Janusz J. Malinowski

Two-phase partitioning bioreactors in fermentation technology.

The two-phase partitioning bioreactor concept appears to have a great potential in enhancing the productivity of many bioprocesses. The proper selection of an organic solvent is the key to successful application of this approach in industrial practice. The integration of fermentation and a primary product separation step has a positive impact on the productivity of many fermentation processes. The controlled substrate delivery from the organic to the aqueous phase opens a new area of application of this strategy to biodegradation of xenobiotics. In this review, the most recent advances in the application of two-liquid phase partitioning bioreactors for product or substrate partitioning are discussed. Modeling and performance optimization studies related to those bioreactor systems are also reviewed.

Evaluation of liquid extraction potentials for downstream separation of 1,3-propanediol

The application of liquid-liquid extraction for the downstream separation of 1,3-propanediol from dilute aqueous solutions has been tested. Preliminary solvent screening was performed using the group contribution method. Experimental verification of the predictions revealed that the distribution of 1,3-propanediol into organic solvents is not good enough to make simple extraction efficient.

Reactive Extraction for Downstream Separation of 1,3-Propanediol

The downstream separation of 1,3‐propanediol from dilute aqueous solution was studied. A process combining reversible reaction of 1,3‐propanediol with acetaldehyde to 2‐methyl‐1,3‐dioxane and a simultaneous extraction of the product by organic solvent appears to be technically feasible and attractive. The dioxane yield was 91−92%, the overall conversion of 1,3‐propanediol was ca. 98%, and recovery of dioxane into the organic extractant was 75%.

Continuous fermentation of high-strength glucose feeds to ethanol

SummaryAqueous feeds of 413 and 495 g/L glucose were fermented to ethanol at 90–95% conversion in a continuous flow extractive fermentation system with cell recycle. Compared to the continuous conventional fermentation of a 195 g/L glucose medium, the volumetric productivity was more than doubled in extractive mode, with no deleterious effects on cell viability, specific glucose consumption rate or ethanol yield. The use of an effective, biocompatible and stable in situ extractant with flash vaporization can also produce a concentrated ethanol vapour stream, reducing distillation costs of the product.

Drag and mass transfer in multiple drop slow motion in a power law fluid

Abstract Upper and lower bounds on the drag coefficient for a swarm of drops or bubbles moving in a power law fluid are obtained using variational principles and a free surface cell model. The effects of a wide range of shear thinning, holdup and viscosity parameters on the drag and mass transfer rate are discussed. Recently published predictions of the approximate analytical solution are found to be reasonable if shear thinning behaviour is not pronounced.

Potentials and Prospects for Application of Supercritical Fluid Technology in Bioprocessing

Abstract Recent investigations on the application of supercritical (SC) fluid technology in bio- and food chemistry are reviewed. The gas-antisolvent crystallization and rapid expansion of SC fluid emerge as attractive methods for micron-size particle formation. Also gaining ground is enzymic catalysis in SC CO 2 , which offers the possibility of integrated synthesis-product recovery processes. These processes, successfully tested on a laboratory scale, need further scale-up and optimization. Supercritical CO 2 has proven to be unfriendly, or even toxic, for living microorganisms, which precludes direct fermentation in dense CO 2 but does not rule out other useful applications.

Thermostability and esterification activity ofMucor javanicus lipase entrapped in silica aerogel matrix and in organic solvents

The lipase ofMucor javanicus (nowM. circinelloides) entrapped in silica matrix by the sol-gel method esterified primary and secondary alcohols with conversions ranging from 30 to 35% and 10 to 15%, respectively. Loss in activity of the preparations after incubation at 100°C for 1 h with petroleum ether, dodecane, 1-heptanol or oleyl alcohol was about half of that observed for the native lipase.

DRAG AND MASS TRANSFER IN SLOW NON-NEWTONIAN FLOWS OVER AN ENSEMBLE OF NEWTONIAN SPHERICAL DROPS OR BUBBLES

An approximate solution for the slow motion of an ensemble of spherical drops through a power law fluid is obtained using Happels free-surface cell model. It is shown that the drag coefficient decreases with decrease of the flow index and that this reduction is more significant at low voidage and large viscosity ratio parameter. The effect of the pseudoplastic anomaly on the mass transfer rate is more pronounced at low voidage for large values of viscosity ratio parameter, unlike the case of a single spherical drop The present analysis covers the whole range of values of viscosity ratio parameter from infinity (an assemblage of solid spheres) to zero (a swarm of bubbles) and reduces to the solutions for those cases already known The results for the motion of an ensemble of spherical drops also provide the basis for proposing a tentative expression for the expansion of liquid-liquid fluidized bed at low Reynolds number.

Transient mass and heat transfer from drops or bubbles in slow non-Newtonian flows

Abstract A theoretical analysis of transient mass (heat) transfer to or from liquid droplets or gas bubbles into a power-law or a Carreau fluid is carried out, and the effects of holdup, shear thinning and elastic properties are discussed. A modified form of the Chao criterion is derived, from which the condition for steady-state transfer can be simply determined.

Structure analysis of nanocrystalline MgO aerogel prepared by sol-gel method

Wet gel obtained by sol-gel technique was dried in supercritical CO2 to prepare hydrated form of magnesium oxide. Calcination at 723 K under vacuum yielded nanocrystalline MgO aerogel. Structure studies were performed by X-ray diffraction, scanning and transmission electron microcopies. Electron microscopy images reveal rough, unfolded and ramified structure of solid skeleton. Specific surface area SBET was equal to 238 m2/g. X-ray pattern reveals the broadened diffraction lines of periclase, the only crystalline form of magnesium oxide. The gamma crystallite size distribution was determined using FW 5 4 / 5 1 M method proposed by R. Pielaszek. The obtained values of and σ (measure of polydispersity) of particle size parameters are equal to 6.5 nm and 1.8 nm, respectively, whereas the average crystallite size estimated by Williamson-Hall procedure was equal to 6.0 nm. The obtained at Rietveld refinement Rwp, and S fitting parameters equal to 6.62% and 1.77, respectively, seem to be satisfactory due to the nanosize of MgO crystallites and because of the presence of amorphous phase.