carbon footprint associated with current screenings disposal techniques.

  6. METHODS FOR MODELING THE PACKING OF FUEL ELEMENTS IN PEBBLE BED REACTORS

    SciTech Connect

    Abderrafi M. Ougouag; Joshua J. Cogliati; Jan-Leen Kloosterman

    2005-09-01

    Two methods for the modeling of the packing of pebbles in the pebble bed reactors are presented and compared. The first method is based on random generation of potential centers for the pebbles, followed by rejection of points that are not compatible with the geometric constraint of no (or limited) pebbles overlap. The second method models the actual physical packing process, accounting for the dynamic of pebbles as they are dropped onto the pebble bed and as they settle therein. A simplification in the latter model is the assumption of a starting point with very dilute packing followed by settling. The results from the two models are compared and the properties of the second model and the dependence of its results on many of the modeling parameters are presented. The first model (with no overlap allowed) has been implemented into a code to compute Dancoff factors. The second model will soon be implemented into that same code and will also be used to model flow of pebbles in a reactor and core densification in the simulation of earthquakes. Both methods reproduce experimental values well, with the latter displaying a high level of fidelity.

  7. Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

    PubMed

    Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

    2016-07-28

    To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas.

  8. Production and optimization of biodiesel using mixed immobilized biocatalysts in packed bed reactor.

    PubMed

    Bakkiyaraj, S; Syed, Mahin Basha; Devanesan, M G; Thangavelu, Viruthagiri

    2016-05-01

    Vegetable oils are used as raw materials for biodiesel production using transesterification reaction. Several methods for the production of biodiesel were developed using chemical (alkali and acidic compounds) and biological catalysts (lipases). Biodiesel production catalyzed by lipases is energy and cost-saving processes and is carried out at normal temperature and pressure. The need for an efficient method for screening larger number of variables has led to the adoption of statistical experimental design. In the present study, packed bed reactor was designed to study with mixed immobilized biocatalysts to have higher productivity under optimum conditions. Contrary to the single-step acyl migration mechanism, a two-step stepwise reaction mechanism involving immobilized Candida rugosa lipase and immobilized Rhizopus oryzae cells was employed for the present work. This method was chosen because enzymatic hydrolysis followed by esterification can tolerate high free fatty acid containing oils. The effects of flow rate and bed height on biodiesel yield were studied using two factors five-level central composite design (CCD) and response surface methodology (RSM). Maximum biodiesel yield of 85 and 81 % was obtained for jatropha oil and karanja oil with the optimum bed height and optimum flow rate of 32.6 cm and 1.35 L/h, and 32.6 cm and 1.36 L/h, respectively.

  9. Performance of co-immobilized yeast and glucoamylase in a fluidized bed reactor for fuel ethanol production

    SciTech Connect

    Sun, M.Y.; Bienkowski, P.R.; Davison, B.H. |; Spurrier, M.A.; Webb, O.F.

    1996-07-01

    The performance of co-immobilized Saccharomyces cerevisiae and glucoamylase was evaluated in a fluidized bed reactor. Soluble starch and yeast extract were used as feed stocks. The biocatalyst performed well and demonstrated no significant loss of activity or physical integrity during 10 weeks of continuous operation. The reactor was easily operated and required no pH control. No operational problems were encountered from bacterial contaminants even though the reactor was operated under non-sterile conditions over the entire course of experiments. Productivities ranged between 25 to 44 g ethanol L{sup -1} h{sup -1}. The experiments demonstrated that ethanol inhibition and bed loading had significant effects on bed performance.

  10. Biodegradation of pharmaceuticals in hospital wastewater by staged Moving Bed Biofilm Reactors (MBBR).

    PubMed

    Casas, Mònica Escolà; Chhetri, Ravi Kumar; Ooi, Gordon; Hansen, Kamilla M S; Litty, Klaus; Christensson, Magnus; Kragelund, Caroline; Andersen, Henrik R; Bester, Kai

    2015-10-15

    Hospital wastewater represents a significant input of pharmaceuticals into municipal wastewater. As Moving Bed Biofilm Reactors (MBBRs) appear to remove organic micro-pollutants, hospital wastewater was treated with a pilot plant consisting of three MBBRs in series. The removal of pharmaceuticals was studied in two experiments: 1) A batch experiment where pharmaceuticals were spiked to each reactor and 2) a continuous flow experiment at native concentrations. DOC removal, nitrification as well as removal of pharmaceuticals (including X-ray contrast media, β-blockers, analgesics and antibiotics) occurred mainly in the first reactor. In the batch experiment most of the compounds followed a single first-order kinetics degradation function, giving degradation rate constants ranged from 5.77 × 10(-3) to 4.07 h(-1), from -5.53 × 10(-3) to 9.24 × 10(-1) h(-1) and from 1.83 × 10(-3) to 2.42 × 10(-1) h(-1) for first, second and third reactor respectively. Generally, the highest removal rate constants were found in the first reactor while the lowest were found in the third one. This order was inverted for most compounds, when the removal rate constants were normalized to biomass, indicating that the last tank had the most effective biofilms. In the batch experiment, 21 out of 26 compounds were assessed to be degraded with more than 20% within the MBBR train. In the continuous flow experiment the measured removal rates were lower than those estimated from the batch experiments. PMID:26164801

  11. Biodegradation of pharmaceuticals in hospital wastewater by staged Moving Bed Biofilm Reactors (MBBR).

    PubMed

    Casas, Mònica Escolà; Chhetri, Ravi Kumar; Ooi, Gordon; Hansen, Kamilla M S; Litty, Klaus; Christensson, Magnus; Kragelund, Caroline; Andersen, Henrik R; Bester, Kai

    2015-10-15

    Hospital wastewater represents a significant input of pharmaceuticals into municipal wastewater. As Moving Bed Biofilm Reactors (MBBRs) appear to remove organic micro-pollutants, hospital wastewater was treated with a pilot plant consisting of three MBBRs in series. The removal of pharmaceuticals was studied in two experiments: 1) A batch experiment where pharmaceuticals were spiked to each reactor and 2) a continuous flow experiment at native concentrations. DOC removal, nitrification as well as removal of pharmaceuticals (including X-ray contrast media, β-blockers, analgesics and antibiotics) occurred mainly in the first reactor. In the batch experiment most of the compounds followed a single first-order kinetics degradation function, giving degradation rate constants ranged from 5.77 × 10(-3) to 4.07 h(-1), from -5.53 × 10(-3) to 9.24 × 10(-1) h(-1) and from 1.83 × 10(-3) to 2.42 × 10(-1) h(-1) for first, second and third reactor respectively. Generally, the highest removal rate constants were found in the first reactor while the lowest were found in the third one. This order was inverted for most compounds, when the removal rate constants were normalized to biomass, indicating that the last tank had the most effective biofilms. In the batch experiment, 21 out of 26 compounds were assessed to be degraded with more than 20% within the MBBR train. In the continuous flow experiment the measured removal rates were lower than those estimated from the batch experiments.

  12. Performance evaluation of cigarette filter rods as a biofilm carrier in an anaerobic moving bed biofilm reactor.

    PubMed

    Sabzali, Ahmad; Nikaeen, Mahnaz; Bina, Bijan

    2012-01-01

    Biocarriers are an important component of anaerobic moving bed biofilm reactors (AMBBRs). In this study, the capability of cigarette filter rods (CFRs) as a biocarrier in an anaerobic moving bed biofilm reactor was evaluated. Two similar lab-scale anaerobic moving bed biofilm reactors were undertaken using Kaldnes-K3 plastic media and cigarette filter rods (wasted filters from tobacco factories) as biofilm attachment media for wastewater treatment. Organic substance and total posphours (TP) removal was investigated over 100 days. Synthetic wastewater was prepared with ordinary water and glucose as the main sources of carbon and energy, plus balanced macro- and micro-nutrients. Process performance was studied by increasing the organic loading rate (OLR) in the range of 1.6-4.5 kg COD/m3 x d. The COD average removal efficiency were 61.3% and 64.5% for AMBBR with cigarette filter rods (Reactor A) and AMBBR with Kaldnes plastic media (Reactor B), respectively. The results demonstrate that the performance of the AMBBR containing 0.25 litres of cigarette filters was comparable with a similar reactor containing 1.5 litres of Kaldnes plastic media. An average phosphorus removal of 67.7% and 72.9% was achieved by Reactors A and B, respectively.

  13. Aerobic biodegradation of a sulfonated phenylazonaphthol dye by a bacterial community immobilized in a multistage packed-bed BAC reactor.

    PubMed

    Ruiz-Arias, Alfredo; Juárez-Ramírez, Cleotilde; de los Cobos-Vasconcelos, Daniel; Ruiz-Ordaz, Nora; Salmerón-Alcocer, Angélica; Ahuatzi-Chacón, Deifilia; Galíndez-Mayer, Juvencio

    2010-11-01

    A microbial community able to aerobically degrade the azo dye Acid Orange 7 was selected from riparian or lacustrine sediments collected at sites receiving textile wastewaters. Three bacterial strains, pertaining to the genera Pseudomonas, Arthrobacter, and Rhizobium, constitute the selected community. The biodegradation of AO7 was carried out in batch-suspended cell culture and in a continuously operated multistage packed-bed BAC reactor. The rapid decolorization observed in batch culture, joined to a delay of about 24 h in COD removal and cell growth, suggests that enzymes involved in biodegradation of the aromatic amines generated after AO7 azo-bond cleavage (1-amino-2-naphthol [1-A2N] and 4-aminobenzenesulfonic acid [4-ABS]), are inducible in this microbial consortium. After this presumptive induction period, the accumulated byproducts, measured through COD, were partially metabolized and transformed in cell mass. At all azo dye loading rates used, complete removal of AO7 and 1-A2N was obtained in the multistage packed-bed BAC reactor (PBR).; however, the overall COD (eta ( COD )) and 4-ABS (eta ( ABS )) removal efficiencies obtained in steady state continuous culture were about 90%. Considering the toxicity of 1-A2N, its complete removal has particular relevance. In the first stages of the packed-bed BAC reactor (Fig. 4a-c), major removal was observed. In the last stage, only a slight removal of COD and 4-ABS was obtained. Comparing to several reported studies, the continuously operated multistage packed-bed BAC reactor showed similar or superior results. In addition, the operation of large-packed-bed BAC reactors could be improved by using several shallow BAC bed stages, because the pressure drop caused by bed compaction of a support material constituted by small and fragile particles can be reduced.

  14. Evaluation of Selected Chemical Processes for Production of Low-cost Silicon, Phase 3. [using a fluidized bed reactor

    NASA Technical Reports Server (NTRS)

    Blocher, J. M., Jr.; Browning, M. F.

    1979-01-01

    The construction and operation of an experimental process system development unit (EPSDU) for the production of granular semiconductor grade silicon by the zinc vapor reduction of silicon tetrachloride in a fluidized bed of seed particles is presented. The construction of the process development unit (PDU) is reported. The PDU consists of four critical units of the EPSDU: the fluidized bed reactor, the reactor by product condenser, the zinc vaporizer, and the electrolytic cell. An experimental wetted wall condenser and its operation are described. Procedures are established for safe handling of SiCl4 leaks and spills from the EPSDU and PDU.

  15. Modeling phosphorus removal and recovery from anaerobic digester supernatant through struvite crystallization in a fluidized bed reactor.

    PubMed

    Rahaman, Md Saifur; Mavinic, Donald S; Meikleham, Alexandra; Ellis, Naoko

    2014-03-15

    The cost associated with the disposal of phosphate-rich sludge, the stringent regulations to limit phosphate discharge into aquatic environments, and resource shortages resulting from limited phosphorus rock reserves, have diverted attention to phosphorus recovery in the form of struvite (MAP: MgNH4PO4·6H2O) crystals, which can essentially be used as a slow release fertilizer. Fluidized-bed crystallization is one of the most efficient unit processes used in struvite crystallization from wastewater. In this study, a comprehensive mathematical model, incorporating solution thermodynamics, struvite precipitation kinetics and reactor hydrodynamics, was developed to illustrate phosphorus depletion through struvite crystal growth in a continuous, fluidized-bed crystallizer. A thermodynamic equilibrium model for struvite precipitation was linked to the fluidized-bed reactor model. While the equilibrium model provided information on supersaturation generation, the reactor model captured the dynamic behavior of the crystal growth processes, as well as the effect of the reactor hydrodynamics on the overall process performance. The model was then used for performance evaluation of the reactor, in terms of removal efficiencies of struvite constituent species (Mg, NH4 and PO4), and the average product crystal sizes. The model also determined the variation of species concentration of struvite within the crystal bed height. The species concentrations at two extreme ends (inlet and outlet) were used to evaluate the reactor performance. The model predictions provided a reasonably good fit with the experimental results for PO4-P, NH4-N and Mg removals. Predicated average crystal sizes also matched fairly well with the experimental observations. Therefore, this model can be used as a tool for performance evaluation and process optimization of struvite crystallization in a fluidized-bed reactor.

  16. Simulation and control of water-gas shift packed bed reactor with inter-stage cooling

    NASA Astrophysics Data System (ADS)

    Saw, S. Z.; Nandong, J.

    2016-03-01

    Water-Gas Shift Reaction (WGSR) has become one of the well-known pathways for H2 production in industries. The issue with WGSR is that it is kinetically favored at high temperatures but thermodynamically favored at low temperatures, thus requiring careful consideration in the control design in order to ensure that the temperature used does not deactivate the catalyst. This paper studies the effect of a reactor arrangement with an inter-stage cooling implemented in the packed bed reactor to look at its effect on outlet temperature. A mathematical model is developed based on one-dimensional heat and mass transfers which incorporate the intra-particle effects. It is shown that the placement of the inter-stage cooling and the outlet temperature exiting the inter-stage cooling have strong influence on the reaction conversion. Several control strategies are explored for the process. It is shown that a feedback- feedforward control strategy using Multi-scale Control (MSC) is effective to regulate the reactor temperature profile which is critical to maintaining the catalysts activity.

  17. Application of a moving bed biofilm reactor for tertiary ammonia treatment in high temperature industrial wastewater.

    PubMed

    Shore, Jennifer L; M'Coy, William S; Gunsch, Claudia K; Deshusses, Marc A

    2012-05-01

    This study examines the use of a moving bed biofilm reactor (MBBR) as a tertiary treatment step for ammonia removal in high temperature (35-45°C) effluents, and quantifies different phenotypes of ammonia and nitrite oxidizing bacteria responsible for nitrification at elevated temperatures. Bench scale reactors operating at 35 and 40°C were able to successfully remove greater than 90% of the influent ammonia (up to 19 mg L(-1) NH(3)-N) in both the synthetic and industrial wastewater. No biotreatment was observed at 45°C, although effective nitrification was rapidly recovered when the temperature was lowered to 30°C. Using qPCR, Nitrosomonas oligotropha was found to be the dominant ammonia oxidizing bacterium in the biofilm for the first phases of reactor operation. In the later phases, Nitrosomonas nitrosa was observed and its increased presence may have been responsible for improved ammonia treatment efficiency. Accumulation of nitrite in some instances appeared to correlate with temporary low presence of Nitrospira spp.

  18. Fluidized Bed Membrane Reactors for Ultra Pure H₂ Production--A Step forward towards Commercialization.

    PubMed

    Helmi, Arash; Fernandez, Ekain; Melendez, Jon; Pacheco Tanaka, David Alfredo; Gallucci, Fausto; van Sint Annaland, Martin

    2016-03-19

    In this research the performance of a fluidized bed membrane reactor for high temperature water gas shift and its long term stability was investigated to provide a proof-of-concept of the new system at lab scale. A demonstration unit with a capacity of 1 Nm³/h of ultra-pure H₂ was designed, built and operated over 900 h of continuous work. Firstly, the performance of the membranes were investigated at different inlet gas compositions and at different temperatures and H₂ partial pressure differences. The membranes showed very high H₂ fluxes (3.89 × 10(-6) mol·m(-2)·Pa(-1)·s(-1) at 400 °C and 1 atm pressure difference) with a H₂/N₂ ideal perm-selectivity (up to 21,000 when integrating five membranes in the module) beyond the DOE 2015 targets. Monitoring the performance of the membranes and the reactor confirmed a very stable performance of the unit for continuous high temperature water gas shift under bubbling fluidization conditions. Several experiments were carried out at different temperatures, pressures and various inlet compositions to determine the optimum operating window for the reactor. The obtained results showed high hydrogen recovery factors, and very low CO concentrations at the permeate side (in average <10 ppm), so that the produced hydrogen can be directly fed to a low temperature PEM fuel cell.

  19. Kinetics study of palm oil hydrolysis using immobilized lipase Candida rugosa in packed bed reactor.

    PubMed

    Min, C S; Bhatia, S; Kamaruddin, A H

    1999-01-01

    Continuous hydrolysis of palm oil triglyceride in organic solvent using immobilized Candida rugosa on the Amberlite MB-1 as a source of immobilized lipase was studied in packed bed reactor. The enzymatic kinetics of hydrolysis reaction was studied by changing the substrate concentration, reaction temperature and residence time(tau) in the reactor. At 55 degrees C, the optimum water concentration was found to be 15 % weight per volume of solution (%w/v). The Michaelis-Menten kinetic model was used to obtain the reaction parameters, Km(app) and V max(app). The activation energies were found to be quite low indicating that the lipase-catalyzed process is controlled by diffusion of substrates. The Michaelis-Menten kinetic model was found to be suitable at low water concentration 10-15 %w/v of solution. At higher water concentration, substrate inhibition model was used for data analysis. Reactor operation was found to play an important role in the palm oil hydrolysis kinetic.

  20. Denitrification of groundwater using PHBV blends in packed bed reactors and the microbial diversity.

    PubMed

    Chu, Libing; Wang, Jianlong

    2016-07-01

    In the present study, three kinds of biopolymers, PHBV, PHBV/starch and PHBV/bamboo powder (BP) blends were used as carbon source and biofilm carriers for denitrification in packed bed reactors to remove nitrate from groundwater. Results showed that a fast start-up was obtained in bioreactors filled with both PHBV/Starch and PHBV/BP blends without external inocula and it took more than 3 month for PHBV reactor to reach the same loading rate. The PHBV/BP packed reactor exhibited a better nitrate removal efficiency (87.4 ± 7.0%) and less adverse effects in nitrite accumulation and DOC release (below 0.5 mg NO2N L(-1) and 10.5 mg DOC L(-1) in the effluent) during stable operation. Pyrosequencing analysis demonstrated that bacteria belonging to genus Clostridium in phylum Firmicus, which play the primary role in degrading the biopolymers, are the most dominant (33-15% of the sequences). The predominant species in all samples is related to Clostridium crotonatovorans. All the identified 11 genera of denitrifying bacteria affiliated with phylum Proteobacteria and constituted 30-55% in the representative sequences. The PHBV/BP blend is economically attractive carbon source with good denitrification performance. PMID:27145420

  1. Denitrification of groundwater using PHBV blends in packed bed reactors and the microbial diversity.

    PubMed

    Chu, Libing; Wang, Jianlong

    2016-07-01

    In the present study, three kinds of biopolymers, PHBV, PHBV/starch and PHBV/bamboo powder (BP) blends were used as carbon source and biofilm carriers for denitrification in packed bed reactors to remove nitrate from groundwater. Results showed that a fast start-up was obtained in bioreactors filled with both PHBV/Starch and PHBV/BP blends without external inocula and it took more than 3 month for PHBV reactor to reach the same loading rate. The PHBV/BP packed reactor exhibited a better nitrate removal efficiency (87.4 ± 7.0%) and less adverse effects in nitrite accumulation and DOC release (below 0.5 mg NO2N L(-1) and 10.5 mg DOC L(-1) in the effluent) during stable operation. Pyrosequencing analysis demonstrated that bacteria belonging to genus Clostridium in phylum Firmicus, which play the primary role in degrading the biopolymers, are the most dominant (33-15% of the sequences). The predominant species in all samples is related to Clostridium crotonatovorans. All the identified 11 genera of denitrifying bacteria affiliated with phylum Proteobacteria and constituted 30-55% in the representative sequences. The PHBV/BP blend is economically attractive carbon source with good denitrification performance.

  2. Application of a moving bed biofilm reactor for tertiary ammonia treatment in high temperature industrial wastewater.

    PubMed

    Shore, Jennifer L; M'Coy, William S; Gunsch, Claudia K; Deshusses, Marc A

    2012-05-01

    This study examines the use of a moving bed biofilm reactor (MBBR) as a tertiary treatment step for ammonia removal in high temperature (35-45°C) effluents, and quantifies different phenotypes of ammonia and nitrite oxidizing bacteria responsible for nitrification at elevated temperatures. Bench scale reactors operating at 35 and 40°C were able to successfully remove greater than 90% of the influent ammonia (up to 19 mg L(-1) NH(3)-N) in both the synthetic and industrial wastewater. No biotreatment was observed at 45°C, although effective nitrification was rapidly recovered when the temperature was lowered to 30°C. Using qPCR, Nitrosomonas oligotropha was found to be the dominant ammonia oxidizing bacterium in the biofilm for the first phases of reactor operation. In the later phases, Nitrosomonas nitrosa was observed and its increased presence may have been responsible for improved ammonia treatment efficiency. Accumulation of nitrite in some instances appeared to correlate with temporary low presence of Nitrospira spp. PMID:22444639

  3. Fluidized Bed Membrane Reactors for Ultra Pure H₂ Production--A Step forward towards Commercialization.

    PubMed

    Helmi, Arash; Fernandez, Ekain; Melendez, Jon; Pacheco Tanaka, David Alfredo; Gallucci, Fausto; van Sint Annaland, Martin

    2016-01-01

    In this research the performance of a fluidized bed membrane reactor for high temperature water gas shift and its long term stability was investigated to provide a proof-of-concept of the new system at lab scale. A demonstration unit with a capacity of 1 Nm³/h of ultra-pure H₂ was designed, built and operated over 900 h of continuous work. Firstly, the performance of the membranes were investigated at different inlet gas compositions and at different temperatures and H₂ partial pressure differences. The membranes showed very high H₂ fluxes (3.89 × 10(-6) mol·m(-2)·Pa(-1)·s(-1) at 400 °C and 1 atm pressure difference) with a H₂/N₂ ideal perm-selectivity (up to 21,000 when integrating five membranes in the module) beyond the DOE 2015 targets. Monitoring the performance of the membranes and the reactor confirmed a very stable performance of the unit for continuous high temperature water gas shift under bubbling fluidization conditions. Several experiments were carried out at different temperatures, pressures and various inlet compositions to determine the optimum operating window for the reactor. The obtained results showed high hydrogen recovery factors, and very low CO concentrations at the permeate side (in average <10 ppm), so that the produced hydrogen can be directly fed to a low temperature PEM fuel cell. PMID:27007361

  4. Anaerobic treatment of real textile wastewater with a fluidized bed reactor.

    PubMed

    Sen, S; Demirer, G N

    2003-04-01

    Anaerobic treatability of a real cotton textile wastewater was investigated in a fluidized bed reactor (FBR) with pumice as the support material. The immobilized biomass or attached volatile solids level on the support material was 0.073 g VSS/g support material at the end of the 128-d start-up period. During the operation period, real cotton textile wastewater was fed to the anaerobic FBR both unsupplemented (in Stages 1 and 2) and supplemented (with synthetic municipal wastewater in Stage 3 and glucose in Stages 4-6). The effect of operational conditions such as organic loading rate (OLR), hydraulic retention time (HRT), influent glucose concentration as the co-substrate, etc. was investigated to achieve the maximum color removal efficiency in the reactor. Results indicated that anaerobic treatment of textile wastewater studied was possible with the supplementation of an external carbon source in the form of glucose (about 2g/l). The corresponding maximum COD, BOD(5) and color removals were found to be around 82%, 94% and 59%, respectively, for HRT of around 24h and OLR of 3 kg COD/m(3)/d. Further increase in external carbon source added to real textile wastewater did not improve the color removal efficiency of the anaerobic FBR reactor.

  5. Simultaneous saccharification and fermentation of starch for ethanol production in a fluidized-bed reactor

    SciTech Connect

    Nghiem, N.P.; Davison, B.H.; Sun, M.Y.; Bienkowski, P.R.

    1997-12-31

    Immobilized Zymomonas mobilis has been used to produce ethanol from glucose in fluidized-bed reactor at volumetric productivity as high as 60 g/L-h and theoretical yield. This research was extended to study the production of ethanol from starch. The bacteria were co-immobilized with an industrial glucoamylase within small uniform beads (2 to 2.5 mm diameter) of k-carrageenan. The reactor was a glass column of 1.2 m in length with a uniform 2.54 cm diameter. The substrate included a commercially available maltodextrin and a soluble starch solution which was produced by hydrolysis of ground corn meals using amylase under the conditions commonly used in an industrial process. Light steep water was used as the complex nutrient source. Statistical experimental design was used to study the effects of substrate concentration and feed rate on ethanol yield and reactor productivity. The experiments were performed at 30{degrees}C and pH 5. The substrate concentration ranged from 93 to 2.7 g/L and the feed rates from 6.6 to 26.7 mL/min. The results of these studies will be discussed.

  6. Simultaneous Coproduction of Hydrogen and Ethanol in Anaerobic Packed-Bed Reactors

    PubMed Central

    dos Reis, Cristiane Marques; Silva, Edson Luiz

    2014-01-01

    This study evaluated the use of an anaerobic packed-bed reactor for hydrogen production at different hydraulic retention times (HRT) (1–8 h). Two reactors filled with expanded clay and fed with glucose (3136–3875 mg L−1) were operated at different total upflow velocities: 0.30 cm s−1 (R030) and 0.60 cm s−1 (R060). The effluent pH of the reactors was maintained between 4 and 5 by adding NaHCO3 and HCl solutions. It was observed a maximum hydrogen production rate of 0.92 L H2 h−1 L−1 in R030 at HRT of 1 h. Furthermore, the highest hydrogen yield of 2.39 mol H2 mol−1 glucose was obtained in R060. No clear trend was observed by doubling the upflow velocities at this experiment. High ethanol production was also observed, indicating that the ethanol-pathway prevailed throughout the experiment. PMID:25295279

  7. Treatment of rayon grade pulp drain effluent by upflow anaerobic fixed packed bed reactor (UAFPBR).

    PubMed

    Satyawali, Yamini; Pant, Deepak; Singh, Anoop; Srivastava, R K

    2009-09-01

    The Rayon grade pulp (RGP) drain effluent of pulp and paper mill was studied to find out pollutant loading and its control measures by low cost and efficient treatment method. Upflow anaerobic fixed packed bed reactor (UAFPBR) with brick ballasts as packing material was used for this purpose. This was compared with conventional anaerobic treatment method. The digested slurry was taken as inoculum from the active cow dung biogas plant. After stabilization of the reactors the reduction in pollutant loading was found to be higher in UAFPBR than conventional anaerobic reactor (CAR). Hydraulic retention time (HRT) of 12 hr was optimum for the treatment of effluent when 74.5% COD and 81% BOD reduction was obtained. 30% inoculum concentration was best for the anaerobic treatment of RGP colour drain effluent. The maximum biogas production (1.37 l l(-1) of effluent) was when the effluent was inoculated with 30% seeding material. Thus, UAFPBR system was very efficient in terms of BOD, COD, TSS and TDS removal from RGP drain of paper mills in ambient environmental conditions.

  8. Process development and modeling of fluidized-bed reactor with coimmobilized biocatalyst for fuel ethanol production

    NASA Astrophysics Data System (ADS)

    Sun, May Yongmei

    This research focuses on two steps of commercial fuel ethanol production processes: the hydrolysis starch process and the fermentation process. The goal of this research is to evaluate the performance of co-immobilized biocatalysts in a fluidized bed reactor with emphasis on economic and engineering aspects and to develop a predictive mathematical model for this system. The productivity of an FBR is higher than productivity of a traditional batch reactor or CSTR. Fluidized beds offer great advantages over packed beds for immobilized cells when small particles are used or when the reactant feed contains suspended solids. Plugging problems, excessive pressure drops (and thus attrition), or crushing risks may be avoided. No mechanical stirring is required as mixing occurs due to the natural turbulence in the fluidized process. Both enzyme and microorganism are immobilized in one catalyst bead which is called co-immobilization. Inside this biocatalyst matrix, starch is hydrolyzed by the enzyme glucoamylase to form glucose and then converted to ethanol and carbon dioxide by microorganisms. Two biocatalysts were evaluated: (1) co-immobilized yeast strain Saccharomyces cerevisiae and glucoamylase. (2) co-immobilized Zymomonas mobilis and glucoamylase. A co-immobilized biocatalyst accomplishes the simultaneous saccharification and fermentation (SSF process). When compared to a two-step process involving separate saccharification and fermentation stages, the SSF process has productivity values twice that given by the pre-saccharified process when the time required for pre-saccharification (15--25 h) was taken into account. The SSF process should also save capital cost. The information about productivity, fermentation yield, concentration profiles along the bed, ethanol inhibition, et al., was obtained from the experimental data. For the yeast system, experimental results showed that: no apparent decrease of productivity occurred after two and half months, the productivity

  9. Accumulation of radionuclides in bed sediments of the Columbia River between Hanford reactors and McNary Dam

    USGS Publications Warehouse

    Nelson, Jack L.; Haushild, W.L.

    1970-01-01

    Amounts of radionuclides from the Hanford reactors contained in bed sediments of the Columbia River were estimated by two methods: (1) from data on radionuclide concentration for the bed sediments between the reactors and McNary Dam, and (2) from data on radionuclide discharge for river stations at Pasco, Washington, and Umatilla, Oregon. Umatilla is 3.2 kilometers below McNary Dam. Accumulations of radionuclides in the Pasco to Umatilla reach estimated by the two methods agree within about 8%. In October 1965 approximately 16,000 curies of gamma emitting radionuclides were resident in bed sediments of the river between the Hanford reactors and McNary Dam. Concentrations and accumulations of chromium-51, zinc-65, cobalt-60, manganese-54, and scandium-46 generally are much higher near McNary Dam than they are in the vicinity of the reactors. These changes are caused by an increase downstream from the reactors in the proportion of the bed sediment that is fine grained and the proportions of the transported zinc, cobalt, manganese, and scandium radionuclides associated with sediment particles.

  10. Anaerobic/aerobic treatment of a petrochemical wastewater from two aromatic transformation processes by fluidized bed reactors.

    PubMed

    Estrada-Arriaga, Edson B; Ramirez-Camperos, Esperanza; Moeller-Chavez, Gabriela E; García-Sanchez, Liliana

    2012-01-01

    An integrated fluidized bed reactor (FBR) has been employed as the treatment for petrochemical industry wastewaters with high organic matter and aromatic compounds, under anaerobic and aerobic conditions. The system was operated at hydraulic residence time (HRT) of 2.7 and 2.2 h in the anaerobic and aerobic reactor, respectively. The degree of fluidization in the beds was 30%. This system showed a high performance on the removal of organic matter and aromatic compounds. At different organic loading rates (OLR), the chemical oxygen demand (COD) removal in the anaerobic reactor was close to 85% and removals of the COD up to 94% were obtained in the aerobic reactor. High removals of benzene, toluene, ethylbenzene, xylenes, styrene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene and naphthalene were achieved in this study. PMID:23109595

  11. Flash Pyrolysis and Fractional Pyrolysis of Oleaginous Biomass in a Fluidized-bed Reactor

    NASA Astrophysics Data System (ADS)

    Urban, Brook

    Thermochemical conversion methods such as pyrolysis have the potential for converting diverse biomass feedstocks into liquid fuels. In particular, bio-oil yields can be maximized by implementing flash pyrolysis to facilitate rapid heat transfer to the solids along with short vapor residence times to minimize secondary degradation of bio-oils. This study first focused on the design and construction of a fluidized-bed flash pyrolysis reactor with a high-efficiency bio-oil recovery unit. Subsequently, the reactor was used to perform flash pyrolysis of soybean pellets to assess the thermochemical conversion of oleaginous biomass feedstocks. The fluidized bed reactor design included a novel feed input mechanism through suction created by flow of carrier gas through a venturi which prevented plugging problems that occur with a more conventional screw feeders. In addition, the uniquely designed batch pyrolysis unit comprised of two tubes of dissimilar diameters. The bottom section consisted of a 1" tube and was connected to a larger 3" tube placed vertically above. At the carrier gas flow rates used in these studies, the feed particles remained fluidized in the smaller diameter tube, but a reduction in carrier gas velocity in the larger diameter "disengagement chamber" prevented the escape of particles into the condensers. The outlet of the reactor was connected to two Allihn condensers followed by an innovative packed-bed dry ice condenser. Due to the high carrier gas flow rates in fluidized bed reactors, bio-oil vapors form dilute aerosols upon cooling which that are difficult to coalesce and recover by traditional heat exchange condensers. The dry ice condenser provided high surface area for inertial impaction of these aerosols and also allowed easy recovery of bio-oils after natural evaporation of the dry ice at the end of the experiments. Single step pyrolysis was performed between 250-610°C with a vapor residence time between 0.3-0.6s. At 550°C or higher, 70% of

  12. Nitrogen and carbon removal from synthetic wastewater in a vertical structured-bed reactor under intermittent aeration.

    PubMed

    Moura, Rafael B; Damianovic, Márcia H R Z; Foresti, Eugenio

    2012-05-15

    The removal of nitrogen and organic matter using a single reactor has been a common focus of investigation, and reactors operated in batch mode and under intermittent aeration have attracted special attention. This study aimed to evaluate the application of a new reactor configuration consisting of a fixed-bed reactor that was operated under conditions of continuous feeding and intermittent aeration. The reactor was built using acrylic, with a working volume of 6.1L. The fixed bed used for biomass support was composed of polyurethane foam cylinders vertically oriented inside the reaction zone. The reactor was operated under intermittent aeration (2h aerated and 1h non-aerated) and a recirculation ratio Q(r)/Q=5. Three different operating conditions (Phase I, Phase II, and Phase III) corresponding to hydraulic retention times (HRT) of 12h, 8h, and 10h, respectively, were tested. In Phase I, the system achieved total nitrogen (TN) and chemical oxygen demand (COD) removal efficiencies of 82% and 89%, respectively. At HRTs of 8 h and 10 h, the reactor was unstable with respect to TN removal, and the average resultant removal efficiencies were 49% and 45%, respectively. However, COD removal efficiencies remained high with mean values of 85% and 88% for Phases II and III, respectively. Based on these results, it can be concluded that this new reactor configuration constitutes an alternative method for effective removal of organic matter and nitrogen from wastewater.

  13. Nitrogen and carbon removal from synthetic wastewater in a vertical structured-bed reactor under intermittent aeration.

    PubMed

    Moura, Rafael B; Damianovic, Márcia H R Z; Foresti, Eugenio

    2012-05-15

    The removal of nitrogen and organic matter using a single reactor has been a common focus of investigation, and reactors operated in batch mode and under intermittent aeration have attracted special attention. This study aimed to evaluate the application of a new reactor configuration consisting of a fixed-bed reactor that was operated under conditions of continuous feeding and intermittent aeration. The reactor was built using acrylic, with a working volume of 6.1L. The fixed bed used for biomass support was composed of polyurethane foam cylinders vertically oriented inside the reaction zone. The reactor was operated under intermittent aeration (2h aerated and 1h non-aerated) and a recirculation ratio Q(r)/Q=5. Three different operating conditions (Phase I, Phase II, and Phase III) corresponding to hydraulic retention times (HRT) of 12h, 8h, and 10h, respectively, were tested. In Phase I, the system achieved total nitrogen (TN) and chemical oxygen demand (COD) removal efficiencies of 82% and 89%, respectively. At HRTs of 8 h and 10 h, the reactor was unstable with respect to TN removal, and the average resultant removal efficiencies were 49% and 45%, respectively. However, COD removal efficiencies remained high with mean values of 85% and 88% for Phases II and III, respectively. Based on these results, it can be concluded that this new reactor configuration constitutes an alternative method for effective removal of organic matter and nitrogen from wastewater. PMID:22277346

  14. Novel fluidized bed reactor for integrated NOx adsorption-reduction with hydrocarbons

    SciTech Connect

    Terris T. Yang; Hsiaotao T. Bi

    2009-07-01

    In order to avoid the negative impact of excessive oxygen in the combustion flue gases on the selectivity of most hydrocarbon selective catalytic reduction (HC-SCR) catalysts, an integrated NOx adsorption-reduction process has been proposed in this study for the treatment of flue gases under lean burn conditions by decoupling the adsorption and reduction into two different zones. The hypothesis has been validated in a novel internal circulating fluidized bed (ICFB) reactor using Fe/ZSM-5 as the catalyst and propylene as the reducing agent. Effects of propylene to the NOx molar ratio, flue gas oxygen concentration, and gas velocity on NOx conversion were studied using simulated flue gases. The results showed that increasing the ratio of HC:NO improved the reduction performance of Fe/ZSM-5 in the ICFB reactor. NOx conversion decreased with an increasing flue gas flow velocity in the annulus U{sub A} but increased with an increasing reductant gas flow velocity in the draft tube U{sub D}. The NOx adsorption ratio decreased with increasing U{sub A}. In most cases, NOx conversion was higher than the adsorption ratio due to the relatively poor adsorption performance of the catalyst. Fe/ZSM-5 showed a promising reduction performance and a strong inhibiting ability on the negative impact of excessive O{sub 2} in the ICFB reactor, proving that such an ICFB reactor possessed the ability to overcome the negative impact of excessive O{sub 2} in the flue gas using Fe/ZSM-5 as the deNOx catalyst. 22 refs., 10 figs.

  15. [Performance and substrate inhibition kinetics model of nitritation process in inverse turbulent bed reactor].

    PubMed

    Jin, Ren-Cun; Yang, Guang-Feng; Ma, Chun; Zheng, Ping

    2011-01-01

    The performance of a nitritation inverse turbulent bed (ITB) reactor was tested and the substrate inhibition kinetics characteristics of the reactor were analyzed. The results showed that a rapid reactor startup could be realized within 20 d with a strategy that combined the biofilm attachment method named "precoating carrier treatment" and "rapid suspending sludge discharge", with the feeding strategy named "low strength, high load". When operated at a hydraulic retention time of 3 h and influent NH4(+) -N of 700 mg x L(-1), corresponding to a nitrogen loading rate of 5.60 kg x (m3 x d)(-1), a maximum NH4(+) -N removal rate of 4.25 kg x (m3 x d)(-1) was observed. The maximum NO2(-) -N production rate was as high as 3.70 kg x (m3 x d)(-1). Four inhibition kinetic models (Haldane, Edwards, Aiba and Luong) were analyzed through non-linear regression to represent the inhibitions caused by substrate of nitritation process and the parameters of models were gained, which were r(max) of 1.84 kg x (m3 x d)(-1), K(IH) of 97.4 mg x L(-1) and K(m) of 0.188 mg x L(-1) for Haldane model, and r(max) of 1.83 kg x (m3 x d)(-1) and K(IA) of 114 mg x L(-1) for Aiba model. It was proposed that Haldane and Aiba models well fitted the process data harvested in the ITB reactor.

  16. Aging biofilm from a full-scale moving bed biofilm reactor: characterization and enzymatic treatment study.

    PubMed

    Huang, Hui; Ren, Hongqiang; Ding, Lili; Geng, Jinju; Xu, Ke; Zhang, Yan

    2014-02-01

    Effective removal of aging biofilm deserves to receive more attention. This study aimed to characterized aging biofilm from a full-scale moving bed biofilm reactor treating pharmaceutical wastewater and evaluate the hydrolysis effects of biofilm by different enzymatic treatments. Results from FTIR and biochemical composition analyses showed that it was a predominately organic-based biofilm with the ratio of total protein (PN) to polysaccharide (PS) of 20.17. A reticular structure of extracellular polymeric matrix (EPM) with filamentous bacteria as the skeleton was observed on the basal layer through SEM-EDS test. Among the four commercial proteases and amylases from Genencor®, proteases were shown to have better performances than amylases either on the removal of MLSS and PN/MLSS or on DOC (i.e., dissolved organic carbon)/MLSS raising of biofilm pellets. Difference of dynamic fluorescence characteristics of dissolved organic matters after treated by the two proteases indicated distinguishing mechanisms of the treating process.

  17. A long life zinc oxide-titanium oxide sorbent for moving bed reactors

    SciTech Connect

    Copeland, R.; Cesario, M.; Dubovik, M.; Feinberg, D.; Windecker, B.; Yang, J.

    1996-12-31

    Coal Fired Gasifier Combined Cycles (GCCs) have both high efficiency and very low emissions. GCCs are in critical need of a method to remove the H{sub 2}S produced from the sulfur in the coal from the hot gases. There has been extensive research on hot gas clean-up systems, focused on the use of a zinc oxide based sorbent (e.g., zinc titanate). However, the previous sorbents show significant losses in sulfur capacity with cycling. TDA Research, Inc. recently increased the zinc oxide content and sulfur loadings while simultaneously improving the attrition resistance. The improved fabrication method produces long life, low cost sorbent containing zinc oxide. The authors are currently testing sorbents at conditions simulating a moving bed reactor for GCC [i.e., 20 atm, 482 C (900 F) to 538 C (1,000 F), and 1% H{sub 2}S].

  18. Axial dispersion in packed bed reactors involving viscoinelastic and viscoelastic non-Newtonian fluids.

    PubMed

    Gupta, Renu; Bansal, Ajay

    2013-08-01

    Axial dispersion is an important parameter in the performance of packed bed reactors. A lot of fluids exhibit non-Newtonian behaviour but the effect of rheological parameters on axial dispersion is not available in literature. The effect of rheology on axial dispersion has been analysed for viscoinelastic and viscoelastic non-Newtonian fluids. Aqueous solutions of carboxymethyl cellulose and polyacrylamide have been chosen to represent viscoinelastic and viscoelastic liquid-phases. Axial dispersion has been measured in terms of BoL number. The single parameter axial dispersion model has been applied to analyse RTD response curve. The BoL numbers were observed to increase with increase in liquid flow rate and consistency index 'K' for viscoinelastic as well as viscoelastic fluids. Bodenstein correlation for Newtonian fluids proposed has been modified to account for the effect of fluid rheology. Further, Weissenberg number is introduced to quantify the effect of viscoelasticity.

  19. Two-dimensional thermal-hydraulics analyses of the Pellet Bed Reactor for Nuclear Thermal Propulsion

    NASA Technical Reports Server (NTRS)

    Morley, Nicholas J.; El-Genk, Mohamed S.

    1993-01-01

    Thermal-hydraulics design and analyses of the Pellet Bed Reactor for nuclear thermal propulsion are performed using the nuclear propulsion thermal-hydraulic analysis model to determine the 2D steady-state temperature, pressure, and flow fields in the core and optimize the orificing in the hot-frit to avoid hot spots in the core at full power operation. Results show that by properly adjusting the axial porosity profile in the hot frit, hot spots in the core can be essentially eliminated during full power operation. This important accomplishment is achieved at the expense of slightly larger pressure losses in the core because of flow restriction at the hot frit. However, the overall pressure losses is only about 11 percent of the propellant inlet pressure.

  20. Modelling of moving bed biofilm membrane reactors (MBBMR) for on-site greywater treatment.

    PubMed

    Jabornig, Simon; Rauch, Wolfgang

    2015-01-01

    The study evaluates with a mechanistic model the pilot plant results of a combined moving bed biofilm process and membrane filtration (MBBMR) treating single household greywater. It mainly includes the simulation of reactor hydraulics, degradation of pollutants, development of biomass and settlement of sludge. Iterative calibration was made with steady-state results of a 10-month pilot test. The model shows good predictions of readily biodegradable chemical oxygen demand and ammonium removal, as well as biomass concentration on carriers and in suspension. Also, a sensitivity analysis was made which calculates the relative significance factor of each model coefficient and by this provides comparability with other studies. Simulation data and actually measured parameters show that the suggested process was rather independent of ambient temperatures and short-term load fluctuations. Obtained datasets and model structure could be of use for future designers, as well as sellers and users of this process for on-site greywater reclamation. PMID:25909728

  1. Sulfidation of mixed metal oxides in a fluidized-bed reactor

    SciTech Connect

    Christoforou, S.C.; Efthimiadis, E.A.; Vasalos, I.A. )

    1995-01-01

    Mixed metal oxides were used for the removal of hydrogen sulfide from a hot gas stream. Sorbents were prepared according to the dry and wet impregnation techniques. The desulfurization performance of the metal oxide sorbents was experimentally tested in a fluidized-bed reactor system. Sulfidation experiments performed under reaction conditions similar to those at the exit of a coal gasifier showed that the preparation procedure and technique, the type and the amount of the impregnated metal oxide, the type of the solid carrier, and the size of the solid reactant affect the H[sub 2]S removal capacity of the sorbents. The pore structure of fresh and sulfided sorbents was analyzed using mercury porosimetry, nitrogen adsorption, and scanning electron microscopy.

  2. Removal of phenols, thiocyanate and ammonium from coal gasification wastewater using moving bed biofilm reactor.

    PubMed

    Li, Hui-qiang; Han, Hong-jun; Du, Mao-an; Wang, Wei

    2011-04-01

    A laboratory-scale moving bed biofilm reactor (MBBR) with a volume of 4 L was used to study the biodegradation of coal gasification wastewater. Maximum removal efficiencies of 81%, 89%, 94% and 93% were obtained for COD, phenols, SCN(-) and NH(4)(+)-N, respectively. NO(2)(-)-N accumulation induced increase of effluent COD concentration when the hydraulic residence time (HRT) decreased. Phenols removal was not affected when the HRT decreased from 48 to 32 h. Effluent SCN(-) and NH(4)(+)-N concentration increased with the decrease of the HRT, and decreased gradually when the HRT returned to 48 h. Batch experiments were carried out to study performance of the suspended and attached growth biomass in the MBBR.

  3. Study of moving bed biofilm reactor in diethyl phthalate and diallyl phthalate removal from synthetic wastewater.

    PubMed

    Ahmadi, Ehsan; Gholami, Mitra; Farzadkia, Mahdi; Nabizadeh, Ramin; Azari, Ali

    2015-05-01

    Phthalic acid esters have received significant attention over the last few years since they are considered as priority pollutants. In this study, effects of different operation conditions including hydraulic retention time, phthalates loading rates and aeration rate on process performance of moving bed biofilm reactor (MBBR) for removing diethyl phthalate (DEP) and diallyl phthalate (DAP) from synthetic wastewater was evaluated. In optimum conditions, 94.96% and 93.85% removal efficiency were achieved for DEP and DAP, respectively. Moreover, MBBR achieved to remove more than 92% of COD for both phthalates. The results showed that DEP had a higher biodegradation rate compared to DAP, according to the selected parameters such as half saturation constant, overall reaction rate and maximum specific growth rate. The Grau second order model found as the best model for predicting MBBR performance due to its high correlation coefficients and more conformity of its kinetic coefficients to the results.

  4. Growth kinetics of calcium fluoride at high supersaturation in a fluidized bed reactor.

    PubMed

    Jiang, K; Zhou, K G; Yang, Y C; Du, H

    2014-01-01

    Crystallization process in a fluidized bed reactor (FBR) has been regarded as an environmentally friendly technology for the removal and recovery of fluoride from industrial wastewater. The growth kinetics of calcium fluoride at high supersaturation was studied for design, control, and operation of an FBR. The main variables, including supersaturation, superficial velocity, pH value, and particle size of seed that influenced the crystal growth were investigated. Then, a growth model was used to predict the linear growth rate of calcium fluoride at a high influent concentration of fluoride. The pressure difference in the FBR was used as a feature to characterize the growth rate of calcium fluoride. The aggregation and adsorption between seeds and fine particles were proven to be a possible mechanism for growth of calcium fluoride.

  5. Modelling of moving bed biofilm membrane reactors (MBBMR) for on-site greywater treatment.

    PubMed

    Jabornig, Simon; Rauch, Wolfgang

    2015-01-01

    The study evaluates with a mechanistic model the pilot plant results of a combined moving bed biofilm process and membrane filtration (MBBMR) treating single household greywater. It mainly includes the simulation of reactor hydraulics, degradation of pollutants, development of biomass and settlement of sludge. Iterative calibration was made with steady-state results of a 10-month pilot test. The model shows good predictions of readily biodegradable chemical oxygen demand and ammonium removal, as well as biomass concentration on carriers and in suspension. Also, a sensitivity analysis was made which calculates the relative significance factor of each model coefficient and by this provides comparability with other studies. Simulation data and actually measured parameters show that the suggested process was rather independent of ambient temperatures and short-term load fluctuations. Obtained datasets and model structure could be of use for future designers, as well as sellers and users of this process for on-site greywater reclamation.

  6. Apparatus, components and operating methods for circulating fluidized bed transport gasifiers and reactors

    SciTech Connect

    Vimalchand, Pannalal; Liu, Guohai; Peng, Wan Wang

    2015-02-24

    The improvements proposed in this invention provide a reliable apparatus and method to gasify low rank coals in a class of pressurized circulating fluidized bed reactors termed "transport gasifier." The embodiments overcome a number of operability and reliability problems with existing gasifiers. The systems and methods address issues related to distribution of gasification agent without the use of internals, management of heat release to avoid any agglomeration and clinker formation, specific design of bends to withstand the highly erosive environment due to high solid particles circulation rates, design of a standpipe cyclone to withstand high temperature gasification environment, compact design of seal-leg that can handle high mass solids flux, design of nozzles that eliminate plugging, uniform aeration of large diameter Standpipe, oxidant injection at the cyclone exits to effectively modulate gasifier exit temperature and reduction in overall height of the gasifier with a modified non-mechanical valve.

  7. Impact of free ammonia on anammox rates (anoxic ammonium oxidation) in a moving bed biofilm reactor.

    PubMed

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2012-06-01

    Using a bench scale moving bed bioreactor (MBBR), the effect of free ammonia (FA, NH(3), the un-ionized form of ammonium NH(4)(+)) concentration on anoxic ammonium oxidation (anammox) was evaluated based on the volumetric nitrogen removal rate (NRR). Although, a detailed microbial analysis was not conducted, the major NRR observed was assumed to be by anammox, based on the nitrogen conversion ratios of nitrite to ammonium and nitrate to ammonium. Since the concentration of free ammonia as a proportion of the total ammonia concentration is pH-dependent, the impact of changing the operating pH from 6.9 to 8.2, was investigated under constant nitrogen loading conditions during continuous reactor operation. Furthermore, the effect of sudden nitrogen load changes was investigated under constant pH conditions. Batch tests were conducted to determine the immediate response of the anammox consortium to shifts in pH and FA concentrations. It was found that FA was inhibiting NRR at concentrations exceeding 2 mg N L(-1). In the pH range 7-8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 120 mg N L(-1) did not negatively affect NRR for up to 3.5 h. It was concluded that a stable NRR in a moving bed biofilm reactor depended on maintaining FA concentrations below 2 mg N L(-1) when the pH was maintained between 7 and 8.

  8. Stress Analysis of Coated Particle Fuel in the Deep-Burn Pebble Bed Reactor Design

    SciTech Connect

    B. Boer; A. M. Ougouag

    2010-05-01

    High fuel temperatures and resulting fuel particle coating stresses can be expected in a Pu and minor actinide fueled Pebble Bed Modular Reactor (400 MWth) design as compared to the ’standard’ UO2 fueled core. The high discharge burnup aimed for in this Deep-Burn design results in increased power and temperature peaking in the pebble bed near the inner and outer reflector. Furthermore, the pebble power in a multi-pass in-core pebble recycling scheme is relatively high for pebbles that make their first core pass. This might result in an increase of the mechanical failure of the coatings, which serve as the containment of radioactive fission products in the PBMR design. To investigate the integrity of the particle fuel coatings as a function of the irradiation time (i.e. burnup), core position and during a Loss Of Forced Cooling (LOFC) incident the PArticle STress Analysis code (PASTA) has been coupled to the PEBBED code for neutronics, thermal-hydraulics and depletion analysis of the core. Two deep burn fuel types (Pu with or without initial MA fuel content) have been investigated with the new code system for normal and transient conditions including the effect of the statistical variation of thickness of the coating layers.

  9. Fuel Design for Particle-Bed Reactors for Thermal Propulsion Applications

    NASA Astrophysics Data System (ADS)

    Husser, Dewayne L.; Evans, Robert S.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    The design of particle bed reactor (PBR) fuels is an iterative process involving close coordination of design and manufacturing operations. The process starts with the generation of an initial particle design, based on a knowledge of the system requirements and interfaces (such as, fissile loading requirements, coolant type, exit gas temperatures, operation time, number of cycles, contacting materials, etc.). The designer must consider materials property data, heat-transfer and thermal-hydraulic characteristics of the particle and particle bed, and available (or anticipated) manufacturing technology. The design process also uses parametric studies to identify the influences of composition, size, and coating thickness on fuel performance. This resulting design is then used to provide a target manufacturing specification against which initial manufacturing development can be assessed and which provides the framework for manufacturing and testing derived feedback that can be incorporated into the subsequent particle design modifications. In this paper, an example of this design process for a hypothetical particle using a (U,Zr)C kernel and a NbC outer coating designed for a thermal propulsion application is given.

  10. Biodegradation of toluene vapor in coir based upflow packed bed reactor by Trichoderma asperellum isolate.

    PubMed

    Gopinath, M; Mohanapriya, C; Sivakumar, K; Baskar, G; Muthukumaran, C; Dhanasekar, R

    2016-03-01

    In the present study, a new biofiltration system involving a selective microbial strain isolated from aerated municipal sewage water attached with coir as packing material was developed for toluene degradation. The selected fungal isolate was identified as Trichoderma asperellum by 16S ribosomal RNA (16S rRNA) sequencing method, and pylogenetic tree was constructed using BLASTn search. Effect of various factors on growth and toluene degradation by newly isolated T. asperellum was studied in batch studies, and the optimum conditions were found to be pH 7.0, temperature 30 °C, and initial toluene concentration 1.5 (v/v)%. Continuous removal of gaseous toluene was monitored in upflow packed bed reactor (UFPBR) using T. asperellum. Effect of various parameters like column height, flow rate, and the inlet toluene concentration were studied to evaluate the performance of the biofilter. The maximum elimination capacity (257 g m(-3) h(-1)) was obtained with the packing height of 100 cm with the empty bed residence time of 5 min. Under these optimum conditions, the T. asperellum showed better toluene removal efficiency. Kinetic models have been developed for toluene degradation by T. asperellum using macrokinetic approach of the plug flow model incorporated with Monod model.

  11. Bubbling bed catalytic hydropyrolysis process utilizing larger catalyst particles and smaller biomass particles featuring an anti-slugging reactor

    DOEpatents

    Marker, Terry L; Felix, Larry G; Linck, Martin B; Roberts, Michael J

    2014-09-23

    This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.

  12. A laboratory-scale riffle-bed reactor system for 2,4,6-trinitrotoluene contaminated soils

    SciTech Connect

    Wilson, M.B.; Quaisi, K.; Constant, W.D.

    1995-12-31

    This study investigates transport mechanisms of trinitrotoluene (TNT) within contaminated soils. Extraction and degradation parameters are modeled in a system called a riffle-bed reactor. The riffle-bed is comprised of a TNT leaching bed followed by a pool for phytodegradation. It has been documented that photodegradation and microbial transformations play a significant role in TNT disappearance. Both dynamic and static reactors were examined to determine if the leaching process was controlled by water-side or soil-side resistance, and models were developed to best fit the data. In a low-level contaminated soil, the diffusion of TNT through the soil is the limiting factor. In highly contaminated soils, the water-side resistance controls the flux.

  13. Advanced start-up of anaerobic attached film expanded bed reactor by pre-aeration of biofilm carrier.

    PubMed

    Ye, Fen-xia; Chen, Ying-xu; Feng, Xiao-shan

    2005-01-01

    The start-up and performance of the anaerobic attached film expanded bed (AAFEB) reactor with pre-aeration of carrier were investigated. The carriers of the reactors had been aerated for 10 days before they were put into the AAFEB reactors. The results indicated that the reactors advance the start-up by 15 days, and maintain higher efficiency when they were subjected to organic and hydraulic loading shock, but during steady-state operation, the reactors did not show better performance than the control reactors without pre-aeration of carrier. The thicker biofilm and higher biomass concentration of the reactors with pre-aeration were observed during the start-up period, but the difference between two types of reactors tapered with the time course, and at the steady-state operation, the difference between two types of reactors on these two parameters was not obvious. Maximum specific methane or acids production rates, dehydrogenase activity and coenzyme F(420) content were continuously higher than those of the control reactors. After running 30 days, filamentous bacteria dominated in the reactors with pre-aeration, whereas the cocci were predominant species in the control reactors. It was suggested that the action of the biofilm is strongly dependent on the biofilm thickness or the biomass concentration in normal circumstances, but under adverse circumstances, such as organic or hydraulic loading shock, the characteristics and activity of the anaerobic granular sludge play key roles on the reactor performance. These results clearly indicated that pre-aeration of carrier favor to enhance the start-up and performance of AAFEB reactor. PMID:15364089

  14. A novel fast mass transfer anaerobic inner loop fluidized bed biofilm reactor for PTA wastewater treatment.

    PubMed

    Chen, Yingwen; Zhao, Jinlong; Li, Kai; Xie, Shitao

    2016-01-01

    In this paper, a fast mass transfer anaerobic inner loop fluidized bed biofilm reactor (ILFBBR) was developed to improve purified terephthalic acid (PTA) wastewater treatment. The emphasis of this study was on the start-up mode of the anaerobic ILFBBR, the hydraulic loadings and the operation stability. The biological morphology of the anaerobic biofilm in the reactors was also analyzed. The anaerobic column could operate successfully for 46 days due to the pre-aerating process. The anaerobic column had the capacity to resist shock loadings and maintained a high stable chemical oxygen demand (COD) and terephthalic acid removal rates at a hydraulic retention time of 5-10 h, even under conditions of organic volumetric loadings as high as 28.8 kg COD·m(-3).d(-1). The scanning electron microscope analysis of the anaerobic carrier demonstrated that clusters of prokaryotes grew inside of pores and that the filaments generated by pre-aeration contributed to the anaerobic biofilm formation and stability. PMID:27642828

  15. Successional development of biofilms in moving bed biofilm reactor (MBBR) systems treating municipal wastewater.

    PubMed

    Biswas, Kristi; Taylor, Michael W; Turner, Susan J

    2014-02-01

    Biofilm-based technologies, such as moving bed biofilm reactor (MBBR) systems, are widely used to treat wastewater. Biofilm development is important for MBBR systems as much of the microbial biomass is retained within reactors as biofilm on suspended carriers. Little is known about this process of biofilm development and the microorganisms upon which MBBRs rely. We documented successional changes in microbial communities as biofilms established in two full-scale MBBR systems treating municipal wastewater over two seasons. 16S rRNA gene-targeted pyrosequencing and clone libraries were used to describe microbial communities. These data indicate a successional process that commences with the establishment of an aerobic community dominated by Gammaproteobacteria (up to 52 % of sequences). Over time, this community shifts towards dominance by putatively anaerobic organisms including Deltaproteobacteria and Clostridiales. Significant differences were observed between the two wastewater treatment plants (WWTPs), mostly due to a large number of sequences (up to 55 %) representing Epsilonproteobacteria (mostly Arcobacter) at one site. Archaea in young biofilms included several lineages of Euryarchaeota and Crenarchaeota. In contrast, the mature biofilm consisted entirely of Methanosarcinaceae (Euryarchaeota). This study provides new insights into the community structure of developing biofilms at full-scale WWTPs and provides the basis for optimizing MBBR start-up and operational parameters.

  16. Performance of a fixed-bed biofilm reactor with microbubble aeration in aerobic wastewater treatment.

    PubMed

    Zhang, Lei; Liu, Junliang; Liu, Chun; Zhang, Jing; Yang, Jingliang

    2016-01-01

    Microbubble aeration is supposed to be highly efficient for oxygen supply in aerobic wastewater treatment. In the present study, the performance of a fixed-bed biofilm reactor microbubble-aerated using a Shirasu porous glass (SPG) membrane system was investigated when treating synthetic municipal wastewater. The biofilm formation on the carriers was enhanced with microbubble aeration due to the strong adhesion of microbubbles to the solid surface. The dissolved oxygen concentration, the removals of chemical oxygen demand (COD) and nitrogen, and the oxygen utilization efficiency were influenced by the organic loading rate at a certain oxygen supply capacity. The relatively optimal organic loading rate was determined as 0.82 kgCOD/(m(3)d) when the oxygen supply capacity was 0.93 kgO(2)/(m(3)d), where COD and ammonia removal efficiencies were 91.7% and 53.9%, respectively. The corresponding SPG membrane area-based COD removal capacity was 6.88 kgCOD/(m(2)d). The oxygen utilization efficiency of microbubble aeration was obviously higher compared to conventional bubble aeration. The simultaneous nitrification and denitrification occurred in the biofilm reactor and the total nitrogen removal efficiency of 50.4% was achieved under these conditions. In addition, the increase in air supply capacity of the SPG membrane system was suggested to improve its energy utilization efficiency. PMID:27386991

  17. Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor.

    PubMed

    Azizi, Shohreh; Kamika, Ilunga; Tekere, Memory

    2016-01-01

    For the effective application of a modified packed bed biofilm reactor (PBBR) in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni) was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT) of 2 hours. The heavy metal content of the wastewater outlet stream was then compared to the source material. Different biomass concentrations in the reactor were assessed. The results show that the system can efficiently treat 20 (mg/l) concentrations of combined heavy metals at an optimum HRT condition (2 hours), while above this strength there should be a substantially negative impact on treatment efficiency. Average organic reduction, in terms of the chemical oxygen demand (COD) of the system, is reduced above the tolerance limits for heavy metals as mentioned above. The PBBR biological system, in the presence of high surface area carrier media and a high microbial population to the tune of 10 000 (mg/l), is capable of removing the industrial contamination in wastewater.

  18. Simultaneous removal of phenol and nitrate in an anoxic fluidized bed reactor.

    PubMed

    Omena, Sylvia P F; Sader, Leandro T; Silva, Edson L

    2013-01-01

    The general purpose of this study was to characterize a biological treatment system for phenol removal in an anoxic fluidized bed reactor (AFBR) that employed nitrate as the final electron acceptor. The average influent phenol concentrations in the study were 52, 107, 201, 335, and 518 mg/L so that phenol was not detected in the effluent for influent concentrations up to 335 mg/L. The removal efficiency dropped to 70% when the AFBR was operated with influent phenol concentrations above 500 mg/L. The ratio of carbon (derived solely from phenol) to nitrate (N-NO(3)) was approximately 1. Hence, the average influent N-NO(3) concentrations in the study were 45, 79, 157, 260, and 362 mg/L, with corresponding nitrogen removal efficiencies of 94%, 89%, 86%, 79%, and 51%. Nitrite accumulation was not observed because the average effluent N-NO(3) concentration during the entire reactor operation period was 1.5 mg/L.

  19. Fluidized-bed reactor modeling for production of silicon by silane pyrolysis

    NASA Technical Reports Server (NTRS)

    Dudukovic, M. P.; Ramachandran, P. A.; Lai, S.

    1986-01-01

    An ideal backmixed reactor model (CSTR) and a fluidized bed bubbling reactor model (FBBR) were developed for silane pyrolysis. Silane decomposition is assumed to occur via two pathways: homogeneous decomposition and heterogeneous chemical vapor deposition (CVD). Both models account for homogeneous and heterogeneous silane decomposition, homogeneous nucleation, coagulation and growth by diffusion of fines, scavenging of fines by large particles, elutriation of fines and CVD growth of large seed particles. At present the models do not account for attrition. The preliminary comparison of the model predictions with experimental results shows reasonable agreement. The CSTR model with no adjustable parameter yields a lower bound on fines formed and upper estimate on production rates. The FBBR model overpredicts the formation of fines but could be matched to experimental data by adjusting the unkown jet emulsion exchange efficients. The models clearly indicate that in order to suppress the formation of fines (smoke) good gas-solid contacting in the grid region must be achieved and the formation of the bubbles suppressed.

  20. Aerobic moving bed biofilm reactor treating thermomechanical pulping whitewater under thermophilic conditions.

    PubMed

    Jahren, Sigrun J; Rintala, Jukka A; Odegaard, Hallvard

    2002-02-01

    The continuously operated laboratory scale Kaldnes moving bed biofilm reactor (MBBR) was used for thermophilic (55 degrees C) aerobic treatment of TMP whitewater. In the MBBR, the biomass is grown on carrier elements that move along with the water in the reactor. Inoculation with mesophilic activated sludge gave 60-65% SCOD removal from the first day onwards. During the 107 days of experiment, the 60-65% SCOD removals were achieved at organic loading rates of 2.5-3.5 kg SCODm(-3) d(-1), the highest loading rates applied during the run and HRT of 13-22h. Carbohydrates, which contributed to 50-60% of the influent SCOD. were removed by 90-95%, while less than 15% of the lignin-like material (30-35% of SCODin) was removed. The sludge yield was 0.23g VSSg SCOD(-1)removed. The results show that the aerobic biofilm process can be successfully operated under thermophilic conditions. PMID:11848344

  1. Fluidized-bed reactor modeling for production of silicon by silane pyrolysis

    NASA Astrophysics Data System (ADS)

    Dudukovic, M. P.; Ramachandran, P. A.; Lai, S.

    1986-02-01

    An ideal backmixed reactor model (CSTR) and a fluidized bed bubbling reactor model (FBBR) were developed for silane pyrolysis. Silane decomposition is assumed to occur via two pathways: homogeneous decomposition and heterogeneous chemical vapor deposition (CVD). Both models account for homogeneous and heterogeneous silane decomposition, homogeneous nucleation, coagulation and growth by diffusion of fines, scavenging of fines by large particles, elutriation of fines and CVD growth of large seed particles. At present the models do not account for attrition. The preliminary comparison of the model predictions with experimental results shows reasonable agreement. The CSTR model with no adjustable parameter yields a lower bound on fines formed and upper estimate on production rates. The FBBR model overpredicts the formation of fines but could be matched to experimental data by adjusting the unkown jet emulsion exchange efficients. The models clearly indicate that in order to suppress the formation of fines (smoke) good gas-solid contacting in the grid region must be achieved and the formation of the bubbles suppressed.

  2. Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor.

    PubMed

    Azizi, Shohreh; Kamika, Ilunga; Tekere, Memory

    2016-01-01

    For the effective application of a modified packed bed biofilm reactor (PBBR) in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni) was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT) of 2 hours. The heavy metal content of the wastewater outlet stream was then compared to the source material. Different biomass concentrations in the reactor were assessed. The results show that the system can efficiently treat 20 (mg/l) concentrations of combined heavy metals at an optimum HRT condition (2 hours), while above this strength there should be a substantially negative impact on treatment efficiency. Average organic reduction, in terms of the chemical oxygen demand (COD) of the system, is reduced above the tolerance limits for heavy metals as mentioned above. The PBBR biological system, in the presence of high surface area carrier media and a high microbial population to the tune of 10 000 (mg/l), is capable of removing the industrial contamination in wastewater. PMID:27186636

  3. A novel fast mass transfer anaerobic inner loop fluidized bed biofilm reactor for PTA wastewater treatment.

    PubMed

    Chen, Yingwen; Zhao, Jinlong; Li, Kai; Xie, Shitao

    2016-01-01

    In this paper, a fast mass transfer anaerobic inner loop fluidized bed biofilm reactor (ILFBBR) was developed to improve purified terephthalic acid (PTA) wastewater treatment. The emphasis of this study was on the start-up mode of the anaerobic ILFBBR, the hydraulic loadings and the operation stability. The biological morphology of the anaerobic biofilm in the reactors was also analyzed. The anaerobic column could operate successfully for 46 days due to the pre-aerating process. The anaerobic column had the capacity to resist shock loadings and maintained a high stable chemical oxygen demand (COD) and terephthalic acid removal rates at a hydraulic retention time of 5-10 h, even under conditions of organic volumetric loadings as high as 28.8 kg COD·m(-3).d(-1). The scanning electron microscope analysis of the anaerobic carrier demonstrated that clusters of prokaryotes grew inside of pores and that the filaments generated by pre-aeration contributed to the anaerobic biofilm formation and stability.

  4. Capacitive charging and desalination dynamics of a packed-bed reactor.

    PubMed

    Li, Mengying; Hu, Howard H; Bau, Haim H

    2015-03-21

    We study theoretically the charging and desalination dynamics of a packed-bed reactor comprising two percolating granular aggregates that form two porous electrodes. The two porous electrodes are separated with an ion-permeable, electrically insulating spacer, are confined between two long, parallel, current collecting plates, and are saturated with an electrolyte solution. The porous electrodes are ideally polarizable. The electrolyte is binary, and dilute. The electric double layers next to the pore surface are thin. We use volume-averaging (homogenization) theory for porous electrodes and the Gouy-Chapman-Stern model for the electric double layer. Both the cases of finite and infinite aggregate electric conductivities subjected to step changes in the collecting plates' potentials are considered. We determine the potential and concentration distributions and the charging time as functions of space, time, and reactor characteristics. Significantly, we find that the charging time depends only weakly on the solid matrix conductivity as long as the solid matrix conductivity is of comparable magnitude or greater than that of the electrolyte. Furthermore, there is an optimal, finite solid matrix conductivity for which the charging time is minimized.

  5. Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor

    PubMed Central

    Azizi, Shohreh; Kamika, Ilunga; Tekere, Memory

    2016-01-01

    For the effective application of a modified packed bed biofilm reactor (PBBR) in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni) was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT) of 2 hours. The heavy metal content of the wastewater outlet stream was then compared to the source material. Different biomass concentrations in the reactor were assessed. The results show that the system can efficiently treat 20 (mg/l) concentrations of combined heavy metals at an optimum HRT condition (2 hours), while above this strength there should be a substantially negative impact on treatment efficiency. Average organic reduction, in terms of the chemical oxygen demand (COD) of the system, is reduced above the tolerance limits for heavy metals as mentioned above. The PBBR biological system, in the presence of high surface area carrier media and a high microbial population to the tune of 10 000 (mg/l), is capable of removing the industrial contamination in wastewater. PMID:27186636

  6. Simulation for Supporting Scale-Up of a Fluidized Bed Reactor for Advanced Water Oxidation

    PubMed Central

    Abdul Raman, Abdul Aziz; Daud, Wan Mohd Ashri Wan

    2014-01-01

    Simulation of fluidized bed reactor (FBR) was accomplished for treating wastewater using Fenton reaction, which is an advanced oxidation process (AOP). The simulation was performed to determine characteristics of FBR performance, concentration profile of the contaminants, and various prominent hydrodynamic properties (e.g., Reynolds number, velocity, and pressure) in the reactor. Simulation was implemented for 2.8 L working volume using hydrodynamic correlations, continuous equation, and simplified kinetic information for phenols degradation as a model. The simulation shows that, by using Fe3+ and Fe2+ mixtures as catalyst, TOC degradation up to 45% was achieved for contaminant range of 40–90 mg/L within 60 min. The concentration profiles and hydrodynamic characteristics were also generated. A subsequent scale-up study was also conducted using similitude method. The analysis shows that up to 10 L working volume, the models developed are applicable. The study proves that, using appropriate modeling and simulation, data can be predicted for designing and operating FBR for wastewater treatment. PMID:25309949

  7. Fluidized-bed design for ICF reactor blankets using solid-lithium compounds

    SciTech Connect

    Sucov, E.W.; Malick, F.S.; Green, L.; Hall, B.O.

    1983-01-01

    A fluidized-bed concept for blankets of dry or wetted first-wall ICF reactors using solid-lithium compounds is described. The reaction chamber is a right cylinder, 32 m high and 20 m in diameter; the blanket is composed of 36 steel tanks, 32 m high, which carry the sintered Li/sub 2/O particles in the fluidizing helium gas. Each tank has a radial thickness of 2 m which generates a tritium breeding ration (TBR) of 1.27 and absorbs over 98% of the neutron energy; reducing the thickness to 1.2 m produces a TBR of 1.2 and energy absorption of 97% which satisfy the design goals. Calculations of tritium diffusion through the grains and heat removal from the grains showed that neither could be removed by the carrier gas; tritium and heat are therefore removed by removing the grains themselves by varying the helium flow rate. The particles are continuously fed into the bottom of the tanks at 300/sup 0/C and removed at the top at 475/sup 0/C. Tritium and heat extraction are easily and conveniently done outside the reactor.

  8. Treatment of wastewater from coffee bean processing in anaerobic fixed bed reactors with different support materials: performance and kinetic modeling.

    PubMed

    Fia, Fátima R L; Matos, Antonio T; Borges, Alisson C; Fia, Ronaldo; Cecon, Paulo R

    2012-10-15

    An evaluation was performed of three upflow anaerobic fixed bed reactors for the treatment of wastewater from coffee bean processing (WCP). The supports used were: blast furnace cinders, polyurethane foam and crushed stone with porosities of 53, 95 and 48%, respectively. The testing of these 139.5 L reactors consisted of increasing the COD of the influent (978; 2401 and 4545 mg L(-1)), while maintaining the retention time of 1.3 days. For the maximum COD applied, the reactor filled with foam presented removals of 80% (non-filtered samples) and 83% (filtered samples). The greater performance of the reactor filled with foam is attributed to its porosity, which promoted greater collection of biomass. From the results, it could be concluded that the reactors presented satisfactory performance, especially when using the foam as a support. Furthermore, the modified Stover-Kincannon and second order for multicomponent substrate degradation models were successfully used to develop a model of the experimental data.

  9. CO{sub 2} capture from flue gases using three Ca-based sorbents in a fluidized bed reactor

    SciTech Connect

    Li, Z.S.; Fang, F.; Cai, N.S.

    2009-06-15

    Abstract: Experiments of CO{sub 2} capture and sorbent regeneration characteristics of limestone, dolomite, and CaO/Ca{sub 1}2Al{sub 14}O{sub 3}3 at high temperature were investigated in a thermogravimetric analyzer (TGA) and a fluidized bed reactor. The effect of reactivity decay of limestone, dolomite, and CaO/Ca{sub 12}Al{sub 14}O{sub 3}3 sorbents on CO{sub 2} capture and sorbent regeneration processes was studied. The experimental results indicated that the operation time of high efficient CO{sub 2} capture stage declined continuously with increasing of the cyclic number due to the loss of the sorbent activity, and the final CO{sub 2} capture efficiency would remain nearly constant, due to the sorbent already reaching the final residual capture capacity. After the CO{sub 2} capture step, the Ca-based sorbents need to be regenerated to be used for a subsequent cycle, and the multiple calcination processes of Ca-based sorbent under different calcination conditions are studied and discussed. Reactivity loss of limestone, dolomite and CaO/Ca{sub 12}Al{sub 14}O{sub 3}3 sorbents from a fluidized bed reactor at both mild and severe calcination conditions was compared with the TGA data. At mild calcination conditions, TGA results of sorbent reactivity loss were similar to the experimental results of fluidized bed reactor for three sorbents at 850 degrees C calcination temperature, and this indicated that TGA experimental results can be used as a reference to predict sorbent reactivity loss behavior in fluidized bed reactor. At severe calcination condition, sorbent reactivity loss behavior for limestone and dolomite from TGA compare well with the result from a fluidized bed reactor.

  10. Heat-transfer characteristics of flowing and stationary particle-bed-type fusion-reactor blankets

    SciTech Connect

    Nietert, R.E.

    1983-02-01

    The following five appendices are included: (1) physical properties of materials, (2) thermal entrance length Nusselt number variations, (3) stationary particle bed temperature variations, (4) falling bed experimental data and calculations, and (5) stationary bed experimental data and calculations. (MOW)

  11. Tertiary nitrification using moving-bed biofilm reactor: a case study in Tunisia.

    PubMed

    Houda, Nasr; Abdelwaheb, Chatti; Asma, Ben Rajeb; Ines, Mehri; Ahmed, Landoulsi; Abdennaceur, Hassen

    2015-04-01

    In this study, the effect of operational conditions on biofilm development and nitrification in moving-bed biofilm reactor (MBBR) was investigated. The reactor was operated in a continuously fed regime during 170 days and with theoretical hydraulic retention time of 7 h, respectively. The presence of chemical oxygen demand (COD) increased the time required to form stable nitrifying. Subsequent stepwise increase of influent COD caused an increment in total polysaccharide (PS) and protein (PN) content, which was accompanied by an attachment of the biofilm, as shown by atomic force microscope (AFM). PS and PN concentrations proved to be good indicators of biomass development and attachment in MBBR system. Reactor was operated and water quality was characterized before and after treatment. Parameters including pH, 5-day biochemical oxygen demand (BOD5), total suspended solids (TSS) (COD), PN, PS, and fecal bacteria in both raw and treated wastewater were monitored during the treatment. The removal rates of ammonium-nitrogen (NH4 (+)-N), BOD5, COD, and TSS are 95, 67.5, 69.2, and 73.33 %, respectively. The average bacterial reduction between the inlet and the outlet was of the order of 5 ± 1 logarithmic units for fecal coliforms. AFM showed that distinct biofilm and extracellular polymeric substances were formed in biofilm was thicker in the 70 days than in the 30 days. These results showed that the consumption rate for each substrate increased parabolically with biofilm thickness due to the increased amount of biomass Thus, MBBR can serve as a promising technology for wastewater treatment and can be scaled up for small communities in the developing countries. PMID:25561403

  12. Tertiary nitrification using moving-bed biofilm reactor: a case study in Tunisia.

    PubMed

    Houda, Nasr; Abdelwaheb, Chatti; Asma, Ben Rajeb; Ines, Mehri; Ahmed, Landoulsi; Abdennaceur, Hassen

    2015-04-01

    In this study, the effect of operational conditions on biofilm development and nitrification in moving-bed biofilm reactor (MBBR) was investigated. The reactor was operated in a continuously fed regime during 170 days and with theoretical hydraulic retention time of 7 h, respectively. The presence of chemical oxygen demand (COD) increased the time required to form stable nitrifying. Subsequent stepwise increase of influent COD caused an increment in total polysaccharide (PS) and protein (PN) content, which was accompanied by an attachment of the biofilm, as shown by atomic force microscope (AFM). PS and PN concentrations proved to be good indicators of biomass development and attachment in MBBR system. Reactor was operated and water quality was characterized before and after treatment. Parameters including pH, 5-day biochemical oxygen demand (BOD5), total suspended solids (TSS) (COD), PN, PS, and fecal bacteria in both raw and treated wastewater were monitored during the treatment. The removal rates of ammonium-nitrogen (NH4 (+)-N), BOD5, COD, and TSS are 95, 67.5, 69.2, and 73.33 %, respectively. The average bacterial reduction between the inlet and the outlet was of the order of 5 ± 1 logarithmic units for fecal coliforms. AFM showed that distinct biofilm and extracellular polymeric substances were formed in biofilm was thicker in the 70 days than in the 30 days. These results showed that the consumption rate for each substrate increased parabolically with biofilm thickness due to the increased amount of biomass Thus, MBBR can serve as a promising technology for wastewater treatment and can be scaled up for small communities in the developing countries.

  13. Low temperature partial nitritation/anammox in a moving bed biofilm reactor treating low strength wastewater.

    PubMed

    Gilbert, Eva M; Agrawal, Shelesh; Karst, Søren M; Horn, Harald; Nielsen, Per H; Lackner, Susanne

    2014-01-01

    Municipal wastewater collected in areas with moderate climate is subjected to a gradual temperature decrease from around 20 °C in summer to about 10 °C in winter. A lab-scale moving bed biofilm reactor (MBBR) with carrier material (K3 from AnoxKaldnes) was used to test the tolerance of the overall partial nitritation/anammox process to this temperature gradient. A synthetic influent, containing only ammonium and no organic carbon was used to minimize denitrification effects. After stable reactor operation at 20 °C, the temperature was slowly reduced by 2 °C per month and afterward held constant at 10 °C. Along the temperature decrease, the ammonium conversion dropped from an average of 40 gN m(-3) d(-1) (0.2 gN kgTSS h(-1)) at 20 °C to about 15 gN m(-3) d(-1) (0.07 gN kg TSS h(-1)) at 10 °C, while the effluent concentration was kept <8 mg NH4-N l(-1) during the whole operation. This also resulted in doubling of the hydraulic retention time over the temperature ramp. The MBBR with its biofilm on 10 mm thick carriers proved to sufficiently sustain enough biomass to allow anammox activity even at 10 °C. Even though there was a minor nitrite-build up when the temperature dropped below 12.5 °C, reactor performance recovered as the temperature decrease continued. Microbial community analysis by 16S rRNA amplicon analysis revealed a relatively stable community composition over the entire experimental period.

  14. Use of activated carbon and natural zeolite as support materials, in an anaerobic fluidised bed reactor, for vinasse treatment.

    PubMed

    Fernández, N; Fdz-Polanco, F; Montalvo, S J; Toledano, D

    2001-01-01

    In Cuba, the alcohol distillation process from cane sugar molasses, produces a final waste (vinasse), with an enormous polluting potential and a high sulfate content. Applying the anaerobic technology, most of the biodegradable organic matter can turn into biogas, rich in methane but with concentrations of sulfide above 1%. The present work develops two experiences with anaerobic fluidized bed reactors (AFBR) using both Cuban raw material, activated carbon and natural zeolite, as support media, with the purpose of obtaining high organic matter removal rates and keeping sulfide and ammonium concentrations in the permissible ranges. The reactors were operated during 120 days, achieving an organic loading rate of 10 kg COD/m3 day, with COD removal above 70%, and a methane production of 2 L/d. The activated carbon and natural zeolite used support materials in anaerobic fluidized bed reactors, and showed good results of distillery waste removal. PMID:11575071

  15. Biodiesel production in a magnetically-stabilized, fluidized bed reactor with an immobilized lipase in magnetic chitosan microspheres.

    PubMed

    Zhou, Gui-Xiong; Chen, Guan-Yi; Yan, Bei-Bei

    2014-01-01

    Biodiesel production by immobilized Rhizopus oryzae lipase in magnetic chitosan microspheres (MCMs) was carried out using soybean oil and methanol in a magnetically-stabilized, fluidized bed reactor (MSFBR). The maximum content of methyl ester in the reaction mixture reached 91.3 (w/v) at a fluid flow rate of 25 ml/min and a magnetic field intensity of 150 Oe. In addition, the MCMs-immobilized lipase in the reactor showed excellent reusability, retaining 82 % productivity even after six batches, which was much better than that in a conventional fluidized bed reactor. These results suggested that a MSFRB using MCMs-immobilized lipase is a promising method for biodiesel production. PMID:24062133

  16. Biodiesel production in a magnetically-stabilized, fluidized bed reactor with an immobilized lipase in magnetic chitosan microspheres.

    PubMed

    Zhou, Gui-Xiong; Chen, Guan-Yi; Yan, Bei-Bei

    2014-01-01

    Biodiesel production by immobilized Rhizopus oryzae lipase in magnetic chitosan microspheres (MCMs) was carried out using soybean oil and methanol in a magnetically-stabilized, fluidized bed reactor (MSFBR). The maximum content of methyl ester in the reaction mixture reached 91.3 (w/v) at a fluid flow rate of 25 ml/min and a magnetic field intensity of 150 Oe. In addition, the MCMs-immobilized lipase in the reactor showed excellent reusability, retaining 82 % productivity even after six batches, which was much better than that in a conventional fluidized bed reactor. These results suggested that a MSFRB using MCMs-immobilized lipase is a promising method for biodiesel production.

  17. Characterization of chemical looping combustion of coal in a 1 kW{sub th} reactor with a nickel-based oxygen carrier

    SciTech Connect

    Shen, Laihong; Wu, Jiahua; Gao, Zhengping; Xiao, Jun

    2010-05-15

    Chemical looping combustion is a novel technology that can be used to meet the demand on energy production without CO{sub 2} emission. To improve CO{sub 2} capture efficiency in the process of chemical looping combustion of coal, a prototype configuration for chemical looping combustion of coal is made in this study. It comprises a fast fluidized bed as an air reactor, a cyclone, a spout-fluid bed as a fuel reactor and a loop-seal. The loop-seal connects the spout-fluid bed with the fast fluidized bed and is fluidized by steam to prevent the contamination of the flue gas between the two reactors. The performance of chemical looping combustion of coal is experimentally investigated with a NiO/Al{sub 2}O{sub 3} oxygen carrier in a 1 kW{sub th} prototype. The experimental results show that the configuration can minimize the amount of residual char entering into the air reactor from the fuel reactor with the external circulation of oxygen carrier particles giving up to 95% of CO{sub 2} capture efficiency at a fuel reactor temperature of 985 C. The effect of the fuel reactor temperature on the release of gaseous products of sulfur species in the air and fuel reactors is carried out. The fraction of gaseous sulfur product released in the fuel reactor increases with the fuel reactor temperature, whereas the one in the air reactor decreases correspondingly. The high fuel reactor temperature results in more SO{sub 2} formation, and H{sub 2}S abatement in the fuel reactor. The increase of SO{sub 2} in the fuel reactor accelerates the reaction of SO{sub 2} with CO to form COS, and COS concentration in the fuel reactor exit gas increases with the fuel reactor temperature. The SO{sub 2} in the air reactor exit gas is composed of the product of sulfur in residual char burnt with air and that of nickel sulfide oxidization with air in the air reactor. Due to the evident decrease of residual char in the fuel reactor with increasing fuel reactor temperature, it results in the

  18. Chemisorption of oxygen onto activated carbon can enhance the stability of biological perchlorate reduction in fixed bed biofilm reactors.

    PubMed

    Choi, Young Chul; Li, Xu; Raskin, Lutgarde; Morgenroth, Eberhard

    2008-07-01

    Fixed bed biofilm reactors with granular activated carbon (GAC) or glass beads as support media were used to evaluate the influence of short-term (12h) and long-term (23 days) increases of influent dissolved oxygen (DO) concentrations on biological perchlorate removal. The goal was to evaluate the extent by which chemisorption of oxygen to GAC can enhance the stability of biological perchlorate reduction. Baseline influent concentrations were 50 microg/L of perchlorate, 2 mg/L of acetate as C, and 1mg/L of DO. Perchlorate removal in the glass bead reactor seized immediately after increasing influent DO concentrations from 1 to 4 mg/L since glass beads have no sorptive capacity. In the biologically active carbon (BAC) reactor, chemisorption of oxygen to GAC removed a substantial fraction of the influent DO, and perchlorate removal was maintained during short-term increases of influent DO levels up to 8 mg/L. During long-term exposure to influent DO concentrations of 8.5mg/L, effluent perchlorate and DO concentrations increased slowly. Subsequent exposure of the BAC reactor bed to low DO concentrations partially regenerated the capacity for oxygen chemisorption. Microbial analyses indicated similar microbial communities in both reactors, which confirmed that the differences in reactor performance during dynamic loading conditions could be attributed to the sorptive properties of GAC. Using a sorptive biofilm support medium can enhance biological perchlorate removal under dynamic loading conditions.

  19. A combined upflow anaerobic sludge bed, aerobic, and anoxic fixed-bed reactor system for removing tetramethylammonium hydroxide and nitrogen from light-emitting diode wastewater.

    PubMed

    Lin, Han-Lin; Chen, Sheng-Kun; Huang, Yu-Wen; Chen, Wei-Cheng; Chien, Wei-Cheng; Cheng, Sheng-Shung

    2016-01-01

    A laboratory study using a combined upflow anaerobic sludge bed (UASB) and aerobic and anoxic fixed-bed reactor system was undertaken to explore its capability for removing tetramethylammonium hydroxide (TMAH) and nitrogen from light-emitting diode wastewater. When the organic loading rate was maintained at 0.26-0.65 kg TMAH m(-3 )d(-1), the UASB reactor removed 70-100% of TMAH through methanogenesis. When the [Formula: see text] -N loading rate was maintained at 0.73-1.4 kg [Formula: see text]-N m(-3 )d(-1), the aerobic reactor oxidized 31-59% of [Formula: see text]-N to [Formula: see text]-N through nitritation. When the nitrogen loading rate was maintained at 0.42-0.75 kg N m(-3 )d(-1), the anoxic reactor removed 27-63% of nitrogen through anammox. The performance data of the combined reactor system agreed well with the stoichiometric relationships of methanogenesis, nitritation, and anammox. The batch studies showed that a higher initial TMAH concentration of up to 2520 mg L(-1) gave a higher methanogenic activity of up to 16 mL CH4 g(-1) VSS d(-1). An increase in the initial TMAH concentration of up to 500 mg L(-1) gradually decreased the activity of ammonia-oxidizing bacteria; whereas an increase in the initial TMAH concentration of up to 47 mg L(-1) imposed a marked inhibiting effect on the activity of anammox bacteria.

  20. Supplemental Report on Nuclear Safeguards Considerations for the Pebble Bed Modular Reactor (PBMR)

    SciTech Connect

    Moses, David Lewis; Ehinger, Michael H

    2010-05-01

    Recent reports by Department of Energy National Laboratories have discussed safeguards considerations for the low enriched uranium (LEU) fueled Pebble Bed Modular Reactor (PBMR) and the need for bulk accountancy of the plutonium in used fuel. These reports fail to account effectively for the degree of plutonium dilution in the graphitized-carbon pebbles that is sufficient to meet the International Atomic Energy Agency's (IAEA's) 'provisional' guidelines for termination of safeguards on 'measured discards.' The thrust of this finding is not to terminate safeguards but to limit the need for specific accountancy of plutonium in stored used fuel. While the residual uranium in the used fuel may not be judged sufficiently diluted to meet the IAEA provisional guidelines for termination of safeguards, the estimated quantities of {sup 232}U and {sup 236}U in the used fuel at the target burn-up of {approx}91 GWD/MT exceed specification limits for reprocessed uranium (ASTM C787) and will require extensive blending with either natural uranium or uranium enrichment tails to dilute the {sup 236}U content to fall within specification thus making the PBMR used fuel less desirable for commercial reprocessing and reuse than that from light water reactors. Also the PBMR specific activity of reprocessed uranium isotopic mixture and its A{sub 2} values for effective dose limit if released in a dispersible form during a transportation accident are more limiting than the equivalent values for light water reactor spent fuel at 55 GWD/MT without accounting for the presence of the principal carry-over fission product ({sup 99}Tc) and any possible plutonium contamination that may be present from attempted covert reprocessing. Thus, the potentially recoverable uranium from PBMR used fuel carries reactivity penalties and radiological penalties likely greater than those for reprocessed uranium from light water reactors. These factors impact the economics of reprocessing, but a more significant

  1. Esterification of oleic acid in a three-phase, fixed-bed reactor packed with a cation exchange resin catalyst.

    PubMed

    Son, Sung Mo; Kimura, Hiroko; Kusakabe, Katsuki

    2011-01-01

    Esterification of oleic acid was performed in a three-phase fixed-bed reactor with a cation exchange resin catalyst (Amberlyst-15) at high temperature, which was varied from 80 to 120 °C. The fatty acid methyl ester (FAME) yields in the fixed-bed reactor were increased with increases in the reaction temperature, methanol flow rate and bed height. Moreover, the FAME yields were higher than those obtained using a batch reactor due to an equilibrium shift toward the product that resulted from continuous evaporation of the produced water. In addition, there was no catalyst deactivation during the esterification of oleic acid. However, addition of sunflower oil to the oleic acid reduced the FAME yield obtained from simultaneous esterification and transesterification. The FAME yield was 97.5% at a reaction temperature of 100 °C in the fixed-bed with a height of 5 cm when the methanol and oleic acid feed rates were 8.6 and 9.0 mL/h, respectively.

  2. ANAEROBIC/AEROBIC BIODEGRADATION OF PENTACHLOROPHENOL USING GAC FLUIDIXED BED REACTORS: OPTIMIZATION OF THE EMPTY BED CONTACT TIME

    EPA Science Inventory

    An integrated reactor system has been developed to remediate pentachlorophenol (PCP) containing wastes using sequential anaerobic and aerobic biodegradation. Anaerobically, PCP was degraded to approximately equimolar concentrations (>99%) of chlorophenol (CP) in a granular activa...

  3. Study of the electrowinning of copper using a fluidized-bed electrochemical reactor

    SciTech Connect

    Felker, D.L.

    1982-12-01

    A study was done on the use of a fluidized bed electrochemical reactor for the recovery of copper from aqueous solutions. Electrolyte solutions containing 0 to 8 g/l copper, 0 to 8 g/l iron and 200 g/l sulfuric acid were used. Porous diaphragms were used to separate the cathode and anode regions. The current efficiency, energy consumption rate and volumetric reaction rate were calculated for the experimental conditions. When the catholyte and anolyte are circulated from a common reservoir and iron(II) is present in the electrolyte, the energy consumption rate exhibits a minimum value of about 1.5 kWh/lb a volumetric reaction rate (VRR) of about 100 lb Cu/m/sup 3/ h. When the anolyte and catholyte are separated, the energy consumption rate rises linearly with VRR, being about 1 kWh/lb Cu at 100 lb Cu/m/sup 3/ h (this is roughly 2x the VRR of a conventional electrowinning cell). The optimum bed width in the direction of current flow was about 2 cm. A mathematical model which takes into account the dissolution of copper by ferric ion and oxygen is shown to explain the changes in the current efficiency and the VRR with current density seen in most of the experiments. Results indicate that separation of the catholyte and anolyte is imperative. Experiments showed that this can be accomplished using a porous Vycor glass diaphragm, which also eliminated the problem with copper dendrites growing through the diaphragm.

  4. Pyrolucite fluidized-bed reactor (PFBR): a robust and compact process for removing manganese from groundwater.

    PubMed

    Dashtban Kenari, Seyedeh Laleh; Barbeau, Benoit

    2014-02-01

    The purpose of this paper is to introduce a pyrolucite fluidized-bed reactor (PFBR) as a potential drinking water process to treat groundwater containing high levels of dissolved manganese (Mn(II)) (0.5-3 mg/L) and reduce its concentration to <0.02 mg/L in treated water. A pilot-scale study was conducted under dynamic conditions using synthetic groundwater (SGW), to elucidate the effect of operational conditions and groundwater composition on manganese (Mn) removal achieved by the PFBR. Results demonstrated almost complete Mn removal (close to 100%) in less than 1 min under all tested operational conditions (influent Mn concentration of 0.5-3 mg/L, calcium (Ca(2+)) hardness of 0-200 mg CaCO3/L, pH of 6.2-7.8, temperature of 9 & 23 °C and high hydraulic loading rate (HLR) of 24-63 m/h (i.e., bed expansion of 0-30%)). Improved Mn removal profile was achieved at higher water temperature. Also, the results showed that adsorption of Mn(II) onto pyrolucite and subsequent slower surface oxidation of sorbed Mn(II) was the only mechanism responsible for Mn removal while direct oxidation of Mn(II) by free chlorine did not occur even at high concentrations of Mn(II) and free chlorine and elevated temperatures. Higher average mass transfer coefficient and consequently adsorption rate was achieved at elevated HLR. Increasing effluent free chlorine residuals from 1.0 to 2.0-2.6 mg Cl2/L allowed increasing the operation time needed for media regeneration from 6 days to >12 days. Turbidity was maintained around 0.2 NTU during the entire test periods indicating good capture of MnOx colloids within the PFBR. PMID:24183400

  5. Feasibility of expanded granular sludge bed reactors for the anaerobic treatment of low-strength soluble wastewaters

    SciTech Connect

    Kato, M.T.; Field, J.A.; Versteeg, P.; Lettinga, G. . Dept. of Environmental Technology)

    1994-08-05

    The application of the expanded granular sludge bed (EGSB) reactor for the anaerobic treatment of low-strength soluble wastewaters using ethanol as a model substrate was investigated in laboratory-scale reactors at 30 C. Chemical oxygen demand (COD) removal efficiency was above 80% at organic loading rates up to 12 g COD/L [center dot] d with influent concentrations as low as 100 to 200 mg COD/L. These results demonstrate the suitability of the EGSB reactor for the anaerobic treatment of low-strength wastewaters. The high treatment performance can be attributed to the intense mixing regime obtained by high hydraulic and organic loads. Good mixing of the bulk liquid phase for the substrate-biomass contact and adequate expansion of the sludge bed for the degassing were obtained when the liquid upflow velocity (V[sub up]) was greater than 2.5 m/h. Under such conditions, an extremely low apparent K[sub s] value for acetoclastic methanogenesis of 9.8 mg COD/L was observed. The presence of dissolved oxygen in the wastewater had no detrimental effect on the treatment performance. Sludge piston flotation from pockets of biogas accumulating under the sludge bed occurred at V[sub up] lower than 2.5 m/h due to poor bed expansion. This problem is expected only in small diameter laboratory-scale reactors. A more important restriction of the EGSB reactor was the sludge washout occurring at V[sub up] higher than 5.5 m/h and which was intensified at organic loads higher than 7 g COD/L [center dot] d due to buoyancy forces from the gas production.

  6. On the evaluation of pebble bed reactor critical experiments using the PEBBED code

    SciTech Connect

    Hans D. Gougar; R. Sonat Sen

    2001-10-01

    The PEBBED pebble bed reactor fuel management code under development at the Idaho National Laboratory is designed for rapid design and analysis of pebble bed high temperature reactors (PBRs). Embedded within the code are the THERMIX-KONVEK thermal fluid solver and the COMBINE-7 spectrum generation code for inline cross section homogenization. Because 1D symmetry can be found at each stage of core heterogeneity; spherical at TRISO and pebble levels, and cylindrical at the control rod and core levels, the 1-D transport capability of ANISN is assumed to be sufficient in most cases for generating flux solutions for cross section homogenization. Furthermore, it is fast enough to be executed during the analysis or the equilibrium core. Multi-group diffusion-based design codes such as PEBBED and VSOP are not expected to yield the accuracy and resolution of continuous energy Monte Carlo codes for evaluation of critical experiments. Nonetheless, if the preparation of multigroup cross sections can adequately capture the physics of the mixing of PBR fuel elements and leakage from the core, reasonable results may be obtained. In this paper, results of the application of PEBBED to two critical experiments (HTR Proteus and HTR-10) and associated computational models are presented. The embedded 1-D transport solver is shown to capture the double heterogeneity of the pebble fuel in unit cell calculations. Eigenvalue calculations of a whole core are more challenging, particularly if the boron concentration is uncertain. The sensitivity of major safety parameters to variations in modeling assumptions, however, is shown to be minimal. The embedded transport solver can also be used to obtain control rod worths but only with adjustment of the local spectrum. Results are compared to those of other codes as well as Core 4 of the HTR-Proteus experiment which contains partially inserted rods. They indicate the need for a reference solution to adjust the radius of the graphite in the

  7. Colour removal from a simulated dye wastewater using a two-phase anaerobic packed bed reactor.

    PubMed

    Mahdavi Talarposhti, A; Donnelly, T; Anderson, G K

    2001-02-01

    In recent years, rapid technological advances in the textile and dyeing industry have yielded benefits to society but have also generated new and significant environmental problems. The treatment alternatives applicable for the removal of colour vary, depending upon the type of dye wastewater. A synthetic, simulated mixed dye waste (Basic Yellow 28, Basic Yellow 21, Basic Red 18.1, Basic Violet Red 16, Basic Red 46, Basic Blue 16, Basic Blue 41) representing a known waste from a fibre production factory, was investigated. The biological process of anaerobic digestion has been recognised as a simple and energy-efficient means of treating and stabilising a wide range of organic industrial wastewaters. This study sets out to demonstrate the effect of different loading rates, dye concentrations and hydraulic retention times (HRTs) on colour removal efficiency under mesophilic anaerobic conditions. The reactor was operated under mesophilic conditions at different organic loading rates (OLRs) and HRTs for nine months. The results of this study show that a 2-stage mesophilic anaerobic up-flow packed bed reactor can remove up to 90% of the colour from a mixed cationic dye containing 1000 mg/l of dye. Colour removal efficiency falls as the influent dye concentration increases, but rises with increased hydraulic retention time and increased organic loading. The primary colour removal mechanism was one of biosorption with subsequent biodegradation. Acetoclastic methanogens were moderately inhibited at low organic loading rates of 0.25 kg COD/m3 d, at which level, acidogenesis and acetogenesis appeared to be unaffected. Inhibition of acidogenesis became marked at higher OLRs (1 kg COD/m3 d) and when the HRT was reduced from 5 to 3 days.

  8. Enhanced struvite recovery from wastewater using a novel cone-inserted fluidized bed reactor.

    PubMed

    Guadie, Awoke; Xia, Siqing; Jiang, Wei; Zhou, Lijie; Zhang, Zhiqiang; Hermanowicz, Slawomir W; Xu, Xiaoyin; Shen, Shuang

    2014-04-01

    The feasibility of struvite recovery at low (12.5 mg/L) and high (120 mg/L) phosphorus concentrations was studied by constructing a novel fluidized bed reactor with cones (FBRwc) and without cones (FBRwoc). The crystallization process was continuously operated for 133 days under different hydraulic retention times (HRT = 1-10 hr), pH (7.5-10), and molar ratios of Mg/P (0.75-1.75), N/P (1-10) and Ca/Mg (0-2). The optimum operating conditions of HRT, pH, Mg/P and N/P molar ratios were found to be 2 hr, 9, 1.25, and 7.5, respectively. Under these optimum conditions, the phosphorus precipitation efficiencies of FBRwc were 93% for low and 98% for high phosphorus influent; however, the efficiencies were 78% and 81% for FBRwoc, respectively. Due to crystal losses at each junction (17%-31%), the crystal recovery efficiency of FBRwoc was relatively low (47%-65%) for both influent concentrations. However, the losses were minimal in FBRwc, which showed 75% and 92% crystal recovery for low and high phosphorus concentrations, respectively. At low calcium concentration, crystal chemical analysis showed the product to be pure struvite (> 99%). The scanning electron microscope and X-ray diffraction results further confirmed that the crystal recovered from FBRwc contained pure struvite, which could be considered a high quality fertilizer. Except HRT, all parameters (pH, Mg/P, N/P and Ca/Mg) were found to be influencing factors for FBRwc performance. Overall, inserting cones in each part of the reactor played a significant role in enhancing struvite recovery from a wide range of phosphorus-containing wastewater. PMID:25079406

  9. Nitrification of an industrial wastewater in a moving-bed biofilm reactor: effect of salt concentration.

    PubMed

    Vendramel, Simone; Dezotti, Marcia; Sant'Anna, Geraldo L

    2011-01-01

    Nitrification of wastewaters from chemical industries can pose some challenges due to the presence of inhibitory compounds. Some wastewaters, besides their organic complexity present variable levels of salt concentration. In order to investigate the effect of salt (NaCl) content on the nitrification of a conventional biologically treated industrial wastewater, a bench scale moving-bed biofilm reactor was operated on a sequencing batch mode. The wastewater presenting a chloride content of 0.05 g l(-1) was supplemented with NaCl up to 12 g Cl(-) l(-1). The reactor operation cycle was: filling (5 min), aeration (12 or 24h), settling (5 min) and drawing (5 min). Each experimental run was conducted for 3 to 6 months to address problems related to the inherent wastewater variability and process stabilization. A PLC system assured automatic operation and control of the pertinent process variables. Data obtained from selected batch experiments were adjusted by a kinetic model, which considered ammonia, nitrite and nitrate variations. The average performance results indicated that nitrification efficiency was not influenced by chloride content in the range of 0.05 to 6 g Cl(-) l(-1) and remained around 90%. When the chloride content was 12 g Cl(-) l(-1), a significant drop in the nitrification efficiency was observed, even operating with a reaction period of 24 h. Also, a negative effect of the wastewater organic matter content on nitrification efficiency was observed, which was probably caused by growth of heterotrophs in detriment of autotrophs and nitrification inhibition by residual chemicals.

  10. On-line interrogation of pebble bed reactor fuel using passive gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Chen, Jianwei

    The Pebble Bed Reactor (PBR) is a helium-cooled, graphite-moderated high temperature nuclear power reactor. In addition to its inherently safe design, a unique feature of this reactor is its multipass fuel cycle in which graphite fuel pebbles (of varying enrichment) are randomly loaded and continuously circulated through the core until they reach their prescribed end-of-life burnup limit (˜80,000--100,000 MWD/MTU). Unlike the situation with conventional light water reactors (LWRs), depending solely on computational methods to perform in-core fuel management will be highly inaccurate. As a result, an on-line measurement approach becomes the only accurate method to assess whether a particular pebble has reached its end-of-life burnup limit. In this work, an investigation was performed to assess the feasibility of passive gamma-ray spectrometry assay as an approach for on-line interrogation of PBR fuel for the simultaneous determination of burnup and enrichment on a pebble-by-pebble basis. Due to the unavailability of irradiated or fresh pebbles, Monte Carlo simulations were used to study the gamma-ray spectra of the PBR fuel at various levels of burnup. A pebble depletion calculation was performed using the ORIGEN code, which yielded the gamma-ray source term that was introduced into the input of an MCNP simulation. The MCNP simulation assumed the use of a high-purity coaxial germanium detector. Due to the lack of one-group high temperature reactor cross sections for ORIGEN, a heterogeneous MCNP model was developed to describe a typical PBR core. Subsequently, the code MONTEBURNS was used to couple the MCNP model and ORIGEN. This approach allowed the development of the burnup-dependent, one-group spectral-averaged PBR cross sections to be used in the ORIGEN pebble depletion calculation. Based on the above studies, a relative approach for performing the measurements was established. The approach is based on using the relative activities of Np-239/I-132 in combination

  11. Effect of small-scale biomass gasification at the state of refractory lining the fixed bed reactor

    NASA Astrophysics Data System (ADS)

    Janša, Jan; Peer, Vaclav; Pavloková, Petra

    2016-06-01

    The article deals with the influence of biomass gasification on the condition of the refractory lining of a fixed bed reactor. The refractory lining of the gasifier is one part of the device, which significantly affects the operational reliability and durability. After removing the refractory lining of the gasifier from the experimental reactor, there was done an assessment how gasification of different kinds of biomass reflected on its condition in terms of the main factors affecting its life. Gasification of biomass is reflected on the lining, especially through sticking at the bottom of the reactor. Measures for prolonging the life of lining consist in the reduction of temperature in the reactor, in this case, in order to avoid ash fusion biomass which it is difficult for this type of gasifier.

  12. Steady-state inhibition model for the biodegradation of sulfonated amines in a packed bed reactor.

    PubMed

    Juárez-Ramírez, Cleotilde; Galíndez-Mayer, Juvencio; Ruiz-Ordaz, Nora; Ramos-Monroy, Oswaldo; Santoyo-Tepole, Fortunata; Poggi-Varaldo, Héctor

    2015-05-25

    Aromatic amines are important industrial products having in their molecular structure one or more aromatic rings. These are used as precursors for the synthesis of dyes, adhesives, pesticides, rubber, fertilizers and surfactants. The aromatic amines are common constituents of industrial effluents, generated mostly by the degradation of azo dyes. Several of them are a threat to human health because they can by toxic, allergenic, mutagenic or carcinogenic. The most common are benzenesulfonic amines, such as 4-ABS (4-aminobenzene sulfonic acid) and naphthalene sulfonic amines, such as 4-ANS (4-amino naphthalene sulfonic acid). Sometimes, the mixtures of toxic compounds are more toxic or inhibitory than the individual compounds, even for microorganisms capable of degrading them. Therefore, the aim of this study was to evaluate the degradation of the mixture 4-ANS plus 4-ABS by a bacterial community immobilized in fragments of volcanic stone, using a packed bed continuous reactor. In this reactor, the amines loading rates were varied from 5.5 up to 69 mg L(-1) h(-1). The removal of the amines was determined by high-performance liquid chromatography and chemical oxygen demand. With this information, we have studied the substrate inhibition of the removal rate of the aromatic amines during the degradation of the mixture of sulfonated aromatic amines by the immobilized microorganisms. Experimental results were fitted to parabolic, hyperbolic and linear inhibition models. The model that best characterizes the inhibition of the specific degradation rate in the biofilm reactor was a parabolic model with values of RXM=58.15±7.95 mg (10(9) cells h)(-1), Ks=0.73±0.31 mg L(-1), Sm=89.14±5.43 mg L(-1) and the exponent m=5. From the microbial community obtained, six cultivable bacterial strains were isolated and identified by sequencing their 16S rDNA genes. The strains belong to the genera Variovorax, Pseudomonas, Bacillus, Arthrobacter, Nocardioides and Microbacterium. This

  13. Steady-state inhibition model for the biodegradation of sulfonated amines in a packed bed reactor.

    PubMed

    Juárez-Ramírez, Cleotilde; Galíndez-Mayer, Juvencio; Ruiz-Ordaz, Nora; Ramos-Monroy, Oswaldo; Santoyo-Tepole, Fortunata; Poggi-Varaldo, Héctor

    2015-05-25

    Aromatic amines are important industrial products having in their molecular structure one or more aromatic rings. These are used as precursors for the synthesis of dyes, adhesives, pesticides, rubber, fertilizers and surfactants. The aromatic amines are common constituents of industrial effluents, generated mostly by the degradation of azo dyes. Several of them are a threat to human health because they can by toxic, allergenic, mutagenic or carcinogenic. The most common are benzenesulfonic amines, such as 4-ABS (4-aminobenzene sulfonic acid) and naphthalene sulfonic amines, such as 4-ANS (4-amino naphthalene sulfonic acid). Sometimes, the mixtures of toxic compounds are more toxic or inhibitory than the individual compounds, even for microorganisms capable of degrading them. Therefore, the aim of this study was to evaluate the degradation of the mixture 4-ANS plus 4-ABS by a bacterial community immobilized in fragments of volcanic stone, using a packed bed continuous reactor. In this reactor, the amines loading rates were varied from 5.5 up to 69 mg L(-1) h(-1). The removal of the amines was determined by high-performance liquid chromatography and chemical oxygen demand. With this information, we have studied the substrate inhibition of the removal rate of the aromatic amines during the degradation of the mixture of sulfonated aromatic amines by the immobilized microorganisms. Experimental results were fitted to parabolic, hyperbolic and linear inhibition models. The model that best characterizes the inhibition of the specific degradation rate in the biofilm reactor was a parabolic model with values of RXM=58.15±7.95 mg (10(9) cells h)(-1), Ks=0.73±0.31 mg L(-1), Sm=89.14±5.43 mg L(-1) and the exponent m=5. From the microbial community obtained, six cultivable bacterial strains were isolated and identified by sequencing their 16S rDNA genes. The strains belong to the genera Variovorax, Pseudomonas, Bacillus, Arthrobacter, Nocardioides and Microbacterium. This

  14. A simplified DEM-CFD approach for pebble bed reactor simulations

    SciTech Connect

    Li, Y.; Ji, W.

    2012-07-01

    In pebble bed reactors (PBR's), the pebble flow and the coolant flow are coupled with each other through coolant-pebble interactions. Approaches with different fidelities have been proposed to simulate similar phenomena. Coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) approaches are widely studied and applied in these problems due to its good balance between efficiency and accuracy. In this work, based on the symmetry of the PBR geometry, a simplified 3D-DEM/2D-CFD approach is proposed to speed up the DEM-CFD simulation without significant loss of accuracy. Pebble flow is simulated by a full 3-D DEM, while the coolant flow field is calculated with a 2-D CFD simulation by averaging variables along the annular direction in the cylindrical geometry. Results show that this simplification can greatly enhance the efficiency for cylindrical core, which enables further inclusion of other physics such as thermal and neutronic effect in the multi-physics simulations for PBR's. (authors)

  15. Lewis Research Center's coal-fired, pressurized, fluidized-bed reactor test facility

    NASA Technical Reports Server (NTRS)

    Kobak, J. A.; Rollbuhler, R. J.

    1981-01-01

    A 200-kilowatt-thermal, pressurized, fluidized-bed (PFB) reactor, research test facility was designed, constructed, and operated as part of a NASA-funded project to assess and evaluate the effect of PFB hot-gas effluent on aircraft turbine engine materials that might have applications in stationary-power-plant turbogenerators. Some of the techniques and components developed for this PFB system are described. One of the more important items was the development of a two-in-one, gas-solids separator that removed 95+ percent of the solids in 1600 F to 1900 F gases. Another was a coal and sorbent feed and mixing system for injecting the fuel into the pressurized combustor. Also important were the controls and data-acquisition systems that enabled one person to operate the entire facility. The solid, liquid, and gas sub-systems all had problems that were solved over the 2-year operating time of the facility, which culminated in a 400-hour, hot-gas, turbine test.

  16. Membrane distillation combined with an anaerobic moving bed biofilm reactor for treating municipal wastewater.

    PubMed

    Kim, Hyun-Chul; Shin, Jaewon; Won, Seyeon; Lee, Jung-Yeol; Maeng, Sung Kyu; Song, Kyung Guen

    2015-03-15

    A fermentative strategy with an anaerobic moving bed biofilm reactor (AMBBR) was used for the treatment of domestic wastewater. The feasibility of using a membrane separation technique for post-treatment of anaerobic bio-effluent was evaluated with emphasis on employing a membrane distillation (MD). Three different hydrophobic 0.2 μm membranes made of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polypropylene (PP) were examined in this study. The initial permeate flux of the membranes ranged from 2.5 to 6.3 L m(-2) h(-1) when treating AMBBR effluent at a temperature difference between the feed and permeate streams of 20 °C, with the permeate flux increasing in the order PP < PVDF < PTFE. The permeate flux of the PTFE membrane gradually decreased to 84% of the initial flux after the 45 h run for distillation, while a flux decline in MD with either the PVDF or PP membrane was not found under the identical distillation conditions. During long-term distillation with the PVDF membrane, total phosphorus was completely rejected and >98% rejection of dissolved organic carbon was also achieved. The characterization of wastewater effluent organic matter (EfOM) using an innovative suite of analytical tools verified that almost all of the EfOM was rejected via the PVDF MD treatment. PMID:25600301

  17. Immobilised native plant cysteine proteases: packed-bed reactor for white wine protein stabilisation.

    PubMed

    Benucci, Ilaria; Lombardelli, Claudio; Liburdi, Katia; Acciaro, Giuseppe; Zappino, Matteo; Esti, Marco

    2016-02-01

    This research presents a feasibility study of using a continuous packed-bed reactor (PBR), containing immobilised native plant cysteine proteases, as a specific and mild alternative technique relative to the usual bentonite fining for white wine protein stabilisation. The operational parameters for a PBR containing immobilised bromelain (PBR-br) or immobilised papain (PBR-pa) were optimised using model wine fortified with synthetic substrate (Bz-Phe-Val-Arg-pNA). The effectiveness of PBR-br, both in terms of hazing potential and total protein decrease, was significantly higher than PBR-pa, in all the seven unfined, white wines used. Among the wines tested, Sauvignon Blanc, given its total protein content as well as its very high intrinsic instability, was selected as a control wine to evaluate the effect of the treatment on wine as to its soluble protein profile, phenolic composition, mineral component, and sensory properties. The treatment in a PBR containing immobilised bromelain appeared effective in decreasing both wine hazing potential and total protein amount, while it did not significantly affect the phenol compounds, the mineral component nor the sensory quality of wine. The enzymatic treatment in PBR was shown to be a specific and mild technique for use as an alternative to bentonite fining for white wine protein stabilisation. PMID:27162393

  18. Typical Application of Sound Field in Wastewater Treatment with Fluidized Bed Photocatalytic Reactor.

    PubMed

    Si, Chong-dian; Zhou, Jing; Gao, Hong-tao; Liu, Guang-jun; Wu, Jian-jun

    2015-04-01

    The effect of a sound field on wastewater treatment with a fluidized bed photocatalytic reactor (FBPR) was investigated. With Alizarin Green (AG) being the sole infectant, the Fe-doped TiO2 catalyst prepared was used as the fluidized media. According to the Langmuir-Hinshelwood model, the photocatalytic degradation follows the pseudo-first-order reaction kinetics with respect to the concentration of AG. Sound field application allowed the fluidization of the fine powder at high liquid flow rates; thus, the mass transfer rate between organic pollutant and particle photocatalyst was enhanced and the efficiency of degradation was increased. As expected, the degradation rate constant increased with increasing sound pressure level, as well as increased with increasing sound frequency ranging from 50 to 100 Hz, then further decreased with increasing sound frequency from 100 to 200 Hz. In addition, Fe doping is also responsible for the enhanced photocurrent response of the Fe-doped TiO2 nanoparticle in FBPR relative to pure TiO2. PMID:26462082

  19. Catalytic hydrolysis of urea from wastewater using different aluminas by a fixed bed reactor.

    PubMed

    Shen, Shuguang; Li, Meina; Li, Binbin; Zhao, Zhijun

    2014-11-01

    In order to find an effective method for treating urea wastewater, the experiments on the hydrolysis of urea in wastewater were conducted in a fixed bed reactor with different aluminas (α-Al2O3, γ-Al2O3, and η-Al2O3) as catalysts respectively in contrast with inert ceramic particle. The results indicate that the three alumina catalysts show obvious catalytic activity for urea hydrolysis at 125 °C. The order of activity is η-Al2O3 > γ-Al2O3 > α-Al2O3, and the activity difference increases with increasing temperature. According to the characterization results, surface acidity has little impact on the activity of catalyst. However, it was found that surface basicity of alumina catalyst plays an important role in catalytic hydrolysis of urea, and the activity of catalyst may be also influenced by the basic strength. With η-Al2O3 as catalyst, the urea concentration in wastewater is reduced to 4.96 mg/L at a temperature of 165 °C. Moreover, the η-Al2O3 shows a good stability for urea hydrolysis. The hydrolysis of urea over η-Al2O3 catalyst can evidently reduce the reaction temperature and is promising to replace industrial thermal hydrolysis process.

  20. Treatment of winery wastewater in a full-scale fixed bed biofilm reactor.

    PubMed

    Andreottola, G; Foladori, P; Nardelli, P; Denicolo, A

    2005-01-01

    The treatment of winery wastewater was performed at full-scale applying a two-stage fixed bed biofilm reactor (FBBR) system for the discharge in the sewerage. The results of the first year of operation at the full-scale plant are presented. Values of removed organic loads and effluent concentrations were interpreted on the basis of the COD fractionation of influent wastewater assessed through respirometric tests. The average removal efficiency of total COD was 91 %. It was not possible to reach an higher efficiency because of the unbiodegradable soluble fraction of COD (about 10% of total COD on average during the whole year), that cannot be removed by biological process or settling. Due to the high empty space offered by the plastic carriers, FBBRs did not require backwashing during the seasonal operationing period of the plant (September-March). In comparison with other treatment systems the FBBR configuration allows one to ensure a simple management, to obtain high efficiency also in the case of higher fluctuations of flow and loads and to guarantee a good settleability of the sludge, without bulking problems.

  1. Assessing the treatment of acetaminophen-contaminated brewery wastewater by an anaerobic packed-bed reactor.

    PubMed

    Abdullah, Norhayati; Fulazzaky, Mohamad Ali; Yong, Ee Ling; Yuzir, Ali; Sallis, Paul

    2016-03-01

    The treatment of high-strength organic brewery wastewater with added acetaminophen (AAP) by an anaerobic digester was investigated. An anaerobic packed-bed reactor (APBR) was operated as a continuous process with an organic loading rate of 1.5-g COD per litre per day and a hydraulic retention time of three days. The results of steady-state analysis showed that the greatest APBR performances for removing COD and TOC were as high as 98 and 93%, respectively, even though the anaerobic digestibility after adding the different AAP concentrations of 5, 10 and 15 mg L(-1) into brewery wastewater can affect the efficiency of organic matter removal. The average CH4 production decreased from 81 to 72% is counterbalanced by the increased CO2 production from 11 to 20% before and after the injection of AAP, respectively. The empirical kinetic models for substrate utilisation and CH4 production were used to predict that, under unfavourable conditions, the performance of the APBR treatment process is able to remove COD with an efficiency of only 6.8%.

  2. Packed-bed reactor/silent-discharge plasma design data report

    SciTech Connect

    1996-05-01

    In 1992, Congress passed the Federal Facility Compliance Act requiring the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with Resource Conservation and Recovery Act (RCRA) land disposal restrictions (LDRs). The DOE Albuquerque Operations Office (AL) currently does not have adequate systems to treat the mixed wastes generated and stored at the nine DOE-AL sites. In response to the need for mixed-waste treatment capacity, DOE-AL organized a Treatment Selection Team under the Mixed-Waste Treatment Program (MWTP) to match mixed wastes with treatment options and develop a strategy for treatment of its mixed waste. The strategy developed by the Treatment Selection Team, as described in the AL Mixed-Waste Treatment Plan (DOE 1994), is to use available off-site commercial treatment facilities for all wastes that can be successfully and cost-effectively treated by such facilities. Where no appropriate commercial treatment facilities exist, mobile treatment units (MTUs) would be developed to treat wastes at the sites where the wastes are generated. Treatment processes used for mixed waste must not only address the hazardous component (i.e., meet LDRs) but also must contain the radioactive component in a form that allows final disposal while protecting workers, the public, and the environment. The packed-bed reactor/silent discharge plasma was chosen as a potential candidate for the treatment of the mixed wastes. The process is described.

  3. Jute stick pyrolysis for bio-oil production in fluidized bed reactor.

    PubMed

    Asadullah, M; Anisur Rahman, M; Mohsin Ali, M; Abdul Motin, M; Borhanus Sultan, M; Robiul Alam, M; Sahedur Rahman, M

    2008-01-01

    Pyrolysis of jute stick for bio-oil production has been investigated in a continuous feeding fluidized bed reactor at different temperatures ranging from 300 degrees C to 600 degrees C. At 500 degrees C, the yields of bio-oil, char and non-condensable gas were 66.70 wt%, 22.60 wt% and 10.70 wt%, respectively based on jute stick. The carbon based non-condensable gas was the mixture of carbon monoxide, carbon dioxide, methane, ethane, ethene, propane and propene. The density and viscosity of bio-oil were found to be 1.11 g/mL and 2.34 cP, respectively. The lower heating value (LHV) of bio-oil was found to be 18.2 5 MJ/kg. Since bio-oil contains some organic acids such as formic acid, acetic acid, etc., the pH and acid value of the bio-oil were found to be around 4 and 135 mg KOH/g, respectively. The water, lignin, solid and ash contents of bio-oil were determined and found to be around 15 wt%, 4.90 wt%, 0.02 wt% and 0.10 wt%, respectively.

  4. Membrane distillation combined with an anaerobic moving bed biofilm reactor for treating municipal wastewater.

    PubMed

    Kim, Hyun-Chul; Shin, Jaewon; Won, Seyeon; Lee, Jung-Yeol; Maeng, Sung Kyu; Song, Kyung Guen

    2015-03-15

    A fermentative strategy with an anaerobic moving bed biofilm reactor (AMBBR) was used for the treatment of domestic wastewater. The feasibility of using a membrane separation technique for post-treatment of anaerobic bio-effluent was evaluated with emphasis on employing a membrane distillation (MD). Three different hydrophobic 0.2 μm membranes made of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polypropylene (PP) were examined in this study. The initial permeate flux of the membranes ranged from 2.5 to 6.3 L m(-2) h(-1) when treating AMBBR effluent at a temperature difference between the feed and permeate streams of 20 °C, with the permeate flux increasing in the order PP < PVDF < PTFE. The permeate flux of the PTFE membrane gradually decreased to 84% of the initial flux after the 45 h run for distillation, while a flux decline in MD with either the PVDF or PP membrane was not found under the identical distillation conditions. During long-term distillation with the PVDF membrane, total phosphorus was completely rejected and >98% rejection of dissolved organic carbon was also achieved. The characterization of wastewater effluent organic matter (EfOM) using an innovative suite of analytical tools verified that almost all of the EfOM was rejected via the PVDF MD treatment.

  5. Immobilised native plant cysteine proteases: packed-bed reactor for white wine protein stabilisation.

    PubMed

    Benucci, Ilaria; Lombardelli, Claudio; Liburdi, Katia; Acciaro, Giuseppe; Zappino, Matteo; Esti, Marco

    2016-02-01

    This research presents a feasibility study of using a continuous packed-bed reactor (PBR), containing immobilised native plant cysteine proteases, as a specific and mild alternative technique relative to the usual bentonite fining for white wine protein stabilisation. The operational parameters for a PBR containing immobilised bromelain (PBR-br) or immobilised papain (PBR-pa) were optimised using model wine fortified with synthetic substrate (Bz-Phe-Val-Arg-pNA). The effectiveness of PBR-br, both in terms of hazing potential and total protein decrease, was significantly higher than PBR-pa, in all the seven unfined, white wines used. Among the wines tested, Sauvignon Blanc, given its total protein content as well as its very high intrinsic instability, was selected as a control wine to evaluate the effect of the treatment on wine as to its soluble protein profile, phenolic composition, mineral component, and sensory properties. The treatment in a PBR containing immobilised bromelain appeared effective in decreasing both wine hazing potential and total protein amount, while it did not significantly affect the phenol compounds, the mineral component nor the sensory quality of wine. The enzymatic treatment in PBR was shown to be a specific and mild technique for use as an alternative to bentonite fining for white wine protein stabilisation.

  6. Aging biofilm from a full-scale moving bed biofilm reactor: characterization and enzymatic treatment study.

    PubMed

    Huang, Hui; Ren, Hongqiang; Ding, Lili; Geng, Jinju; Xu, Ke; Zhang, Yan

    2014-02-01

    Effective removal of aging biofilm deserves to receive more attention. This study aimed to characterized aging biofilm from a full-scale moving bed biofilm reactor treating pharmaceutical wastewater and evaluate the hydrolysis effects of biofilm by different enzymatic treatments. Results from FTIR and biochemical composition analyses showed that it was a predominately organic-based biofilm with the ratio of total protein (PN) to polysaccharide (PS) of 20.17. A reticular structure of extracellular polymeric matrix (EPM) with filamentous bacteria as the skeleton was observed on the basal layer through SEM-EDS test. Among the four commercial proteases and amylases from Genencor®, proteases were shown to have better performances than amylases either on the removal of MLSS and PN/MLSS or on DOC (i.e., dissolved organic carbon)/MLSS raising of biofilm pellets. Difference of dynamic fluorescence characteristics of dissolved organic matters after treated by the two proteases indicated distinguishing mechanisms of the treating process. PMID:24384319

  7. Application of rumen microbes to enhance food waste hydrolysis in acidogenic leach-bed reactors.

    PubMed

    Yan, Bing Hua; Selvam, Ammaiyappan; Wong, Jonathan W C

    2014-09-01

    Effect of rumen microorganisms on hydrolysis of food waste in leach bed reactor (LBR) was investigated. LBRs were inoculated (20%, w/w) with cow manure and anaerobically digested sludge at different ratios, 0:1 (LBR-A), 1:3 (LBR-B), 1:1 (LBR-C), 3:1 (LBR-D) and 1:0 (LBR-E). High volatile solids (VS) conversion efficiency of 68% was achieved in LBR-E. Compared with LBR-A, chemical oxygen demand, total soluble products and total Kjeldahl nitrogen leaching of LBR-E were increased by 16%, 14.3% and 27%, respectively. Recovery of the highest amounts of ethanol and butyrate in LBR-E indicated that the metabolic pathway mediated by rumen microorganisms was favorable for subsequent methanogenesis. Phylogenetic analysis confirmed that the enhanced hydrolysis in LBR-E was mainly due to strong degraders, e.g. Enterobacter, Bifidobacterium thermacidophilum and Caloramator sourced from cow manure. Results demonstrate that rumen microorganisms rapidly degrade the VS and produce useful VFAs with high methane yields in subsequent methanogenesis.

  8. Recovery of energy and iron from oily sludge pyrolysis in a fluidized bed reactor.

    PubMed

    Qin, Linbo; Han, Jun; He, Xiang; Zhan, Yiqiu; Yu, Fei

    2015-05-01

    In the steel industry, about 0.86 ton of oily sludge is produced for every 1000 tons of rolling steel. Due to the adverse impact on human health and the environment, oily sludge is designated as a hazardous waste in the Resource Conservation and Recovery Act (RCRT). In this paper, the pyrolysis treatment of oily sludge is studied in a fluidized bed reactor at a temperature range of 400-600 °C. During oily sludge pyrolysis, a maximum oil yield of 59.2% and a minimum energy loss of 19.0% are achieved at 500 °C. The energy consumption of treating 1 kg oily sludge is only 2.4-2.9 MJ. At the same time, the energy of produced oil, gas and solid residue are 20.8, 6.32, and 0.83 MJ, respectively. In particular, it is found that the solid residue contains more than 42% iron oxide, which can be used as the raw material for iron production. Thus, the simultaneous recovery of energy and iron from oil sludge by pyrolysis is feasible. PMID:25728916

  9. Tar Production from Biomass Pyrolysis in a Fluidized Bed Reactor: A Novel Turbulent Multiphase Flow Formulation

    NASA Technical Reports Server (NTRS)

    Bellan, J.; Lathouwers, D.

    2000-01-01

    A novel multiphase flow model is presented for describing the pyrolysis of biomass in a 'bubbling' fluidized bed reactor. The mixture of biomass and sand in a gaseous flow is conceptualized as a particulate phase composed of two classes interacting with the carrier gaseous flow. The solid biomass is composed of three initial species: cellulose, hemicellulose and lignin. From each of these initial species, two new solid species originate during pyrolysis: an 'active' species and a char, thus totaling seven solid-biomass species. The gas phase is composed of the original carrier gas (steam), tar and gas; the last two species originate from the volumetric pyrolysis reaction. The conservation equations are derived from the Boltzmann equations through ensemble averaging. Stresses in the gaseous phase are the sum of the Newtonian and Reynolds (turbulent) contributions. The particulate phase stresses are the sum of collisional and Reynolds contributions. Heat transfer between phases, and heat transfer between classes in the particulate phase is modeled, the last resulting from collisions between sand and biomass. Closure of the equations must be performed by modeling the Reynolds stresses for both phases. The results of a simplified version (first step) of the model are presented.

  10. Heavy metal removal by combining anaerobic upflow packed bed reactors with water hyacinth ponds.

    PubMed

    Sekomo, Christian Birame; Kagisha, Vedaste; Rousseau, Diederik; Lens, Piet

    2012-06-01

    The removal of four selected heavy metals (Cu, Cd, Pb and Zn) has been assessed in an upflow anaerobic packed bed reactor filled with porous volcanic rock as an adsorbent and an attachment surface for bacterial growth. Two different feeding regimes were applied using low (5 mg L(-1) of heavy metal each) and high (10 mg L(-1) of heavy metal each) strength wastewater. After a start-up and acclimatization period of 44 days, each regime was operated for a period of 10 days with a hydraulic retention time of one day. Good removal efficiencies of at least 86% were achieved for both the low and high strength wastewater. A subsequent water hyacinth pond with a hydraulic retention time of one day removed an additional 61% Cd, 59% Cu, 49% Pb and 42% Zn, showing its importance as a polishing step. The water hyacinth plant in the post-treatment step accumulated heavy metals mainly in the root system. Overall metal removal efficiencies at the outlet of the integrated system were 98% for Cd, 99% for Cu, 98% for Pb and 84% for Zn. Therefore, the integrated system can be used as an alternative treatment system for metal-polluted wastewater, especially in developing countries. PMID:22856321

  11. Impact of fine mesh sieve primary treatment on nitrogen removal in moving bed biofilm reactors.

    PubMed

    Rusten, B; Razafimanantsoa, V A; Andriamiarinjaka, M A; Otis, C L; Sahu, A K; Bilstad, T

    2016-01-01

    The purpose of this project was to investigate the effect of selective particle removal during primary treatment on nitrogen removal in moving bed biofilm reactors (MBBRs). Two small MBBR pilot plants were operated in parallel, where one train treated 2 mm screened municipal wastewater and the other train treated wastewater that had passed through a Salsnes Filter SF1000 rotating belt sieve (RBS) with a 33 µs sieve cloth. The SF1000 was operated without a filter mat on the belt. The tests confirmed that, for the wastewater characteristics at the test plant, Salsnes Filter primary treatment with a 33 µs RBS and no filter mat produced a primary effluent that was close to optimum. Removal of organic matter with the 33 µs sieve had no negative effect on the denitrification process. Nitrification rates improved by 10-15% in the train with 33 µs RBS primary treatment. Mass balance calculations showed that without RBS primary treatment, the oxygen demand in the biological system was 36% higher. Other studies have shown that the sludge produced by RBS primary treatment is beneficial for biogas production and will also significantly improve sludge dewatering of the combined primary and biological sludge. PMID:26819389

  12. Evaluating the effect of biofilm thickness on nitrification in moving bed biofilm reactors.

    PubMed

    Piculell, Maria; Welander, Pia; Jönsson, Karin; Welander, Thomas

    2016-01-01

    This study evaluates the effect of biofilm thickness on the nitrifying activity in moving bed biofilm reactors (MBBRs) in a controlled environment. In-depth understanding of biofilm properties in MBBRs and their effect on the overall treatment efficiency is the key to optimizing process stability and efficiency. However, evaluating biofilm properties in continuously operated MBBRs can be extremely challenging. This study uses a carrier design which enables comparison of four different biofilm thicknesses, in otherwise equally operated lab-scale MBBRs. The results show that within the studied range (200-500 µm) and specific operation conditions, biofilm thickness alone had no significant effect on the overall ammonium removal. The nitrate production, however, decreased with a decreasing biofilm thickness, and the ratio between nitrite and ammonia-oxidizing activity decreased both with increasing load and decreasing oxygen concentration for all thicknesses. The suggestion that nitratation is disfavoured in thin biofilms is an interesting contribution to the current research being performed on nitrite-oxidizing bacteria inhibition for deammonification applications. By indicating that different groups of bacteria respond differently to biofilm thickness, this study accentuates the importance of further evaluation of these complex systems.

  13. Assessing the treatment of acetaminophen-contaminated brewery wastewater by an anaerobic packed-bed reactor.

    PubMed

    Abdullah, Norhayati; Fulazzaky, Mohamad Ali; Yong, Ee Ling; Yuzir, Ali; Sallis, Paul

    2016-03-01

    The treatment of high-strength organic brewery wastewater with added acetaminophen (AAP) by an anaerobic digester was investigated. An anaerobic packed-bed reactor (APBR) was operated as a continuous process with an organic loading rate of 1.5-g COD per litre per day and a hydraulic retention time of three days. The results of steady-state analysis showed that the greatest APBR performances for removing COD and TOC were as high as 98 and 93%, respectively, even though the anaerobic digestibility after adding the different AAP concentrations of 5, 10 and 15 mg L(-1) into brewery wastewater can affect the efficiency of organic matter removal. The average CH4 production decreased from 81 to 72% is counterbalanced by the increased CO2 production from 11 to 20% before and after the injection of AAP, respectively. The empirical kinetic models for substrate utilisation and CH4 production were used to predict that, under unfavourable conditions, the performance of the APBR treatment process is able to remove COD with an efficiency of only 6.8%. PMID:26760229

  14. Combined production and purification of hydrogen from methanol using steam iron process in fixed bed reactor

    NASA Astrophysics Data System (ADS)

    Campo, R.; Durán, P.; Plou, J.; Herguido, J.; Peña, J. A.

    2013-11-01

    A research work is being conducted to study the combined production and purification of hydrogen by means of redox processes departing from biomass fast pyrolysis oils (bio-oils). To achieve that goal, methanol has been used as featured material because it is the most representative compound of the alcoholic fraction of bio-oils. The study has been carried out in a fixed bed reactor where methanol decomposes in H2 and CO when gets in contact with a reactive solid based in an iron oxide at temperatures above 600 °C. During the first stage of the “steam-iron” process, reactive gases reduce the iron oxide to metallic iron. Afterward, in a following step, the previously reduced iron is reoxidized by steam producing a high purity hydrogen stream. Although coke deposition does exist during the reducing stage, this behaves as inert during the reoxidation process. Coke inert role has been corroborated by GC, SEM and TEM techniques, showing that carbon deposits were constituted by ordered structures (carbon nanotubes). The determination of the hydrogen production along successive cycles allowed the evaluation of the effect of temperature and alternating reactive atmospheres on the stability of the solid, as well as the optimum conditions for such purpose.

  15. [Influence of Temperature on the Anaerobic Packed Bed Reactor Performance and Methanogenic Community].

    PubMed

    Xie, Hai-ying; Wang, Xin; Li, Mu-yuan; Yan, Xu-you; Igarashi, Yasuo; Luo, Feng

    2015-11-01

    This study aimed to analyze the effect of temperature on performance and microbial community structure of an anaerobic packed bed reactor (APBR). The temperature was increased step-wise from room temperature (22 degrees C ± 1 degrees C) to psychrophilic (15 degrees C ± 1 degrees C), mesophilic (37 degrees C ± 1 degrees C) and thermophilic (55 degrees C ± 1 degrees C). The results showed that, in the temperature changing process, the higher the temperature of APBR was, the higher COD removal rate and daily gas production were. After temperature changed to psychrophilic, mesophilic and thermophilic, COD removal rate and daily gas production were 25%, 45%, 60% and 2.3 L x d(-1), 4.0 L x d(-1), 8.5 L x d(-1) respectively. However, there was no significant change in biogas composition (-60%). A sudden temperature change caused a simultaneous increase in the concentration of volatile fatty acids (VFA), which had been fluctuating. Using 16S rRNA gene clone library screening, Euryarchaeota was commonly found, including important methanogens: MBT (Methanobacteriales), Mst (Methanosaetaceae) , Msc (Methanosarcinaceae) and MMB (Methanomicrobiales), as well as thermophilic bacteria and few spring Archaea. However, the diversity of methanogenic groups was reduced, especially at mesophilic. The results of quantitative PCR showed that the 16S rRNA gene concentrations of Mst, MMB and Msc were reduced by temperature changes. Although the relative proportion of every kind of methanogen was significantly affected, Mst was the dominant methanogen. PMID:26911011

  16. Ex situ treatment of N-nitrosodimethylamine (NDMA) in groundwater using a fluidized bed reactor.

    PubMed

    Webster, Todd S; Condee, Charles; Hatzinger, Paul B

    2013-02-01

    N-nitrosodimethylamine (NDMA) is a suspected human carcinogen that has traditionally been treated in water using ultraviolet irradiation (UV). The objective of this research was to examine the application of a laboratory-scale fluidized bed reactor (FBR) as an alternative technology for treating NDMA to part-per-trillion (ng/L) concentrations in groundwater. Previous studies have shown that the bacterium Rhodococcus ruber ENV425 is capable of cometabolizing NDMA during growth on propane as a primary substrate in batch culture (Fournier et al., 2009) and in a bench-scale membrane bioreactor (Hatzinger et al., 2011) to low ng/L concentrations. R. ruber ENV425 was inoculated into the FBR during this study. With a hydraulic residence time (HRT) of 20 min, the FBR was found to be an effective means to treat 10-20 μg/L of NDMA to effluent concentrations less than 100 ng/L. When the HRT was increased to 30 min and oxygen and propane addition rates were optimized, the FBR system demonstrated treatment of the NDMA to effluent concentrations of less than 10 ng/L. Short-term shutdowns and the presence of trichloroethene (TCE) at 6 μg/L as a co-contaminant had minimal effect on the treatment of NDMA in the FBR. The data suggest that the FBR technology can be a viable alternative to UV for removing NDMA from groundwater. PMID:23206498

  17. Heavy metal removal by combining anaerobic upflow packed bed reactors with water hyacinth ponds.

    PubMed

    Sekomo, Christian Birame; Kagisha, Vedaste; Rousseau, Diederik; Lens, Piet

    2012-06-01

    The removal of four selected heavy metals (Cu, Cd, Pb and Zn) has been assessed in an upflow anaerobic packed bed reactor filled with porous volcanic rock as an adsorbent and an attachment surface for bacterial growth. Two different feeding regimes were applied using low (5 mg L(-1) of heavy metal each) and high (10 mg L(-1) of heavy metal each) strength wastewater. After a start-up and acclimatization period of 44 days, each regime was operated for a period of 10 days with a hydraulic retention time of one day. Good removal efficiencies of at least 86% were achieved for both the low and high strength wastewater. A subsequent water hyacinth pond with a hydraulic retention time of one day removed an additional 61% Cd, 59% Cu, 49% Pb and 42% Zn, showing its importance as a polishing step. The water hyacinth plant in the post-treatment step accumulated heavy metals mainly in the root system. Overall metal removal efficiencies at the outlet of the integrated system were 98% for Cd, 99% for Cu, 98% for Pb and 84% for Zn. Therefore, the integrated system can be used as an alternative treatment system for metal-polluted wastewater, especially in developing countries.

  18. Investigation into adsorption and photocatalytic degradation of gaseous benzene in an annular fluidized bed photocatalytic reactor.

    PubMed

    Geng, Qijin; Tang, Shankang; Wang, Lintong; Zhang, Yunchen

    2015-01-01

    The adsorption and photocatalytic degradation of gaseous benzene were investigated considering the operating variables and kinetic mechanism using nano-titania agglomerates in an annular fluidized bed photocatalytic reactor (AFBPR) designed. The special adsorption equilibrium constant, adsorption active sites, and apparent reaction rate coefficient of benzene were determined by linear regression analysis at various gas velocities and relative humidities (RH). Based on a series of photocatalytic degradation kinetic equations, the influences of operating variables on degradation efficiency, apparent reaction rate coefficient and half-life were explored. The findings indicated that the operating variables have obviously influenced the adsorption/photocatalytic degradation and corresponding kinetic parameters. In the photocatalytic degradation process, the relationship between photocatalytic degradation efficiency and RH indicated that water molecules have a dual-function which was related to the structure characteristics of benzene. The optimal operating conditions for photocatalytic degradation of gaseous benzene in AFBPR were determined as the fluidization number at 1.9 and RH required related to benzene concentration. This investigation highlights the importance of controlling RH and benzene concentration in order to obtain the desired synergy effect in photocatalytic degradation processes.

  19. A novel fixed-bed reactor design incorporating an electrospun PVA/chitosan nanofiber membrane.

    PubMed

    Esmaeili, Akbar; Beni, Ali Aghababai

    2014-09-15

    In this research, a novel fixed-bed reactor was designed with a nanofiber membrane composed of a polyvinyl alcohol (PVA)/chitosan nanofiber blend prepared using an electrospinning technique. The applied voltage, tip-collector distance, and solution flow rate of the electrospinning process were 18 kV, 14.5 cm, and 0.5 mL h(-1), respectively. Brunauer-Emmett-Teller (BET) theory, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize and analyze the nanofiber membranes. Homogeneous electrospun nanofibers with an average diameter of 99.47 nm and surface area of 214.12 m(2)g(-1) were obtained. Adsorption experiments were carried out in a batch system to investigate the effect of different adsorption parameters such as pH, adsorbent dose, biomass dose, contact time, and temperature. The kinetic data, obtained at the optimal pH of 6, were analyzed by pseudo first-order and pseudo second-order kinetic models. Three isotherm models and thermodynamic parameters (ΔG°, ΔH°, and ΔS°) were applied to describe the equilibrium data of the metal ions adsorbed onto the PVA/chitosan nanofiber membrane.

  20. Fluidized bed reactor for the biological treatment of ion-exchange brine containing perchlorate and nitrate.

    PubMed

    Patel, A; Zuo, G; Lehman, S G; Badruzzaman, M; Clifford, D A; Roberts, D J

    2008-10-01

    The removal of perchlorate and nitrate from contaminated drinking water using regenerable ion-exchange processes produces a high salt brine (3-10% NaCl) laden with high concentrations of perchlorate and nitrate. This bench-scale research describes the operation of acetate-fed granular activated carbon (GAC) based fluidized bed reactors (FBR) for perchlorate-only, and combined nitrate and perchlorate removal from synthetic brine (6% NaCl). The GAC was inoculated with a salt-tolerant culture developed by the authors and used previously in batch systems. An FBR was an effective design for perchlorate reduction and exhibited first-order degradation kinetics with respect to perchlorate concentrations. Nitrate was also removed by the organisms in the column and had no negative effects on the removal of perchlorate using the FBR design. However, at higher concentrations of nitrate the FBR was more difficult to operate due to loss of carbon and biomass from the formation of nitrogen bubbles and the high recycle flow rates needed.

  1. Organic matter removal from saline agricultural drainage wastewater using a moving bed biofilm reactor.

    PubMed

    Ateia, Mohamed; Nasr, Mahmoud; Yoshimura, Chihiro; Fujii, Manabu

    2015-01-01

    We investigated the effect of salinity on the removal of organics and ammonium from agricultural drainage wastewater (ADW) using moving bed biofilm reactors (MBBRs). Under the typical salinity level of ADW (total dissolved solids (TDS) concentration up to 2.5 g·L(-1)), microorganisms were acclimated for 40 days on plastic carriers and a stable slime layer of attached biofilm was formed. Next, six batch mode MBBRs were set up and run under different salinity conditions (0.2-20 g-TDS·L(-1)). The removal efficiency of chemical oxygen demand (COD) and ammonium-nitrogen (NH4-N) in 6 hours decreased from 98 and 68% to 64 and 21% with increasing salt concentrations from 2.5 to 20 g-TDS·L(-1), respectively. In addition, at decreasing salt levels of 0.2 g-TDS·L(-1), both COD removal and nitrification were slightly lowered. Kinetic analysis indicated that the first-order reaction rate constant (k1) and specific substrate utilization rate (U) with respect to the COD removal remained relatively constant (10.9-11.0 d(-1) and 13.1-16.1 g-COD-removed.g-biomass(-1)·d(-1), respectively) at the salinity range of 2.5-5.0 g-TDS·L(-1). In this study, the treated wastewater met the standard criteria of organic concentration for reuse in agricultural purposes, and the system performance remained relatively constant at the salinity range of typical ADW.

  2. Achieving nitritation and anammox enrichment in a single moving-bed biofilm reactor treating reject water.

    PubMed

    Zekker, I; Rikmann, E; Tenno, T; Saluste, A; Tomingas, M; Menert, A; Loorits, L; Lemmiksoo, Vallo; Tenno, T

    2012-01-01

    A biofilm with high nitrifying efficiency was converted into a nitritating and thereafter a nitritating-anammox biofilm in a moving-bed biofilm reactor at 26.5 (+/- 0.5) degrees C by means of a combination of intermittent aeration, low dissolved oxygen concentration, low hydraulic retention time, free ammonia and furthermore, also by elevated HCO3- concentration. Nitrite-oxidizing bacteria (NOB) were more effectively suppressed by an enhanced HCO3- concentration range of 1200-2350 mg/L as opposed to free-ammonia-based process control where NOBs recovered from inhibition; the respective total-nitrogen removal rates were 0.3 kg N/(m3 x d) and 0.2 kg N/(m3 x d). The biofilm modification strategies resulted in a shift in bacterial community as the NOB Nitrobacter spp. were replaced with NOB belonging to the genus Nitrospira spp. and were closely related to Candidatus Nitrospira defluvii. A community of anaerobic ammonium-oxidizing microorganisms -uncultured Planctomycetales bacterium clone P4 (closely related to Candidatus Brocadia fulgida)--was developed.

  3. Microalgal growth in municipal wastewater treated in an anaerobic moving bed biofilm reactor.

    PubMed

    Hultberg, Malin; Olsson, Lars-Erik; Birgersson, Göran; Gustafsson, Susanne; Sievertsson, Bertil

    2016-05-01

    Nutrient removal from the effluent of an anaerobic moving bed biofilm reactor (AnMBBR) treated with microalgae was evaluated. Algal treatment was highly efficient in removal of nutrients and discharge limits were met after 3days. Extending the cultivation time from 3 to 5days resulted in a large increase in biomass, from 233.3±49.3 to 530.0±72.1mgL(-1), despite nutrients in the water being exhausted after 3days (ammonium 0.04mgL(-1), orthophosphate <0.05mgL(-1)). Biomass productivity, lipid content and quality did not differ in microalgal biomass produced in wastewater sampled before the AnMBBR. The longer cultivation time resulted in a slight increase in total lipid concentration and a significant decrease in linolenic acid concentration in all treatments. Differences were observed in chemical oxygen demand, which decreased after algal treatment in wastewater sampled before the AnMBBR whereas it increased after algal treatment in the effluent from the AnMBBR.

  4. Calcium fluoride recovery from fluoride wastewater in a fluidized bed reactor.

    PubMed

    Aldaco, R; Garea, A; Irabien, A

    2007-02-01

    In order to contribute to better resource efficiency and industrial waste management leading to a sustainable production and consumption pattern new processes must be developed, which should be operated in such a way that waste production is reduced or avoided. Fluoride removal by precipitation generates huge amounts of a water rich sludge. Calcium fluoride is not recovered from the waste streams and it is not recycled due to the high water content and the low quality of the sludge. Crystallization process in a fluidized bed reactor (FBR) appears as an alternative technology to the conventional chemical precipitation process. In the crystallization process in a FBR silica sand is usually used as seed material, however silica is a deleterious impurity because it causes losses in the yield of HF and its content should be less than 1%. In this paper, granular calcite has been used as seed material in order to obtain synthetic calcium fluoride. According to the composition (CaF(2)>97%, SiO(2)<1%), the synthetic calcium fluoride from the crystallization process in a FBR is able to be recycled as raw material for the manufacture of hydrofluoric acid leading to a reduction of raw materials consumption. The crystallization process in a FBR to remove fluoride from industrial wastewaters contributes to an environmental friendly production, because it allows to reduce the waste production as well as to increase the recovery of materials.

  5. Organic matter removal from saline agricultural drainage wastewater using a moving bed biofilm reactor.

    PubMed

    Ateia, Mohamed; Nasr, Mahmoud; Yoshimura, Chihiro; Fujii, Manabu

    2015-01-01

    We investigated the effect of salinity on the removal of organics and ammonium from agricultural drainage wastewater (ADW) using moving bed biofilm reactors (MBBRs). Under the typical salinity level of ADW (total dissolved solids (TDS) concentration up to 2.5 g·L(-1)), microorganisms were acclimated for 40 days on plastic carriers and a stable slime layer of attached biofilm was formed. Next, six batch mode MBBRs were set up and run under different salinity conditions (0.2-20 g-TDS·L(-1)). The removal efficiency of chemical oxygen demand (COD) and ammonium-nitrogen (NH4-N) in 6 hours decreased from 98 and 68% to 64 and 21% with increasing salt concentrations from 2.5 to 20 g-TDS·L(-1), respectively. In addition, at decreasing salt levels of 0.2 g-TDS·L(-1), both COD removal and nitrification were slightly lowered. Kinetic analysis indicated that the first-order reaction rate constant (k1) and specific substrate utilization rate (U) with respect to the COD removal remained relatively constant (10.9-11.0 d(-1) and 13.1-16.1 g-COD-removed.g-biomass(-1)·d(-1), respectively) at the salinity range of 2.5-5.0 g-TDS·L(-1). In this study, the treated wastewater met the standard criteria of organic concentration for reuse in agricultural purposes, and the system performance remained relatively constant at the salinity range of typical ADW. PMID:26465302

  6. Kinetics of electrooxidation of landfill leachate in a three-dimensional carbon bed electrochemical reactor.

    PubMed

    Nageswara Rao, Neti; Rohit, Misra; Nitin, Gedam; Parameswaran, P N; Astik, J K

    2009-08-01

    The electrooxidation of high strength leachate from an industrial solid waste landfill site was carried out in a three-dimensional carbon bed electrode reactor (TDR). This paper discusses the kinetics and mechanism of electrooxidation on the basis of time course variation of COD, TOC and TKN (total Kjeldahl nitrogen) from the raw leachate. The batch experiments were run at different applied currents (1-3 A) for a period of 6h. A two-stage pseudo-first order reaction kinetics model was developed based on the initial rapid removal of pollutants (Phase I) followed by slow oxidation kinetics (Phase II). About 60-64% COD was removed within 1h with a rate constant 5.83 x 10(-3) min(-1) in Phase I, which was near 5-7 times greater than that of Phase II (0.81-1.03 x 10(-3)min(-1)). The mineralization efficiency was found to be significant in the range 0.83-0.84. The apparent faradic efficiency and specific energy consumption for COD removal were also estimated. The mechanism of electrooxidation was discussed with the help of adsorption, kinetic and SEM results.

  7. Kinetics of acetaminophen degradation by Fenton oxidation in a fluidized-bed reactor.

    PubMed

    de Luna, Mark Daniel G; Briones, Rowena M; Su, Chia-Chi; Lu, Ming-Chun

    2013-01-01

    Acetaminophen (ACT), an analgesic and antipyretic substance, is one of the most commonly detected pharmaceutical compound in surface waters and wastewaters. In this study, fluidized-bed Fenton (FB-Fenton) was used to decompose ACT into its final degradation products. The 1.45-L cylindrical glass reactor had inlet, outlet and recirculating sections. SiO(2) carrier particles were supported by glass beads with 2-4 mm in diameter. ACT concentration was determined by high performance liquid chromatography (HPLC). During the first 40 min of reaction, a fast initial ACT removal was observed and the "two-stage" ACT degradation conformed to a pseudo reaction kinetics. The effects of ferrous ion dosage and [Fe(2+)]/[H(2)O(2)] (FH ratio) were integrated into the derived pseudo second-order kinetic model. A reaction pathway was proposed based on the intermediates detected through SPME/GC-MS. The aromatic intermediates identified were hydroquinone, benzaldehydes and benzoic acids while the non-aromatic substances include alcohols, ketones, aldehydes and carboxylic acids. Rapid initial ACT degradation rate can be accomplished by high initial ferrous ion concentration and/or low FH ratio.

  8. Impact of fine mesh sieve primary treatment on nitrogen removal in moving bed biofilm reactors.

    PubMed

    Rusten, B; Razafimanantsoa, V A; Andriamiarinjaka, M A; Otis, C L; Sahu, A K; Bilstad, T

    2016-01-01

    The purpose of this project was to investigate the effect of selective particle removal during primary treatment on nitrogen removal in moving bed biofilm reactors (MBBRs). Two small MBBR pilot plants were operated in parallel, where one train treated 2 mm screened municipal wastewater and the other train treated wastewater that had passed through a Salsnes Filter SF1000 rotating belt sieve (RBS) with a 33 µs sieve cloth. The SF1000 was operated without a filter mat on the belt. The tests confirmed that, for the wastewater characteristics at the test plant, Salsnes Filter primary treatment with a 33 µs RBS and no filter mat produced a primary effluent that was close to optimum. Removal of organic matter with the 33 µs sieve had no negative effect on the denitrification process. Nitrification rates improved by 10-15% in the train with 33 µs RBS primary treatment. Mass balance calculations showed that without RBS primary treatment, the oxygen demand in the biological system was 36% higher. Other studies have shown that the sludge produced by RBS primary treatment is beneficial for biogas production and will also significantly improve sludge dewatering of the combined primary and biological sludge.

  9. Recovery of energy and iron from oily sludge pyrolysis in a fluidized bed reactor.

    PubMed

    Qin, Linbo; Han, Jun; He, Xiang; Zhan, Yiqiu; Yu, Fei

    2015-05-01

    In the steel industry, about 0.86 ton of oily sludge is produced for every 1000 tons of rolling steel. Due to the adverse impact on human health and the environment, oily sludge is designated as a hazardous waste in the Resource Conservation and Recovery Act (RCRT). In this paper, the pyrolysis treatment of oily sludge is studied in a fluidized bed reactor at a temperature range of 400-600 °C. During oily sludge pyrolysis, a maximum oil yield of 59.2% and a minimum energy loss of 19.0% are achieved at 500 °C. The energy consumption of treating 1 kg oily sludge is only 2.4-2.9 MJ. At the same time, the energy of produced oil, gas and solid residue are 20.8, 6.32, and 0.83 MJ, respectively. In particular, it is found that the solid residue contains more than 42% iron oxide, which can be used as the raw material for iron production. Thus, the simultaneous recovery of energy and iron from oil sludge by pyrolysis is feasible.

  10. Ethanol production during semi-continuous syngas fermentation in a trickle bed reactor using Clostridium ragsdalei.

    PubMed

    Devarapalli, Mamatha; Atiyeh, Hasan K; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

    2016-06-01

    An efficient syngas fermentation bioreactor provides a mass transfer capability that matches the intrinsic kinetics of the microorganism to obtain high gas conversion efficiency and productivity. In this study, mass transfer and gas utilization efficiencies of a trickle bed reactor during syngas fermentation by Clostridium ragsdalei were evaluated at various gas and liquid flow rates. Fermentations were performed using a syngas mixture of 38% CO, 28.5% CO2, 28.5% H2 and 5% N2, by volume. Results showed that increasing the gas flow rate from 2.3 to 4.6sccm increased the CO uptake rate by 76% and decreased the H2 uptake rate by 51% up to Run R6. Biofilm formation after R6 increased cells activity with over threefold increase in H2 uptake rate. At 1662h, the final ethanol and acetic acid concentrations were 5.7 and 12.3g/L, respectively, at 200ml/min of liquid flow rate and 4.6sccm gas flow rate. PMID:26950756

  11. Typical Application of Sound Field in Wastewater Treatment with Fluidized Bed Photocatalytic Reactor.

    PubMed

    Si, Chong-dian; Zhou, Jing; Gao, Hong-tao; Liu, Guang-jun; Wu, Jian-jun

    2015-04-01

    The effect of a sound field on wastewater treatment with a fluidized bed photocatalytic reactor (FBPR) was investigated. With Alizarin Green (AG) being the sole infectant, the Fe-doped TiO2 catalyst prepared was used as the fluidized media. According to the Langmuir-Hinshelwood model, the photocatalytic degradation follows the pseudo-first-order reaction kinetics with respect to the concentration of AG. Sound field application allowed the fluidization of the fine powder at high liquid flow rates; thus, the mass transfer rate between organic pollutant and particle photocatalyst was enhanced and the efficiency of degradation was increased. As expected, the degradation rate constant increased with increasing sound pressure level, as well as increased with increasing sound frequency ranging from 50 to 100 Hz, then further decreased with increasing sound frequency from 100 to 200 Hz. In addition, Fe doping is also responsible for the enhanced photocurrent response of the Fe-doped TiO2 nanoparticle in FBPR relative to pure TiO2.

  12. Electrical conductivity as a state indicator for the start-up period of anaerobic fixed-bed reactors.

    PubMed

    Robles, A; Latrille, E; Ribes, J; Bernet, N; Steyer, J P

    2016-01-01

    The aim of this work was to analyse the applicability of electrical conductivity sensors for on-line monitoring the start-up period of an anaerobic fixed-bed reactor. The evolution of bicarbonate concentration and methane production rate was analysed. Strong linear relationships between electrical conductivity and both bicarbonate concentration and methane production rate were observed. On-line estimations of the studied parameters were carried out in a new start-up period by applying simple linear regression models, which resulted in a good concordance between both observed and predicted values. Electrical conductivity sensors were therefore identified as an interesting method for monitoring the start-up period of anaerobic fixed-bed reactors due to its reliability, robustness, easy operation, low cost, and minimum maintenance compared with the currently used sensors.

  13. Electrical conductivity as a state indicator for the start-up period of anaerobic fixed-bed reactors.

    PubMed

    Robles, A; Latrille, E; Ribes, J; Bernet, N; Steyer, J P

    2016-01-01

    The aim of this work was to analyse the applicability of electrical conductivity sensors for on-line monitoring the start-up period of an anaerobic fixed-bed reactor. The evolution of bicarbonate concentration and methane production rate was analysed. Strong linear relationships between electrical conductivity and both bicarbonate concentration and methane production rate were observed. On-line estimations of the studied parameters were carried out in a new start-up period by applying simple linear regression models, which resulted in a good concordance between both observed and predicted values. Electrical conductivity sensors were therefore identified as an interesting method for monitoring the start-up period of anaerobic fixed-bed reactors due to its reliability, robustness, easy operation, low cost, and minimum maintenance compared with the currently used sensors. PMID:27148733

  14. The effects of temperatures on the pebble flow in a pebble bed high temperature reactor

    SciTech Connect

    Sen, R. S.; Cogliati, J. J.; Gougar, H. D.

    2012-07-01

    The core of a pebble bed high temperature reactor (PBHTR) moves during operation, a feature which leads to better fuel economy (online refueling with no burnable poisons) and lower fuel stress. The pebbles are loaded at the top and trickle to the bottom of the core after which the burnup of each is measured. The pebbles that are not fully burned are recirculated through the core until the target burnup is achieved. The flow pattern of the pebbles through the core is of importance for core simulations because it couples the burnup distribution to the core temperature and power profiles, especially in cores with two or more radial burnup 'zones '. The pebble velocity profile is a strong function of the core geometry and the friction between the pebbles and the surrounding structures (other pebbles or graphite reflector blocks). The friction coefficient for graphite in a helium environment is inversely related to the temperature. The Thorium High Temperature Reactor (THTR) operated in Germany between 1983 and 1989. It featured a two-zone core, an inner core (IC) and outer core (OC), with different fuel mixtures loaded in each zone. The rate at which the IC was refueled relative to the OC in THTR was designed to be 0.56. During its operation, however, this ratio was measured to be 0.76, suggesting the pebbles in the inner core traveled faster than expected. It has been postulated that the positive feedback effect between inner core temperature, burnup, and pebble flow was underestimated in THTR. Because of the power shape, the center of the core in a typical cylindrical PBHTR operates at a higher temperature than the region next to the side reflector. The friction between pebbles in the IC is lower than that in the OC, perhaps causing a higher relative flow rate and lower average burnup, which in turn yield a higher local power density. Furthermore, the pebbles in the center region have higher velocities than the pebbles next to the side reflector due to the

  15. The preliminary analysis on the steady-state and kinetic features of the molten salt pebble-bed reactor

    SciTech Connect

    Xia, B.; Lu, Y.

    2012-07-01

    A novel design concept of molten salt pebble-bed reactor with an ultra-simplified integral primary circuit called 'Nuclear Hot Spring' has been proposed, featured by horizontal coolant flow in a deep pool pebble-bed reactor, providing 'natural safety' features with natural circulation under full power operation and less expensive primary circuit arrangement. In this work, the steady-state physical properties of the equilibrium state of the molten salt pebble-bed reactor are calculated by using the VSOP code, and the steady-state thermo-hydraulic analysis is carried out based on the approximation of absolutely horizontal flow of the coolant through the core. A new concept of 2-dimensional, both axial and radial, multi-pass on-line fuelling scheme is presented. The result reveals that the radial multi-pass scheme provides more flattened power distribution and safer temperature distribution than the one-pass scheme. A parametric analysis is made corresponding to different pebble diameters, the key parameter of the core resistance and the temperature at the pebble center. It is verified that within a wide range of pebble diameters, the maximum pebble center temperatures are far below the safety limit of the fuel, and the core resistance is considerably less than the buoyant force, indicating that the natural circulation under full power operation is achievable and the ultra-simplified integral primary circuit without any pump is possible. For the kinetic properties, it is verified that the negative temperature coefficient is achieved in sufficient under-moderated condition through the preliminary analysis on the temperature coefficients of fuel, coolant and moderator. The requirement of reactivity compensation at the shutdown stages of the operation period is calculated for the further studies on the reactivity control. The molten salt pebble-bed reactor with horizontal coolant flow can provide enhanced safety and economical features. (authors)

  16. High efficiency chlorine removal from polyvinyl chloride (PVC) pyrolysis with a gas-liquid fluidized bed reactor.

    PubMed

    Yuan, G; Chen, D; Yin, L; Wang, Z; Zhao, L; Wang, J Y

    2014-06-01

    In this research a gas-liquid fluidized bed reactor was developed for removing chlorine (Cl) from polyvinyl chloride (PVC) to favor its pyrolysis treatment. In order to efficiently remove Cl within a limited time before extensive generation of hydrocarbon products, the gas-liquid fluidized bed reactor was running at 280-320 °C, where hot N2 was used as fluidizing gas to fluidize the molten polymer, letting the molten polymer contact well with N2 to release Cl in form of HCl. Experimental results showed that dechlorination efficiency is mainly temperature dependent and 300 °C is a proper reaction temperature for efficient dechlorination within a limited time duration and for prevention of extensive pyrolysis; under this temperature 99.5% of Cl removal efficiency can be obtained within reaction time around 1 min after melting is completed as the flow rate of N2 gas was set around 0.47-0.85 Nm(3) kg(-1) for the molten PVC. Larger N2 flow rate and additives in PVC would enhance HCl release but did not change the final dechlorination efficiency; and excessive N2 flow rate should be avoided for prevention of polymer entrainment. HCl is emitted from PVC granules or scraps at the mean time they started to melt and the melting stage should be taken into consideration when design the gas-liquid fluidized bed reactor for dechlorination.

  17. Integrated detoxification methodology of hazardous phenolic wastewaters in environmentally based trickle-bed reactors: Experimental investigation and CFD simulation.

    PubMed

    Lopes, Rodrigo J G; Almeida, Teresa S A; Quinta-Ferreira, Rosa M

    2011-05-15

    Centralized environmental regulations require the use of efficient detoxification technologies for the secure disposal of hazardous wastewaters. Guided by federal directives, existing plants need reengineering activities and careful analysis to improve their overall effectiveness and to become environmentally friendly. Here, we illustrate the application of an integrated methodology which encompasses the experimental investigation of catalytic wet air oxidation and CFD simulation of trickle-bed reactors. As long as trickle-bed reactors are determined by the flow environment coupled with chemical kinetics, first, on the optimization of prominent numerical solution parameters, the CFD model was validated with experimental data taken from a trickle bed pilot plant specifically designed for the catalytic wet oxidation of phenolic wastewaters. Second, several experimental and computational runs were carried out under unsteady-state operation to evaluate the dynamic performance addressing the TOC concentration and temperature profiles. CFD computations of total organic carbon conversion were found to agree better with experimental data at lower temperatures. Finally, the comparison of test data with simulation results demonstrated that this integrated framework was able to describe the mineralization of organic matter in trickle beds and the validated consequence model can be exploited to promote cleaner remediation technologies of contaminated waters. PMID:21377790

  18. Numerical Analysis of the Dynamics of Two- and Three-Dimensional Fluidized Bed Reactors using an Euler-Lagrange Approach

    SciTech Connect

    Pepiot, P.; Desjardins, O.

    2012-04-01

    Biomass thermochemical conversion, often done in fluidized beds, recently gained a lot of attention due to its potential to efficiently produce renewable liquid fuels. Optimization of reactor design and operating conditions, however, requires a fundamental understanding of bed dynamics. In this work, a numerical framework based on an Euler-Lagrange approach is developed and used to perform and analyze large-scale simulations of two- and three-dimensional periodic fluidized beds. Collisions are handled using a soft-sphere model. An efficient parallel implementation allows one to explicitly track over 30 million particles, which is representative of the number of particles found in lab-scale reactor, therefore demonstrating the capability of Lagrangian approaches to simulate realistic systems at that scale. An on-the-fly bubble identification and tracking algorithm is used to characterize bubble dynamics for inlet velocities up to 9 times the minimum fluidization velocity. Statistics for gas volume fraction, gas and particle velocities, bed expansion, and bubble size and velocity, is compared across the two- and three-dimensional configurations, and comparison with literature data generally shows good agreement. The wide distribution of gas residence times observed in the simulations is linked to the different gas hold-up characteristics of the gas-solid system.

  19. Operational stability of naringinase PVA lens-shaped microparticles in batch stirred reactors and mini packed bed reactors-one step closer to industry.

    PubMed

    Nunes, Mário A P; Rosa, M Emilia; Fernandes, Pedro C B; Ribeiro, Maria H L

    2014-07-01

    The immobilization of naringinase in PVA lens-shaped particles, a cheap and biocompatible hydrogel was shown to provide an effective biocatalyst for naringin hydrolysis, an appealing reaction in the food and pharmaceutical industries. The present work addresses the operational stability and scale-up of the bioconversion system, in various types of reactors, namely shaken microtiter plates (volume ⩽ 2 mL), batch stirred tank reactors (volume <400 mL) and a packed-bed reactor (PBR, 6.8 mL). Consecutive batch runs were performed with the shaken/stirred vessels, with reproducible and encouraging results, related to operational stability. The PBR was used to establish the feasibility for continuous operation, running continuously for 54 days at 45°C. The biocatalyst activity remained constant for 40 days of continuous operation. The averaged specific productivity was 9.07 mmol h(-1) g enzyme(-1) and the half-life of 48 days.

  20. Effect of various sources of organic carbon and high nitrite and nitrate concentrations on the selection of denitrifying bacteria. II. Continuous cultures in packed bed reactors.

    PubMed

    Błaszczyk, M

    1983-01-01

    The effect of different organic compounds, nitrites and nitrates at the concentration of 1,000 mg N/l on the quantitative and strain-specific selection of denitrifying bacteria was determined in anaerobic packed bed reactors. Both the source of carbon and nitrogen form influenced strain specificity and the frequency of occurrence of denitrifying bacteria. The frequency of denitrifying bacteria within packed bed reactor ranged in different media from 11% (glucose and nitrates) to 100% (methanol and ethanol with nitrates). A single species selection was observed in the presence of nitrites within packed bed reactor: Pseudomonas aeruginosa in medium with acetate. Pseudomonas stutzeri in medium with ethanol, Pseudomonas mendocina in medium with methanol and Pseudomonas fluorescens in medium with glucose. When nitrates were present in packed bed reactor, the dominating bacteria were: P. stutzeri in medium with acetate, P. fluorescens in medium with ethanol, Paracoccus denitrificans in medium with methanol and Alcaligenes faecalis in medium with glucose. PMID:6194668

  1. Performance of a pilot-scale packed bed reactor for perchlorate reduction using a sulfur oxidizing bacterial consortium.

    PubMed

    Boles, Amber R; Conneely, Teresa; McKeever, Robert; Nixon, Paul; Nüsslein, Klaus R; Ergas, Sarina J

    2012-03-01

    A novel sulfur-utilizing perchlorate reducing bacterial consortium successfully treated perchlorate (ClO₄⁻) in prior batch and bench-scale packed bed reactor (PBR) studies. This study examined the scale up of this process for treatment of water from a ClO ₄⁻ and RDX contaminated aquifer in Cape Cod Massachusetts. A pilot-scale upflow PBR (∼250-L) was constructed with elemental sulfur and crushed oyster shell packing media. The reactor was inoculated with sulfur oxidizing ClO₄⁻ reducing cultures enriched from a wastewater seed. Sodium sulfite provided a good method of dissolved oxygen removal in batch cultures, but was found to promote the growth of bacteria that carry out sulfur disproportionation and sulfate reduction, which inhibited ClO₄⁻ reduction in the pilot system. After terminating sulfite addition, the PBR successfully removed 96% of the influent ClO₄⁻ in the groundwater at an empty bed contact time (EBCT) of 12 h (effluent ClO₄⁻ of 4.2 µg L(-1)). Simultaneous ClO₄⁻ and NO₃⁻ reduction was observed in the lower half of the reactor before reactions shifted to sulfur disproportionation and sulfate reduction. Analyses of water quality profiles were supported by molecular analysis, which showed distinct groupings of ClO₄⁻ and NO₃⁻ degrading organisms at the inlet of the PBR, while sulfur disproportionation was the primary biological process occurring in the top potion of the reactor. PMID:22015922

  2. Kinetics, mass transfer and hydrodynamics in a packed bed aerobic reactor fed with anaerobically treated domestic sewage.

    PubMed

    Fazolo, A; Pasotto, M B; Foresti, E; Zaiat, M

    2006-10-01

    This study presents an assessment of the kinetic, mass transfer and hydrodynamic parameters of a pilot-scale fixed bed reactor containing immobilized biomass in polyurethane matrices and fed with the effluent of a horizontal-flow fixed bed anaerobic reactor, which was used to treat domestic sewage. It was found that the liquid-solid and intra-particle mass transfer resistances significantly affected the overall oxygen consumption rate and that mechanical agitation could minimize such resistances. The volumetric oxygen transfer coefficient (kLa) values for superficial air velocities between 8.4 cm min(-1) and 57.0 cm min(-1) varied from 20.8 h(-1) to 58.8 h(-1) for tap water, and 16.8 h(-1) to 53.0 h(-1) for the anaerobic pre-treated effluent. The intrinsic oxygen uptake rate was estimated to be 19.9 mgO2 gVSS(-1) h(-1). A first-order kinetic model with residual concentration was considered to adequately represent the COD removal rate, whereas nitrogen conversion was considered to be well represented by a model of pseudo-first-order reaction in series. It was also found that the ammonium conversion to nitrite was the limiting step of the overall nitrogen conversion rate. The hydrodynamic behavior of the reactor was represented by three to four completely mixed reactors in series.

  3. Characterization and modeling the dynamic response of butyrate, acetate, and hydrogen utilization in anaerobic fluidized-bed reactors

    SciTech Connect

    Labib, F.

    1989-01-01

    Two continuous flow anaerobic fluidized-bed reactors were utilized to study the characteristics of an acetate-fed and a butyrate-fed microbial culture at steady state and under transient loadings. A mathematical model of the butyrate-fed reactor was developed and calibrated using the experimental results obtained from this reactor. The model could simulate the reactor response to various transient loadings of butyrate, acetate, and hydrogen and was used to predict its response to loadings with potential to cause process failure. At steady state, the specific COD removal rate in the butyrate-fed reactor was about 7 to 9 gCOD/gVS-d and COD removal was greater than 95%. About 95% of the COD removed was converted to methane. The estimated solids retention time (SRT) in the butyrate-fed reactor was under 10 days. At steady state, methanogenesis from acetate was almost saturated (about 80% of the maximum capacity), the butyrate oxidizing capacity was about three times its utilization rate at steady state, and the methanogenic capacity of the H{sub 2}-utilizers was more than ten times its rate at steady state. Formate was used by this culture, and during its metabolism P{sub CO} increased by over 150 fold, and P{sub H2} increased by 10 fold. The methanogenic culture in the acetate-fed reactor was unable to utilize H{sub 2} or formate, and increases in P{sub H2} inhibited methanogenesis from acetate. Application of the butyrate reactor model to various reactor over-loads showed that the pH drop associated with the VFA accumulation to be a major factor in process failure. The model showed higher SRTs could significantly reduce the VFA accumulation and enhance stability of the process. Acetate overloadings, but not H{sub 2} overloadings, predicted potential washout of acetogens and process failure.

  4. Automated spectral zones selection methodology for diffusion theory data preparation for pebble bed reactor analysis

    NASA Astrophysics Data System (ADS)

    Mphahlele, Ramatsemela

    A methodology is developed for the determination of the optimum spectral zones in Pebble Bed Reactors (PBR). In this work a spectral zone is defined as a zone made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. In other words the spectral zones are the regions over which the few-group diffusion parameters are generated. The identification of spectral boundaries is treated as an optimization problem. It is solved by systematically and simultaneously repositioning all zone boundaries to achieve the global minimum error between the reference transport solution (MCNP) and the diffusion code solution (NEM). The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates error in each zone. An iterative determination of group-dependent bucklings is incorporated into the methodology to properly account for spectral effects of neighboring zones. A preferred energy group structure has also been chosen. This optimization approach with the reference transport solution has proved to be accurate and consistent, however the computational effort required to complete the optimization process is significant. Thus a more practical methodology is also developed for the determination of the spectral zones in PBRs. The reactor physics characteristics of the spectral zones have been studied to understand the nature of the spectral zone boundaries. The practical tool involves the use of spectral indices based on few-group diffusion theory whole core calculations. With this methodology, there is no need to first have a reference transport solution. It is shown that the diffusion-theory coarse group fluxes and the effective multiplication factor computed using zones based on the practical index agrees within a narrow tolerance with those of the reference approach. Therefore the "practical" index

  5. Closed Brayton Cycle power system with a high temperature pellet bed reactor heat source for NEP applications

    NASA Astrophysics Data System (ADS)

    Juhasz, Albert J.; El-Genk, Mohamed S.; Harper, William B., Jr.

    1992-10-01

    Capitalizing on past and future development of high temperature gas reactor (HTGR) technology, a low mass 15 MWe closed gas turbine cycle power system using a pellet bed reactor heating helium working fluid is proposed for Nuclear Electric Propulsion (NEP) applications. Although the design of this directly coupled system architecture, comprising the reactor/power system/space radiator subsystems, is presented in conceptual form, sufficient detail is included to permit an assessment of overall system performance and mass. Furthermore, an attempt is made to show how tailoring of the main subsystem design characteristics can be utilized to achieve synergistic system level advantages that can lead to improved reliability and enhanced system life while reducing the number of parasitic load driven peripheral subsystems.

  6. Closed Brayton Cycle power system with a high temperature pellet bed reactor heat source for NEP applications

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.; El-Genk, Mohamed S.; Harper, William B., Jr.

    1992-01-01

    Capitalizing on past and future development of high temperature gas reactor (HTGR) technology, a low mass 15 MWe closed gas turbine cycle power system using a pellet bed reactor heating helium working fluid is proposed for Nuclear Electric Propulsion (NEP) applications. Although the design of this directly coupled system architecture, comprising the reactor/power system/space radiator subsystems, is presented in conceptual form, sufficient detail is included to permit an assessment of overall system performance and mass. Furthermore, an attempt is made to show how tailoring of the main subsystem design characteristics can be utilized to achieve synergistic system level advantages that can lead to improved reliability and enhanced system life while reducing the number of parasitic load driven peripheral subsystems.

  7. Prediction of moving bed biofilm reactor (MBBR) performance for the treatment of aniline using artificial neural networks (ANN).

    PubMed

    Delnavaz, M; Ayati, B; Ganjidoust, H

    2010-07-15

    In this study, the results of 1-year efficiency forecasting using artificial neural networks (ANN) models of a moving bed biofilm reactor (MBBR) for a toxic and hard biodegradable aniline removal were investigated. The reactor was operated in an aerobic batch and continuous condition with 50% by volume which was filled with light expanded clay aggregate (LECA) as carrier. Efficiency evaluation of the reactors was obtained at different retention time (RT) of 8, 24, 48 and 72 h with an influent COD from 100 to 4000 mg/L. Exploratory data analysis was used to detect relationships between the data and dependent evaluated one. The appropriate architecture of the neural network models was determined using several steps of training and testing of the models. The ANN-based models were found to provide an efficient and a robust tool in predicting MBBR performance for treating aromatic amine compounds. PMID:20399558

  8. Nitrate reduction by organotrophic Anammox bacteria in a nitritation/anammox granular sludge and a moving bed biofilm reactor.

    PubMed

    Winkler, Mari K H; Yang, Jingjing; Kleerebezem, Robbert; Plaza, Elzbieta; Trela, Jozef; Hultman, Bengt; van Loosdrecht, Mark C M

    2012-06-01

    The effects of volatile fatty acids (VFAs) on nitrogen removal and microbial community structure in nitritation/anammox process were compared within a granular sludge reactor and a moving bed biofilm reactor. Nitrate productions in both systems were lower by 40-68% in comparison with expected nitrate production. Expected sludge production on VFAs was estimated to be 67-77% higher if heterotrophs were the main acetate degraders suggesting that Anammox bacteria used its organotrophic capability and successfully competed with general heterotrophs for organic carbon, which led to a reduced sludge production. FISH measurements showed a population consisting of mainly Anammox and AOB in both reactors and oxygen uptake rate (OUR) tests also confirmed that flocculent biomass consisted of a minor proportion of heterotrophs with a large proportion of AOBs. The dominant Anammox bacterium was Candidatus "Brocadia fulgida" with a minor fraction of Candidatus "Anammoxoglobus propionicus", both known to be capable of oxidizing VFAs.

  9. A comparison of mass transfer coefficients between trickle-bed, hollow fiber membrane and stirred tank reactors.

    PubMed

    Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

    2013-04-01

    Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed.

  10. A comparison of mass transfer coefficients between trickle-bed, hollow fiber membrane and stirred tank reactors.

    PubMed

    Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

    2013-04-01

    Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed. PMID:23434811

  11. Optimizing and modelling nitrogen removal in a new configuration of the moving-bed biofilm reactor process.

    PubMed

    Larrea, L; Albizuri, J; Abad, A; Larrea, A; Zalakain, G

    2007-01-01

    A new configuration of the moving-bed biofilm reactor process with pre-denitrification and nitrification was investigated in a pilot plant, which is fed with urban raw wastewater, the primary settler is located between the anoxic and the aerobic reactors, and primary sludge is recycled to the anoxic reactor as a hybrid pre-denitrification. The carriers used in the experiments are made of high-density polyethylene, with a diameter of 10 mm and a specific surface area of 400 m(2)/m(3). The new process was compared with conventional pre-denitrification-nitrification using in-series reactors fed with settled wastewater. The new configuration achieved an increase of 45% for the denitrification rate and of 30% for the nitrification rate when compared with conventional configuration. These results were analysed in light of the calibration study of the mixed-culture biofilm (MCB) model and simulations in AQUASIM 2.1 platform. Regarding denitrification, the high values obtained in the new configuration were attributed to a higher removal of the slowly biodegradable substrate (Xs) in the anoxic reactor due to the use of raw wastewater and sludge recycle. Accordingly, the amounts of heterotrophic biomass (XH) and Xs obtained in simulations were higher in both the biofilm and the bulk liquid. Regarding nitrification, the higher values were attributed to a lower removal of Xs in the aerobic reactors and accordingly, a lower accumulation of heterotrophic biomass in the biofilm was found in the simulations. PMID:17547001

  12. Behavior of an Up-flow Anaerobic Sludge Bed (UASB) reactor at extreme salinity.

    PubMed

    Gomec, C Y; Gonuldinc, S; Eldem, N; Ozturk, I

    2005-01-01

    High salinity is one of the most well known inhibitors and salt concentrations above 1% are reported as highly saline. Salt may be found in the main collectors of municipal sewer systems which carry the risk of seawater infiltration and where domestic wastewaters are treated with landfill leachates such cases in Istanbul. Discharging of leachates into sewerage would also result in additional ammonium loads in Municipal Treatment Plants (MTPs). In this study, synthetic wastewater was fed to a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor operated at a constant hydraulic retention time (HRT) of 1 day. The salt concentration was increased artificially whereas the ammonium concentration was fixed at 1000 mg/l throughout the study. Results indicated no significant inhibition up to 2% salinity + 1000 mg/l NH4 and TOC removals could reach up to 88%. Besides, effective total biogas productions having methane content of 84% could be achieved. It is obvious that anaerobic microorganisms (especially methanogens) could well adapt to high salinity ratios. No inhibition at high ammonium concentration might have been attributed to the fact that the pH in the system was not high enough for the formation of free ammonia. Investigation of the combined effect of high salinity and ammonium was carried on by increasing the salinity to 3% in the study. Results indicated that TOC removals decreased to around 56% and 3% salinity caused . a sharp decrease both in organic material removal and total biogas production. Thus the critical salinity level was determined as 3% for the methanogens in the mesophilic anaerobic digesters. PMID:16114624

  13. Accelerating effect of hydroxylamine and hydrazine on nitrogen removal rate in moving bed biofilm reactor.

    PubMed

    Zekker, Ivar; Kroon, Kristel; Rikmann, Ergo; Tenno, Toomas; Tomingas, Martin; Vabamäe, Priit; Vlaeminck, Siegfried E; Tenno, Taavo

    2012-09-01

    In biological nitrogen removal, application of the autotrophic anammox process is gaining ground worldwide. Although this field has been widely researched in last years, some aspects as the accelerating effect of putative intermediates (mainly N₂H₄ and NH₂OH) need more specific investigation. In the current study, experiments in a moving bed biofilm reactor (MBBR) and batch tests were performed to evaluate the optimum concentrations of anammox process intermediates that accelerate the autotrophic nitrogen removal and mitigate a decrease in the anammox bacteria activity using anammox (anaerobic ammonium oxidation) biomass enriched on ring-shaped biofilm carriers. Anammox biomass was previously grown on blank biofilm carriers for 450 days at moderate temperature 26.0 (±0.5) °C by using sludge reject water as seeding material. FISH analysis revealed that anammox microorganisms were located in clusters in the biofilm. With addition of 1.27 and 1.31 mg N L⁻¹ of each NH₂OH and N₂H₄, respectively, into the MBBR total nitrogen (TN) removal efficiency was rapidly restored after inhibitions by NO₂⁻. Various combinations of N₂H₄, NH₂OH, NH₄⁺, and NO₂⁻ were used as batch substrates. The highest total nitrogen (TN) removal rate with the optimum N₂H₄ concentration (4.38 mg N L⁻¹) present in these batches was 5.43 mg N g⁻¹ TSS h⁻¹, whereas equimolar concentrations of N₂H₄ and NH₂OH added together showed lower TN removal rates. Intermediates could be applied in practice to contribute to the recovery of inhibition-damaged wastewater treatment facilities using anammox technology.

  14. Behavior of an Up-flow Anaerobic Sludge Bed (UASB) reactor at extreme salinity.

    PubMed

    Gomec, C Y; Gonuldinc, S; Eldem, N; Ozturk, I

    2005-01-01

    High salinity is one of the most well known inhibitors and salt concentrations above 1% are reported as highly saline. Salt may be found in the main collectors of municipal sewer systems which carry the risk of seawater infiltration and where domestic wastewaters are treated with landfill leachates such cases in Istanbul. Discharging of leachates into sewerage would also result in additional ammonium loads in Municipal Treatment Plants (MTPs). In this study, synthetic wastewater was fed to a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor operated at a constant hydraulic retention time (HRT) of 1 day. The salt concentration was increased artificially whereas the ammonium concentration was fixed at 1000 mg/l throughout the study. Results indicated no significant inhibition up to 2% salinity + 1000 mg/l NH4 and TOC removals could reach up to 88%. Besides, effective total biogas productions having methane content of 84% could be achieved. It is obvious that anaerobic microorganisms (especially methanogens) could well adapt to high salinity ratios. No inhibition at high ammonium concentration might have been attributed to the fact that the pH in the system was not high enough for the formation of free ammonia. Investigation of the combined effect of high salinity and ammonium was carried on by increasing the salinity to 3% in the study. Results indicated that TOC removals decreased to around 56% and 3% salinity caused . a sharp decrease both in organic material removal and total biogas production. Thus the critical salinity level was determined as 3% for the methanogens in the mesophilic anaerobic digesters.

  15. Nitrogen and carbon removal efficiency of a polyvinyl alcohol gel based moving bed biofilm reactor system.

    PubMed

    Gani, Khalid Muzamil; Singh, Jasdeep; Singh, Nitin Kumar; Ali, Muntjeer; Rose, Vipin; Kazmi, A A

    2016-01-01

    In this study, the effectiveness of polyvinyl alcohol (PVA) gel beads in treating domestic wastewater was investigated: a moving bed biofilm reactor (MBBR) configuration (oxic-anoxic and oxic) with 10% filling fraction of biomass carriers was operated in a continuously fed regime at temperatures of 25, 20, 15 and 6 °C with hydraulic retention times (HRTs) of 32 h, 18 h, 12 h and 9 h, respectively. Influent loadings were in the range of 0.22-1.22 kg N m(-3) d(-1) (total nitrogen (TN)), 1.48-7.82 kg chemical oxygen demand (COD) m(-3) d(-1) (organic) and 0.12-0.89 kg NH4(+)-N m(-3)d(-1) (ammonia nitrogen). MBBR performance resulted in the maximum TN removal rate of 1.22 kg N m(-3) d(-1) when the temperature and HRT were 6 °C and 9 h, respectively. The carbon removal rate at this temperature and HRT was 6.82 kg COD m(-3) d(-1). Ammonium removal rates ranged from 0.13 to 0.75 kg NH4(+)-N m(-3) d(-1) during the study. Total phosphorus and suspended solid removal efficiency ranged from 84 to 98% and 85 to 94% at an influent concentration of 3.3-7.1 mg/L and 74-356 mg/L, respectively. The sludge wasted from the MBBR exhibited light weight features characterized by sludge volume index value of 185 mL/g. Experimental data obtained can be useful in further developing the concept of PVA gel based wastewater treatment systems.

  16. Microbial community composition and dynamics of moving bed biofilm reactor systems treating municipal sewage.

    PubMed

    Biswas, Kristi; Turner, Susan J

    2012-02-01

    Moving bed biofilm reactor (MBBR) systems are increasingly used for municipal and industrial wastewater treatment, yet in contrast to activated sludge (AS) systems, little is known about their constituent microbial communities. This study investigated the community composition of two municipal MBBR wastewater treatment plants (WWTPs) in Wellington, New Zealand. Monthly samples comprising biofilm and suspended biomass were collected over a 12-month period. Bacterial and archaeal community composition was determined using a full-cycle community approach, including analysis of 16S rRNA gene libraries, fluorescence in situ hybridization (FISH) and automated ribosomal intergenic spacer analysis (ARISA). Differences in microbial community structure and abundance were observed between the two WWTPs and between biofilm and suspended biomass. Biofilms from both plants were dominated by Clostridia and sulfate-reducing members of the Deltaproteobacteria (SRBs). FISH analyses indicated morphological differences in the Deltaproteobacteria detected at the two plants and also revealed distinctive clustering between SRBs and members of the Methanosarcinales, which were the only Archaea detected and were present in low abundance (<5%). Biovolume estimates of the SRBs were higher in biofilm samples from one of the WWTPs which receives both domestic and industrial waste and is influenced by seawater infiltration. The suspended communities from both plants were diverse and dominated by aerobic members of the Gammaproteobacteria and Betaproteobacteria. This study represents the first detailed analysis of microbial communities in full-scale MBBR systems and indicates that this process selects for distinctive biofilm and planktonic communities, both of which differ from those found in conventional AS systems.

  17. Polyhydroxyalkanoate biosynthesis from paper mill wastewater treated by a moving bed biofilm reactor.

    PubMed

    Jarpa, Mayra; Pozo, Guillermo; Baeza, Rocío; Martínez, Miguel; Vidal, Gladys

    2012-01-01

    Polyhydroxyalkanoate (PHA) biosynthesis in paper mill wastewater treated by a Moving Bed Biofilm Reactor (MBBR) was evaluated. A MBBR was operated during 300 d. The increasing effect of the Organic Load Rate (OLR) from 0.13 kg BOD(5)/m(3)·d to 2.99 kg BOD(5)/m(3)·d and the influence of two relationship of BOD(5:) N: P (100: 5: 1 and 100: 1: 0.3) on the PHA biosynthesis were evaluated. With an OLR of 0.13 kg BOD(5)/m(3)·d, the maximum organic matter removal measure as Biochemical Oxygen Demand (BOD(5)) was 98.7% for a BOD(5:) N: P relationship of 100: 5: 1. Meanwhile for BOD(5): N: P relationship of 100: 1: 0.3, the maximum efficiency was 87.2% (OLR: 2.99 kg BOD(5)/m(3)·d). The behaviour of the Chemical Oxygen Demand (COD) and total phenolic compound removal efficiencies were below 65.0% and 41.0%, respectively. PHA biosynthesis was measured as a percentage of cells that accumulate PHA, where the maximum percentage was 85.1% and 78.7% when MBBR was operated under a BOD(5): N: P relationship of 100: 5: 1 and 100: 1: 0.3, respectively. Finally, the PHA yields in this study were estimated to range between 0.11 to 0.72 mg PHA/mg VSS and 0.06 to 0.15 mg PHA/mg COD. PMID:22871002

  18. Microbial community composition and dynamics of moving bed biofilm reactor systems treating municipal sewage.

    PubMed

    Biswas, Kristi; Turner, Susan J

    2012-02-01

    Moving bed biofilm reactor (MBBR) systems are increasingly used for municipal and industrial wastewater treatment, yet in contrast to activated sludge (AS) systems, little is known about their constituent microbial communities. This study investigated the community composition of two municipal MBBR wastewater treatment plants (WWTPs) in Wellington, New Zealand. Monthly samples comprising biofilm and suspended biomass were collected over a 12-month period. Bacterial and archaeal community composition was determined using a full-cycle community approach, including analysis of 16S rRNA gene libraries, fluorescence in situ hybridization (FISH) and automated ribosomal intergenic spacer analysis (ARISA). Differences in microbial community structure and abundance were observed between the two WWTPs and between biofilm and suspended biomass. Biofilms from both plants were dominated by Clostridia and sulfate-reducing members of the Deltaproteobacteria (SRBs). FISH analyses indicated morphological differences in the Deltaproteobacteria detected at the two plants and also revealed distinctive clustering between SRBs and members of the Methanosarcinales, which were the only Archaea detected and were present in low abundance (<5%). Biovolume estimates of the SRBs were higher in biofilm samples from one of the WWTPs which receives both domestic and industrial waste and is influenced by seawater infiltration. The suspended communities from both plants were diverse and dominated by aerobic members of the Gammaproteobacteria and Betaproteobacteria. This study represents the first detailed analysis of microbial communities in full-scale MBBR systems and indicates that this process selects for distinctive biofilm and planktonic communities, both of which differ from those found in conventional AS systems. PMID:22138984

  19. Nitrogen and carbon removal efficiency of a polyvinyl alcohol gel based moving bed biofilm reactor system.

    PubMed

    Gani, Khalid Muzamil; Singh, Jasdeep; Singh, Nitin Kumar; Ali, Muntjeer; Rose, Vipin; Kazmi, A A

    2016-01-01

    In this study, the effectiveness of polyvinyl alcohol (PVA) gel beads in treating domestic wastewater was investigated: a moving bed biofilm reactor (MBBR) configuration (oxic-anoxic and oxic) with 10% filling fraction of biomass carriers was operated in a continuously fed regime at temperatures of 25, 20, 15 and 6 °C with hydraulic retention times (HRTs) of 32 h, 18 h, 12 h and 9 h, respectively. Influent loadings were in the range of 0.22-1.22 kg N m(-3) d(-1) (total nitrogen (TN)), 1.48-7.82 kg chemical oxygen demand (COD) m(-3) d(-1) (organic) and 0.12-0.89 kg NH4(+)-N m(-3)d(-1) (ammonia nitrogen). MBBR performance resulted in the maximum TN removal rate of 1.22 kg N m(-3) d(-1) when the temperature and HRT were 6 °C and 9 h, respectively. The carbon removal rate at this temperature and HRT was 6.82 kg COD m(-3) d(-1). Ammonium removal rates ranged from 0.13 to 0.75 kg NH4(+)-N m(-3) d(-1) during the study. Total phosphorus and suspended solid removal efficiency ranged from 84 to 98% and 85 to 94% at an influent concentration of 3.3-7.1 mg/L and 74-356 mg/L, respectively. The sludge wasted from the MBBR exhibited light weight features characterized by sludge volume index value of 185 mL/g. Experimental data obtained can be useful in further developing the concept of PVA gel based wastewater treatment systems. PMID:27054722

  20. Effect of HCO3- concentration on anammox nitrogen removal rate in a moving bed biofilm reactor.

    PubMed

    Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Vabamäe, Priit; Kroon, Kristel; Loorits, Liis; Saluste, Alar; Tenno, Taavo

    2012-01-01

    Anammox biomass enriched in a moving bed biofilm reactor (MBBR) fed by actual sewage sludge reject water and synthetically added NO2- was used to study the total nitrogen (TN) removal rate of the anammox process depending on bicarbonate (HCO3-) concentration. MBBR performance resulted in the maximum TN removal rate of 1100 g N m(-3) d(-1) when the optimum HCO3- concentration (910 mg L(-1)) was used. The average reaction ratio of NO2- removal, NO3- production and NH4+ removal were 1.18/0.20/1. When the HCO3- concentration was increased to 1760mg L(-1) the TN removal rate diminished to 270 g N m(-3) d(-1). The process recovered from bicarbonate inhibition within 1 week. The batch tests performed with biomass taken from the MBBR showed that for the HCO3- concentration of 615 mg L(-1) the TN removal rate was 3.3 mg N L(-1) h(-1), whereas for both lower (120 mg L(-1)) and higher (5750 mg L(-1)) HCO3- concentrations the TN removal rates were 2.3 (+/- 0.15) and 1.6 (+/- 0.12) mg N L(-1) d(-1), respectively. PCR and DGGE analyses resulted in the detection of uncultured Planctomycetales bacterium clone P4 and, surprisingly, low-oxygen-tolerant aerobic ammonia oxidizers. The ability of anammox bacteria for mixotrophy was established by diminished amounts of nitrate produced when comparing the experiments with an organic carbon source and an inorganic carbon source.

  1. Polyhydroxyalkanoate biosynthesis from paper mill wastewater treated by a moving bed biofilm reactor.

    PubMed

    Jarpa, Mayra; Pozo, Guillermo; Baeza, Rocío; Martínez, Miguel; Vidal, Gladys

    2012-01-01

    Polyhydroxyalkanoate (PHA) biosynthesis in paper mill wastewater treated by a Moving Bed Biofilm Reactor (MBBR) was evaluated. A MBBR was operated during 300 d. The increasing effect of the Organic Load Rate (OLR) from 0.13 kg BOD(5)/m(3)·d to 2.99 kg BOD(5)/m(3)·d and the influence of two relationship of BOD(5:) N: P (100: 5: 1 and 100: 1: 0.3) on the PHA biosynthesis were evaluated. With an OLR of 0.13 kg BOD(5)/m(3)·d, the maximum organic matter removal measure as Biochemical Oxygen Demand (BOD(5)) was 98.7% for a BOD(5:) N: P relationship of 100: 5: 1. Meanwhile for BOD(5): N: P relationship of 100: 1: 0.3, the maximum efficiency was 87.2% (OLR: 2.99 kg BOD(5)/m(3)·d). The behaviour of the Chemical Oxygen Demand (COD) and total phenolic compound removal efficiencies were below 65.0% and 41.0%, respectively. PHA biosynthesis was measured as a percentage of cells that accumulate PHA, where the maximum percentage was 85.1% and 78.7% when MBBR was operated under a BOD(5): N: P relationship of 100: 5: 1 and 100: 1: 0.3, respectively. Finally, the PHA yields in this study were estimated to range between 0.11 to 0.72 mg PHA/mg VSS and 0.06 to 0.15 mg PHA/mg COD.

  2. Microbial Community Composition and Dynamics of Moving Bed Biofilm Reactor Systems Treating Municipal Sewage

    PubMed Central

    Turner, Susan J.

    2012-01-01

    Moving bed biofilm reactor (MBBR) systems are increasingly used for municipal and industrial wastewater treatment, yet in contrast to activated sludge (AS) systems, little is known about their constituent microbial communities. This study investigated the community composition of two municipal MBBR wastewater treatment plants (WWTPs) in Wellington, New Zealand. Monthly samples comprising biofilm and suspended biomass were collected over a 12-month period. Bacterial and archaeal community composition was determined using a full-cycle community approach, including analysis of 16S rRNA gene libraries, fluorescence in situ hybridization (FISH) and automated ribosomal intergenic spacer analysis (ARISA). Differences in microbial community structure and abundance were observed between the two WWTPs and between biofilm and suspended biomass. Biofilms from both plants were dominated by Clostridia and sulfate-reducing members of the Deltaproteobacteria (SRBs). FISH analyses indicated morphological differences in the Deltaproteobacteria detected at the two plants and also revealed distinctive clustering between SRBs and members of the Methanosarcinales, which were the only Archaea detected and were present in low abundance (<5%). Biovolume estimates of the SRBs were higher in biofilm samples from one of the WWTPs which receives both domestic and industrial waste and is influenced by seawater infiltration. The suspended communities from both plants were diverse and dominated by aerobic members of the Gammaproteobacteria and Betaproteobacteria. This study represents the first detailed analysis of microbial communities in full-scale MBBR systems and indicates that this process selects for distinctive biofilm and planktonic communities, both of which differ from those found in conventional AS systems. PMID:22138984

  3. Final Report on Utilization of TRU TRISO Fuel as Applied to HTR Systems Part I: Pebble Bed Reactors

    SciTech Connect

    Brian Boer; Abderrafi M. Ougouag

    2011-03-01

    The Deep-Burn (DB) concept [ ] focuses on the destruction of transuranic nuclides from used light water reactor (LWR) fuel. These transuranic nuclides are incorporated into tri-isotopic (TRISO) coated fuel particles and used in gas-cooled reactors with the aim of a fractional fuel burnup of 60 to 70% in fissions per initial metal atom (FIMA). This high performance is expected through the use of multiple recirculation passes of the fuel in pebble form without any physical or chemical changes between passes. In particular, the concept does not call for reprocessing of the fuel between passes. In principle, the DB pebble bed concept employs the same reactor designs as the presently envisioned low-enriched uranium core designs, such as the 400 MWth Pebble Bed Modular Reactor (PBMR-400) [ ]. Although it has been shown in the previous Fiscal Year (FY) (2009) that a PuO2 fueled pebble bed reactor concept is viable, achieving a high fuel burnup while remaining within safety-imposed prescribed operational limits for fuel temperature, power peaking, and temperature reactivity feedback coefficients for the entire temperature range, is challenging. The presence of the isotopes 239Pu, 240Pu, and 241Pu that have resonances in the thermal energy range significantly modifies the neutron thermal energy spectrum as compared to a standard, UO2-fueled core. Therefore, the DB pebble bed core exhibits a relatively hard neutron energy spectrum. However, regions within the pebble bed that are near the graphite reflectors experience a locally softer spectrum. This can lead to power and temperature peaking in these regions. Furthermore, a shift of the thermal energy spectrum with increasing temperature can lead to increased absorption in the resonances of the fissile Pu isotopes. This can lead to a positive temperature reactivity coefficient for the graphite moderator under certain operating conditions. Regarding the coated particle performance, the FY 2009 investigations showed that no

  4. Cold test with a benchtop set-up for fluidized bed reactor using quartz sand to simulate gasification of coal cokes by concentrated solar radiation

    NASA Astrophysics Data System (ADS)

    Gokon, Nobuyuki; Tanabe, Tomoaki; Shimizu, Tadaaki; Kodama, Tatsuya

    2016-05-01

    The impacts of internal circulation of a mixture of coal-coke particles and quartz sand on the fluidization state in a fluidized bed reactor are investigated by a cold test with a benchtop set-up in order to design 10-30 kWth scale prototype windowed fluidized-bed reactor. Firstly, a basic relationship between pressure loss of inlet gas and gas velocity was experimentally examined using quartz sand with different particle sizes by a small-scale quartz tube with a distributor at ambient pressure and temperature. Based on the results, an appropriate particle range of quartz sand and layer height/layer diameter ratio (L/D ratio) was determined for a design of the fluidized bed reactor. Secondly, a windowed reactor mock-up was designed and fabricated for solar coke gasification using quartz sand as a bed material. The pressure loss between the inlet and outlet gases was examined, and descending cokes and sand particles on the sidewall of the reactor was observed in the reactor mock-up. The moving velocity and distance of descending particles/sands from the top to bottom of fluidized bed were measured by the visual observation of the colored tracer particles on outside wall of the reactor.

  5. Two-stage anaerobic digestion of tomato, cucumber, common reed and grass silage in leach-bed reactors and upflow anaerobic sludge blanket reactors.

    PubMed

    Jagadabhi, Padma Shanthi; Kaparaju, Prasad; Rintala, Jukka

    2011-04-01

    Anaerobic digestion of tomato, cucumber, common reed and grass silage was studied in four separate two-stage reactor configuration consisting of leach bed reactor (LBR) and upflow anaerobic sludge blanket reactor (UASB). LBR studies showed that COD solubilization for cucumber and grass silage was higher (50%) than tomato (35%) and common reed (15%). Results also showed that 31-39% of initial TKN present in tomato and cucumber was solubilized in the leachates and 47-54% of the solubilized TKN was converted to NH(4)-N. The corresponding values for common reed and grass silage were 38-50% and 18-36%, respectively. Biomethanation of the leachates in UASB reactors resulted in methane yields of 0.03-0.14 m(3) CH(4) kg(-1)VS(fed) for the studied crop materials. Thus, high COD solubilization, high nitrogen mineralization and solubilization rates were feasible during anaerobic digestion of lignocellulosic materials in a two-stage LBR-UASB reactor system.

  6. Two-stage anaerobic digestion of tomato, cucumber, common reed and grass silage in leach-bed reactors and upflow anaerobic sludge blanket reactors.

    PubMed

    Jagadabhi, Padma Shanthi; Kaparaju, Prasad; Rintala, Jukka

    2011-04-01

    Anaerobic digestion of tomato, cucumber, common reed and grass silage was studied in four separate two-stage reactor configuration consisting of leach bed reactor (LBR) and upflow anaerobic sludge blanket reactor (UASB). LBR studies showed that COD solubilization for cucumber and grass silage was higher (50%) than tomato (35%) and common reed (15%). Results also showed that 31-39% of initial TKN present in tomato and cucumber was solubilized in the leachates and 47-54% of the solubilized TKN was converted to NH(4)-N. The corresponding values for common reed and grass silage were 38-50% and 18-36%, respectively. Biomethanation of the leachates in UASB reactors resulted in methane yields of 0.03-0.14 m(3) CH(4) kg(-1)VS(fed) for the studied crop materials. Thus, high COD solubilization, high nitrogen mineralization and solubilization rates were feasible during anaerobic digestion of lignocellulosic materials in a two-stage LBR-UASB reactor system. PMID:21316953

  7. Design of Complex Systems to Achieve Passive Safety: Natural Circulation Cooling of Liquid Salt Pebble Bed Reactors

    NASA Astrophysics Data System (ADS)

    Scarlat, Raluca Olga

    This dissertation treats system design, modeling of transient system response, and characterization of individual phenomena and demonstrates a framework for integration of these three activities early in the design process of a complex engineered system. A system analysis framework for prioritization of experiments, modeling, and development of detailed design is proposed. Two fundamental topics in thermal-hydraulics are discussed, which illustrate the integration of modeling and experimentation with nuclear reactor design and safety analysis: thermal-hydraulic modeling of heat generating pebble bed cores, and scaled experiments for natural circulation heat removal with Boussinesq liquids. The case studies used in this dissertation are derived from the design and safety analysis of a pebble bed fluoride salt cooled high temperature nuclear reactor (PB-FHR), currently under development in the United States at the university and national laboratories level. In the context of the phenomena identification and ranking table (PIRT) methodology, new tools and approaches are proposed and demonstrated here, which are specifically relevant to technology in the early stages of development, and to analysis of passive safety features. A system decomposition approach is proposed. Definition of system functional requirements complements identification and compilation of the current knowledge base for the behavior of the system. Two new graphical tools are developed for ranking of phenomena importance: a phenomena ranking map, and a phenomena identification and ranking matrix (PIRM). The functional requirements established through this methodology were used for the design and optimization of the reactor core, and for the transient analysis and design of the passive natural circulation driven decay heat removal system for the PB-FHR. A numerical modeling approach for heat-generating porous media, with multi-dimensional fluid flow is presented. The application of this modeling

  8. Removal of ammonium via simultaneous nitrification-denitrification nitrite-shortcut in a single packed-bed batch reactor.

    PubMed

    Daniel, Leonidia Maria Castro; Pozzi, Eloísa; Foresti, Eugenio; Chinalia, Fabio Alexandre

    2009-02-01

    A polyurethane packed-bed-biofilm sequential batch reactor was fed with synthetic substrate simulating the composition of UASB reactor effluents. Two distinct ammonia nitrogen concentrations (125 and 250 mg l(-1)) were supplied during two sequential long-term experiments of 160 days each (320 total). Cycles of 24h under intermittent aeration for periods of 1h were applied, and ethanol was added as a carbon source at the beginning of each anoxic period. Nitrite was the main oxidized nitrogen compound which accumulated only during the aerated phases of the batch cycle. A consistent decrease of nitrite concentration started always immediately after the interruption of oxygen supply and addition of the electron donor. Removal to below detection limits of all nitrogen soluble forms was always observed at the end of the 24h cycles for both initial concentrations. Polyurethane packed-bed matrices and ethanol amendments conferred high process stability. Microbial investigation by cloning suggested that nitrification was carried out by Nitrosomonas-like species whereas denitrification was mediated by unclassified species commonly observed in denitrifying environments. The packed-bed batch bioreactor favored the simultaneous colonization of distinct microbial groups within the immobilized microbial biomass. The biofilm was capable of actively oxidizing ammonium and denitrification at high ratios in intermittent intervals within 24h cycles. PMID:18793833

  9. The impact of influent total ammonium nitrogen concentration on nitrite-oxidizing bacteria inhibition in moving bed biofilm reactor.

    PubMed

    Kouba, Vojtech; Catrysse, Michael; Stryjova, Hana; Jonatova, Ivana; Volcke, Eveline I P; Svehla, Pavel; Bartacek, Jan

    2014-01-01

    The application of nitrification-denitrification over nitrite (nitritation-denitritation) with municipal (i.e. diluted and cold (or low-temperature)) wastewater can substantially improve the energy balance of municipal wastewater treatment plants. For the accumulation of nitrite, it is crucial to inhibit nitrite-oxidizing bacteria (NOB) with simultaneous proliferation of ammonium-oxidizing bacteria (AOB). The present study describes the effect of the influent total ammonium nitrogen (TAN) concentration on AOB and NOB activity in two moving bed biofilm reactors operated as sequencing batch reactors (SBR) at 15 °C (SBR I) and 21 °C (SBR II). The reactors were fed with diluted reject water containing 600, 300, 150 and 75 mg TAN L(-1). The only factor limiting NOB activity in these reactors was the high concentrations of free ammonia and/or free nitrous acid (FNA) during the SBR cycles. Nitrite accumulation was observed with influents containing 600, 300 and 150 mg TAN L(-1) in SBR I and 600 and 300 in SBR II. Once nitrate production established in the reactors, the increase of influent TAN concentration up to the original 600 mg TAN L(-1) did not limit NOB activity. This was due to the massive development of NOB clusters throughout the biofilm that were able to cope with faster formation of FNA. The results of the fluorescence in situ hybridization analysis preliminarily showed the stratification of bacteria in the biofilm.

  10. Investigation of flow dynamics of liquid phase in a pilot-scale trickle bed reactor using radiotracer technique.

    PubMed

    Pant, H J; Sharma, V K

    2016-10-01

    A radiotracer investigation was carried out to measure residence time distribution (RTD) of liquid phase in a trickle bed reactor (TBR). The main objectives of the investigation were to investigate radial and axial mixing of the liquid phase, and evaluate performance of the liquid distributor/redistributor at different operating conditions. Mean residence times (MRTs), holdups (H) and fraction of flow flowing along different quadrants were estimated. The analysis of the measured RTD curves indicated radial non-uniform distribution of liquid phase across the beds. The overall RTD of the liquid phase, measured at the exit of the reactor was simulated using a multi-parameter axial dispersion with exchange model (ADEM), and model parameters were obtained. The results of model simulations indicated that the TBR behaved as a plug flow reactor at most of the operating conditions used in the investigation. The results of the investigation helped to improve the existing design as well as to design a full-scale industrial TBR for petroleum refining applications. PMID:27544314

  11. Investigation of flow dynamics of liquid phase in a pilot-scale trickle bed reactor using radiotracer technique.

    PubMed

    Pant, H J; Sharma, V K

    2016-10-01

    A radiotracer investigation was carried out to measure residence time distribution (RTD) of liquid phase in a trickle bed reactor (TBR). The main objectives of the investigation were to investigate radial and axial mixing of the liquid phase, and evaluate performance of the liquid distributor/redistributor at different operating conditions. Mean residence times (MRTs), holdups (H) and fraction of flow flowing along different quadrants were estimated. The analysis of the measured RTD curves indicated radial non-uniform distribution of liquid phase across the beds. The overall RTD of the liquid phase, measured at the exit of the reactor was simulated using a multi-parameter axial dispersion with exchange model (ADEM), and model parameters were obtained. The results of model simulations indicated that the TBR behaved as a plug flow reactor at most of the operating conditions used in the investigation. The results of the investigation helped to improve the existing design as well as to design a full-scale industrial TBR for petroleum refining applications.

  12. Combination of upflow anaerobic sludge blanket (UASB) reactor and partial nitritation/anammox moving bed biofilm reactor (MBBR) for municipal wastewater treatment.

    PubMed

    Malovanyy, Andriy; Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta

    2015-03-01

    In this study the combination of an upflow anaerobic sludge blanket (UASB) reactor and a deammonification moving bed biofilm reactor (MBBR) for mainstream wastewater treatment was tested. The competition between aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied during a 5months period of transition from reject water to mainstream wastewater followed by a 16months period of mainstream wastewater treatment. The decrease of influent ammonium concentration led to a wash-out of suspended biomass which had a major contribution to nitrite production. Influence of a dissolved oxygen concentration and a transient anoxia mechanism of NOB suppression were studied. It was shown that anoxic phase duration has no effect on NOB metabolism recovery and oxygen diffusion rather than affinities of AOB and NOB to oxygen determine the rate of nitrogen conversion in a biofilm system. Anammox activity remained on the level comparable to reject water treatment systems.

  13. Development and applications of methodologies for the neutronic design of the Pebble Bed Advanced High Temperature Reactor (PB-AHTR)

    NASA Astrophysics Data System (ADS)

    Fratoni, Massimiliano

    This study investigated the neutronic characteristics of the Pebble Bed Advanced High Temperature Reactor (PB-AHTR), a novel nuclear reactor concept that combines liquid salt (7LiF-BeF2---flibe) cooling and TRISO coated-particle fuel technology. The use of flibe enables operation at high power density and atmospheric pressure and improves passive decay-heat removal capabilities, but flibe, unlike conventional helium coolant, is not transparent to neutrons. The flibe occupies 40% of the PB-AHTR core volume and absorbs ˜8% of the neutrons, but also acts as an effective neutron moderator. Two novel methodologies were developed for calculating the time dependent and equilibrium core composition: (1) a simplified single pebble model that is relatively fast; (2) a full 3D core model that is accurate and flexible but computationally intensive. A parametric analysis was performed spanning a wide range of fuel kernel diameters and graphite-to-heavy metal atom ratios to determine the attainable burnup and reactivity coefficients. Using 10% enriched uranium ˜130 GWd/tHM burnup was found to be attainable, when the graphite-to-heavy metal atom ratio (C/HM) is in the range of 300 to 400. At this or smaller C/HM ratio all reactivity coefficients examined---coolant temperature, coolant small and full void, fuel temperature, and moderator temperature, were found to be negative. The PB-AHTR performance was compared to that of alternative options for HTRs, including the helium-cooled pebble-bed reactor and prismatic fuel reactors, both gas-cooled and flibe-cooled. The attainable burnup of all designs was found to be similar. The PB-AHTR generates at least 30% more energy per pebble than the He-cooled pebble-bed reactor. Compared to LWRs the PB-AHTR requires 30% less natural uranium and 20% less separative work per unit of electricity generated. For deep burn TRU fuel made from recycled LWR spent fuel, it was found that in a single pass through the core ˜66% of the TRU can be

  14. Effect of bone on the pyrolysis product distribution and composition in a fixed bed reactor

    NASA Astrophysics Data System (ADS)

    Alhassan, M.; Andresen, J. M.

    2012-04-01

    Co-pyrolysis of Biomass including Pistachio shell (PS), Pine wood (PW) and Wheat Straw (WS) with Bone matter (BM) have been investigated to determine the effect of bone on the quality of bio-char and bio-oil produced. The aim of this study is to generate stable and nitrogen enriched bio-char that can act as fertilizer while at the same time optimizes the chemical stability of the char to act as a Carbon Capture and Storage system (CCS) and co-produce high quality oils for renewable energy generation. To achieve this, the present study has focused on the influence of bone matter addition from 0wt% to 25wt% to the biomasses in a fixed bed pyrolysis reactor at 3000C. The analysis of the char products shows that the addition of bone to the biomass increased their char yields up to 10wt% addition. Higher addition was found to reduce the overall char yield from the biomass. At 10wt% bone addition, the carbon, hydrogen, and nitrogen content, and the gross calorific value of the chars were increased by 7wt%, 29wt%, 163wt% and 19Mj/kg, for Wheat straw, 62wt%, 46wt%, 135wt%, 110Mj/kg for Pine wood and 7wt%, 76wt%, 42wt% and 33Mj/kg for Pistachio shells. The oxygen content of the Wheat straw, Pistachio shells and pine wood mixed with 10wt% BM decreased by 28wt%, 21wt%, and 93wt%, respectively. The bio-oil yield increased for the bone addition up to 5%wt% for all the samples, its energy value and concentration of its major chemical components was improved for fuel and pharmaceutical use. Port experiment has shown that plant grown on soil amended with the bio-char produced gave higher yield as compared to that from un-amended soil. Comparison between the three biomasses investigated showed similar pattern of change. Hence it can be concluded that at optimum addition of bone to the biomass, bio-chars and oil yield could be optimized for soil amendment, energy production, while retaining carbon for sequestration.

  15. Stabilization of fine fraction from landfill mining in anaerobic and aerobic laboratory leach bed reactors.

    PubMed

    Mönkäre, Tiina J; Palmroth, Marja R T; Rintala, Jukka A

    2015-11-01

    Fine fraction (FF, <20 mm) from mined landfill was stabilized in four laboratory-scale leach bed reactors (LBR) over 180 days. The aim was to study feasibility of biotechnological methods to treat FF and if further stabilization of FF is possible. Four different stabilization methods were compared and their effects upon quality of FF were evaluated. Also during the stabilization experiment, leachate quality as well as gas composition and quantity were analyzed. The methods studied included three anaerobic LBRs (one without water addition, one with water addition, and one with leachate recirculation) and one aerobic LBR (with water addition). During the experiment, the most methane was produced in anaerobic LBR without water addition (18.0 L CH4/kg VS), while water addition and leachate recirculation depressed methane production slightly, to 16.1 and 16.4 L CH4/kg VS, respectively. Organic matter was also removed via the leachate and was measured as chemical oxygen demand (COD). Calculated removal of organic matter in gas and leachate was highest in LBR with water addition (59 g COD/kg VS), compared with LBR without water addition or with leachate recirculation (51 g COD/kg VS). Concentrations of COD, ammonium nitrogen and anions in leachate decreased during the experiment, indicating washout mechanism caused by water additions. Aeration increased sulfate and nitrate concentrations in leachate due to oxidized sulfide and ammonium. Molecular weight distributions of leachates showed that all the size categories decreased, especially low molecular weight compounds, which were reduced the most. Aerobic stabilization resulted in the lowest final VS/TS (13.1%), lowest respiration activity (0.9-1.2 mg O2/g TS), and lowest methane production after treatment (0.0-0.8 L CH4/kg VS), with 29% of VS being removed from FF. Anaerobic stabilization methods also reduced organic matter by 9-20% compared with the initial amount. Stabilization reduced the quantity of soluble nitrogen

  16. Stabilization of fine fraction from landfill mining in anaerobic and aerobic laboratory leach bed reactors.

    PubMed

    Mönkäre, Tiina J; Palmroth, Marja R T; Rintala, Jukka A

    2015-11-01

    Fine fraction (FF, <20 mm) from mined landfill was stabilized in four laboratory-scale leach bed reactors (LBR) over 180 days. The aim was to study feasibility of biotechnological methods to treat FF and if further stabilization of FF is possible. Four different stabilization methods were compared and their effects upon quality of FF were evaluated. Also during the stabilization experiment, leachate quality as well as gas composition and quantity were analyzed. The methods studied included three anaerobic LBRs (one without water addition, one with water addition, and one with leachate recirculation) and one aerobic LBR (with water addition). During the experiment, the most methane was produced in anaerobic LBR without water addition (18.0 L CH4/kg VS), while water addition and leachate recirculation depressed methane production slightly, to 16.1 and 16.4 L CH4/kg VS, respectively. Organic matter was also removed via the leachate and was measured as chemical oxygen demand (COD). Calculated removal of organic matter in gas and leachate was highest in LBR with water addition (59 g COD/kg VS), compared with LBR without water addition or with leachate recirculation (51 g COD/kg VS). Concentrations of COD, ammonium nitrogen and anions in leachate decreased during the experiment, indicating washout mechanism caused by water additions. Aeration increased sulfate and nitrate concentrations in leachate due to oxidized sulfide and ammonium. Molecular weight distributions of leachates showed that all the size categories decreased, especially low molecular weight compounds, which were reduced the most. Aerobic stabilization resulted in the lowest final VS/TS (13.1%), lowest respiration activity (0.9-1.2 mg O2/g TS), and lowest methane production after treatment (0.0-0.8 L CH4/kg VS), with 29% of VS being removed from FF. Anaerobic stabilization methods also reduced organic matter by 9-20% compared with the initial amount. Stabilization reduced the quantity of soluble nitrogen

  17. Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor

    PubMed Central

    Bertin, Lorenzo; Colao, Maria Chiara; Ruzzi, Maurizio; Marchetti, Leonardo; Fava, Fabio

    2006-01-01

    Background Olive mill wastewater (OMW) is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools. Results The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl-1day-1 of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl-1day-1 of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter, enriched significantly in

  18. Functionalization of polymers using an atmospheric plasma jet in a fluidized bed reactor and the impact on SLM-processes

    SciTech Connect

    Sachs, M. Schmitt, A. Schmidt, J. Peukert, W. Wirth, K-E

    2014-05-15

    In order to improve thermoplastics (e.g. Polyamide, Polypropylene and Polyethylene) for Selective Laser Beam Melting (SLM) processes a new approach to functionalize temperature sensitive polymer powders in a large scale is investigated. This is achieved by combining an atmospheric pressure plasma jet and a fluidized bed reactor. Using pressurized air as the plasma gas, radicals like OH* are created. The functionalization leads to an increase of the hydrophilicity of the treated polymer powder without changing the bulk properties. Using the polymers in a SLM process to build single layers of melted material leads to an improvement of the melted layers.

  19. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor

    SciTech Connect

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-01

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  20. Functionalization of polymers using an atmospheric plasma jet in a fluidized bed reactor and the impact on SLM-processes

    NASA Astrophysics Data System (ADS)

    Sachs, M.; Schmitt, A.; Schmidt, J.; Peukert, W.; Wirth, K.-E.

    2014-05-01

    In order to improve thermoplastics (e.g. Polyamide, Polypropylene and Polyethylene) for Selective Laser Beam Melting (SLM) processes a new approach to functionalize temperature sensitive polymer powders in a large scale is investigated. This is achieved by combining an atmospheric pressure plasma jet and a fluidized bed reactor. Using pressurized air as the plasma gas, radicals like OH* are created. The functionalization leads to an increase of the hydrophilicity of the treated polymer powder without changing the bulk properties. Using the polymers in a SLM process to build single layers of melted material leads to an improvement of the melted layers.

  1. Bisphenol A removal by a Pseudomonas aeruginosa immobilized on granular activated carbon and operating in a fluidized bed reactor.

    PubMed

    Mita, Luigi; Grumiro, Laura; Rossi, Sergio; Bianco, Carmen; Defez, Roberto; Gallo, Pasquale; Mita, Damiano Gustavo; Diano, Nadia

    2015-06-30

    Serratia rubidiae, Pseudomonas aeruginosa and Escherichia coli K12 have been studied for their ability of Bisphenol A removal from aqueous systems and biofilm formation on activated granule carbon. Mathematical equations for biodegradation process have been elaborated and discussed. P. aeruginosa was found the best strain to be employed in the process of Bisphenol A removal. The yield in BPA removal of a P. aeruginosa biofilm grown on GAC and operating in a fluidized bed reactor has been evaluated. The results confirm the usefulness in using biological activated carbon (BAC process) to remove phenol compounds from aqueous systems.

  2. Drag conveyors in 1913 head house, Spouts in background feed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Drag conveyors in 1913 head house, Spouts in background feed hopper scales and convey grain from hopper scales to storage bins. - Stewart Company Grain Elevator, 16 West Carson Street, Pittsburgh, Allegheny County, PA

  3. Loading spout and wheel for 1913 power grain shovel inside ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Loading spout and wheel for 1913 power grain shovel inside covered hopper loading dock at railroad level looking west - Stewart Company Grain Elevator, 16 West Carson Street, Pittsburgh, Allegheny County, PA

  4. 25. Interior view, second floor, showing numerous spouts and Simpson ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. Interior view, second floor, showing numerous spouts and Simpson Rotex sifter (Orville Simpson, Co; Cincinnati) on floor in middle-foreground. - Fisher-Fallgatter Mill, Waupaca, Waupaca County, WI

  5. 7. Peavey Duluth Terminal Elevator spout floorgrain dryer on north ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Peavey Duluth Terminal Elevator spout floor-grain dryer on north wall. - Peavey Duluth Terminal Elevator, Workhouse, South side of first slip, north from outer end of Rice's Point, east of Garfield Avenue, Duluth, St. Louis County, MN

  6. State-of-the-art review and report on critical aspects and scale-up considerations in the design of fluidized-bed reactors. Final report on Phase 1

    SciTech Connect

    Not Available

    1980-01-01

    Information is given on the design of distributor plates and opening geometry to provide uniform flow over the reactor area. The design of granular bed filters is also considered. Pressure drops and particle size in the bed are discussed. (LTN)

  7. Utilization of moving bed biofilm reactor for industrial wastewater treatment containing ethylene glycol: kinetic and performance study.

    PubMed

    Hassani, Amir Hessam; Borghei, Seyed Mehdi; Samadyar, Hassan; Ghanbari, Bastam

    2014-01-01

    One of the requirements for environmental engineering, which is currently being considered, is the removal of ethylene glycol (EG) as a hazardous environmental pollutant from industrial wastewater. Therefore, in a recent study, a moving bed biofilm reactor (MBBR) was applied at pilot scale to treat industrial effluents containing different concentrations of EG (600, 800, 1200, and 1800 mg L-1 ). The removal efficiency and kinetic analysis of the system were examined at different hydraulic retention times of 6, 8, 10, and 12 h as well as influent chemical oxygen demand (COD) ranged between values of 1000 and 3000mg L-1. In minimum and maximum COD Loadings, the MBBR showed 95.1% and 60.7% removal efficiencies, while 95.9% and 66.2% EG removal efficiencies were achieved in the lowest and highest EG concentrations. The results of the reactor modelling suggested compliance of the well-known modified Stover-Kincannon model with the system. PMID:24600890

  8. Application of a combined process of moving-bed biofilm reactor (MBBR) and chemical coagulation for dyeing wastewater treatment.

    PubMed

    Shin, D H; Shin, W S; Kim, Y H; Han, Myung Ho; Choi, S J

    2006-01-01

    A combined process consisted of a Moving-Bed Biofilm Reactor (MBBR) and chemical coagulation was investigated for textile wastewater treatment. The pilot scale MBBR system is composed of three MBBRs (anaerobic, aerobic-1 and aerobic-2 in series), each reactor was filled with 20% (v/v) of polyurethane-activated carbon (PU-AC) carrier for biological treatment followed by chemical coagulation with FeCl2. ln the MBBR process, 85% of COD and 70% of color (influent COD = 807.5 mg/L and color = 3,400 PtCo unit) were removed using relatively low MLSS concentration and short hydraulic retention time (HRT = 44 hr). The biologically treated dyeing wastewater was subjected to chemical coagulation. After coagulation with FeCl2, 95% of COD and 97% of color were removed overall. The combined process of MBBR and chemical coagulation has promising potential for dyeing wastewater treatment. PMID:17163056

  9. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems.

    PubMed

    Mazioti, Aikaterini A; Stasinakis, Athanasios S; Pantazi, Ypapanti; Andersen, Henrik R

    2015-09-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic. PMID:26093257

  10. Utilization of moving bed biofilm reactor for industrial wastewater treatment containing ethylene glycol: kinetic and performance study.

    PubMed

    Hassani, Amir Hessam; Borghei, Seyed Mehdi; Samadyar, Hassan; Ghanbari, Bastam

    2014-01-01

    One of the requirements for environmental engineering, which is currently being considered, is the removal of ethylene glycol (EG) as a hazardous environmental pollutant from industrial wastewater. Therefore, in a recent study, a moving bed biofilm reactor (MBBR) was applied at pilot scale to treat industrial effluents containing different concentrations of EG (600, 800, 1200, and 1800 mg L-1 ). The removal efficiency and kinetic analysis of the system were examined at different hydraulic retention times of 6, 8, 10, and 12 h as well as influent chemical oxygen demand (COD) ranged between values of 1000 and 3000mg L-1. In minimum and maximum COD Loadings, the MBBR showed 95.1% and 60.7% removal efficiencies, while 95.9% and 66.2% EG removal efficiencies were achieved in the lowest and highest EG concentrations. The results of the reactor modelling suggested compliance of the well-known modified Stover-Kincannon model with the system.

  11. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems.

    PubMed

    Mazioti, Aikaterini A; Stasinakis, Athanasios S; Pantazi, Ypapanti; Andersen, Henrik R

    2015-09-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic.

  12. Laundry greywater treatment using a fluidized bed reactor: a proposed model based on greywater biodegradation and residence time distribution approach.

    PubMed

    David, Pierre-luc; Bulteau, Gaëlle; Humeau, Philippe; Gérente, Claire; Andrès, Yves

    2013-01-01

    The increasing demand for water and the decrease in global water resources require research into alternative solutions to preserve them. The present study deals with the optimization of a treatment process, i.e. an aerobic fluidized bed reactor and the modelling of the degradation that takes place within it. The methodology employed is based on the hydrodynamics of the treatment process linked to the biodegradation kinetics of greywater coming from a washing machine. The residence time distribution (RTD) approach is selected for the hydrodynamic study. Biodegradation kinetics are quantified by respirometry and dissolved organic carbon (DOC) analysis on several mass quantities of colonized particles. RTD determinations show that there are no dysfunctions in the fluidized bed. Its hydrodynamic behaviour is similar to the one of a continuous stirred-tank reactor. A first-order reaction is obtained from the DOC biodegradation study. A model describing the degradation that takes place into the reactor is proposed, and from a sensitive study, the influence of the operating conditions on DOC biodegradation is defined. The theoretical results calculated from the first-order equation C(t) = 0.593 x C(0) x e(-kt) are compared with the experimental results and validated by a Student test. The value of the kinetic constant k is 0.011 h(-1) in the presence of a biomass carrier. The results highlight that it is possible to design a reactor in order to obtain a carbon content lower than 15 mg C L(-1) when the characteristics of raw greywater are known.

  13. Continuous biosynthesis of biodiesel from waste cooking palm oil in a packed bed reactor: optimization using response surface methodology (RSM) and mass transfer studies.

    PubMed

    Halim, Siti Fatimah Abdul; Kamaruddin, Azlina Harun; Fernando, W J N

    2009-01-01

    This study aimed to develop an optimal continuous procedure of lipase-catalyzes transesterification of waste cooking palm oil in a packed bed reactor to investigate the possibility of large scale production further. Response surface methodology (RSM) based on central composite rotatable design (CCRD) was used to optimize the two important reaction variables packed bed height (cm) and substrate flow rate(ml/min) for the transesterification of waste cooking palm oil in a continuous packed bed reactor. The optimum condition for the transesterification of waste cooking palm oil was as follows: 10.53 cm packed bed height and 0.57 ml/min substrate flow rate. The optimum predicted fatty acid methyl ester (FAME) yield was 80.3% and the actual value was 79%. The above results shows that the RSM study based on CCRD is adaptable for FAME yield studied for the current transesterification system. The effect of mass transfer in the packed bed reactor has also been studied. Models for FAME yield have been developed for cases of reaction control and mass transfer control. The results showed very good agreement compatibility between mass transfer model and the experimental results obtained from immobilized lipase packed bed reactor operation, showing that in this case the FAME yield was mass transfer controlled.

  14. Pebble Bed Reactor Power Systems for Lunar Outposts: Long Operation Life and End-of Life Storage

    NASA Astrophysics Data System (ADS)

    El-Genk, Mohamed S.; Schriener, Timothy M.

    2010-09-01

    The Pellet Bed Reactor(PeBR) and power system for supporting future lunar outposts offer many desirable design, operation and safety features and address post operation storage of spent nuclear fuel. In addition to its long, full power operation life of 66 year, the PeBR is launched without fuel and loaded after placement below grade on the lunar surface with spherical fuel pellets, designed to fully contain fission products. The fuel pellets(~1.0 cm dia.) are launched separately in subcritical canisters. The post-operation PeBR is stored below grade for > 300 year to allow the radioactivity in the spent fuel to decay to a sufficiently low level. The PeBR power system, designed for avoidance of single point failures in reactor cooling and energy conversion, nominally generates ~100 kWe at a thermal efficiency of ~ 21%. In addition to the sectored reactor core, it uses three Closed Brayton Cycle loops with centrifugal flow turbo-machines for energy conversion and He-Xe(40 g/mol) binary gas mixture working fluid and reactor coolant.

  15. Anaerobic degradation of landfill leachate using an upflow anaerobic fixed-bed reactor with microbial sulfate reduction.

    PubMed

    Thabet, Olfa Ben Dhia; Bouallagui, Hassib; Cayol, Jean-luc; Ollivier, Bernard; Fardeau, Marie-Laure; Hamdi, Moktar

    2009-08-15

    This study evaluated the anaerobic degradation of landfill leachate and sulfate reduction as a function of COD/(SO(4)(2-)) ratio in an upflow anaerobic fixed-bed reactor. The reactor, which was inoculated with a mixed consortium, was operated under a constant hydraulic retention time (HRT) of 5 days. We investigated the effect of COD/(SO(4)(2-)) ratio variation on the sulfate reduction efficiency, hydrogen sulfide production, chemical oxygen demand (COD) removal, conductivity, and pH variation. The best reactor performance, with significant sulfate reduction efficiency and COD removal efficiency of 91% and 87%, respectively, was reached under a COD/(SO(4)(2-)) ratio of 1.17. Under these conditions, microscopic analysis showed the abundance of vibrios and rod-shaped bacterial cells. Two anaerobic bacteria were isolated from the reactor sludge. Phylogenetic studies performed on these strains identified strain A1 as affiliated to Clostridium genus and strain H1 as a new species of sulfate-reducing bacteria affiliated to the Desulfovibrio genus. The closest phylogenetic relative of strain H1 was Desulfovibrio desulfuricans, at 96% similarity for partial 16S RNA gene sequence data. Physiological and metabolic characterization was performed for this strain.

  16. Tracking the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors operated at different COD/N ratios.

    PubMed

    Bassin, J P; Abbas, B; Vilela, C L S; Kleerebezem, R; Muyzer, G; Rosado, A S; van Loosdrecht, M C M; Dezotti, M

    2015-09-01

    In this study, the impact of COD/N ratio and feeding regime on the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors was addressed. Based on DGGE analysis of 16S rRNA genes, the influent COD was found to be the main factor determining the overall bacterial diversity. The amoA-gene-based analysis suggested that the dynamic behavior of the substrate in continuous and pulse-feeding reactors influenced the selection of specific ammonium-oxidizing bacteria (AOB) strains. Furthermore, AOB diversity was directly related to the applied COD/N ratio and ammonium-nitrogen load. Maximum specific ammonium oxidation rates observed under non-substrate-limiting conditions were observed to be proportional to the fraction of nitrifiers within the bacterial community. FISH analysis revealed that Nitrosomonas genus dominated the AOB community in all reactors. Moreover, Nitrospira was found to be the only nitrite-oxidizing bacteria (NOB) in the fully autotrophic system, whereas Nitrobacter represented the dominant NOB genus in the organic carbon-fed reactors. PMID:26025351

  17. Long-term operation performance and variation of substrate tolerance ability in an anammox attached film expanded bed (AAFEB) reactor.

    PubMed

    Zhang, Yanlong; Niu, Qigui; Ma, Haiyuan; He, Shilong; Kubota, Kengo; Li, Yu-You

    2016-07-01

    An anammox attached film expanded bed (AAFEB) reactor was operated to study the long-term performance and the variation of substrate tolerance ability. The results indicated that the nitrogen loading potential (NLP) was significantly enhanced from 13.56gN·(L·d)(-)(1) to 20.95gN·(L·d)(-)(1) during the stable operation period. The inhibitory concentration of 10% (IC10) for free ammonia (FA), free nitrous acid (FNA) and SNinf (diluted substrate concentration) increased from 18mg/L, 12μgL(-1) and 370mgNL(-)(1) to 31mg/L, 19μgL(-1) and 670mgNL(-)(1), respectively. However, the substrate shock of 2500mgNL(-)(1) for 24h terribly weakened the treatment performance and substrate tolerance ability of the reactor. The results of batch tests indicated that the existence of lag phase made the AAFEB reactor more vulnerable to substrate variation. The SNinf was accurate to be used to monitor the reactor performance and should be maintained below 320mgNL(-)(1) to ensure the absolute stable operation. PMID:26995619

  18. Effects of octahedral molecular sieve on treatment performance, microbial metabolism, and microbial community in expanded granular sludge bed reactor.

    PubMed

    Pan, Fei; Xu, Aihua; Xia, Dongsheng; Yu, Yang; Chen, Guo; Meyer, Melissa; Zhao, Dongye; Huang, Ching-Hua; Wu, Qihang; Fu, Jie

    2015-12-15

    This study evaluated the effects of synthesized octahedral molecular sieve (OMS-2) nanoparticles on the anaerobic microbial community in a model digester, expanded granular sludge bed (EGSB) reactor. The addition of OMS-2 (0.025 g/L) in the EGSB reactors resulted in an enhanced operational performance, i.e., COD removal and biogas production increased by 4% and 11% respectively, and effluent volatile fatty acid (VFA) decreased by 11% relative to the control group. The Biolog EcoPlate™ test was employed to investigate microbial metabolism in the EGSB reactors. Results showed that OMS-2 not only increased the microbial metabolic level but also significantly changed the community level physiological profiling of the microorganisms. The Illumina MiSeq high-throughput sequencing of 16S rRNA gene indicated OMS-2 enhanced the microbial diversity and altered the community structure. The largest bacterial genus Lactococcus, a lactic acid bacterium, reduced from 29.3% to 20.4% by abundance in the presence of 0.25 g/L OMS-2, which may be conducive to decreasing the VFA production and increasing the microbial diversity. OMS-2 also increased the quantities of acetogenic bacteria and Archaea, and promoted the acetogenesis and methanogenesis. The X-ray photoelectron spectroscopy illustrated that Mn(IV)/Mn(III) with high redox potential in OMS-2 were reduced to Mn(II) in the EGSB reactors; this in turn affected the microbial community. PMID:26397455

  19. Continuous methane fermentation and the production of vitamin B12 in a fixed-bed reactor packed with loofah.

    PubMed

    Yang, Yingnan; Zhang, Zhenya; Lu, Jun; Maekawa, Takaaki

    2004-05-01

    A fixed-bed reactor with acclimated methanogens immobilized on a loofah support was studied on a laboratory scale to evaluate the system producing methane from the mixture of CO(2) and H(2) gas, with the production of vitamin B(12) as a by-product. Fermentation using CO(2)/H(2) acclimated methanogens was conducted in a jar fermentor with hydraulic retention times (HRTs) of three and six days. The performance of the reactor was mainly dependent on the HRT. With an HRT of three days, the methane production rate and the vitamin B(12) concentration in the culture broth were 6.18 l/l-reactor/h and 2.88 mg/l-culture liquid; these values were 11.96 l/l-reactor/h and 37.54 mg/l-culture liquid for an HRT of six days. A higher total cell mass of methanogens retained 42.5 g dry cell/l-culture liquid was achieved in the HRT of six days. The loofah carrier immobilized almost 95% of the methanogens, which led to a more effective bio-reaction. It was also observed that the fermentation system had a better ability to buffer pH, especially for an HRT of six days.

  20. Treatment of food processing wastewater in a full-scale jet biogas internal loop anaerobic fluidized bed reactor.

    PubMed

    Wei, Chaohai; Zhang, Tao; Feng, Chunhua; Wu, Haizhen; Deng, Zhiyi; Wu, Chaofei; Lu, Bin

    2011-04-01

    A full-scale jet biogas internal loop anaerobic fluidized bed (JBILAFB) reactor, which requires low energy input and allows enhanced mass transfer, was constructed for the treatment of food processing wastewater. This reactor has an active volume of 798 m(3) and can treat 33.3 m(3) wastewater per hour. After pre-treating the raw wastewater by settling, oil separating and coagulation-air floating processes, the reactor was operated with a relatively shorter start-up time (55 days). Samples for the influent and effluent of the JBILAFB reactor were taken and analyzed daily for the whole process including both the start-up and stable running periods. When the volumetric COD loading fluctuated in the range of 1.6-5.6 kg COD m(-3) day(-1), the COD removal efficiency, the volatile fatty acid(VFA)/alkalinity ratio, the maximum biogas production and the content of CH(4) in total biogas of the reactor were found to be 80.1 ± 5%, 0.2-0.5, 348.5 m(3 )day(-1) and 94.5 ± 2.5%, respectively. Furthermore, the scanning electron microscope (SEM) results showed that anaerobic granular sludge and microorganism particles with biofilm coexisted in the reactor, and that the bacteria mainly in bacilli and cocci were observed as predominant species. All the data demonstrated that the enhanced mass transfer for gas, liquid and solid phases was achieved, and that the formation of microorganism granules and the removal of inhibitors increased the stability of the system.

  1. Application of k- and q-space encoding NMR techniques on granular media in a 3D model fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Harms, Silke; Stapf, Siegfried; Blümich, Bernhard

    2006-02-01

    A combination of PFG-NMR imaging and velocity encoding methods was applied to investigate the dynamic behavior of a bed of poppy seeds subjected to air flow, representing a model setup for fluidized bed reactors. The particle motion is described both from a statistical point of view, by determining propagators and dispersion coefficients representing an average over the whole bed volume, as well as combined with spatial resolution by generating velocity maps. Velocity images of different horizontal slices in the bed confirm the notion of a toroidal particle flow pattern inside the shallow granular bed. Despite the need of considerable averaging due to the random motion of the relatively few particles in the bed, quantitative velocity images and statistical information about the random particle motion can be obtained from monitoring the fluid component in the seeds by conventional spin-echo techniques.

  2. Improvement of heat transfer in a packed-bed reactor for a chemical heat pump using sodium carbonate decahydrate dehydration

    SciTech Connect

    Matsumura, Yukihiko; Yoshida, Kunio

    1997-06-01

    To improve the heat transfer characteristics of a gas-solid packed-bed reactor, an inert solvent was added to the reactor. For sodium carbonate decahydrate dehydration, used in a chemical heat pump, n-pentanol was chosen as a solvent, and the dehydration rate in the solvent was measured. The dehydration rate was found to be proportional to the total surface area of the decahydrate particles, and the rate equation was determined. Particle size distribution (less than 400 {micro}m) remained unchanged for a three-time cyclic operation. The packed-bed of decahydrate with n-pentanol solvent showed considerable improvement in heat transfer characteristics compared with the case having no solvent, and cold heat generation was more than doubled. A simulation study showed that the addition of n-pentanol may make it possible to construct a high-performance heat pump with cold storage capability, attaining 280 K in less than 5 s and total heat release within 1,600 s.

  3. Long-term testing of the zinc titanate for desulfurization of hot coal gas in a fluidized-bed reactor

    SciTech Connect

    Jain, S.C.; Gupta, R.; Gangwal, S.K.

    1993-12-31

    Research Triangle Institute (RTI) under contract to the US Department of Energy (DOE), Morgantown energy Technology Center has recently completed a long-term test consisting of 100 sulfidation-regeneration cycles on a zinc titanate material intended for use as a high-temperature, regenerable sorbent to desulfurize coal-derived gas. The primary motivation for this development is to generate a more economical, environmentally superior, and reliable process to purify the product gas of coal gasifiers for use in gas turbines and fuel cells. This zinc titanate formulation (designated as ZT-4 and containing Zn-to-Ti in a molar ratio of 1.5) exhibited the best overall performance in terms of chemical reactivity, sulfur capacity, regenerability, structural properties and, most importantly, the attrition resistance based on multicycle testing of a number of sorbent formulations in a bench scale fluidized-bed reactor. The conditions in the test were -- desulfurization temperature: 750C (1382F); pressure: 1.52 MPa (220 psia); coal gas: simulated Texaco entrained-bed oxygen-blown gasifier gas containing 12,000 ppmv of H{sub 2}S; superficial gas velocity: 15 cm/s (0.49 ft/s). The ZT-4 sorbent used in this test was prepared using a granulation technique and 500 g of the sorbent in the 100 to 300 microns particle diameter range were used in a 5.1-cm (2-inch) i.d. stainless steel reactor.

  4. Removal of sulfur dioxide from a continuously operated binary fluidized bed reactor using inert solids and hydrated lime.

    PubMed

    Pisani, R; de Moraes, D

    2004-06-18

    Sulfur dioxide pollutant was treated in the laboratory with hydrated lime particles having a mean diameter of 9.1 microm in a continuously operating binary fluidized bed reactor also containing inert sand particles with sizes varying from 500 to 590 microm. The influence of temperature (500, 600, 700 and 800 degrees C) on the reaction medium, of the superficial velocity of the gas (0.8, 1.0 and 1.2 m/s), and of the Ca/S molar ratio (1, 2 and 3) on the SO2 removal efficiency were investigated for an inflow gas concentration of 1000 ppm and an initially static bed height of 10.0 cm. The pollutant removal efficiency proved to depend on the temperature and the velocity of the gaseous flow and was strongly influenced by the Ca/S molar ratio. The maximum efficiency of 97.7% was achieved at a temperature of 700 degrees C, a Ca/S ratio of 3 and a velocity of 0.8 m/s. The lime particles' mean residence time was determined by an indirect method, which consisted of integrating the gas concentration curves normalized with respect to time. Based on a calculation of the critical transition velocities, it was concluded that the reactor operated in a bubbling regime under each condition investigated here. PMID:15177758

  5. Bioregeneration of perchlorate-laden gel-type anion-exchange resin in a fluidized bed reactor.

    PubMed

    Venkatesan, Arjun K; Sharbatmaleki, Mohamadali; Batista, Jacimaria R

    2010-05-15

    Selective ion-exchange resins are very effective to remove perchlorate from contaminated waters. However, these resins are currently incinerated after one time use, making the ion-exchange process incomplete and unsustainable for perchlorate removal. Resin bioregeneration is a new concept that combines ion-exchange with biological reduction by directly contacting perchlorate-laden resins with a perchlorate-reducing bacterial culture. In this research, feasibility of the bioregeneration of perchlorate-laden gel-type anion-exchange resin was investigated. Bench-scale bioregeneration experiments, using a fluidized bed reactor and a bioreactor, were performed to evaluate the feasibility of the process and to gain insight into potential mechanisms that control the process. The results of the bioregeneration tests suggested that the initial phase of the bioregeneration process might be controlled by kinetics, while the later phase seems to be controlled by diffusion. Feasibility study showed that direct bioregeneration of gel-type resin was effective in a fluidized-bed reactor, and that the resin could be defouled, reused, and repeatedly regenerated using the method applied in this research.

  6. Biodegradation of Phenol in Synthetic Wastewater Using a Fixed Bed Reactor With up Flow Sludge Blanket Filtration (FUSBF)

    PubMed Central

    Ghannadzadeh, Mohammad-Javad; Jonidi-Jafari, Ahmad; Rezaee, Abbas; Soltani, Reza Darvishi Cheshmeh

    2015-01-01

    In the present study, the removal of phenol from synthetic wastewater was evaluated in a fixed bed reactor with up flow sludge blanket filtration (FUSBF) in comparison with a typical USBF system. At hydraulic retention time (HRT) of 24 hours and solid retention time (SRT) of 20 day, the effect of initial concentration of phenol (260-1020 mg/L) on phenol and chemical oxygen demand (COD) removal efficiency (%) was investigated in both systems. The effect of the presence of fixed bed was determined throughout the operational period. The results showed that the FUSBF system had a better ability than the typical USBF system in terms of phenol and COD removal. The average phenol and COD removal at phenol concentration of 312 mg/L was 97.52% and 92.82% for the FUSBF system and 92.80% and 82.18% for the typical USBF system, respectively. At HRT of 24 h and organic loading rate (OLR) of 30 g/m-3.h-1, the amount of phenol removal was 82.1%. At OLR of 30 g/m-3.h-1, role of fixed bed in phenol and COD removal was 25.01% and 29.3%, respectively, overall, the FUSBF system has a higher efficiency and ability than that of typical USBF and can be used for the purification of industrial wastewater containing refractory organic compounds such as phenol. PMID:26153212

  7. Influence of particle size on pyrolysis and gasification performance of municipal solid waste in a fixed bed reactor.

    PubMed

    Luo, Siyi; Xiao, Bo; Hu, Zhiquan; Liu, Shiming; Guan, Yanwen; Cai, Lei

    2010-08-01

    Pyrolysis and gasification of municipal solid waste (MSW) were carried out in a lab-scale fixed bed reactor in order to evaluate the effects of particle size at different bed temperatures on product yield and composition. The bed temperature was varied from 600 to 900 degrees C and the MSW was separated into three different size fractions (below 5 mm, 50-10 mm and above 10 mm). Particle size and temperature had integrated effects on product yield and composition: higher temperature resulted in higher gas yield with less tar and char, and, at the same temperature, dry gas yield increased with a decrease in particle size, and char and tar yield decreased. The differences due to particle sizes in pyrolysis and gasification performance practically disappeared at the highest temperatures tested. Smaller particle sizes resulted in higher H(2) and CO contents for both pyrolysis and gasification of MSW. Minimizing the size of raw materials is an alternative method to improve the gas quality of MSW pyrolysis and gasification. PMID:20363619

  8. Treatment of petroleum refinery wastewater containing heavily polluting substances in an aerobic submerged fixed-bed reactor.

    PubMed

    Vendramel, S; Bassin, J P; Dezotti, M; Sant'Anna, G L

    2015-01-01

    Petroleum refineries produce large amount of wastewaters, which often contain a wide range of different compounds. Some of these constituents may be recalcitrant and therefore difficult to be treated biologically. This study evaluated the capability of an aerobic submerged fixed-bed reactor (ASFBR) containing a corrugated PVC support material for biofilm attachment to treat a complex and high-strength organic wastewater coming from a petroleum refinery. The reactor operation was divided into five experimental runs which lasted more than 250 days. During the reactor operation, the applied volumetric organic load was varied within the range of 0.5-2.4 kgCOD.m(-3).d(-1). Despite the inherent fluctuations on the characteristics of the complex wastewater and the slight decrease in the reactor performance when the influent organic load was increased, the ASFBR showed good stability and allowed to reach chemical oxygen demand, dissolved organic carbon and total suspended solids removals up to 91%, 90% and 92%, respectively. Appreciable ammonium removal was obtained (around 90%). Some challenging aspects of reactor operation such as biofilm quantification and important biofilm constituents (e.g. polysaccharides (PS) and proteins (PT)) were also addressed in this work. Average PS/volatile attached solids (VAS) and PT/VAS ratios were around 6% and 50%, respectively. The support material promoted biofilm attachment without appreciable loss of solids and allowed long-term operation without clogging. Microscopic observations of the microbial community revealed great diversity of higher organisms, such as protozoa and rotifers, suggesting that toxic compounds found in the wastewater were possibly removed in the biofilm.

  9. Bioenergy production from diluted poultry manure and microbial consortium inside Anaerobic Sludge Bed Reactor at sub-mesophilic conditions.

    PubMed

    Jaxybayeva, Aigerim; Yangin-Gomec, Cigdem; Cetecioglu, Zeynep; Ozbayram, E Gozde; Yilmaz, Fatih; Ince, Orhan

    2014-01-01

    In this study, anaerobic treatability of diluted chicken manure (with an influent feed ratio of 1 kg of fresh chicken manure to 6 L of tap water) was investigated in a lab-scale anaerobic sludge bed (ASB) reactor inoculated with granular seed sludge. The ASB reactor was operated at ambient temperature (17-25°C) in order to avoid the need of external heating up to higher operating temperatures (e.g., up to 35°C for mesophilic digestion). Since heat requirement for raising the temperature of incoming feed for digestion is eliminated, energy recovery from anaerobic treatment of chicken manure could be realized with less operating costs. Average biogas production rates were calculated ca. 210 and 242 L per kg of organic matter removed from the ASB reactor at average hydraulic retention times (HRTs) of 13 and 8.6 days, respectively. Moreover, average chemical oxygen demand (COD) removal of ca. 89% was observed with suspended solids removal more than 97% from the effluent of the ASB reactor. Influent ammonia, on the other hand, did not indicate any free ammonia inhibition due to dilution of the raw manure while pH and alkalinity results showed stability during the study. Microbial quantification results indicated that as the number of bacterial community decreased, the amount of Archaea increased through the effective digestion volume of the ASB reactor. Moreover, the number of methanogens displayed an uptrend like archaeal community and a strong correlation (-0.645) was found between methanogenic community and volatile fatty acid (VFA) concentration especially acetate. PMID:25065830

  10. Effects of bed materials on the performance of an anaerobic sequencing batch biofilm reactor treating domestic sewage.

    PubMed

    Garcia, M L; Lapa, K R; Foresti, E; Zaiat, M

    2008-09-01

    The objective of this study was to determine the best performance of an anaerobic sequencing batch biofilm reactor (AnSBBR) based on the use of four different bed materials as support for biomass immobilization. The bed materials utilized were polyurethane foam (PU), vegetal carbon (VC), synthetic pumice (SP), and recycled low-density polyethylene (PE). The AnSBBR, with a total volume of 7.2L, was operated in 8-h batch cycles over 10 months, and fed with domestic sewage with an average influent chemical oxygen demand (COD) of 358+/-110 mg/L. The average effluent COD values were 121+/-31, 208+/-54, 233+/-52, and 227+/-51 mg/L, for PU, VC, SP, and PE, respectively. A modified first-order kinetic model was adjusted to temporal profiles of COD during a batch cycle, and the apparent kinetic constants were 0.52+/-0.05, 0.37+/-0.05, 0.80+/-0.04, and 0.30+/-0.02 h(-1) for PU, VC, SP, and PE, respectively. Specific substrate utilization rates of 1.08, 0.11, and 0.86 mg COD/mg VS day were obtained for PU, VC, and PE, respectively. Although SP yielded the highest kinetic coefficient, PU was considered the best support, since SP presented loss of chemical constituents during the reactor's operational phase. In addition, findings on the microbial community were associated with the reactor's performance data. Although PE did not show a satisfactory performance, an interesting microbial diversity was found on its surface. Based on the morphology and denaturing gradient gel electrophoresis (DGGE) results, PE showed the best capacity for promoting the attachment of methanogenic organisms, and is therefore a material that merits further analysis. PU was considered the most suitable material showing the best performance in terms of efficiency of solids and COD removal.

  11. Mesophilic hydrogen production in acidogenic packed-bed reactors (APBR) using raw sugarcane vinasse as substrate: Influence of support materials.

    PubMed

    Nunes Ferraz Júnior, Antônio Djalma; Etchebehere, Claudia; Zaiat, Marcelo

    2015-08-01

    Bio-hydrogen production from sugarcane vinasse in anaerobic up-flow packed-bed reactors (APBR) was evaluated. Four types of support materials, expanded clay (EC), charcoal (Ch), porous ceramic (PC), and low-density polyethylene (LDP) were tested as support for biomass attachment. APBR (working volume - 2.3 L) were operated in parallel at a hydraulic retention time of 24 h, an organic loading rate of 36.2 kg-COD m(-3) d(-1), at 25 °C. Maximum volumetric hydrogen production values of 509.5, 404, 81.4 and 10.3 mL-H2 d(-1) L(-1)reactor and maximum yields of 3.2, 2.6, 0.4 and 0.05 mol-H2 mol(-1) carbohydrates total, were observed during the monitoring of the reactors filled with LDP, EC, Ch and PC, respectively. Thus, indicating the strong influence of the support material on H2 production. LDP was the most appropriate material for hydrogen production among the materials evaluated. 16S rRNA gene by Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and scanning electron microscopy confirmed the selection of different microbial populations. 454-pyrosequencing performed on samples from APBR filled with LDP revealed the presence of hydrogen-producing organisms (Clostridium and Pectinatus), lactic acid bacteria and non-fermentative organisms. PMID:25891935

  12. Molecular analysis of the biomass of a fluidized bed reactor treating synthetic vinasse at anaerobic and micro-aerobic conditions.

    PubMed

    Rodríguez, Elisa; Lopes, Alexandre; Fdz-Polanco, María; Stams, Alfons J M; García-Encina, Pedro A

    2012-03-01

    The microbial communities (Bacteria and Archaea) established in an anaerobic fluidized bed reactor used to treat synthetic vinasse (betaine, glucose, acetate, propionate, and butyrate) were characterized by denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis. This study was focused on the competitive and syntrophic interactions between the different microbial groups at varying influent substrate to sulfate ratios of 8, 4, and 2 and anaerobic or micro-aerobic conditions. Acetogens detected along the anaerobic phases at substrate to sulfate ratios of 8 and 4 seemed to be mainly involved in the fermentation of glucose and betaine, but they were substituted by other sugar or betaine degraders after oxygen application. Typical fatty acid degraders that grow in syntrophy with methanogens were not detected during the entire reactor run. Likely, sugar and betaine degraders outnumbered them in the DGGE analysis. The detected sulfate-reducing bacteria (SRB) belonged to the hydrogen-utilizing Desulfovibrio. The introduction of oxygen led to the formation of elemental sulfur (S(0)) and probably other sulfur compounds by sulfide-oxidizing bacteria (γ-Proteobacteria). It is likely that the sulfur intermediates produced from sulfide oxidation were used by SRB and other microorganisms as electron acceptors, as was supported by the detection of the sulfur respiring Wolinella succinogenes. Within the Archaea population, members of Methanomethylovorans and Methanosaeta were detected throughout the entire reactor operation. Hydrogenotrophic methanogens mainly belonging to the genus Methanobacterium were detected at the highest substrate to sulfate ratio but rapidly disappeared by increasing the sulfate concentration. PMID:21861082

  13. Microscale packed bed reactor for controlled hydrogen peroxide decomposition as a fuel cell oxidant aboard unmanned undersea vehicles

    NASA Astrophysics Data System (ADS)

    Lennon, E.; Burke, A. A.; Ocampo, M.; Besser, R. S.

    The multiphase catalytic decomposition of hydrogen peroxide into water and oxygen is notoriously susceptible to thermal runaway (heat of reaction: -98 kJ mol -1). The high surface area to volume ratio (S/ V) in a microscale packed bed (MPB) reactor (radius 0.5 mm) was investigated for reducing the risk of thermal runaway during hydrogen peroxide decomposition to oxygen intended as a fuel cell oxidant aboard an unmanned undersea vehicle (UUV). A microscale reactor channel with a S/ V of ∼2 × 10 3 m 2 m -3 simulated under convective cooling generated a significant heat rise (T rise ∼ 100 K), whereas a microreactor with a higher S/ V (∼200 × 10 3 m 2 m -3) achieved thermal control (T rise < 10 K) over the simulated reaction zone. Although thermal management was successfully accomplished using the higher S/ V, experimental conversions of hydrogen peroxide to oxygen (5-18%) measured from the outlet were lower than simulated conversions (38-63%). Simulation assumptions, such as homogeneously dispersed flow and perfect catalyst interaction among other factors, contributed to the discrepancies between the simulated and experimental degrees of peroxide conversion to oxygen. Even though thermal control of the MPB was achieved, this work indicates that mass transfer limitations are a factor in the MPB reactor during a multiphase reaction, like decomposition of hydrogen peroxide to oxygen and water, and suggests means to overcome them even on the microscale level.

  14. Microbial community of granules in expanded granular sludge bed reactor for simultaneous biological removal of sulfate, nitrate and lactate.

    PubMed

    Chen, Chuan; Ren, Nanqi; Wang, Aijie; Yu, Zhenguo; Lee, Duu-Jong

    2008-07-01

    This study studied the cultivation of granules from an expanded granular sludge bed reactor that simultaneously transforms sulfates, nitrates, and oxygen to elementary sulfur, nitrogen gas, and carbon dioxides, respectively. The living cells accumulate at the granule outer layers, as revealed by the multicolor staining and confocal laser scanning microscope technique. The microbial community comprises sulfate-reducing bacteria (SRB, Desulfomicrobium sp.), heterotrophic (Pseudomonas aeruginosa and Sulfurospirillum sp.), and autotrophic denitrifiers (Sulfurovum sp. and Paracoccus denitrificans) whose population dynamics at different sulfate and nitrate loading rates are monitored with the single-strand conformation polymorphism and denaturing gradient gel electrophoresis technique. The Desulfomicrobium sp. presents one of the dominating strains following reactor startup. At high sulfate and nitrate loading rates, the heterotrophic denitrifiers overcompete autotrophic denitrifiers to reduce SRB activities. Conversely, suddenly reducing nitrate loading rates completely removes the heterotrophic denitrifier Sulfurospirillum sp. from the granules and activates the autotrophic denitrifiers. The physical fixation of different groups of functional strains in granules fine-tunes the strains' activities, and hence the reactor performance. PMID:18483736

  15. Mesophilic hydrogen production in acidogenic packed-bed reactors (APBR) using raw sugarcane vinasse as substrate: Influence of support materials.

    PubMed

    Nunes Ferraz Júnior, Antônio Djalma; Etchebehere, Claudia; Zaiat, Marcelo

    2015-08-01

    Bio-hydrogen production from sugarcane vinasse in anaerobic up-flow packed-bed reactors (APBR) was evaluated. Four types of support materials, expanded clay (EC), charcoal (Ch), porous ceramic (PC), and low-density polyethylene (LDP) were tested as support for biomass attachment. APBR (working volume - 2.3 L) were operated in parallel at a hydraulic retention time of 24 h, an organic loading rate of 36.2 kg-COD m(-3) d(-1), at 25 °C. Maximum volumetric hydrogen production values of 509.5, 404, 81.4 and 10.3 mL-H2 d(-1) L(-1)reactor and maximum yields of 3.2, 2.6, 0.4 and 0.05 mol-H2 mol(-1) carbohydrates total, were observed during the monitoring of the reactors filled with LDP, EC, Ch and PC, respectively. Thus, indicating the strong influence of the support material on H2 production. LDP was the most appropriate material for hydrogen production among the materials evaluated. 16S rRNA gene by Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and scanning electron microscopy confirmed the selection of different microbial populations. 454-pyrosequencing performed on samples from APBR filled with LDP revealed the presence of hydrogen-producing organisms (Clostridium and Pectinatus), lactic acid bacteria and non-fermentative organisms.

  16. Start-up performance of Anammox process in a fixed bed reactor (FBR) filled with honeycomb-like polypropylene carriers.

    PubMed

    Wang, Tao; Shen, Boxiong; Zhang, Sha; Wang, Zhiqiang; Tian, Li

    2016-01-01

    Novel honeycomb-like carriers, made of polypropylene, were applied to enhance biomass retention capacity so as to improve Anammox start-up performance in a fixed bed reactor (FBR). The reactor was operated for 3 months. On day 45, Anammox activity appeared. After 61 days' operation, the removal efficiencies of ammonium and nitrite were both over 91% based on 70 mg N L(-1) of the influent ammonium and influent nitrite, indicating that a remarkable Anammox activity was attained. A final specific Anammox activity of 0.12 g NH4(+)-N gVSS(-1) d(-1) was reached (VSS: volatile suspended solids). The FBR showed a good capacity for resisting shock loading and was more able to resist shock loading of nitrogen concentration than resist hydraulic shock loading. Phylogenetic analysis showed that Candidatus Brocadia anammoxidans' and Candidatus Kuenenia stuttgartiensis' were detected in the mature biofilm, and Candidatus Brocadia anammoxidans' was the dominant Anammox strain. Candidatus Kuenenia stuttgartiensis' played a positive role in the reactor performance, as it could consumed nitrite quickly and efficiently so as to avoid an adverse effect of temporary nitrite accumulation. The results showed that the honeycomb-like carriers were suitable for start-up of Anammox. PMID:27120639

  17. The characteristics of extracellular polymeric substances and soluble microbial products in moving bed biofilm reactor-membrane bioreactor.

    PubMed

    Duan, Liang; Jiang, Wei; Song, Yonghui; Xia, Siqing; Hermanowicz, Slawomir W

    2013-11-01

    The characteristics of extracellular polymeric substances (EPS) and soluble microbial products (SMP) in conventional membrane bioreactor (MBR) and in moving bed biofilm reactor-membrane bioreactors (MBBR-MBR) were investigated in long-term (170 days) experiments. The results showed that all reactors had high removal efficiency of ammonium and COD, despite very different fouling conditions. The MBBR-MBR with media fill ratio of 26.7% had much lower total membrane resistance and no obvious fouling were detected during the whole operation. In contrast, MBR and MBBR-MBR with lower and higher media fill experienced more significant fouling. Low fouling at optimum fill ratio may be due to the higher percentage of small molecular size (<1 kDa) and lower percentage of large molecular size (>100 kDa) of EPS and SMP in the reactor. The composition of EPS and SMP affected fouling due to different O-H bonds in hydroxyl functional groups, and less polysaccharides and lipids.

  18. Copper removal using a heavy-metal resistant microbial consortium in a fixed-bed reactor.

    PubMed

    Carpio, Isis E Mejias; Machado-Santelli, Glaucia; Sakata, Solange Kazumi; Ferreira Filho, Sidney Seckler; Rodrigues, Debora Frigi

    2014-10-01

    A heavy-metal resistant bacterial consortium was obtained from a contaminated river in São Paulo, Brazil and utilized for the design of a fixed-bed column for the removal of copper. Prior to the design of the fixed-bed bioreactor, the copper removal capacity by the live consortium and the effects of copper in the consortium biofilm formation were investigated. The Langmuir model indicated that the sorption capacity of the consortium for copper was 450.0 mg/g dry cells. The biosorption of copper into the microbial biomass was attributed to carboxyl and hydroxyl groups present in the microbial biomass. The effect of copper in planktonic cells to form biofilm under copper rich conditions was investigated with confocal microscopy. The results revealed that biofilm formed after 72 h exposure to copper presented a reduced thickness by 57% when compared to the control; however 84% of the total cells were still alive. The fixed-bed bioreactor was set up by growing the consortium biofilm on granular activated carbon (GAC) and analyzed for copper removal. The biofilm-GAC (BGAC) column retained 45% of the copper mass present in the influent, as opposed to 17% in the control column that contained GAC only. These findings suggest that native microbial communities in sites contaminated with heavy metals can be immobilized in fixed-bed bioreactors and used to treat metal contaminated water. PMID:24952346

  19. Particles fluidized bed receiver/reactor with a beam-down solar concentrating optics: 30-kWth performance test using a big sun-simulator

    NASA Astrophysics Data System (ADS)

    Kodama, Tatsuya; Gokon, Nobuyuki; Cho, Hyun Seok; Matsubara, Koji; Etori, Tetsuro; Takeuchi, Akane; Yokota, Shin-nosuke; Ito, Sumie

    2016-05-01

    A novel concept of particles fluidized bed receiver/reactor with a beam-down solar concentrating optics was performed using a 30-kWth window type receiver by a big sun-simulator. A fluidized bed of quartz sand particles was created by passing air from the bottom distributor of the receiver, and about 30 kWth of high flux visible light from 19 xenon-arc lamps of the sun-simulator was directly irradiated on the top of the fluidized bed in the receiver through a quartz window. The particle bed temperature at the center position of the fluidized bed went up to a temperature range from 1050 to 1200°C by the visible light irradiation with the average heat flux of about 950 kW/m2, depending on the air flow rate. The output air temperature from the receiver reached 1000 - 1060°C.

  20. Effect of acidity and elevated PCO2 on acid. Neutralization within pulsed limestone bed reactors receiving coal mine drainage

    USGS Publications Warehouse

    Watten, B.J.; Sibrell, P.L.; Schwartz, M.F.

    2004-01-01

    Limestone has potential for reducing reagent costs and sludge volume associated with the treatment of acid mine drainage (AMD), but its use has been restricted by slow dissolution rates and sensitivity to scale forming reactions that retard transport of H+ at the solid-liquid interface. We evaluated a pulsed limestone bed (PLB) remediation process designed to circumvent these problems through use of intermittently fluidized beds of granular limestone and elevated carbon dioxide pressure. PLB limestone dissolution (LD, mg/L), and effluent alkalinity (Alk, mg/L) were correlated with reactor pressure (PCO2, kPa), influent acidity (Acy, mg/L) and reactor bed height (H, cm) using a prototype capable of processing 10 L/min. The PLB process effectively neutralized sulfuric acid acidity over the range of 6-1033 mg/L (as CaCO3) while generating high concentrations of alkalinity (36-1086 mg/L) despite a hydraulic residence time of just 4.2-5.0 min. Alk and LD (mg/L CaCO3) rose with increases in influent acidity and PCO2 (p < 0.001) according to the models: Alk = 58 + 38.4 (PCO2)0.5 + 0.080 (Acy) - 0.0059(PCO2) 0.5 (Acy); LD = 55 + 38.3 (PCO2)0.5 + 1.08 (Acy) - 0.0059 (PCO2)0.5 (Acy). Alkalinity decreased at an increasing rate with reductions in H over the range of 27.3-77.5 cm (p < 0.001). Carbon dioxide requirements (Q(avg)CO2, L/min) increased with PCO2 (p < 0.001) following the model Q(avg)CO2 = 0.858 (PCO2)0.620, resulting in a greater degree of pH buffering (depression) within the reactors, a rise in limestone solubility and an increase in limestone dissolution related to carbonic acid attack. Corresponding elevated concentrations of effluent alkalinity allow for sidestream treatment with blending. Numerical modeling demonstrated that carbon dioxide requirements are reduced as influent acidity rises and when carbon dioxide is recovered from system effluent and recycled. Field trials demonstrated that the PLB process is capable of raising the pH of AMD above that

  1. Kinetics of organic removal in fixed-bed aerobic biological reactor.

    PubMed

    Borghei, S M; Sharbatmaleki, M; Pourrezaie, P; Borghei, G

    2008-03-01

    The process kinetics of a lab-scale upflow aerobic immobilized biomass (UAIB) reactor using simulated sugar-manufacturing wastewater as feed was investigated. The experimental unit consisted of a 22l reactor filled with high porosity pumice stone. The UAIB reactor was tested under different organic loads and different hydraulic retention times (HRT) and the substrate loading removal rate was compared with prediction of Stover-Kincannon model, second-order model and the first order substrate removal model. After obtaining steady-state conditions, organic loading rate was increased from 750 to 4500 g COD/m(3) day to resemble wastewater from sugar production lines, and hydraulic retention time was decreased from 1 to 0.5 days, stepwise. Nine different operational conditions were applied changing these two parameters in a certain program. As a result of the calculations, Stover-Kincannon model and second-order model known as "Grau" model were found to be the most appropriate models for this reactor. Stover-Kincannon model and Grau second-order model gave high correlation coefficients, which were 99.7% and 99.4%, respectively. Therefore, these models could be used in predicting the behavior or design of the UAIB reactors.

  2. Design of Complex Systems to Achieve Passive Safety: Natural Circulation Cooling of Liquid Salt Pebble Bed Reactors

    NASA Astrophysics Data System (ADS)

    Scarlat, Raluca Olga

    This dissertation treats system design, modeling of transient system response, and characterization of individual phenomena and demonstrates a framework for integration of these three activities early in the design process of a complex engineered system. A system analysis framework for prioritization of experiments, modeling, and development of detailed design is proposed. Two fundamental topics in thermal-hydraulics are discussed, which illustrate the integration of modeling and experimentation with nuclear reactor design and safety analysis: thermal-hydraulic modeling of heat generating pebble bed cores, and scaled experiments for natural circulation heat removal with Boussinesq liquids. The case studies used in this dissertation are derived from the design and safety analysis of a pebble bed fluoride salt cooled high temperature nuclear reactor (PB-FHR), currently under development in the United States at the university and national laboratories level. In the context of the phenomena identification and ranking table (PIRT) methodology, new tools and approaches are proposed and demonstrated here, which are specifically relevant to technology in the early stages of development, and to analysis of passive safety features. A system decomposition approach is proposed. Definition of system functional requirements complements identification and compilation of the current knowledge base for the behavior of the system. Two new graphical tools are developed for ranking of phenomena importance: a phenomena ranking map, and a phenomena identification and ranking matrix (PIRM). The functional requirements established through this methodology were used for the design and optimization of the reactor core, and for the transient analysis and design of the passive natural circulation driven decay heat removal system for the PB-FHR. A numerical modeling approach for heat-generating porous media, with multi-dimensional fluid flow is presented. The application of this modeling

  3. Pd-Ag Membrane Coupled to a Two-Zone Fluidized Bed Reactor (TZFBR) for Propane Dehydrogenation on a Pt-Sn/MgAl2O4 Catalyst

    PubMed Central

    Medrano, José-Antonio; Julián, Ignacio; Herguido, Javier; Menéndez, Miguel

    2013-01-01

    Several reactor configurations have been tested for catalytic propane dehydrogenation employing Pt-Sn/MgAl2O4 as a catalyst. Pd-Ag alloy membranes coupled to the multifunctional Two-Zone Fluidized Bed Reactor (TZFBR) provide an improvement in propane conversion by hydrogen removal from the reaction bed through the inorganic membrane in addition to in situ catalyst regeneration. Twofold process intensification is thereby achieved when compared to the use of traditional fluidized bed reactors (FBR), where coke formation and thermodynamic equilibrium represent important process limitations. Experiments were carried out at 500–575 °C and with catalyst mass to molar flow of fed propane ratios between 15.1 and 35.2 g min mmol−1, employing three different reactor configurations: FBR, TZFBR and TZFBR + Membrane (TZFBR + MB). The results in the FBR showed catalyst deactivation, which was faster at high temperatures. In contrast, by employing the TZFBR with the optimum regenerative agent flow (diluted oxygen), the process activity was sustained throughout the time on stream. The TZFBR + MB showed promising results in catalytic propane dehydrogenation, displacing the reaction towards higher propylene production and giving the best results among the different reactor configurations studied. Furthermore, the results obtained in this study were better than those reported on conventional reactors. PMID:24958620

  4. Pd-Ag Membrane Coupled to a Two-Zone Fluidized Bed Reactor (TZFBR) for Propane Dehydrogenation on a Pt-Sn/MgAl2O4 Catalyst.

    PubMed

    Medrano, José-Antonio; Julián, Ignacio; Herguido, Javier; Menéndez, Miguel

    2013-01-01

    Several reactor configurations have been tested for catalytic propane dehydrogenation employing Pt-Sn/MgAl2O4 as a catalyst. Pd-Ag alloy membranes coupled to the multifunctional Two-Zone Fluidized Bed Reactor (TZFBR) provide an improvement in propane conversion by hydrogen removal from the reaction bed through the inorganic membrane in addition to in situ catalyst regeneration. Twofold process intensification is thereby achieved when compared to the use of traditional fluidized bed reactors (FBR), where coke formation and thermodynamic equilibrium represent important process limitations. Experiments were carried out at 500-575 °C and with catalyst mass to molar flow of fed propane ratios between 15.1 and 35.2 g min mmol-1, employing three different reactor configurations: FBR, TZFBR and TZFBR + Membrane (TZFBR + MB). The results in the FBR showed catalyst deactivation, which was faster at high temperatures. In contrast, by employing the TZFBR with the optimum regenerative agent flow (diluted oxygen), the process activity was sustained throughout the time on stream. The TZFBR + MB showed promising results in catalytic propane dehydrogenation, displacing the reaction towards higher propylene production and giving the best results among the different reactor configurations studied. Furthermore, the results obtained in this study were better than those reported on conventional reactors. PMID:24958620

  5. A model of coal particle drying in fluidized bed combustion reactor

    SciTech Connect

    Komatina, M.; Manovic, V.; Saljnikov, A.

    2007-02-15

    Experimental and theoretical investigation on drying of a single coal particle in fluidized bed combustor is presented. Coal particle drying was considered via the moist shrinking core mechanism. The results of the drying test runs of low-rank Serbian coals were used for experimental verification of the model. The temperature of the coal particle center was measured, assuming that drying was completed when the temperature equalled 100{sup o}C. The influence of different parameters (thermal conductivity and specific heat capacity of coal, fluidized bed temperature, moisture content and superheating of steam) on drying time and temperature profile within the coal particle was analyzed by a parametric analysis. The experimentally obtained results confirmed that the moist shrinking core mechanism can be applied for the mathematical description of a coal particle drying, while dependence between drying time and coal particle radius, a square law relationship, implicates heat transfer control of the process and confirms the validity of assumptions used in modeling.

  6. Temperatures of coal particle during devolatilization in fluidized bed combustion reactor

    SciTech Connect

    Komatina, M.; Manovic, V.; Saljnikov, A.

    2006-11-15

    The purpose of this study was to investigate the thermal behavior of coal during devolatilization in fluidized bed. Temperatures in the center of single coal particle were measured by thermocouple. Two coals were tested (brown coal Bogovina and lignite Kosovo), using dry coal particle, shaped into spherical form of diameters 7 and 10 mm, in temperature range from 300 to 850{sup o}C. Unsteady behavior of coal particle during heating and devolatilization in fluidized bed was described by a model that takes into account heat transfer between bed and particle surface, heat transfer through particle and an endothermic chemical reaction of first-order. Based on the mathematical model analysis and compared with experimental results, values of heat conductivity {lambda}{sub C} and heat capacity (C-p) of coal were determined. The best agreement was obtained for constant thermal properties, for brown coal {lambda}{sub C} = 0.20 W/mK and C{sub p} = 1200 J/kgK and for lignite {lambda}{sub C} = 0.17 W/mK and C-p = 1100 J/kgK.

  7. Physicochemical characteristics and microbial community evolution of biofilms during the start-up period in a moving bed biofilm reactor.

    PubMed

    Zhu, Yan; Zhang, Yan; Ren, Hong-Qiang; Geng, Jin-Ju; Xu, Ke; Huang, Hui; Ding, Li-Li

    2015-03-01

    This study aimed to investigate biofilm properties evolution coupled with different ages during the start-up period in a moving bed biofilm reactor system. Physicochemical characteristics including adhesion force, extracellular polymeric substances (EPS), morphology as well as volatile solid and microbial community were studied. Results showed that the formation and development of biofilms exhibited four stages, including (I) initial attachment and young biofilm formation, (II) biofilms accumulation, (III) biofilm sloughing and updating, and (IV) biofilm maturation. During the whole start-up period, adhesion force was positively and significantly correlated with the contents of EPS, especially the content of polysaccharide. In addition, increased adhesion force and EPS were beneficial for biofilm retention. Gram-negative bacteria mainly including Sphaerotilus, Zoogloea and Haliscomenobacter were predominant in the initial stage. Actinobacteria was beneficial to resist sloughing. Furthermore, filamentous bacteria were dominant in maturation biofilm.

  8. High purity H2 by sorption-enhanced chemical looping reforming of waste cooking oil in a packed bed reactor.

    PubMed

    Pimenidou, P; Rickett, G; Dupont, V; Twigg, M V

    2010-12-01

    High purity hydrogen (>95%) was produced at 600 degrees C and 1 atm by steam reforming of waste cooking oil at a molar steam to carbon ratio of 4 using chemical looping, a process that features redox cycles of a Ni catalyst with the in-situ carbonation/calcination of a CO(2) sorbent (dolomite) in a packed bed reactor under alternated feedstreams of fuel-steam and air. The fuel and steam conversion were higher with the sorbent present than without it. Initially, the dolomite carbonation was very efficient (100%), and 98% purity hydrogen was produced, but the carbonation decreased to around 56% with a purity of 95% respectively in the following cycles. Reduction of the nickel catalyst occurred alongside steam reforming, water gas shift and carbonation, with H(2) produced continuously under fuel-steam feeds. Catalyst and CO(2)-sorbent regeneration was observed, and long periods of autothermal operation within each cycle were demonstrated.

  9. Functionalization of polymer powders for SLS-processes using an atmospheric plasma jet in a fluidized bed reactor

    SciTech Connect

    Sachs, Marius; Schmitt, Adeliene; Schmidt, Jochen; Peukert, Wolfgang; Wirth, Karl-Ernst

    2015-05-22

    Recently additive manufacturing processes such as selective laser sintering (SLS) of polymers have gained more importance for industrial applications [1]. Tailor-made modification of polymers is essential in order to make these processes more efficient and to cover the industrial demands. The so far used polymer materials show weak performance regarding the mechanical stability of processed parts. To overcome this limitation, a new route to functionalize the surface of commercially available polymer particles (PA12; PE-HD; PP) using an atmospheric plasma jet in combination with a fluidized bed reactor has been investigated. Consequently, an improvement of adhesion and wettability [2] of the polymer surface without restraining the bulk properties of the powder is achieved. The atmospheric plasma jet process can provide reactive species at moderate temperatures which are suitable for polymer material. The functionalization of the polymer powders improves the quality of the devices build in a SLS-process.

  10. KUGEL: a thermal, hydraulic, fuel performance, and gaseous fission product release code for pebble bed reactor core analysis

    SciTech Connect

    Shamasundar, B.I.; Fehrenbach, M.E.

    1981-05-01

    The KUGEL computer code is designed to perform thermal/hydraulic analysis and coated-fuel particle performance calculations for axisymmetric pebble bed reactor (PBR) cores. This computer code was developed as part of a Department of Energy (DOE)-funded study designed to verify the published core performance data on PBRs. The KUGEL code is designed to interface directly with the 2DB code, a two-dimensional neutron diffusion code, to obtain distributions of thermal power, fission rate, fuel burnup, and fast neutron fluence, which are needed for thermal/hydraulic and fuel performance calculations. The code is variably dimensioned so that problem size can be easily varied. An interpolation routine allows variable mesh size to be used between the 2DB output and the two-dimensional thermal/hydraulic calculations.

  11. Corn stalks char from fast pyrolysis as precursor material for preparation of activated carbon in fluidized bed reactor.

    PubMed

    Wang, Zhiqi; Wu, Jingli; He, Tao; Wu, Jinhu

    2014-09-01

    Corn stalks char from fast pyrolysis was activated by physical and chemical activation process in a fluidized bed reactor. The structure and morphology of the carbons were characterized by N2 adsorption and SEM. Effects of activation time and activation agents on the structure of activation carbon were investigated. The physically activated carbons with CO2 have BET specific surface area up to 880 m(2)/g, and exhibit microporous structure. The chemically activated carbons with H3PO4 have BET specific surface area up to 600 m(2)/g, and exhibit mesoporous structure. The surface morphology shows that physically activated carbons exhibit fibrous like structure in nature with long ridges, resembling parallel lines. Whereas chemically activated carbons have cross-interconnected smooth open pores without the fibrous like structure.

  12. Nox Reduction in a Fluidized Bed Reactor with Fe/ZSM-5 Catalyst and Propylene as Reductant

    NASA Astrophysics Data System (ADS)

    Yang, Terris; Bi, Xiaotao

    The performance of a fluidized bed catalytic reactor was investigated for NOx reduction using a Fe/ZSM-5 catalyst and propylene as the reducing agent. The effects of inlet NOx concentration, propylene to NOx molar ratio, flue gas oxygen concentration and fluidizing gas velocity on NOx conversion were studied using simulated flue gases. The results showed that the NOx conversion decreased with decreasing the inlet NOx concentration, and propylene to NOx molar ratio. The increase in flue gas oxygen concentration also imposed a significant negative impact. As the flue gas oxygen concentration increased, NOx reduction decreased while propylene conversion increased at a given propylene to NOx molar ratio, due to the oxidation of propylene in the presence of high oxygen concentration. The increase in fluidization gas velocity reduced the contact time between reactant and the catalyst particles due to the increased bubble size and bubble rise velocity. As a result, the NOx reduction decreased as the gas velocity increased.

  13. Analysis of the impact of random summing on passive assay of pebble bed reactor fuel using gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Chen, J.; Hawari, A. I.

    2007-08-01

    Pebble bed reactors (PBR) are characterized by multi-pass fuel systems in which spherical fuel pebbles are circulated through the core until they reach a proposed burnup limit. The fuel is assayed on-line to ensure that the burnup limit is not breached. However, random summing effects can impact the response of the burnup measurement system and result in distortions that degrade the accuracy of the assay results. Monte Carlo analysis was performed to estimate the magnitude and effect of random summing on the absolute and relative indicators that have been identified as usable in on-line assay. For a throughput rate of 10 5 counts/s and trapezoidal pulse shaping of the signals, the results show that absolute indicators suffer from severe distortions due to this effect. Relative indicators are found to be resistant to random summing with the deviation in the ratio of peak areas remaining less than 5-15% depending on pulse width.

  14. Fast pyrolysis of microalgae remnants in a fluidized bed reactor for bio-oil and biochar production.

    PubMed

    Wang, Kaige; Brown, Robert C; Homsy, Sally; Martinez, Liliana; Sidhu, Sukh S

    2013-01-01

    In this study, pyrolysis of microalgal remnants was investigated for recovery of energy and nutrients. Chlorella vulgaris biomass was first solvent-extracted for lipid recovery then the remnants were used as the feedstock for fast pyrolysis experiments using a fluidized bed reactor at 500 °C. Yields of bio-oil, biochar, and gas were 53, 31, and 10 wt.%, respectively. Bio-oil from C. vulgaris remnants was a complex mixture of aromatics and straight-chain hydrocarbons, amides, amines, carboxylic acids, phenols, and other compounds with molecular weights ranging from 70 to 1200 Da. Structure and surface topography of the biochar were analyzed. The high inorganic content (potassium, phosphorous, and nitrogen) of the biochar suggests it may be suitable to provide nutrients for crop production. The bio-oil and biochar represented 57% and 36% of the energy content of the microalgae remnant feedstock, respectively.

  15. Catalytic steam gasification of pig compost for hydrogen-rich gas production in a fixed bed reactor.

    PubMed

    Wang, Jingbo; Xiao, Bo; Liu, Shiming; Hu, Zhiquan; He, Piwen; Guo, Dabin; Hu, Mian; Qi, Fangjie; Luo, Siyi

    2013-04-01

    The catalytic steam gasification of pig compost (PC) for hydrogen-rich gas production was experimentally investigated in a fixed bed reactor using the developed NiO on modified dolomite (NiO/MD) catalyst. A series of experiments have been performed to explore the effects of catalyst, catalytic temperature, steam to PC ratio and PC particle size on the gas quality and yield. The results indicate that the NiO/MD catalyst could significantly eliminate the tar in the gas production and increase the hydrogen yield, and the catalyst lives a long lifetime in the PC steam gasification. Moreover, the higher catalytic temperature and smaller PC particle size can contribute to more hydrogen production and gas yield. Meanwhile, the optimal ratio of steam to PC (S/P) is found to be 1.24.

  16. Microbial community distribution and extracellular enzyme activities in leach bed reactor treating food waste: effect of different leachate recirculation practices.

    PubMed

    Xu, Su Yun; Karthikeyan, Obuli P; Selvam, Ammaiyappan; Wong, Jonathan W C

    2014-09-01

    This study aimed at understanding the relationship between microbial community and extracellular enzyme activities of leach bed reactor (LBR) treating food waste under different leachate recirculation practices (once per day and continuous) and liquid to solid (L/S) ratios (1:1 and 0.5:1). Microbial community analysis using PCR-DGGE revealed that Lactobacillus sp., Bifidobacter sp., and Proteobacteria were the most abundant species. Number of phylotypes was higher in LBRs with intermittent recirculation; whereas, lower number of phylotypes dominated by the key players of degradation was observed with continuous recirculation. The L/S ratio of 1:1 significantly enhanced the volatile solids removal compared with 0.5:1; however, this effect was insignificant under once a day leachate recirculation. Continuous leachate recirculation with 1:1 L/S ratio significantly improved the organic leaching (240 g COD/kgvolatile solid) and showed distinct extracellular enzyme activities suitable for food waste acidogenesis.

  17. Modeling the operation of a three-stage fluidized bed reactor for removing CO2 from flue gases.

    PubMed

    Mohanty, C R; Meikap, B C

    2011-03-15

    A bubbling counter-current multistage fluidized bed reactor for the sorption of carbon dioxide (CO(2)) by hydrated lime particles was simulated employing a two-phase model, with the bubble phase assumed to be in plug flow, and the emulsion phase in plug flow and perfectly mixed flow conditions. To meet prescribed permissible limit to emit carbon dioxide from industrial flue gases, dry scrubbing of CO(2) was realized. For the evaluation, a pilot plant was built, on which also the removal efficiency of CO(2) was verified at different solids flow rates. The model results were compared with experimental data in terms of percentage removal efficiency of carbon dioxide. The comparison showed that the EGPF model agreed well with the experimental data satisfactorily. The removal efficiency was observed to be mainly influenced by flow rates of adsorbent and CO(2) concentration. PMID:21255918

  18. High-nitrate wastewater treatment in an expanded granular sludge bed reactor and microbial diversity using 454 pyrosequencing analysis.

    PubMed

    Liao, Runhua; Shen, Ke; Li, Ai-Min; Shi, Peng; Li, Yan; Shi, Qianqian; Wang, Zhu

    2013-04-01

    Denitrification of high concentration of nitrate wastewater was investigated in expanded granular sludge bed (EGSB) reactor with sodium acetate as the carbon source. The optimal parameters were achieved with C/N mole ratio of 2.0, liquid up-flow velocity (Vup) of 3.0 m/h and pH of 6.2-8.2. Complete denitrification can be achieved even with nitrate nitrogen concentration as high as 14000 mg/L. Furthermore, 454-pyrosequencing technology was used to analyze bacterial diversity. Results showed that a total of 5573 sequences were obtained which could be affiliated to 6 phylogenetic groups, including Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, Chloroflexi and unclassified phylum. Proteobacteria (84.53%) was the dominant microbial population, followed by Firmicutes (13.24%) and Actinobacteria (0.38%). The dominate phylum was different from that in other anaerobic system. PMID:23500551

  19. Studies on the Role of Nitrogen in the Feed for Fischer-Tropsch Synthesis Under Fixed-Bed Reactor System.

    PubMed

    Hong, Gi Hoon; Jung, Jae-Sun; Kim, Na-Young; Lee, Sang Yong; Moon, Dong Ju

    2016-02-01

    In this study, Co/Al203 catalyst for Fischer-Tropsch synthesis was prepared via slurry impregnation method and the catalyst was characterized by various techniques such as TPR, XRD, TGA and N2 physisorption. To dissolve the wax, after-reaction catalyst was dewaxed using n-Hexane at 60 *C. The experiments were performed in a bench-scale fixed-bed reactor, under the reaction condition of 230 degrees C, 20 bar and feed volume ratio of H2:CO:N2 = 2:1:0.5-1.5. The methane selectivity and the ratio of olefin to paraffin among C2-C4 hydrocarbons were increased with higher contents of nitrogen in feed gas which result in higher partial pressure ratio of H2 to CO, and also affect methane selectivity which has a significant role in increased CO conversion. PMID:27433695

  20. New functional biocarriers for enhancing the performance of a hybrid moving bed biofilm reactor-membrane bioreactor system.

    PubMed

    Deng, Lijuan; Guo, Wenshan; Ngo, Huu Hao; Zhang, Xinbo; Wang, Xiaochang C; Zhang, Qionghua; Chen, Rong

    2016-05-01

    In this study, new sponge modified plastic carriers for moving bed biofilm reactor (MBBR) was developed. The performance and membrane fouling behavior of a hybrid MBBR-membrane bioreactor (MBBR-MBR) system were also evaluated. Comparing to the MBBR with plastic carriers (MBBR), the MBBR with sponge modified biocarriers (S-MBBR) showed better effluent quality and enhanced nutrient removal at HRTs of 12h and 6h. Regarding fouling issue of the hybrid systems, soluble microbial products (SMP) of the MBR unit greatly influenced membrane fouling. The sponge modified biocarriers could lower the levels of SMP in mixed liquor and extracellular polymeric substances in activated sludge, thereby mitigating cake layer and pore blocking resistances of the membrane. The reduced SMP and biopolymer clusters in membrane cake layer were also observed. The results demonstrated that the sponge modified biocarriers were capable of improving overall MBBR performance and substantially alleviated membrane fouling of the subsequent MBR unit.

  1. Linking nitrifying biofilm characteristics and nitrification performance in moving-bed biofilm reactors for polluted raw water pretreatment.

    PubMed

    Zhang, Shuangfu; Wang, Yayi; He, Weitao; Xing, Meiyan; Wu, Min; Yang, Jian; Gao, Naiyun; Sheng, Guangyao; Yin, Daqiang; Liu, Shanhu

    2013-10-01

    Biofilm physiology was characterized by four biofilm constituents, i.e., polysaccharides, proteins (PN), humic-like substances and phospholipids (PL), for the first time to explore the relationships between biofilm characteristics and nitrification performance in moving-bed biofilm reactors (MBBRs) designed for pretreatment of polluted raw surface water for potable supply. The biofilm compositions depended highly on the balance of microbial decay and nitrification processes. The increased ammonia loading greatly regulated the community structure, promoting the dominance of nitrifiers and their proportions in the nitrifying biofilm. Nitrification rate and activity correlated linearly with the fractions of volatile solids (VS), PN and PL, which were related to nitrification processes in the biofilm. The specific biofilm activity demonstrated an exponential-asymptotic relationship with ratios of PN/VS and PL/VS. Thus, analyzing biofilm characteristics can be valid for estimating nitrification performance in MBBRs, and may offer engineers with basis to optimize MBBR design and operation.

  2. Essential factors of an integrated moving bed biofilm reactor-membrane bioreactor: Adhesion characteristics and microbial community of the biofilm.

    PubMed

    Tang, Bing; Yu, Chunfei; Bin, Liying; Zhao, Yiliang; Feng, Xianfeng; Huang, Shaosong; Fu, Fenglian; Ding, Jiewei; Chen, Cuiqun; Li, Ping; Chen, Qianyu

    2016-07-01

    This work aims at revealing the adhesion characteristics and microbial community of the biofilm in an integrated moving bed biofilm reactor-membrane bioreactor, and further evaluating their variations over time. With multiple methods, the adhesion characteristics and microbial community of the biofilm on the carriers were comprehensively illuminated, which showed their dynamic variation along with the operational time. Results indicated that: (1) the roughness of biofilm on the carriers increased very quickly to a maximum value at the start-up stage, then, decreased to become a flat curve, which indicated a layer of smooth biofilm formed on the surface; (2) the tightly-bound protein and polysaccharide was the most important factor influencing the stability of biofilm; (3) the development of biofilm could be divided into three stages, and Gammaproteobacteria were the most dominant microbial species in class level at the last stage, which occupied the largest ratio (51.48%) among all microbes.

  3. Influence of carrier filling ratio on the performance of moving bed biofilm reactor in treating coking wastewater.

    PubMed

    Gu, Qiyuan; Sun, Tichang; Wu, Gen; Li, Mingyue; Qiu, Wei

    2014-08-01

    This study aims to evaluate the effect of carrier filling ratio on the performance of a moving bed biofilm reactor in degrading chemical oxygen demand, phenol, thiocyanate, and ammonia from coking wastewater at 20h of hydraulic retention time. The operational experiments under different carrier filling ratios ranging from 20% to 60% were investigated. The maximum removal efficiency of 89%, 99% and 99% for COD, phenol and thiocyanate, and minimum sensitivity to the increasing contaminants concentration in the influent were achieved at 50% carrier filling ratio. The Haldane competitive substrate inhibition kinetics model was used to describe the relationship between the oxygen uptake rate of ammonium oxidizers and the concentration of free ammonium. The highest biofilm microbial community functional diversity (Shannon's diversity index, H') and evenness (Shannon's evenness index, E') were obtained at 50% carrier filling ratio in all runs using a Biolog ECO microplate.

  4. Treatment of gas industry wastes using the biological granular activated carbon fluidized bed reactor process. Annual report, August 1994

    SciTech Connect

    Hickey, R.; Wagner, D.; Sunday, A.; Heine, B.; Rajan, R.

    1994-08-01

    The Granular Activated Carbon-Fluidized Bed Reactor (GAC-FBR) system is a high rate process that combines the advantages of biological and physical-chemical treatment in a single unit operation. The process is particularly well-suited to treatment of contaminants present in water and wastewater at relatively low concentrations. Process economics indicate the GAC-FBR can be extremely cost-effective compared to aqueous phase GAC adsorption and air stripping followed by vapor phase control. Accordingly, three field trials are scheduled for the next 18 months; one at a manufactured gas plant site (PAHs), one at a gas dehydration site (BTEX), and one to treat a chlorinated solvent (TCE) at a government installation.

  5. Removal of oxytetracycline (OTC) in a synthetic pharmaceutical wastewater by a sequential anaerobic multichamber bed reactor (AMCBR)/completely stirred tank reactor (CSTR) system: biodegradation and inhibition kinetics.

    PubMed

    Sponza, Delia Teresa; Çelebi, Hakan

    2012-01-01

    An anaerobic multichamber bed reactor (AMCBR) was effective in removing both molasses-chemical oxygen demand (COD), and the antibiotic oxytetracycline (OTC). The maximum COD and OTC removals were 99% in sequential AMCBR/completely stirred tank reactor (CSTR) at an OTC concentration of 300 mg L(-1). 51%, 29% and 9% of the total volatile fatty acid (TVFA) was composed of acetic, propionic acid and butyric acids, respectively. The OTC loading rates at between 22.22 and 133.33 g OTC m(-3) d(-1) improved the hydrolysis of molasses-COD (k), the maximum specific utilization of molasses-COD (k(mh)) and the maximum specific utilization rate of TVFA (k(TVFA)). The direct effect of high OTC loadings (155.56 and -177.78 g OTC m(-3) d(-1)) on acidogens and methanogens were evaluated with Haldane inhibition kinetic. A significant decrease of the Haldane inhibition constant was indicative of increases in toxicity at increasing loading rates.

  6. Treatment of cane sugar mill wastewater in an upflow anaerobic sludge bed reactor.

    PubMed

    Nacheva, P Mijaylova; Chávez, G Moeller; Chacón, J Matías; Chuil, A Canul

    2009-01-01

    The performance of a mesophilic UASB reactor was studied for the treatment of sugar cane mill wastewater previously pre-treated for solid separation. The experimental work was carried out in a reactor with 80 L total volume. Four organic loads were applied and the process performance was evaluated during two months for each experimental stage. Removal efficiencies higher than 90% were obtained with organic loads up to 16 kg COD m(-3) d(-1). Stable process performance and high biogas production were obtained. The COD removal rate increased substantially with the load increase to 24 kg COD m(-3) d(-1). However, the obtained removal was of only 78-82%, which can be attributed to the accumulation of volatile organic acids. The kinetic coefficients were obtained using first order model for the substrate removal rate and Monod's equation for bacteria specific growth rate. The UASB reactor is a good option for the biological treatment of pre-treated sugar cane mill wastewaters. The discharge requirements for COD concentration can be accomplished if the reactor is operated at a low organic load of 4 kg COD m(-3) d(-1). At higher loads, an additional biological treatment stage is needed.

  7. Application of a fluidized bed reactor charged with aragonite for control of alkalinity, pH and carbon dioxide in marine recirculating aquaculture systems

    USGS Publications Warehouse

    Paul S Wills, PhD; Pfeiffer, Timothy; Baptiste, Richard; Watten, Barnaby J.

    2016-01-01

    Control of alkalinity, dissolved carbon dioxide (dCO2), and pH are critical in marine recirculating aquaculture systems (RAS) in order to maintain health and maximize growth. A small-scale prototype aragonite sand filled fluidized bed reactor was tested under varying conditions of alkalinity and dCO2 to develop and model the response of dCO2 across the reactor. A large-scale reactor was then incorporated into an operating marine recirculating aquaculture system to observe the reactor as the system moved toward equilibrium. The relationship between alkalinity dCO2, and pH across the reactor are described by multiple regression equations. The change in dCO2 across the small-scale reactor indicated a strong likelihood that an equilibrium alkalinity would be maintained by using a fluidized bed aragonite reactor. The large-scale reactor verified this observation and established equilibrium at an alkalinity of approximately 135 mg/L as CaCO3, dCO2 of 9 mg/L, and a pH of 7.0 within 4 days that was stable during a 14 day test period. The fluidized bed aragonite reactor has the potential to simplify alkalinity and pH control, and aid in dCO2 control in RAS design and operation. Aragonite sand, purchased in bulk, is less expensive than sodium bicarbonate and could reduce overall operating production costs.

  8. Biodegradation of Methyl Orange by alginate-immobilized Aeromonas sp. in a packed bed reactor: external mass transfer modeling.

    PubMed

    Kathiravan, Mathur Nadarajan; Praveen, Siluvai Antony; Gim, Geun Ho; Han, Gui Hawn; Kim, Si Wouk

    2014-11-01

    Azo dyes are recalcitrant and xenobiotic nature makes these compounds a challenging task for continuous biodegradation up to satisfactorily levels in large-scale. In the present report, the biodegradation efficiency of alginate immobilized indigenous Aeromonas sp. MNK1 on Methyl Orange (MO) in a packed bed reactor was explored. The experimental results were used to determine the external mass transfer model. Complete MO degradation and COD removal were observed at 0.20 cm bead size and 120 ml/h flow rate at 300 mg/l of initial dye concentration. The degradation of MO decreased with increasing bead sizes and flow rates, which may be attributed to the decrease in surface of the beads and higher flux of MO, respectively. The experimental rate constants (k ps) for various beads sizes and flow rates were calculated and compared with theoretically obtained rate constants using external film diffusion models. From the experimental data, the external mass transfer effect was correlated with a model J D = K Re (-(1 - n)). The model was tested with K value (5.7) and the Colburn factor correlation model for 0.20, 0.40 and 0.60 bead sizes were J D = 5.7 Re (-0.15), J D = 5.7 Re (-0.36) and J D = 5.7 Re (-0.48), respectively. Based on the results, the Colburn factor correlation models were found to predict the experimental data accurately. The proposed model was constructive to design and direct industrial applications in packed bed reactors within acceptable limits.

  9. Effect of temperature, hydraulic residence time and elevated PCO2 on acid neutralization within a pulsed limestone bed reactor

    USGS Publications Warehouse

    Watten, B.J.; Lee, P.C.; Sibrell, P.L.; Timmons, M.B.

    2007-01-01

    Limestone has potential for reducing reagent costs and sludge volume associated with treatment of acid mine drainage, but its use is restricted by slow dissolution rates and the deposition of Fe, Al and Mn-based hydrolysis products on reactive surfaces. We evaluated a pulsed limestone bed (PLB) reactor (15 L/min capacity) that uses a CO2 pretreatment step to accelerate dissolution and hydraulic shearing forces provided by intermittent fluidization to abrade and carry away surface scales. We established the effects of hydraulic residence time (HRT, 5.1-15.9 min), temperature (T, 12-22 ??C) and CO2 tension (PCO2, 34.5-206.8 kPa) on effluent quality when inlet acidity (Acy) was fixed at 440 mg/L (pH=2.48) with H2SO4. The PLB reactor neutralized all H+ acidity (N=80) while concurrently providing unusually high levels of effluent alkalinity (247-1028 mg/L as CaCO3) that allow for side-stream treatment with blending. Alkalinity (Alk) yields rose with increases in PCO2, HRT and settled bed height (BH, cm) and decreased with T following the relationship (R2=0.926; p<0.001): (Alk)non-filtered=-548.726+33.571??(PCO2)0.5+33.671??(HRT)+7.734??(BH)-5.197??(T). Numerical modeling showed CO2 feed requirements for a target Alk yield decrease with increases in HRT, T and the efficiency of off-gas (CO2) recycling. ?? 2007 Elsevier Ltd. All rights reserved.

  10. A two-stage combined trickle bed reactor/biofilter for treatment of styrene/acetone vapor mixtures.

    PubMed

    Vanek, Tomas; Halecky, Martin; Paca, Jan; Zapotocky, Lubos; Gelbicova, Tereza; Vadkertiova, Renata; Kozliak, Evguenii; Jones, Kim

    2015-01-01

    Performance of a two-stage biofiltration system was investigated for removal of styrene-acetone mixtures. High steady-state acetone loadings (above C(in)(Ac) = 0.5 g.m(-3) corresponding to the loadings > 34.5 g.m(-3).h(-1)) resulted in a significant inhibition of the system's performance in both acetone and styrene removal. This inhibition was shown to result from the acetone accumulation within the upstream trickle-bed bioreactor (TBR) circulating mineral medium, which was observed by direct chromatographic measurements. Placing a biofilter (BF) downstream to this TBR overcomes the inhibition as long as the biofilter has a sufficient bed height. A different kind of inhibition of styrene biodegradation was observed within the biofilter at very high acetone loadings (above C(in)(Ac) = 1.1 g.m(-3) or 76 g.m(-3).h(-1) loading). In addition to steady-state measurements, dynamic tests confirmed that the reactor overloading can be readily overcome, once the accumulated acetone in the TBR fluids is degraded. No sizable metabolite accumulation in the medium was observed for either TBR or BF. Analyses of the biodegradation activities of microbial isolates from the biofilm corroborated the trends observed for the two-stage biofiltration system, particularly the occurrence of an inhibition threshold by excess acetone.

  11. The effect of Jatropha torrified biomass and coal preparation on steam co-gasification in a fixed bed reactor

    NASA Astrophysics Data System (ADS)

    Aloqaili, Mashal Mohammed

    Coal fired power stations produce vast amounts of harmful products that may affect our health and environment. Co-gasification of coal and biomass could be a solution to this issue as an emerging technology. Biomass may reduce emissions significantly and it may contribute to reducing capital operational cost while providing high gas yields. This research tests the co-gasification of coal and biomass blended chars. Coal and biomass were both prepared. Coal Illinois No #6 was prepared as coal semi-char and coal-char while Jatropha biomass was torrefied at six different temperatures ranging from [200-300] ºC. The co-gasification experiments was conducted in a fixed-bed reactor. A gasification temperature was 900 ºC and a constant flow rate of 100 mL/min. Carbon conversion, maximum char reactivity, products yield and amount of hydrogen produced were evaluated and studied based on data obtained from the G.C. Additionally, weight of bed material and ash leftover weight from gasification process were significantly contributed in calculating the carbon conversion percentages.

  12. Engine-cycle analysis for a particle-bed reactor nuclear rocket. Final report, May-Jul 90

    SciTech Connect

    Suzuki, D.E.

    1991-03-01

    This report addresses three candidate engine cycles for a particle bed nuclear rocket; bleed cycle with uncooled carbon - carbon composite nozzle; bleed cycle with regeneratively cooled Aluminum nozzle; expander cycle with regeneratively cooled Aluminum nozzle. The analysis was performed using the SALT System Analysis Language Translator code with the following amendments; particle bed reactor was modeled as a simple heater; a regeneratively cooled nozzle model was added which includes the heating of the coolant due to hot exhaust gases and nuclear heating of nozzle. The conclusion of the analysis were the topping cycle should be pursued for Mars missions and the bleed cycle should be pursued for OTV (Orbital Transfer Vehicle) missions. This study indicates that a regeneratively cooled aluminum nozzle can be sufficiently cooled to allow its use with a PBR rocket engine. This result is based on nozzle heating due to hot exhaust gases at a maximum chamber temperature and nuclear heating effects. The highest temperatures occur at the nozzle throat, where a composite or alloy coating could protect the aluminum. Further investigation of nozzle cooling should include modeling the nozzle with more nodes, and including more accurate dimensions for the nozzle wall thicknesses and coolant flow passages. The study also indicates that an expander cycle with a cooled aluminum nozzle can operate with a high pressure PBR at realistic TPA efficiencies. Further investigation should include the improvements to the regeneratively cooled nozzle model and more accurate performance maps for the TPA components.

  13. Improvement of hydrogen production via ethanol-type fermentation in an anaerobic down-flow structured bed reactor.

    PubMed

    Anzola-Rojas, Mélida del Pilar; Zaiat, Marcelo; De Wever, Heleen

    2016-02-01

    Although a novel anaerobic down-flow structured bed reactor has shown feasibility and stable performance for a long-term compared to other anaerobic fixed bed systems for continuous hydrogen production, the volumetric rates and yields have so far been too low. In order to improve the performance, an operation strategy was applied by organic loading rate (OLR) variation (12-96 g COD L(-1) d(-1)). Different volumetric hydrogen rates, and yields at the same OLR indicated that the system was mainly driven by the specific organic load (SOL). When SOL was kept between 3.8 and 6.2 g sucrose g(-1) VSS d(-1), the volumetric rates raised from 0.1 to 8.9 L H2 L(-1) d(-1), and the yields were stable around 2.0 mol H2 mol(-1) converted sucrose. Furthermore, hydrogen was produced mainly via ethanol-type fermentation, reaching a total energy conversion rate of 23.40 kJ h(-1) L(-1) based on both hydrogen and ethanol production.

  14. Local liquid velocity measurement in trickle bed reactors (TBRs) using the x-ray digital industrial radiography (DIR) technique

    NASA Astrophysics Data System (ADS)

    Anuar Mohd Salleh, Khairul; Lee, Hyoung Koo; Al-Dahhan, Muthanna H.

    2014-01-01

    This work describes the development of a new technique to measure local liquid velocity (VLL) for multiphase flows in trickle bed reactors (TBRs) (gas-liquid-solid system). In the studied TBR, the liquid phase is represented by water, gas by air and 3 mm expanded polystyrene beads as the solid packing. Three different superficial liquid velocities (VSL) and a constant superficial gas velocity (VSG) were used in the packed bed with an internal diameter of 4.25 cm. While the liquid is moving into the packed bed, tracking particles of 106-125 μm diameter (16.45% difference) are injected. The movement of the tracking particles is monitored and digitally recorded by a complementary metal-oxide-semiconductor detector. In this experiment, x-rays were used as the radiation source. Four replications were made with fresh packing. Comparable observations can be found from other published techniques (i.e. magnetic resonance imaging). Results from this study indicate that, at VSL = 0.13 cm s-1, the measured VLL can reach up to 51 times that of its VSL, while for VSL = 0.27 cm s-1, the measured VLL reached up to 35 times higher than the VSL and for VSL = 0.39 cm s-1, the VLL reached up to 39.8 times higher than its VSL. Through statistical analysis, the implementation of such a method is found to be reproducible throughout the experiments. The mean per cent difference in the measured VLL was 10% and 5% for lower implemented VSL of 0.13 and 0.27 cm s-1, respectively. At higher VSL (0.39 cm s-1), the particle tracer was greatly distributed and carried away by the high liquid flow rate. The variance or the range of the measured VLL does not vary for all replications in every VSL, which confirms the reproducibility of the experimental measurements, regardless of the VSL.

  15. Production of biohythane from food waste via an integrated system of continuously stirred tank and anaerobic fixed bed reactors.

    PubMed

    Yeshanew, Martha M; Frunzo, Luigi; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

    2016-11-01

    The continuous production of biohythane (mixture of biohydrogen and methane) from food waste using an integrated system of a continuously stirred tank reactor (CSTR) and anaerobic fixed bed reactor (AFBR) was carried out in this study. The system performance was evaluated for an operation period of 200days, by stepwise shortening the hydraulic retention time (HRT). An increasing trend of biohydrogen in the CSTR and methane production rate in the AFBR was observed regardless of the HRT shortening. The highest biohydrogen yield in the CSTR and methane yield in the AFBR were 115.2 (±5.3)L H2/kgVSadded and 334.7 (±18.6)L CH4/kgCODadded, respectively. The AFBR presented a stable operation and excellent performance, indicated by the increased methane production rate at each shortened HRT. Besides, recirculation of the AFBR effluent to the CSTR was effective in providing alkalinity, maintaining the pH in optimal ranges (5.0-5.3) for the hydrogen producing bacteria. PMID:27591517

  16. Biological removal of phenol from saline wastewater using a moving bed biofilm reactor containing acclimated mixed consortia.

    PubMed

    Nakhli, Seyyed Ali Akbar; Ahmadizadeh, Kimia; Fereshtehnejad, Mahmood; Rostami, Mohammad Hossein; Safari, Mojtaba; Borghei, Seyyed Mehdi

    2014-01-01

    In this study, the performance of an aerobic moving bed biofilm reactor (MBBR) was assessed for the removal of phenol as the sole substrate from saline wastewater. The effect of several parameters namely inlet phenol concentration (200-1200 mg/L), hydraulic retention time (8-24 h), inlet salt content (10-70 g/L), phenol shock loading, hydraulic shock loading and salt shock loading on the performance of the 10 L MBBR inoculated with a mixed culture of active biomass gradually acclimated to phenol and salt were evaluated in terms of phenol and chemical oxygen demand (COD) removal efficiencies. The results indicated that phenol and COD removal efficiencies are affected by HRT, phenol and salt concentration in the bioreactor saline feed. The MBBR could remove up to 99% of phenol and COD from the feed saline wastewater at inlet phenol concentrations up to 800 mg/L, HRT of 18 h and inlet salt contents up to 40 g/L. The reactor could also resist strong shock loads. Furthermore, measuring biological quantitative parameters indicated that the biofilm plays a main role in phenol removal. Overall, the results of this investigation revealed that the developed MBBR system with high concentration of the active mixed biomass can play a prominent role in order to treat saline wastewaters containing phenol in industrial applications as a very efficient and flexible technology. PMID:24616843

  17. Production of biohythane from food waste via an integrated system of continuously stirred tank and anaerobic fixed bed reactors.

    PubMed

    Yeshanew, Martha M; Frunzo, Luigi; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

    2016-11-01

    The continuous production of biohythane (mixture of biohydrogen and methane) from food waste using an integrated system of a continuously stirred tank reactor (CSTR) and anaerobic fixed bed reactor (AFBR) was carried out in this study. The system performance was evaluated for an operation period of 200days, by stepwise shortening the hydraulic retention time (HRT). An increasing trend of biohydrogen in the CSTR and methane production rate in the AFBR was observed regardless of the HRT shortening. The highest biohydrogen yield in the CSTR and methane yield in the AFBR were 115.2 (±5.3)L H2/kgVSadded and 334.7 (±18.6)L CH4/kgCODadded, respectively. The AFBR presented a stable operation and excellent performance, indicated by the increased methane production rate at each shortened HRT. Besides, recirculation of the AFBR effluent to the CSTR was effective in providing alkalinity, maintaining the pH in optimal ranges (5.0-5.3) for the hydrogen producing bacteria.

  18. Removal of COD and nitrogen from animal food plant wastewater in an intermittently-aerated structured-bed reactor.

    PubMed

    Wosiack, Priscila Arcoverde; Lopes, Deize Dias; Rissato Zamariolli Damianovic, Márcia Helena; Foresti, Eugenio; Granato, Daniel; Barana, Ana Cláudia

    2015-05-01

    This study evaluated the performance of a continuous flow structured-bed reactor in the simultaneous removal of total nitrogen (TN) and chemical oxygen demand (COD) in the effluent from an animal food plant. The reactor had an intermittent aeration system; hydraulic retention time (HRT) of one day; temperature of 30 °C; and recirculation ratio of five times the flow. An experimental central composite rotational delineation (CCRD) type design was used to define the aeration conditions and nitrogen load (factors) to be studied. Response surface methodology was used to analyse the influence of the factors above the results, the removal of TN and COD. It was observed that the aeration factor showed the greatest significance for the results and that the affluent TKN concentration did not have a significant effect, at a 95% level of confidence, on COD removal. Throughout the experiment, the COD/N ratio remained between 3.2 and 3.8. The best results for COD and TN removal, 80% and 88%, respectively, were obtained with 158 min of aeration on a cycle of 180 min and 255 mg L(-1) of Total Kjeldahl Nitrogen (TKN) in the substrate.

  19. Deammonification process start-up after enrichment of anammox microorganisms from reject water in a moving-bed biofilm reactor.

    PubMed

    Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Kroon, Kristel; Vabamäe, Priit; Salo, Erik; Loorits, Liis; Rubin, Sergio S C dC; Vlaeminck, Siegfried E; Tenno, Taavo

    2013-01-01

    Deammonification via intermittent aeration in biofilm process for the treatment of sewage sludge digester supernatant (reject water) was started up using two opposite strategies. Two moving-bed biofilm reactors were operated for 2.5 years at 26 (+/- 0.5 degree C with spiked influent(and hence free ammonia (FA)) addition. In the first start-up strategy, an enrichment of anammox biomass was first established, followed by the development of nitrifying biomass in the system (R1). In contrast, the second strategy aimed at the enrichment of anammox organisms into a nitrifying biofilm (R2). The first strategy was most successful, reaching higher maximum total nitrogen (TN) removal rates over a shorter start-up period. For both reactors, increasing FA spiking frequency and increasing effluent concentrations of the anammox intermediate hydrazine correlated to decreasing aerobic nitrate production (nitritation). The bacterial consortium of aerobic and anaerobic ammonium oxidizing bacteria in the bioreactor was determined via denaturing gel gradient electrophoresis, polymerase chain reaction and pyrosequencing. In addition to a shorter start-up with a better TN removal rate, nitrite oxidizing bacteria (Nitrospira) were outcompeted by spiked ammonium feeding from R1.

  20. Anaerobic co-digestion of vegetable waste and swine wastewater in high-rate horizontal reactors with fixed bed.

    PubMed

    Mazareli, Raissa Cristina da Silva; Duda, Rose Maria; Leite, Valderi Duarte; Oliveira, Roberto Alves de

    2016-06-01

    Considering the high waste generation that comes from agriculture and livestock farming, as well as the demand for natural gas, it is necessary to develop sustainable technologies which can reduce environmental impact. There is no available literature on the use of high-rate horizontal anaerobic reactors with fixed bed (HARFB) and continuous feed for the co-digestion of vegetable wastes (VW) and swine wastewater (SW). The aim of this work was to evaluate the reactor performance in terms of methane production, organic matter consumption, and removal of total and thermotolerant coliforms under different proportions of SW and VW, and organic loading rates (OLR) of 4.0, 5.2 and 11.0g COD (Ld)(-)(1). The mixture of SW and VW in the proportions of 90:10, 80:20 and 70:30 (SW:VW) with those OLRs provided great buffering capacity, with partial alkalinity reaching 3552mgL(-1), thereby avoiding the inhibition of methane production by volatile fatty acids produced during the fermentation process. Higher proportions of VW and higher OLR improved volumetric methane production with a maximum value of 1.08LCH4 (Ld)(-)(1), organic matter removal rates up to 98% and total and thermotolerant coliform removal rates of 99% were also observed. PMID:27055364