Aplicación de técnicas de biología molecular para la caracterización de la población microbiana en la degradación de compuestos orgánicos volátiles (COV) mediante biofiltros y biofiltros percoladores

Los compuestos orgánicos volátiles (COV) son unos de los principales contaminantes atmosféricos presentes en las emisiones gaseosas de una gran variedad de industrias. El conocimiento de los efectos nocivos que presentan estas sustancias sobre el medio ambiente y la salud humana ha tenido como consecuencia el desarrollo de normativas ambientales en la Unión Europea en relación al control de las emisiones industriales de COV. Esto ha originado, a su vez, el interés por el desarrollo de nuevas tecnologías de depuración para la reducción de estos contaminantes. En este sentido, los sistemas biológicos como los biofiltros y los biofiltros percoladores se presentan como una alternativa de tratamiento eficaz, económica y respetuosa con el medio ambiente. En la actualidad existen numerosos estudios de laboratorio realizados bajo condiciones de operación controladas cuyo fin principal es determinar la eficacia del biotratamiento. Sin embargo, la información a nivel microbiológico del proceso es todavía escasa. El desarrollo de nuevas aplicaciones de las técnicas de biología molecular para la identificación microbiana en ecología ambiental proporciona nuevas posibilidades para profundizar en el papel que la comunidad microbiana tiene en el proceso de biofiltración, siendo ésta una de las líneas emergentes en este campo. La presente tesis doctoral se ha centrado en la identificación y el seguimiento de las comunidades microbianas en biofiltros y biofiltros percoladores para el tratamiento de emisiones gaseosas de COV, así como en la relación de las mismas con el funcionamiento de estos sistemas. El análisis de las comunidades bacterianas llevó a cabo mediante la puesta a punto y la aplicación de las siguientes técnicas de biología molecular: hibridación fluorescente in situ (FISH), electroforesis en gel con gradiente desnaturalizante (DGGE) y secuenciación del gen 16S ARNr. En una primera parte, las técnicas de biología molecular se aplicaron en experimentos de laboratorio bajo condiciones de funcionamiento controladas en los que se utilizaron tanto biofiltros como biofiltros percoladores para el tratamiento de emisiones gaseosas que contenían un único contaminante. Se realizaron tres estudios experimentales cada uno de ellos con uno de los siguientes compuestos: isopropanol, estireno y 2-butoxietanol; todos ellos constituyentes habituales de las emisiones gaseosas de numerosos sectores industriales. En una segunda parte, se procedió a la transferencia del proceso de biofiltro percolador para su aplicación industrial al tratamiento de las emisiones de COV procedentes del sector de recubrimientos. Se realizaron dos estudios experimentales centrados en la caracterización microbiana, uno a nivel de planta piloto y otro utilizando el proceso de biofiltro percolador como solución final de depuración de las emisiones de una instalación industrial. En los estudios de laboratorio se evaluó la influencia de los parámetros de operación: carga másica volumétrica (CV) y tiempo de residencia a volumen vacío (TRVV), así como del material de relleno y del inóculo empleado sobre la comunidad bacteriana desarrollada y la eficacia del proceso en cada biorreactor. A lo largo de los experimentos se detectó una dinámica de las poblaciones bacterianas con un incremento significativo de la abundancia relativa de grupos bacterianos que incluyen especies con capacidad para degradar compuestos orgánicos y/o para mantener su actividad metabólica en ambientes con elevadas concentraciones de dichos compuestos. En este sentido, el grupo Gammaproteobacteria y el género Pseudomonas sp. que destacan por esta capacidad presentaron finalmente elevada abundancia relativa. Las poblaciones bacterianas desarrolladas demostraron ser diferentes y más complejas a las identificadas en el inóculo. Además, se demostró que el uso de fango activado para la puesta en marcha de los biorreactores fue la mejor opción, ya que, a pesar de la ligera mejora en la capacidad de eliminación utilizando un cultivo puro no se justifica la complejidad que a nivel industrial supone el uso de cultivos puros frente al uso de fango activado para la inoculación de los biorreactores. A nivel industrial, se evaluó la influencia de los parámetros de operación, así como, de los patrones irregulares de emisión en cuanto a concentración y composición, demostrándose la efectividad del proceso de biofiltro percolador para el tratamiento de emisiones industriales. A nivel microbiológico, se corroboraron los resultados a escala de laboratorio indicando la capacidad del grupo Gammaproteobacteria para la degradación de COV.Volatile organic compounds (VOCs) are one of the main air pollutants which are present in gaseous emissions from a wide range of industrial activities. The knowledge of the adverse effects on human health and environment caused by these substances has led to the development of environmental regulations in Europe related to the control of industrial VOC emissions. Thus, these regulations have generated interest on the development of new treatment technologies in order to reduce these pollutants. Therefore, biological processes, such as biofilters and biotrickling filters, provide a successful treatment, which is a cost-effective and environmentally friendly alternative. Nowadays, there are many studies being carried out at laboratory-scale under controlled operational conditions with the aim of determining the biotreatment efficiency. However, information about the process from a microbiological point of view is still scarce. The development of novel applications of molecular biology tools for microbial identification on the field of environmental ecology provides new possibilities to deepen the role that the microbial community plays in the biofiltration process, with this being one of the emergent research subjects in this field. This doctoral thesis focuses on the identification and monitoring of microbial communities in biofilters and biotrickling filters for the removal of VOCs from gaseous emissions, as well as their relationship with the system performance. The analysis of bacterial communities has been carried out by the development and application of the following molecular biological tools: fluorescent in situ hybridisation (FISH), denaturing gradient gel electrophoresis (DGGE) and sequencing of the 16S rRNA gene. Firstly, the molecular biology tools have been applied in laboratory experiments under controlled operating conditions, in which biofilters and biotrickling filters were used for the treatment of gaseous emissions containing a single contaminant. Three experimental studies were performed, each of them with one of the following compounds: isopropanol, styrene and 2-butoxyethanol. All of these are the usual components of gaseous emissions of many industrial activities. Secondly, the process of biotrickling filter was scaled-up to industrial scale to be applied for the treatment of VOC emissions from the coating sector. Two experimental studies focused on the microbial characterization were carried out, one at pilot-scale and the other using a full-scale biotrickling filter as the final solution for the treatment of the waste gas emissions in an industrial facility. In the laboratory studies, the influence of the operational parameters: inlet load (IL) and empty bed residence time (EBRT) and the packing material and the inoculum source on the bacterial community and on the process efficiency in each bioreactor was evaluated. Throughout the experiments, a dynamic of the bacterial populations was observed, with an important increase in the relative abundance of bacterial groups that include species with the ability to degrade organic compounds and/or maintain their metabolic activity in environments with high concentrations of these compounds has been observed. In this sense, the Gammaproteobacteria group and the genus Pseudomonas sp., which were highlighted for this capability, finally presented the highest relative abundance. The bacterial populations were different and more complex than the bacterial community identified in the inoculum source. In addition, the use of activated sludge for the start-up of the bioreactors has been demonstrated as the best option. The slight improvement in the elimination capacity using a pure culture does not justify the complexity that supposes the use of pure cultures compared with the use of activated sludge for the bioreactor inoculation at the industrial scale. At the industrial level, the influence of the operational parameters and the irregular gaseous emission patterns of concentration and composition was evaluated. It demonstrated that the biotrickling filter process is effective for the treatment of industrial emissions. At microbiological level, it demonstrated the importance of the species belonging to the Gammaproteobacteria bacteria group in the degradation of organic solvents, corroborating the conclusions extracted from studies at laboratory and pilot plant scale

Study of Mass Oxygen Transfer in a Biotrickling Filter for Air Pollution Control

Biotrickling filtration is a potential and cost effective alternative for the treatment of volatile organic compound (VOC) emissions in air, so it is necessary to deepen into the key aspects of design and operation for the optimization of this technology. One of these factors is the oxygen mass transfer of the process. This study would facilitate the selection of the packing material and the mathematical modelling and simulation of bioreactors. Four plastic packing materials with a different specific surface area have been evaluated in terms of oxygen mass transfer. For the tested range of superficial liquid velocities, data show a relationship between the kLa and the superficial liquid velocity in all packing materials used, except for the biggest plastic rings. No significant differences in mass transfer coefficients at low liquid velocities were observed, however dependency between oxygen transfer and specific surface area increased considerably for high liquid velocities. No significant influences of the superficial air velocity were observed

Evolution of bacterial community in isopropanol-degrading biotrickling filters by fluorescence in situ hybridization (FISH)

In this study, the bacterial population of two biotrickling filters (BFTs) treating isopropanol by using fluorescence in situ hybridization (FISH) is analyzed. The experimental system consists in two identical laboratoryscale BFTs named as BFT1 and BFT2. The two bioreactors were operated in parallel during an experimental period of one year working under intermittent feeding conditions Operating conditions and maintenance were identical in both BFT

A new prospect of additivity in bankruptcy problems

As it is known, there is no rule satisfying Additivity on the complete domain of bankruptcy problems. This paper proposes a notion of partial Additivity in this context, to be called µ-Additivity. We find that µ-Additivity, together with two quite compelling axioms, Anonymity and Continuity, identify the Minimal Overlap rule, introduced by O'Neill (1982).bankruptcy problems, additivity, minimal overlap rule.

Comparison of inoculums in the removal of 2-butoxyethanol from air emissions by biotrickling filter: Performance and microbial monitoring

2-butoxyethanol is one of the most used glycol ether in industrial activities and the treatment of air 2-butoxyethanol-emissions become necessary. Biotechnologies are potential treatment technologies due to their low operational costs. The use of two inoculums in the treatment of 2-butoxyethanol by biotrickling filters (BTFs) packed with polyurethane-foam was studied. A pure culture of Pseudomonas putida, previously adapted to 2-butoxyethanol, was used as inocula in a BTF operated in the University of Stuttgart. Fresh activated sludge from a municipal waste water treatment plant was used as inocula in a BTF operated in the University of Valencia. An empty bed residence time of 12.5 s and inlet concentrations of 400 and 800 mg/Nm3 were applied. After 40 days of operation at 400 mg/Nm3, the BTF inoculated with Pseudomonas putida reached removal efficiencies (REs) ∼ 80%, whereas the BTF inoculated with activated sludge presented REs ∼ 60%. At 800 mg/Nm3, the BTF inoculated with Pseudomonas putida reached REs ∼ 60%. Microbial community was monitored in both BTFs by using denaturing gradient gel electrophoresis analysis (DGGE) with subsequent 16S sequencing and plating methods using 2-butoxyethanol as sole carbon source

Evolution of Bacterial Community in a Full-scale Biotrickling Filter by Fluorescence in Situ Hybridization (FISH)

The performance of a full-scale biotrickling system for the treatment of exhaust gases from two different paint sources at a furniture facility, was investigated applying Fluorescense in situ hybridization (FISH). This technique allowed the detection of major bacteria groups and, therefore, helped in understanding complex microbial communities. The results indicated that Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria were more predominant than Firmicutes and Actiniobacterias. In addition, a variation in the composition of the bacterial community throughout the time of operation and with the paint source was observed. Betaproteobacteria showed similar relative abundance in all analyzed days. However, Gammaproteobacteria, relevant group in the degradation of VOCs, fluctuated with operational changes and the relative abundance of Alphaproteobacteria decreased when the composition of pollutants of the emission source was changed

MEDICINA VETERINARIA APLICADA AL GANADO VACUNO EN ÉPOCA ROMANA SEGÚN LA OBRA DE LUCIO JUNIO MODERATO COLUMELA (SIGLO I d. C.)

Lucio Junio Moderato Columela was an agronomist writer from ancient Rome. He was born in Gades (present-day Cádiz) in the year 4 A.D. and died in Taras (present-day Tarento, a southern italian city) around the year 70 A.D. His work, De Re Rustica, written in latin, is one of the most complete works on agriculture, livestock and animal medicine from Roman times and it was translated into Spanish for the first time in 1824 by Juan María Álvarez de Sotomayor y Rubio under the title of “The twelve books of agriculture”. The main goal of this final degree project has been examining and understanding what Columela shares about diseases, ailments and treatments that affected cattle in the 1st century A.D. For this, we have read the preface and the 26 chapters (I to XXVI) of the sixth book dedicated to cattle. These chapters describe the most frequent diseases of the time and different remedies for their cure. Among the diseases described, we find indigestion, stomach and intestine pain, ranulas and lack of appetite for food, fever, cough, abscess, lameness, scabies, rabid dog or wolf bites and coriazo, lung ulcers and palate tumors, hoof or leg injuries, bites of poisonous animals and infection by leeches. The medical treatments recommended by Columela are mainly natural and they are based in the use of preparations, ointments or concoctions with medicinal plants, food, minerals or even animals. Surgical procedures are also described, highlighting castration or bleeding. In addition to these remedies, Columela mentions some related to superstitious medicine. Columela’s work allows us to get an idea of the ailments suffered by cattle in Roman times, as well as the treatments used to cure them.Lucio Junio Moderato Columela fue un escritor agrónomo de la Antigua Roma nacido en Gades (actual Cádiz) en el año 4 d.C. y fallecido en Taras (actual ciudad del sur de Italia llamada Tarento) hacia el año 70 d.C. Su obra, De Re Rustica, escrita en latín, es una de las más completas sobre agricultura, ganadería y medicina animal de la época romana y fue traducida al castellano por vez primera en 1824 por Juan María Álvarez de Sotomayor y Rubio bajo el título de, “Los doce libros de agricultura”. El objetivo principal de este trabajo de fin de grado ha sido examinar y comprender los datos que Columela aporta sobre enfermedades, dolencias y tratamientos que afectaban al ganado vacuno en el siglo I d.C. Para ello, hemos realizado la lectura del prefacio y de los 26 capítulos (I a XXVI) del libro sexto dedicado al ganado vacuno. En estos capítulos se describen las enfermedades más frecuentes de la época y diversos remedios para su cura. Entre las enfermedades descritas encontramos la indigestión, dolor de vientre e intestinos, ránulas e inapetencia por la comida, calentura, tos, apostemas, cojeras, sarna, mordedura de perra rabiosa o lobo y coriazo, úlceras de pulmón y tumores de paladar, heridas de pezuñas o piernas, mordedura de animales venenosos y afección por sanguijuelas. Los tratamientos médicos recomendados por Columela son principalmente naturales y se basan en el uso de preparados, ungüentos o brebajes con plantas medicinales, alimentos, minerales e incluso animales. También se describen procedimientos quirúrgicos, entre los que destacan la castración y la sangría. Además de estos remedios Columela menciona algunos relacionados con la medicina supersticiosa. La obra de Columela permite hacernos una idea de las dolencias que padecía el ganado vacuno en época romana, así como de los tratamientos empleados para su curación

Spread between the euro short-term rate (€STR) and the deposit facility rate

Rationale This article analyses the factors that are contributing to the widening of the spread between the euro short-term rate (€STR) and the deposit facility rate, with a view to assessing monetary policy transmission in the Eurosystem. Takeaways •The key factors that explain the behaviour of this spread are the expansion of the Eurosystem’s balance sheet and the change in the monetary policy stance. •The pass-through of the recent interest rate hikes to money market rates has been effective and cannot explain the widening of the spread. •Once the rate hiking cycle comes to an end, the contraction in the Eurosystem’s balance sheet can be expected to curb or even reverse the trend observed in the spread

Implantación de un protocolo de analgesia y sedación en una unidad de urgencias pediátricas

Cada vez más, los pediatras reconocemos la necesidad de realizar procedimientos de analgesia y/o sedación, ya que nos enfrentamos a múltiples situaciones en las que es necesario el control del dolor, disminuir la movilidad del niño para realizar exploraciones diagnósticas o controlar la ansiedad en ciertos procedimientos. El objetivo principal del presente estudio ha sido describir nuestra experiencia con la puesta en marcha de un protocolo de analgesia y sedación en una unidad de Urgencias pediátricas. Se han incluido un total de 100 procedimientos cuyas indicaciones más frecuentes han sido: la reducción de fracturas, la sutura de grandes heridas y la realización de artrocentesis. La asociación farmacológica más frecuentemente utilizada ha sido Midazolam + Ketamina por vía endovenosa en 68 ocasiones. Se ha obtenido un nivel de sedación adecuado en el 90% de los pacientes. El principal efecto adverso observado, ha sido la disminución de la saturación de Oxígeno en 6 casos. La experiencia global para el personal de urgencias pediátricas y las especialidades asociadas con la puesta en marcha de este protocolo, ha sido muy satisfactoria, sin olvidar que el principal beneficiado ha sido el paciente.Procedures of analgesia/sedation are increasingly performed in different situations of the pediatric practice, when pain, mobility or anxiety control is needed to perform diagnostic or therapeutic procedures. The main objective of this study was to evaluate our experience with the implementation of an analgesia/sedation protocol in a Pediatric Emergency Unit. One hundred procedures were included in the study. The most common indications were: fracture reduction, wound suture and arthrocentesis. The most frequent drugs used were intravenous Midazolam and Ketamine (68 cases). An appropriate level of sedation was obtained in 90% of the patients. The main side effect observed was an oxygen saturation decrease in 6 cases. The experience with this protocol has been satisfactory. It has been effective in most of the cases with a low rate of complications, increasing the comfort of the patient and the quality of the procedures performed