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The scarce oil supplies and the emissions of gases of greenhouse effect have caused the interest in production and utilization of lignocellulosic bioethanol. This can substitute partially or totally the fossil fuels. The stages of pretreatment and enzymatic hydrolysis are the most expensive. Different pretreatments have been studied for ethanol production from these materials. Their results depend on the method characteristics and on biomass used. The agroindustrial wastes present a composition with possibilities of being evaluated like raw material for bioethanol production. In the present research, the pretreatment stages with Ultrasound and Ozone are studied, in order to decrease the lignin content and to increase the performance of the fermentative sugars in the lignocellulosic wastes (rice hull and dark tobacco vein). In the first pretreatment procedure, time and waste type were studied and in the second stage, the ozone concentration, waste type and moisture content were the studied variables. A combined procedure was applied to the best preliminary results. It is demonstrated that a decrease in the lignin concentration and the structural transformation of the materials under consideration come true. The best results were gotten for the rice hulls. [ABSTRACT FROM AUTHOR]

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This paper presents the ozonization evaluation of a secondary effluent. Parameters of reactor design as the value of the initial demand and the kinetic constant of consumption of ozone were determined. The obtained values were 1,6 mg/L and 0,192 min-1 respectively. As well as, ozone effluent disinfection was evaluated to determine the most appropriate operation conditions, to guarantee a sure disinfection and to diminish the environmental impact. The ozonization effect on the quality effluent parameters was evaluated. They were chemistry oxygen demand, the absorbance value to 254 nm, conductivity, pH, biochemical oxygen demand and total suspended solids total. The ozone disinfection was very effective for the inactivation of total and fecal coliforms with a Ct of 5 mg.min/L. On the other hand, the secondary effluent was inoculated with a concentration of 3,4 x 10² UFC/mL of Pseudomonas aeruginosa, to simulate a potential contamination. This pathogen microorganism is frequent in this wastewater and it is resistant to the chloration. The results indicated that a dose of 7 mg/L during 5 minutes is enough. The ozone reduces the environmental impact as disinfection stage, since the high chlorine doses generate residual concentrations higher than 3 mg/L. Which is not desirable and it constitutes an ecological risk for the population health, that is supplied of the water receiver body. A design of the contact system was proposed. The chlorination tank can be used as ozonization reactor with a minimum of modifications. The investment costs can be reduced. This diminishes the investment cost for construction cost reduction. A bubble reactor with double baffles is proposed. It is composed by two mixing chambers. The countercurrent contact among the phases is guaranteed. In the third chamber ozone is not injected. The double baffles are recommended to avoid the short circuit effect. [ABSTRACT FROM AUTHOR]

The domestic ozonizers are equipments of reduced size that can be used to obtain small volumes of microbiological high quality drinking water. With the use of this ozonizers it is not necessary to boil water or to consume bottled water. In the Ozone Research Center of Cuba, a line of domestic ozonizers that gives a local solution for drinking water treatment was designed, built and evaluated. The current work deals with the evaluation of the main parameters that characterize the performance of these equipments. They were evaluated in winter and summer, to consider the temperature and humidity variations of Cuban tropical climate. This evaluation included the control of their operation conditions: water pressure, water and gas flows, continuous operation time and gas and liquid ozone concentration as mean parameters. Finally microbiological tests for water quality were carried out. The best operation conditions were: inlet water pressure in the equipment: 1 kg/cm², water flow: 1 L/min, ozone concentration in water: higher than 0.3 mg/L, time of the continuous operation: 10 min, time before the equipment can be turned on again: 15 min. The equipment under these conditions was capable of eliminating high concentrations of different kinds of microorganisms in the water. [ABSTRACT FROM AUTHOR]

The study was performed in a gas-liquid stirred reactor. The knowledge of flow residence time distribution inside the reactor, allows the prediction of its behavior. This information can be obtained by the application of the stimulus-response experimental method. This is the main objective of this study. So in order to characterize the flow patterns though the stirred reactor, it was necessary to perform a tracer test. This test for the determination of the residence time distribution with the use of sodium chloride as a tracer was carried out. Eθ f(θ) curves at different gas flow, liquid flow and agitation speed were obtained. The minimum agitation speed, which guarantees good gas dispersion into the liquid phase, was determined; the value obtained was 420 r/min . The model that adequately represents the flow pattern of the liquid phase was the one of well mixed reactor. The flow pattern of the liquid phase into the reactor was adequately represented by the well mixed reactor model. Moreover, the absence of dead zones and short-circuiting starting from the analysis of the fundamental parameters of the applied hydrodynamic pattern was verified. These parameters characterize the mean residence time distribution for each experimental condition. They are the theoretical and experimental mean time of residence and the variance that indicates the width of the distribution. Finally model proposed by Cholette-Cloutier to corroborate the flow pattern proposed was used. [ABSTRACT FROM AUTHOR]

The pharmaceutical industry is a great consumer of high quality water, which must fulfill severe specifications concerning chemical impurities and endotoxins. In the present work, an industrial installation was built and operation parameters were searched for a high quality water production process by ozone refining treatment. In the design and building of ozonation system, and also in the techniques and procedures for the quality control assurance of the process and the final product, GMP, GLP and up-to-date Pharmacopeia were taken into account. Tap water previously treated to obtain purified water with suitable values of initial conductivity was employed for ozonation. Different ozone concentrations in the gas and in the liquid, liquid flows and the effect of ultraviolet light were assayed. A flow diagram description of the ozonation process is presented. A challenge to the system was conducted in which endotoxins were inoculated into the purified water. The effect of ozonation treatment on endotoxin content was determined. It was shown that, starting with water with good initial conductivity and by an ozonation polishing process it is possible to industrially produce high quality water for pharmaceutical use, which fulfills the international standards. A preliminary analysis showed the economic feasibility of this process compared to another where distillation is employed as a final step. [ABSTRACT FROM AUTHOR]