Biofuel technology seems to be a promising method for economically and environmentally prospective treatments of lignocellulosic wastes from various branches like food processing, forestry, or agriculture. Factors like the lignin content, crystallinity of cellulose, and particle size, limit the digestibility of hemicellulose and cellulose present in lignocelluloses. Biomass size reduction is a mechanical treatment process which due to increasing of the accessible surface area and decreasing of cellulose crystallinity improves the digestibility and the conversion of saccharides during hydrolysis. Informations about equipment design parameters and energy requirements are reviewed in relation to initial and final particle sizes, bulk density, and moisture content in biomass.
In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), as a result of exposure to organic solvents, are summarized. Applications of organic solvents as a carbon source for microalgal growth and production of target molecules are discussed. Possible implementation of various industrial effluents containing organic solvents into microalgal cultivation media, is evaluated. The effect of organic solvents on extraction of target compounds from microalgae is also considered. Techniques for lipid and carotenoid extraction from viable microalgal biomass (milking methods) and dead microalgal biomass (classical methods) are depicted. Moreover, the economic survey of lipid and carotenoid extraction from microalgae biomass, by means of different techniques and solvents, is conducted.
This paper presents an analysis of hydrodynamics in a tank with a 45° and 60° pitched blade turbine impeller operating while emptying the mixer and with an axial agitator working during axial pumping-down of water at different water levels above the impeller. Measurements made with the PIV method confirmed the change in direction of pumping liquid after the level dropped below the critical value, with an almost unchanged liquid stream flowing through the mixer. It was found that an increase in the value of the tangential velocity in the area of the impeller took place and the quantity of this increase depended on the angle of the blade pitch and the rotational frequency of the impeller. Change in this velocity component increased the mixing power.
Carboxymethylcellulose (CMC) and ultrasound gel (USG) seem to be suitable clear model fluids to substitute real ultra-high-performance concretes (UHPCs), enabling experimental monitoring of events occurring within these mixtures at similar flow behaviour. USG is eligible for UHPC mixtures with significant yield stress. CMC having a suitable concentration is better for UHPCs exhibiting indistinct yield stress. The rheological behaviour of real UHPC mixtures as well as substituting model fluids was measured using a non-standard system consisting of a vessel stirred by an anchor or a screw agitator. In addition, a standard rotational rheometer system with concentric cylinder geometry was used for optimization of the above-mentioned method of measurement and also for measuring the rheological parameters of the substituting model fluids. This article deals with the methodology for measuring the rheological properties of these substances and presents the results of the measurements using flow curves and rheological models.
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