PHENOMENA OF MEMBRANE

Author: RODRIGUEZ GRAU ESTEBAN LUIS.
Year: 2004.
University: POLITÉCNICA DE CATALUÑA [www.upc.edu].
Place of defense: INSTITUT POLITÈCNIC DEL CAMPUS DE TERRASSA..
Place of preparation: ETSEIB, EDIFICI H PLANTA 10 Campus SUD.

Summary: The processes of liquid filtration using membranes have gained considerable acceptance for the past 10 years. This development has been driven by a significant legal pressure on Europe and the USA, since they are looking for a reduction of turbidity, chemical disinfection of the water, and disinfection by-products. From the perspective of industry, many separation processes effluent previously used chemical processes (eg flocculation, precipitation) or physical (eg centrifugation) have found in the processes of filtration membrane of an alternative operating simplicity, which allows construction stages or modules, which can offer an improvement in the quality of products produced, not being subjected to aggressive or polluting processes on the product. Furthermore, the operation of the art filtration membrane is normally kind of tangentially, which involves low energy consumption. Similarly, in the field of water treatment, whether in kind or residual purification, today the processes of filtration life provide tertiary treatment with which it is possible to advance in the preservation of the environment, especially in countries where water is a scarce commodity, as is the case with the countries bordering the Mediterranean Sea. However, the current high cost of the membranes in general, and in particular the ceramic membranes, is its main drawback as an alternative treatment fluids. This high cost in the case of ceramic membranes is based on its manufacturing process, which requires sintering temperatures above 1.800Â ° C. This is why the membrane technology has been designed primarily to the treatment and recovery of products with high added value. Through this study has been carried out an investigation which has sought to develop a methodology for manufacture and testing of ceramic membranes for micro and ultrafiltration tangential low-cost, designed for that purpose water treatment. This methodology, which is based on the use of conventional materials and manufacturing to a maximum temperature of between 1,250 and 1.400Â ° C, has seen a complete development, namely: the theoretical formulation of the membranes, selection and procurement of raw materials and equipment needed for their manufacture, the manufacture of membranes, testing quality control of manufactured membranes (morphology, chemical resistance tests, determination of porosity) and pilot plant tests in both laboratory (testing yields filtration), as in a real application (control performance and quality of the filtrate). The specific application that was tested corresponded to the water filtration in a pre drinking water treatment plant in Barcelona, obtaining substantial reductions in turbidity and content of particles in the treated water. Importantly, the development of this study has considered the potential subsequent implementation of the methodology for industrial-scale manufacture locally, which includes the outline of an industrial plant for the manufacture of low-cost ceramic membranes. Finally, it is also understood that the technology proposed to be a contribution to environmental sustainability, since with a significant reduction in costs would implement tertiary treatment of wastewater where costs are prohibitive current implementation.

Author: Pérez Bruzón Rodolfo Naoigt.
Year: 2004.
University: ZARAGOZA [www.unizar.es].
Place of defense: Universidad de Zaragoza.
Place of preparation: Universidad de Zaragoza.

Summary: Experiments have been conducted in neurons of the lymph cerebroideos Helix aspersa. They have been used: 1) techniques and electron microscopy conventional histology for morphological characterization of the system under study; 2) techniques inmunocitoquimia for the characterization of proteins that ion channels expressed in neurons of Helix aspersa, 3) techniques electrophysiology to obtain records bioeléctricos from single neurons in real time and to study the responses induced by exposure to magnetic field (CM) extremely low frequency (ELF) and low intensity. The results were as follows: 1) We have noticed that 82% of the neurons studied in Helix aspersa are magnetosensibles, while the 18% no response from the CM FEB implemented. The observed effects are basically variations in frequency and to a lesser extent, changes in the extent of the potential bioeléctricos. 2) For inmunocitoquimia have found an acceptable agreement between the types of ion channels expressing neurons and electrophysiological activity induced under CM FEB between 0.1 and 217 Hz. 3) To frequency values of the MC next to the frequency of spontaneous neuron (0.1-5 Hz), we have seen an effect on resonant frequency, which translates into maximum neuronal response in this frequency range. 4) The observed effects are reversible, so it follows that the changes are induced functional, not structural. 5) We note also low temperature variations close to the transition phase of the membrane lipids, a pattern similar to that obtained for firing frequency resonance. Various models have been developed to explain the physical interaction of a field CM FEB with the membrane of neurons. 6) It has been widely differential equation momentum bioeléctrico of Hodgkin-Huxley (HH) with the flow cytoplasmic Ca2 + generated by the CM (model HHM). 7) was also considered in the model superdiamagnetismo and explosion coulombiana (del Moral and Azanza, 1992) that the CM was alternate. 8) are obtained, the frequency spectrum and the temporary unit and the frequency, voltage repolarización-hiperpolarización. 9) has been obtained function that describes the behavior of the frequency of firing of the neuron in terms of the frequency of CM implemented. 10) Finally, it has obtained the temporal evolution of voltage depolarization suggesting its independence from the CM FEB aplicado.11) has explained the effect of window often described by Bawin and obtained from experiments on preparations in vitro brain chicken and mammalian

Author: VICENT VELA MARÍA CINTA.
Year: 2005.
University: POLITÉCNICA DE VALENCIA [www.upv.es].
Place of defense: UNIVERSIDAD POLITÉCNICA DE VALENCIA.
Place of preparation: UNIVERSIDAD POLITÉCNICA DE VALENCIA.

Summary: In this Doctoral Thesis discussed the implementation of dynamic models both the theoretical and semi-empíricos to predict the decline in the permeate flux density over time because of the fouling process of ultrafiltration tangential of macromolecules. The phenomena of fouling are present in all applications and ultrafiltration processes are the main limiting factor in the application of membrane technology. Trials were conducted in pilot plant with two ceramic membrane ultrafiltration, food consisting of an aqueous solution of polyethylene glycol. In the experiments were varied tangential velocity, pressure transmembranal, the concentration of polietilenglico and temperature. Experimental data obtained were compared with the results predicted by the models. The results showed the impossibility of predicting quite theoretical variation of the permeate flux density over time under different experimental conditions. One reason is the difficulty in estimating and theoretically all parameters of the models. However, through the Models Hermia modified for tangential filtration, was predicting a good degree of alignment with the experimental results variation of the permeate flux density over time for all the experimental conditions tested using experimental data as the Permeate flux density of initial and stationary. The rest of the parameters calculated from theoretical correlations.