Aislamiento y estudio de la diversidad de las poblaciones de Actinobacterias presentes en muestras de compost

Trabajo de Fin de Grado. Grado en Ciencias Ambientales. Curso académico 2013-2014[ES]Se realizaron aislamientos de Actinobacterias de una muestra de compost y otra de extracto de compost mediante el uso de medios selectivos incubados en condiciones mesófilas (28ºC) y termófilas (50ºC). Las cepas obtenidas se purificaron y se almacenaron en glicerol a fin de garantizar su mantenimiento. Se extrajeron metabolitos de las cepas aisladas y se sometieron a test de bioactividad frente a hongos patógenos a fin de verificar si las Actinobacterias aisladas eran responsables del efecto anti-fúngico observado en la aplicación del compost del que se obtuvieron. Resultó que algunos de los metabolitos generaron inhibición fúngica y se procedió a la secuenciación genética e identificación de las cepas que los habían producido. Las cepas demostraron ser nuevas especies cercanas a los géneros Amycolatopsis y Saccharomonospora

Desarrollo de una aplicación web de gestión de flotas basada en la plataforma de localización de un operador de telefonía móvil

Con el despliegue y evolución de las redes de comunicaciones móviles se abre un universo de nuevos servicios y entre ellos destacan aquellos basados en la localización del usuario (Location Based Services – LBS). Este trabajo trata de desarrollar una solución que permite la gestión de la flota de una empresa de una manera sencilla e intuitiva, basada en la facilidades que ofrecen actualmente plataformas comerciales de localización de algunos operadores de telefonía móvil.Ingeniería de Telecomunicació

Electromethanogenesis at medium-low temperatures: Impact on performance and sources of variability

.In this study we aimed to understand the impact of medium–low temperatures on the two main steps that usually comprise the electromethanogenesis (EM) process: electrothrophic hydrogenesis and hydrogenothrophic methanogenesis. Results revealed that pure CO2 could effectively be converted into a high-purity biogas (∼90:10 CH4/CO2) at 30 °C. However, when temperature was reduced to 15 °C, methane richness greatly decreased (∼40:60 CH4/CO2). This deterioration in performance was mostly attributed to a decline in methanogenic activity (represented mainly by Methanobacterium and Methanobrevibacter). In contrast, the hydrogenic activity (mostly Desulfomicrobium) did not suffer any significant decay. Results also seemed to indicate that methanogenesis, rather than hydrogenesis, is the main source of variability in EM. Increasing the temperature again to 30 °C restored previous performance, which highlights the resilience of EM to wide temperature fluctuations (from 30 to 15 and back 30 °C).S

Charge storage capacity of electromethanogenic biocathodes

[EN] Methanogenic biocathodes (MB) can convert CO2 and electricity into methane. This feature, that allows them to potentially be used for long-term electrical energy storage, has aroused great interest during the past 10 years. MB can also operate as biological supercapacitors, a characteristic that can be exploited for short-term energy storage and that has received much less attention. In this study, we investigate the electrical charge storage capabilities of carbon-felt-based MB modified with graphene oxide. The charge-discharge experiments revealed that the potential of the electrode plays an important role during the discharging period: low potentials (−1.2 V vs Ag/AgCl) created an inrush of faradaic current that masked any capacitive current. At more positive potentials (−0.8 V vs Ag/AgCl), the biological electrodes were outperformed by the abiotic electrodes, and only when the potential was set at −1.0 V vs Ag/AgCl the graphene-modified biological electrode showed its superior charge storage capacity. Overall, results indicated that the graphene modification is crucial to obtain bioelectrodes with improved capacitance: untreated bioelectrodes showed a charge storage capacity inferior to that measured in the abiotic electrodes.SIMCIN/AEI/10.13039/501100011033European Union NextGenerationEU/PRT

Elucidating the impact of power interruptions on microbial electromethanogenesis

Preprint. Submitted version[EN] The need to accommodate power fluctuations intrinsic to high-renewable systems will demand in the future the implementation of large quantities of energy storage capacity. Electromethanogenesis (EM) can potentially absorb the excess of renewable energy and store it as CH4. However, it is still unknown how power fluctuations impact on the performance of EM systems. In this study, power gaps from 24 to 96 h were applied to two 0.5 L EM reactors to assess the effect of power interruptions on current density, methane production and current conversion efficiency. In addition, the cathodes where operated with and without external H2 supplementation during the power-off periods to analyse how power outages affect the two main metabolic stages of the EM (i.e.: the hydrogenic and methanogenic steps). Methane production rates kept around 1000 mL per m2 of electrode and per day regardless of the duration of the power interruptions and of the supplementation of hydrogen. Interestingly, current density increased in the absence of hydrogen (averaged current density during hydrogen supplementation was 0.36 A·m-2 , increasing up to 0.58 A·m-2 without hydrogen). However current was less efficiently used in the production of methane with no hydrogen supplementation. Nevertheless, when the electrical power was restored after the power interruption experiments, performance parameters were similar to those observed before. These results indicate that EM is resilient to power fluctuations, which reinforces the opportunity of using EM as a technology for renewable energy storage.N

Electromethanogenesis for the conversion of hydrothermal carbonization exhaust gases into methane

[EN] Hydrothermal carbonization (HTC) is a biomass conversion process that generates a CO2-rich gaseous phase that is commonly released directly into the atmosphere. Microbial electromethanogeneis (EM) can potentially use this off-gas to convert the residual CO2 into CH4, thus avoiding GHG emissions while adding extra value to the overall bioprocess. In the present work, the HTC gas phase was fed to two mixed-culture biocathodes (replicates) polarized at −1.0V vs. Ag/AgCl. Compared to pure CO2, HTC gas had a marked negative effect on the process, decreasing current density by 61%, while maximum CH₄ yield contracted up to 50%. HTC also had an unequal impact on the cathodic microbial communities, with the methanogenic hydrogenotrophic archaea Methanobacteriaceae experiencing the largest decline. Despite that, the present study demonstrates that HTC can be used in EM as a raw material to produce a biogas with a methane content of up to 70%.S

Microbial electrosynthesis for CO2 conversion and methane production: Influence of electrode geometry on biofilm development

[EN] Electromethanogenesis is a process of microbial electrosynthesis (MES) in whichelectroactive microorganisms reduce carbon dioxide (CO2) to produce methane (CH4), using a cathodeas an electron donor. The efficiency of this reaction is greatly determined by the establishment of arobust microbial community on the biocathodes, which eventually affects the global performance of thebioreactor. Moreover, the development of the biofilm depends on several characteristics of theelectrodes, more specifically their material and geometry. Since electrode geometry is a crucialparameter, this study aims at evaluating the sole influence of the electrode shape by installingcarbon-based electrodes with two different constructions (brush and carbon felt) of biocathodes in anelectromethanogenic reactor for CO2capture. The overall performance of the reactors showedcoulombic efficiencies around 100%, with high-quality biogas reaching methane concentrations above90%. The results reveal that the electrode geometry affects the individual biocathode performance, andthe carbon brush showed a bigger contribution to current generation and electrical capacitance,exhibiting higher peak hydrogen production compared to the carbon felt, which could be reflected inhigher CO2capture and methane generation. Both geometries showed a greater proliferation of archaeaover bacteria (between 53 and 85%), which was more significant on the brush than on the carbon felt.Archaea community was dominated byMethanobacteriumin carbon felt electrodes and codominatedwithMethanobrevibacterin brush electrodes, while bacteria analyses showed a very similar communityfor both geometriesS

Microbial electromethanogenesis for energy storage: Influence of acidic pH on process performance

[EN] Microbial electromethanogenesis (EM) has positioned itself as a promising technology for electrical energy storage using CO2 as a feedstock. However, the selectivity of the final product remains a challenge, being highly dependent of the operating conditions (temperature, pH, conductivity, etc.). This study tries to understand the role that pH plays on the start-up, performance and the structure of microbial communities of an EM system. To that end, two EM reactors were started at pH 7.0 and 5.5 respectively and were subsequently subjected to pH variations between 7.5 and 3.5. The reactor inoculated at pH 5.5 started to produce CH4 earlier than that inoculated at pH 7.0, and the acetogenic activity was gradually displaced by methanogenesis during the start-up period, regardless of the pH. In addition, as the pH of the catholyte became more acidic, the performance improved in terms of methane production, current density and columbic efficiency. Acidic environments – pH around 4.5 – promoted higher methane production due to the selection of Methanobacterium, an acid-tolerant hydrogenotrophic archaea. When pH was set at 3.5, the overall performance declined sharply, probably because it induced unfavourable physiological conditions.SIMinisterio de Ciencia e Innovació

Characterization of Anaerobic Biofilms Growing on Carbon Felt Bioanodes Exposed to Air

Supplementary Materials: The following are available online at https://www.mdpi.com/2073-4344/10/11/1341/s1, Figure S1: Dissolved oxygen profile. Rejected because the data acquisition system was accidentally interrupted at the end of the experiment; Figure S2: Another dissolved oxygen profile. Rejected because the data acquisition system was accidentally interrupted at the end of the experiment.[EN] The role of oxygen in anodic biofilms is still a matter of debate. In this study, we tried to elucidate the structure and performance of an electrogenic biofilm that develops on air-exposed, carbon felt electrodes, commonly used in bioelectrochemical systems. By simultaneously recording the current density produced by the bioanode and dissolved oxygen concentration, both inside and in the vicinity of the biofilm, it was possible to demonstrate the influence of a protective aerobic layer present in the biofilm (mainly formed by Pseudomonas genus bacteria) that prevents electrogenic bacteria (such as Geobacter sp.) from hazardous exposure to oxygen during its normal operation. Once this protective barrier was deactivated for a long period of time, the catalytic capacity of the biofilm was severely affected. In addition, our results highlighted the importance of the material’s porous structure for oxygen penetration in the electrode.SIJunta de Castilla y LeonThis research was possible thanks to the financial support by ‘Consejería de Educación de la Junta de Castilla y León’ (ref: LE320P18), a project co-financed by FEDER funds. R. M. Alonso thanks the University of León for his predoctoral contract

Explorando retos de la electrometanogéneis microbiana: efecto de las interrupciones de corriente, la temperatura, el pH y la composición del gas

198 p.[ES] Las energías renovables y las tecnologías de captura y utilización de carbono han experimentado un aumento en los últimos años como consecuencia de la mayor concienciación sobre el consumo de combustibles fósiles y la contaminación asociada. En este contexto, el biogás procedente del proceso térmico o de la digestión anaeróbica se ha convertido en una tecnología fundamental para lograr simultáneamente la gestión de residuos y la producción de bioenergía. Para cumplir las especificaciones del gas natural, es necesario mejorar el contenido de CH4 del biogás. Las tecnologías convencionales de mejora del biogás utilizan técnicas de separación y sorción y, aunque son tecnologías maduras y aplicables, adolecen de ser intensivas en energía. Los sistemas bioelectroquímicos (BES) han surgido recientemente como alternativa a estos sistemas tradicionales de mejora del biogás. Mediante la electrometanogénesis (EM) en el biocátodo de una BES, la fracción de CO2 del biogás puede reducirse directamente a CH4, utilizando la energía excedente producida con energías renovables. Sin embargo, esta tecnología se encuentra todavía en una fase temprana de desarrollo y adolece de varios problemas, como la intermitencia de la fuente de energía, la influencia de la temperatura, la influencia del pH y los contaminantes presentes en el biogás que se va a mejorar. En este contexto, el objetivo principal de esta tesis será investigar la influencia que estos factores tienen sobre la EM, llevando a cabo un estudio preliminar sobre la variación de la EM, entender el impacto en las etapas electrotróficas hidrogenogénicas y metanogénicas y explorar la viabilidad técnica de utilizar un biogás real como materia prima. La necesidad de acomodar las fluctuaciones intrínsecas a las energías renovables (principalmente solar y eólica) requiere una comprensión del impacto que esta inconstancia de energía tendría en la EM. Esta tesis explora el impacto de los cortes de energía de 24 a 96 horas en los reactores de EM para determinar su efecto en las tasas de producción de metano, el consumo de densidad de corriente, la eficiencia de conversión de corriente y en las comunidades microbianas que componen la biopelícula del cátodo. Durante los cortes de energía, los cátodos fueron operados con y sin suplemento externo de H2 para determinar cómo los cortes de energía afectan a las rutas hidrogenogénicas y metanogénicas. El proceso de EM fue resistente a las fluctuaciones de energía, aunque la eficiencia del proceso disminuyó en ausencia de suplemento de H2. Otro aspecto importante de la EM es el efecto que tienen las temperaturas medias-bajas en las etapas electrotrófica y metanogénica. Para abordar esta cuestión, se sometieron los reactores de EM a diferentes temperaturas (entre 30 y 15 °C). La disminución de la temperatura afectó a la riqueza en metano del producto. La metanogénesis, más que la hidrogénesis, se vio afectada y resultó ser la principal fuente de variabilidad en la EM. La selectividad es otro de los retos a los que se enfrentan los sistemas de EM. Este aspecto depende principalmente de las comunidades microbianas que se seleccionan en el cátodo y nuestra hipótesis es que el pH podría jugar un papel clave. En esta tesis se estudia el impacto del pH en la EM tanto durante el arranque como en condiciones normales de funcionamiento. El entorno ácido permitió un inicio más rápido de la producción de metano, y el descenso del pH mejoró el rendimiento hasta un pH de 4,5. Los resultados también perecían indicar que un pH local elevado en la superficie del cátodo evitaba las graves alteraciones fisiológicas en las comunidades microbianas causadas por un pH global bajo. El último reto que se aborda en esta tesis es el uso del biogás real. La fase off-gas rica en CO2 procedente de la carbonización hidrotermal (HTC) se utilizó como sustrato real para un sistema de EM. El estudio demostró que el off-gas HTC puede ser utilizado como materia prima en un sistema de EM, aunque hay una disminución en la producción de metano de hasta el 50%. Este impacto fue mayor en la parte metanogénica del proceso, probablemente causado por la presencia de CO.[EN] Renewable energy and carbon capture and utilisation technologies have experienced a rise in recent years as a result of increased awareness of fossil fuel consumption and associated pollution. In this context, biogas from thermal process or anaerobic digestion has become a critical technology to simultaneously achieve waste management and bioenergy production. To meet natural gas specifications, the CH4 content of biogas must be upgraded. Conventional biogas upgrading technologies use separation and sorption techniques, and although they are mature and applicable technologies, they are generally energy intensive. Bioelectrochemical systems (BES) have recently emerged as an alternative to these traditional biogas upgrading systems. By means of electromethanogenesis (EM) in the biocathode of a BES, the CO2 fraction of the biogas can be directly reduced to CH4 in a biocathode, using surplus energy produced with renewable energies. However, this technology is still in an early stage of development and suffers from several challenges such as the intermittency of the power source, the influence of temperature, the influence of pH and the pollutants present in the biogas to be upgraded. In this context, the main objective of this thesis will be to investigate the influence that these factors have on EM, to perform a preliminary study on EM variability, understand their impact on the electrotrophic hydrogenogenic and methanogenic stages and to explore the technical feasibility of using a real biogas as feedstock. The need to accommodate fluctuations intrinsic to renewable energy (mainly solar and wind) requires an understanding of the impact this power inconstancy would have on EM. This thesis explores the impact of 24 to 96 h power outages on EM reactors to determine their effect on methane production rates, current density consumption, current conversion efficiency, and on the microbial communities that compose the cathode biofilm. During the power outages, the cathodes were operated with and without external H2 supplementation to determine how the power outages affect the hydrogenogenic and methanogenic pathways. EM was resilient to power fluctuations, although process efficiency decreased in the absence of H2 supplementation. Another important aspect of EM is the effect that medium-low temperatures have on the electrotrophic and methanogenic stages. To address this issue, EM reactors were subjected to different temperatures (between 30 and 15 °C). Decreasing the temperature affected the methane richness of the product. Methanogenesis, rather than hydrogenesis, was affected and proved to be the main source of variability in EM. Selectivity is another challenge faced by EM systems. It mainly dependns on the microbial communities that finally grow on the cathode and our hypothesis is that pH could play a key role. This thesis studies the impact of pH on the EM process both during start-up and during normal operating conditions. The acidic environment allowed a faster onset of methane production, and dropping pH improved performance up to pH of 4.5. Results also seemed to indicate that high local pH on the surface of the cathode prevented severe physiological disruptions on the microbial communities caused by low bulk pH. The last challenge to be addressed in this thesis is the use of real biogas. The CO2-rich off-gas phase from hydrothermal carbonisation (HTC) was used as a real substrate for an EM system. The work demonstrated that off-gas HTC can be used as raw material in an EM system although there is a decrease in methane production of up to 50% probably caused by the presence of CO