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Laboratory Reactor (laboratory + reactor)
Selected AbstractsThe formation of spores in biofilms of Anoxybacillus flavithermusJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2009S.A. Burgess Abstract Aims:, To examine the rate and the extent of spore formation in Anoxybacillus flavithermus biofilms and to test the effect of one key variable , temperature , on spore formation. Methods and Results:, A continuous flow laboratory reactor was used to grow biofilms of the typical dairy thermophile A. flavithermus (strain CM) in skim milk. The reactor was inoculated with either a washed culture or a spore suspension of A. flavithermus CM, and was run over an 8·5 h period at three different temperatures of 48, 55 and 60°C. Change in impedance was used to determine the cell numbers in the milk and on the surface of the stainless steel reactor tubes. The biofilm developed at all three temperatures within 6,8 h. Spores formed at 55 and 60°C and amounted to approx. 10,50% of the biofilm. No spores formed at 48°C. Conclusions:, The results suggest that both biofilm formation and spore formation of A. flavithermus can occur very rapidly and simultaneously. In addition, temperature variation has a considerable effect on the formation of spores. Significance and Impact of the Study:, This information will provide direction for developing improved ways in which to manipulate conditions in milk powder manufacturing plants to control biofilms and spores of A. flavithermus. [source] Effect of culturing processes and copper addition on laccase production by the white-rot fungus Fomes fomentarius MUCL 35117LETTERS IN APPLIED MICROBIOLOGY, Issue 1 2009M. Neifar Abstract Aim:, To produce high laccase activities from the white-rot fungus Fomes fomentarius. Methods and Results:, Different culturing methods, viz, cell immobilization on stainless steel sponges and plastic material and solid-state fermentation (SSF) using wheat bran as substrate were used for laccase production by the white-rot fungus F. fomentarius. The SSF study expresses the highest laccase activities, nearly to 6400 U l,1 after 13 days of laboratory flasks cultivation. When the wheat bran medium was supplemented with 2 mmol l,1 copper sulfate, laccase activity increased by threefold in comparison to control cultures, reaching 27 864 U l,1. With the medium thus optimized, further experiments were performed in a 3 l fixed-bed bioreactor (working volume 1·5 l) leading to a laccase activity of about 6230 U l,1 on day 13. Conclusions:, The results obtained clearly showed the superiority of wheat bran for laccase production over stainless steel sponges and plastic material. Supplementing the wheat bran solid medium with 2 mmol l,1 copper sulfate allowed obtaining high activities at flask scale. The system was scaled to fixed-bed laboratory reactor. Significance and Impact of the Study:, The high enzyme production along with the low-cost of the substrate, showed the suitability of the system F. fomentarius, SSF for industrial purposes. [source] Reactive processing of syndiotactic polystyrene with an epoxy/amine solvent systemMACROMOLECULAR SYMPOSIA, Issue 1 2003Jaap Schut Abstract Syndiotactic polystyrene (sPS) is a new semi-crystalline thermoplastic which is believed to fill the price-performance gap between engineering and commodity plastics. In order to reduce the high processing temperature of sPS (>290°C), an epoxy-amine model system was used as a reactive solvent. Such a processing aid can be used to achieve a 50 to 500 fold lowering of the melt viscosity. When initially homogeneous solutions of sPS in a stoechiometric epoxy-amine mixture are thermally cured, Reaction Induced Phase Separation (RIPS) takes place, leading to phase separated thermoplastic-thermoset polymer blends. We focus our study on low (wt% sPS < 20%) and high concentration blends (wt% sPS > 60%) prepared by two processing techniques (mechanical stirring in a laboratory reactor or internal mixer/ reactive extrusion respectively). These blends have different potential interests. Low concentration blends (sPS domains in an epoxy-amine matrix) are prepared to create new, tunable blend morphologies by choosing the nature of the phase separation process, i.e. either crystallisation followed by polymerization or polymerization followed crystallisation. High concentration blends (sPS matrix containing dispersed epoxy-amine particles after RIPS) are prepared to facilitate the extrusion of sPS. In this case, the epoxy amine model system served as a reactive solvent. The time to the onset of RIPS is in the order of 7-9 min for low concentration blends, while it increases to 20-45 min for high concentration samples, as the reaction rates are substantially slowed down due to lower epoxy and amine concentrations. During the curing reaction the melting temperature of sPS in the reactive solvent mixture evolves back from a depressed value to the level of pure sPS. This indicates a change in the composition of the sPS phase, caused by (complete) phase separation upon reaction. We conclude that our epoxy amine system is suited for reactive processing of sPS, where final properties depend strongly on composition and processing conditions. [source] Experimental and Numerical Studies of Fe2O3 Particle Formation Processes in a Flat Flame BurnerCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2007M. Beck Abstract Particle formation processes are of interest for many industrial applications. This work focuses on investigating Fe2O3 particle formation. The particles form during thermal decomposition of an iron chloride solution in so-called spray roasting reactors. To analyze the reaction process, a laboratory reactor was designed which reproduces the conditions required for a systematic study of the particle formation process. Furthermore, a simplified particle conversion model was developed to simulate the realistic geometries and particle numbers on an industrial scale by CFD codes. [source] Integrating laccase,mediator treatment into an industrial-type sequence for totally chlorine-free bleaching of eucalypt kraft pulpJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2006David Ibarra Abstract Enzymatic delignification using the high-redox potential thermostable laccase from the fungus Pycnoporus cinnabarinus and a chemical mediator (1-hydroxybenzotriazole) was investigated to improve totally chlorine-free (TCF) bleaching of Eucalyptus globulus kraft pulps. Different points of incorporation of the enzyme treatment into an industrial-type bleaching sequence (consisting of double oxygen, chelation and peroxide stages) were investigated in pressurized laboratory reactors. The best final pulp properties were obtained using an OOLQPoP sequence, where a laccase,mediator stage (L) was incorporated between double oxygen and chelation. The worse results, when the enzymatic and chelation treatments were combined in a unique stage, seemed related to partial inhibition of laccase-mediator activity by the chelator. The new TCF sequence including the laccase stage permitted to improve eucalypt pulp delignification to values around kappa 5 (hexenuronic acid contribution over 50%) compared to kappa 7 using only TCF chemical reagents. In a similar way, the final brightness obtained, over 91% ISO, was 3,4 points higher than that obtained in the chemical sequences. Although technical and economic issues are to be solved, the results obtained show the feasibility of integrating a laccase,mediator treatment into a TCF sequence for bleaching eucalypt kraft pulp. Copyright © 2006 Society of Chemical Industry [source] Regioselective Enzymatic Diol Esterification in Batch and Fixed-Bed Adsorptive Reactors: Experiments and ModelingBIOTECHNOLOGY PROGRESS, Issue 4 2000Cristiano Migliorini The dynamic behavior of batch and fixed-bed adsorptive reactors is studied for the enzyme-catalyzed regioselective esterification of propionic acid and 2-ethyl-1,3-hexanediol in hexane. The reaction is equilibrium-limited with an apparent equilibrium constant of 0.6 ± 0.1 at 22 °C. Moreover, accumulation of water produced in the reaction onto the biocatalyst causes a decrease in the catalytic activity. As a result, improvements in both reaction rate and final conversion can be achieved by operating in an adsorptive-reactor mode. Control of water in the reactor is achieved with a catalytically inert ion-exchange resin in Na-form. The resin prevents an excessive accumulation of water on the biocatalyst and reduces equilibrium limitations. The thermodynamic activity of water is identified as a key parameter for the design of such reactors. A mathematical model capable of predicting the water activity as a function of the varying concentrations of reactants and products is thus developed and found to successfully predict the experimental behavior observed in laboratory reactors. Substantial improvements in performance predicted by the model are seen experimentally in batch reactions and during the transient operation of continuous-flow fixed-bed reactors combining adsorptive and catalytic functions. [source] | |||||||||||||