STUDY OF THE TRANSPORT OF HEAVY METAL IONS THROUGH CATION-EXCHANGE MEMBRANES APPLIED TO THE TREATMENT OF INDUSTRIAL EFFLUENTS

La presente Tesis Doctoral consiste en la determinación de las propiedades de transporte de diferentes especies catiónicas a través de membranas de intercambio catiónico. Las membranas de intercambio iónico son un componente clave de los reactores electroquímicos y de los sistemas de electrodiálisis, puesto que determinan el consumo energético y la eficiencia del proceso. La utilización de este tipo de membranas para el tratamiento de efluentes industriales no es muy extendida debido a los requisitos de elevada resistencia química y durabilidad que deben cumplir las membranas. Otro asunto importante radica en la eficiencia en el transporte de los iones que se quieren eliminar a través de la membrana. Normalmente, existe una competencia por el paso a través de las membranas entre diferentes especies debido al carácter multicomponente de los efluentes a tratar. Sin embargo, una mejora en las propiedades de las membranas de intercambio iónico permitiría la implantación del tratamiento mediante reactores electroquímicos de efluentes industriales con un contenido importante en compuestos metálicos, tales como los baños agotados de las industrias de cromado. La utilización de una tecnología limpia como la electrodiálisis conllevaría diferentes ventajas, entre las cuales destacan la recuperación de los efluentes para su reutilización en el proceso industrial, el ahorro en el consumo de agua y la disminución de la descarga de contaminantes al medio ambiente. La determinación de las condiciones de operación óptimas así como la mejora de las propiedades de transporte de las membranas constituye el principal tema de la presente investigación. Para ello, se emplearán diferentes tipos de membrana. En primer lugar, se estudiará el comportamiento de las membranas poliméricas comerciales que poseen unas propiedades de resistencia química elevadas, las cuales se tomarán como referencia. De forma paralela, se producirán membranas conductoras de iones a partir de materiales cerámicos económicos, ya que la resistencia de los materiales cerámicos a sustancias oxidantes y muy ácidas es mayor que la de los materiales poliméricos. Este punto constituye la parte más innovadora de la investigación, puesto que la mayoría de las membranas de intercambio iónico comerciales están basadas en materiales poliméricos que no pueden resistir las condiciones específicas de los efluentes industriales. Una vez determinadas las condiciones de operación óptimas, se realizarán ensayos en plantas piloto con el fin de confirmar los resultados obtenidos mediante las técnicas de caracterización y determinar el grado de recuperación y coste energético asociado a los procesos electrodialíticos de tratamiento de efluentes industriales.Martí Calatayud, MC. (2014). STUDY OF THE TRANSPORT OF HEAVY METAL IONS THROUGH CATION-EXCHANGE MEMBRANES APPLIED TO THE TREATMENT OF INDUSTRIAL EFFLUENTS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/46004TESISPremios Extraordinarios de tesis doctorale

On the rejection and reversibility of fouling in ultrafiltration as assessed by hydraulic impedance spectroscopy

[EN] The manifestation of critical fluxes in membrane filtration has typically served to set an upper value above which detrimental fouling events and a substantial increase of membrane resistance occurs. Despite the usefulness of critical flux concepts for conducting sustainable membrane processes, the specific phenomena causing them cannot be easily identified via conventional membrane filtration modes. Usually arbitrary fouling rates are selected to delimit the boundary between under- and over-critical flux operation. Timescales respective for colloidal matter accumulation are overlooked. Frequency response analysis of transmembrane pressures has been recently presented as a highly-sensitive method to track fouling in ultrafiltration. This hydraulic impedance spectroscopy method allows not only measuring membrane resistances but also corresponding time constants related to colloidal matter accumulation. In this work, hydraulic impedance spectra are gained for the ultrafiltration of different model foulants to assess the origin of critical fluxes for two different membranes. A correlation among characteristic impedance features and the type of fouling could be established: the evolution of phase shift between flux and pressure at increasing fluxes allows identifying the formation of external fouling layers, while registering of hysteresis loops at reversed frequency sequences signals the development of irreversible internal fouling. The hydraulic impedance method emerges as a precise and more sensitive monitoring tool to diagnose the beginning and nature of critical fouling.M.W. acknowledges the support through an Alexander-von-Humboldt Professorship. M.C. Marti-Calatayud is grateful for the funding received from the Generalitat Valenciana (APOSTD/2017/059). M.C. Marti-Calatayud also appreciates the helpful suggestions received by Tao Luo and Georg Linz, as well as the fruitful discussions with Sarah Armbruster. This work was supported by the German Federal Ministry of Education and Research (BMBF) through the project BRAMAR (02WCL1334A). We thank Synder Filtration for the supplied membranes.Martí Calatayud, MC.; Schneider, S.; Wessling, M. (2018). On the rejection and reversibility of fouling in ultrafiltration as assessed by hydraulic impedance spectroscopy. Journal of Membrane Science. 564:532-542. https://doi.org/10.1016/j.memsci.2018.07.021S53254256

Una democracia nada perfecta: continuidades en la financiación de los partidos españoles desde la transición política a nuestros días

Resumen: En este artículo vamos a realizar un pequeño recorrido por la financiación ilegal de partidos políticos en España desde la transición política. Aunque nos vamos a centrar en la primera de ellas, se trata en realidad de dos historias, entremezcladas: la primera es la de la “financiación” de los partidos españoles desde la democracia, lo que sus prácticas y dinámicas financieras cuentan acerca de estas formaciones y, en general, acerca del sistema español de partidos. La segunda, la historia de lo “ilegal” en materia de financiación de partidos: cómo las élites políticas han reaccionado a los escándalos, y dónde han ido poniendo la línea divisoria entre lo legítimo y lo ilegítimo. Ambas retratan una democracia nada perfecta: una que, de hecho, a menudo aparenta no tener aspiraciones de perfeccionarse, sino más bien de perseverar en una cultura organizativa y partidista con fuertes anclajes en las deficiencias del sistema de partidos surgido de la transición política.Palabras clave: Financiación ilegal de partidos políticos, corrupción, transición política, cultura política, modelos de partido, democracia interna.Abstract: This paper analyzes the practices of illegal funding of political parties in Spain since the transition to democracy. It involves two different interrelated narrations: the first one has to do with the “funding” of Spanish parties, with how their financial practices and dynamics tells us about some particularities of these political organizations and the Spanish party system. The second narration addresses the history of what is “illegal” regarding political party funding: how political elites have reacted to scandals, and how the line separating legitimate and illegitimate funding practices has evolved. Both approaches describe a far from perfect party democracy: one that, in fact, often seems not to aspire to improvement, but rather to perseverate in organizational party cultures that are strongly rooted in the deficiencies of the party system emerged from the Spanish political transition to democracy.Keywords: Illegal funding of political parties, corruption, Spanish political transition, political culture, political party models, internal democracy

Desobediencias y creación policial del derecho: de la protesta a la pandemia

La desobediencia ocupa en los discursos jurídicos sobre las prácticas sancionadoras una posición peculiar. Por una parte, es una idea muy presente en los niveles de debate más abstractos, por ejemplo, los que tienen que ver con las justificaciones filosófico-jurídicas del castigo estatal (las «teorías sobre el fin de la pena») basadas en la noción de que es necesario proteger la «fidelidad al derecho», o «reafirmar la vigencia de la norma» o, simplemente, proteger una determinada estructura de autoridad política. Por otra, las desobediencias operan en el plano más concreto y cotidiano del ejercicio del control penal: las infracciones administrativas y penales de desobediencia cumplen la función de dar cobertura legal a la discrecionalidad policial, llegando a veces a permitir, se argumentará aquí, una auténtica creación policial del derecho. En este capítulo se analizarán algunas tendencias en relación con el uso penal y político de la desobediencia en la última década, cristalizadas últimamente durante la gestión de la pandemiaDisobedience holds a peculiar position in legal discourses on punitive practices. On the one hand, it is very present as an idea at the most abstract levels of debate, for instance, those related to the philosophical-legal justifications of state punishment (the «theories of the purpose of punishment») based on the notion that it is necessary to protect «the fidelity to the law», or to «reaffirm the validity of the norm», or simply to protect a certain structure of political authority. On the other hand, disobedience operates on the more concrete, everyday level of penal control: administrative and criminal offences of disobedience serve the function of providing legal cover for police discretion, allowing, it will be argued here, a genuine police construction of the law. This chapter will analyze some trends in relation to the criminal and political use of disobedience in the last decade, most recently crystallized during the management of the pandemi

New bound for incremental constructing arrangements of curves

Let A(Γ) be the arrangement induced by a set Γ of n unbounded Jordan curves in the plane that intersect each other in at most two points. The upper bound for constructing those arrangements by an incremental method is, up to now, O(nλ4(n)). In this paper we improve this bound to O(nλ3(n)).Ministerio de Ciencia y Tecnologí

Mejora continua en el proceso de elaboración de chocolate de la Empresa Machu Picchu Foods SAC - Callao, 2017

En la presente investigación “Mejora continua en el proceso de elaboración de chocolate de la empresa Machu Picchu Foods SAC - Callao, 2017.”, tiene como objetivo describir la mejora continua en el proceso de fabricación de chocolate de la empresa Machu Picchu Foods SAC, con la planteamiento de un plan de mejora continua de procesos como lo es la metodología del ciclo de Deming, esta metodología consintió en solucionar algunos problemas de procesos detectados en el área de cobertura que concebían perdidas económicas a la empresa, especialmente en los procesos de registro de filtros y refinación, esto como efecto de perdida excesiva de mermas de chocolate y polvo refinado, para esto se efectuó un análisis preciso a través de la observación de los procesos reconociendo la información a través de los datos registrados en donde se prestar atención el comportamiento de la variable a través de los herramientas que se emplearon

Interplay between physical cleaning, membrane pore size and fluid rheology during the evolution of fouling in membrane bioreactors

[EN] Fouling is one of the most pressing limitations during operation of membrane bioreactors, as it increases operating costs and is the cause of short membrane lifespans. Conducting effective physical cleanings is thus essential for keeping membrane operation above viable performance limits. The nature of organic foulants present in the sludge and the membrane properties are among the most influential factors determining fouling development and thus, efficiency of fouling mitigation approaches. The role of other factors like sludge viscosity on fouling is still unclear, given that contradictory effects have been reported in the literature. In the present study we use a new research approach by which the complex interplay between fouling type, levels of permeate flux, membrane material and feed properties is analyzed, and the influence of these factors on critical flux and membrane permeability is evaluated. A variety of systems including activated sludge and model solutions with distinct rheological behavior has been investigated for two membranes differing in pore size distribution. We present a novel method for assessing the efficiency of fouling removal by backwash and compare it with the efficiency achieved by means of relaxation. Results obtained have proven that backwash delays development of critical fouling as compared with relaxation and reduces fouling irreversibility regardless of fluid rheology. It was shown that backwash is especially effective for membranes for which internal fouling is the main cause of loss in permeability. Nonetheless, we found out that for membranes with tight pores, both relaxation and backwash are equally effective. The critical flux decreases significantly for high-viscosity fluids, such as activated sludge. This effect is mainly caused by an intensified concentration polarization at the feed side rather than by internal fouling events. However, membrane permeability has been proven to rely more on the permeate viscosity than on the feed viscosity: poor rejection of organic fractions showcasing high viscosity causes an acute decline in membrane permeability as a consequence of increased shear stress inside the membrane pores. (C) 2018 Elsevier Ltd. All rights reserved.M.W. acknowledges the support through an Alexander-von-Humboldt Professorship. M.C. Marti-Calatayud acknowledges the support to Generalitat Valenciana through the funding APOSTD2017. M.C. Marti-Calatayud thanks the contributions of Sybille Hanisch, Sanchita Khandelwal and Sara Vivanco. This work was supported by the German Federal Ministry of Education and Research (BMBF) through the project BRAMAR (02WCL1334A). We thank Synder Filtration for the supplied membranesMartí Calatayud, MC.; Schneider, S.; Yüce, S.; Wessling, M. (2018). Interplay between physical cleaning, membrane pore size and fluid rheology during the evolution of fouling in membrane bioreactors. Water Research. 147:393-402. https://doi.org/10.1016/j.watres.2018.10.017S39340214

Trade-off between operating time and energy consumption in pulsed electric field electrodialysis: A comprehensive simulation study

[EN] Electrodialysis (ED) has been recently introduced in a variety of processes where the recovery of valuable resources is needed; thus, enabling sustainable production routes for a circular economy. However, new applications of ED require optimized operating modes ensuring low energy consumptions. The application of pulsed electric field (PEF) electrodialysis has been demonstrated to be an effective option to modulate concentration polarization and reduce energy consumption in ED systems, but the savings in energy are usually attained by extending the operating time. In the present work, we conduct a comprehensive simulation study about the effects of PEF signal parameters on the time and energy consumption associated with ED processes. Ion transport of NaCl solutions through homogeneous cation-exchange membranes is simulated using a 1-D model solved by a finite-difference method. Increasing the pulse frequency up to a threshold value is effective in reducing the specific energy consumption, with threshold frequencies increasing with the applied current density. Varying the duty cycle causes opposed effects in the time and energy usage needed for a given ED operation. More interestingly, a new mode of PEF functions with the application of low values of current during the relaxation phases has been investigated. This novel PEF strategy has been demonstrated to simultaneously improve the time and the specific energy consumption of ED processes.The authors acknowledge the support of the Ibero-American CYTED network 318RT0551.Martí Calatayud, MC.; Sancho-Cirer Poczatek, M.; Pérez-Herranz, V. (2021). Trade-off between operating time and energy consumption in pulsed electric field electrodialysis: A comprehensive simulation study. Membranes. 11(1):1-15. https://doi.org/10.3390/membranes11010043S11511

Speed and road accidents: behaviors, motives, and assessment of the effectiveness of penalties for speeding

When dealing with the duality of mobility and safety, speed is one of the main factors causing deaths, so this is the reason why speed is one of the most studied topics related to road safety. The main objective of this research was to identify the aspects that modulate the speed-accidents relation. Specifically, the frequency and reasons why drivers speed. On the other hand, it was also considered the perception of drivers regarding the probability of penalty, the penalties imposed, and their severity. Finally, drivers¿ opinion on the effectiveness of such penalty in order to change speeding behavior was also studied. A sample of 1,100 Spanish drivers over 14 years old and having any kind of driving license was used. The results showed that approximately the third part of drivers always or sometimes sped. Among the specific reasons, the hurry, not having noticed, that the limits are too low or that the conditions allow doing so were the most frequent. Likewise, drivers considered as limited the probability of being caught. Finally, more than half of the drivers considered that the penalty they received was appropriate. Moreover, half of the drivers that received a penalty claimed that they changed their speeding habits as a result of such penalty. Drivers who speed are completely aware of the fact that they are breaking the traffic rules. Their speeding behavior is intentional in 80% of the cases. They are not aware of the risks of speeding since they justified their behavior by saying the speed limits are too low, the conditions on the roads allow doing so, or that it was a habit