Substrate treatment for the increment of electric power potential from plants microbial fuel cells

Plants microbial fuel cells (PMFC) is novel systemthat generates renewable, clean, and sustainable electricity with minimal environmentalimpact. However, PMFC has limitations in power generation and current density, since its production values is lower than other renewable technologies. Different studies show that the highest limitation for energy generation through MFC is the high resistivity of the cathode, and the solution is to replace the metallic electrodes with non-metallic materials to obtain a better performance, however, the application of these materials requires complex interdisciplinary work. This study conducted three experimental tests using metallic electrodes for the extraction of electrons and combined a black earth substrate with different natural materials, types of plants, and water to determine their influence in the increment of the electric power output

Integrating microalgae production with anaerobic digestion: a biorefinery approach

This is the peer reviewed version of the following article: [Uggetti, E. , Sialve, B. , Trably, E. and Steyer, J. (2014), Integrating microalgae production with anaerobic digestion: a biorefinery approach. Biofuels, Bioprod. Bioref, 8: 516-529. doi:10.1002/bbb.1469], which has been published in final form at https://doi.org/10.1002/bbb.1469. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingIn the energy and chemical sectors, alternative production chains should be considered in order to simultaneously reduce the dependence on oil and mitigate climate change. Biomass is probably the only viable alternative to fossil resources for production of liquid transportation fuels and chemicals since, besides fossils, it is one of the only available sources of carbon-rich material on Earth. Over recent years, interest in microalgae biomass has grown in both fundamental and applied research fields. The biorefinery concept includes different technologies able to convert biomass into added-value chemicals, products (food and feed) and biofuels (biodiesel, bioethanol, biohydrogen). As in oil refinery, a biorefinery aims at producing multiple products, maximizing the value derived from differences in biomass components, including microalgae. This paper provides an overview of the various microalgae-derived products, focusing on anaerobic digestion for conversion of microalgal biomass into methane. Special attention is paid to the range of possible inputs for anaerobic digestion (microalgal biomass and microalgal residue after lipid extraction) and the outputs resulting from the process (e.g. biogas and digestate). The strong interest in microalgae anaerobic digestion lies in its ability to mineralize microalgae containing organic nitrogen and phosphorus, resulting in a flux of ammonium and phosphate that can then be used as substrate for growing microalgae or that can be further processed to produce fertilizers. At present, anaerobic digestion outputs can provide nutrients, CO2 and water to cultivate microalgae, which in turn, are used as substrate for methane and fertilizer generation.Peer ReviewedPostprint (author's final draft

Studies on microbial fuel cell using rice water as substrate

In the present study, electricity was produced from rice water which is considered as waste product using a H-shaped double chamber microbial fuel cell. The effect of silver nanoparticle, anode surface area, cathode surface area, and chemical treatment of electrodes on voltage and current generated by microbial fuel cell was investigated. It was found that with the help of silver nanoparticle, the maximum value of current produced by microbial fuel cell was increased from 0 .011µA to 10µA. Furthermore, when the anode surface area was increased from 55.25cm2 to 221cm2, the maximum value of power generated by microbial fuel cell was increased from 2070.2nW to 2339.1644nW and an increment of more than 50% power generation was achieved by increasing cathode surface area from 55.25cm2 to 221cm2. Similarly the chemical treatment of electrodes prior to the operation gave the maximum value of power generated by microbial fuel cell that equals to 32980nW while the corresponding current produced was 170µA. Since the conventional proton exchange membranes (nafion) used in microbial fuel cell are expensive. So in the present study, an alternative chitosan membrane which is comparatively cheaper and has lower value of impendence was found to be an effective separator for MFC

Development of new nanostructured electrodes in Microbial Fuel Cells (MFCs)

The aim of my thesis work is to investigate new nanostructured materials, obtained by the electrospinning technique, in order to design 3D arrangement of the electrodes, leading thus to improve the energy efficiency of energy production devices, such as microbial fuel cells (MFCs). The carbon nanofibers reveal to be the most promising material in the field of bio electrochemistry; in fact, up to now the best performing microbial fuel cells are fabricated using carbon and carbon based material electrodes. To further enhance the performances of bio anodes and bio cathodes, a set of properties are then required to be overcome, such as a proper surface morphology and chemistry, good biofilm adhesion and electron transfer, and a good electrical conductivity. This work aims to demonstrate that the electrospun nanofibers own all the necessary properties, revealing themselves as the most innovative and promising structures for anodes and cathodes for microbial fuel cells. The nanofibers ensure all the properties listed above; in particular, during my Ph.D. I have investigated and studied the carbon based nanofibers to be applied as cathode and as anode in these kind of the devices. In this thesis, it will be demonstrated that the nanostructured electrodes improve the efficiency devices thanks both to the low impedance and to the interaction with the microorganisms. The high micrometric porosity characteristics of the realized anodic material create the ideal habitat for the microorganism’s proliferation. Moreover, different solution for the cathode material have been developed using ceramic nanofibers, such as MnxOy nanofibers and carbon nanofibers, in order to improve the performance of the devices. The layer made of these nanofibers, in fact, catalyzes the oxygen reduction reaction if the oxygen is used as terminal electron acceptor in the devices; thus these catalysts can substitute the platinum layer, which is the most used today, granting a cheaper and eco friendlier material

A thin layer of activated carbon deposited on polyurethane cube leads to new conductive bioanode for (plant) microbial fuel cell

Large-scale implementation of (plant) microbial fuel cells is greatly limited by high electrode costs. In this work, the potential of exploiting electrochemically active self-assembled biofilms in fabricating three-dimensional bioelectrodes for (plant) microbial fuel cells with minimum use of electrode materials was studied. Three-dimensional robust bioanodes were successfully developed with inexpensive polyurethane foams (PU) and activated carbon (AC). The PU/AC electrode bases were fabricated via a water-based sorption of AC particles on the surface of the PU cubes. The electrical current was enhanced by growth of bacteria on the PU/AC bioanode while sole current collectors produced minor current. Growth and electrochemical activity of the biofilm were shown with SEM imaging and DNA sequencing of the microbial community. The electric conductivity of the PU/AC electrode enhanced over time during bioanode development. The maximum current and power density of an acetate fed MFC reached 3 mA·m−2 projected surface area of anode compartment and 22 mW·m−3 anode compartment. The field test of the Plant-MFC reached a maximum performance of 0.9 mW·m−2 plant growth area (PGA) at a current density of 5.6 mA·m−2 PGA. A paddy field test showed that the PU/AC electrode was suitable as an anode material in combination with a graphite felt cathode. Finally, this study offers insights on the role of electrochemically active biofilms as natural enhancers of the conductivity of electrodes and as transformers of inert low-cost electrode materials into living electron acceptors.</p

Preparation, Proximate Composition and Culinary Properties of Yellow Alkaline Noodles from Wheat and Raw/Pregelatinized Gadung (Dioscorea Hispida Dennst) Composite Flours

The steady increase of wheat flour price and noodle consumptions has driven researchers to find substitutes for wheat flour in the noodle making process. In this work, yellow alkaline noodles were prepared from composite flours comprising wheat and raw/pregelatinized gadung (Dioscorea hispida Dennst) flours. The purpose of this work was to investigate the effect of composite flour compositions on the cooking properties (cooking yield, cooking loss and swelling index) of yellow alkaline noodle. In addition, the sensory test and nutrition content of the yellow alkaline noodle were also evaluated for further recommendation. The experimental results showed that a good quality yellow alkaline noodle can be prepared from composite flour containing 20% w/w raw gadung flour. The cooking yield, cooking loss and swelling index of this noodle were 10.32 g, 1.20 and 2.30, respectively. Another good quality yellow alkaline noodle can be made from composite flour containing 40% w/w pregelatinized gadung flour. This noodle had cooking yield 8.93 g, cooking loss 1.20, and swelling index of 1.88. The sensory evaluation suggested that although the color, aroma and firmness of the noodles were significantly different (p ≤ 0.05) from wheat flour noodle, but their flavor remained closely similar. The nutrition content of the noodles also satisfied the Indonesian National Standard for noodle. Therefore, it can be concluded that wheat and raw/pregelatinized gadung composite flours can be used to manufacture yellow alkaline noodle with good quality and suitable for functional food

Exploring METland® technology: treating wastewater by integrating electromicrobiology into Nature-based Solutions

El agua, además de ser fuente de vida, es un factor indispensable para un desarrollo social, económico y medioambiental. Actualmente, el uso global de agua se ha multiplicado por seis en los últimos 100 años, y continúa aumentando. Lo que antes era un bien de primera necesidad accesible a la mayoría de la población, ahora ha llegado a cotizar en bolsa (Nasdaq Veles California Water Index) para poder comprar el derecho a usarlo en el futuro. Una de las medidas urgentes que se han adoptado a nivel mundial está recogida en la Agenda 2030 de las Naciones Unidas. En ella se establecen los Objetivos de Desarrollo Sostenible, entre los que se encuentra el “garantizar la disponibilidad de agua y su ordenación y saneamiento sostenible”. Es en este contexto donde las Soluciones basadas en la Naturaleza (NBS, por sus siglas en inglés) pueden aportar una alternativa para el tratamiento de aguas residuales. Los humedales construidos constituyen un tipo de NBS basados en la creación de unas condiciones óptimas para el desarrollo de bacterias capaces de eliminar los contaminantes del agua. Además, cuentan con una vegetación específica que aporta soporte físico y biogeoquímico de la comunidad microbiana, lo que permite que sea un ecosistema muy resiliente. La electroquímica microbiana es una disciplina emergente que estudia la interacción entre microorganismos y materiales conductores de la electricidad. Su vertiente más aplicada está representada por las Tecnologías Electroquímicas Microbianas (METs, por sus siglas en inglés). Estos sistemas aprovechan el mecanismo de transferencia extracelular (EET) que presentan las bacterias electroactivas para convertir la energía química, almacenada en los contaminantes del agua, en corriente eléctrica. Una de las METs con mayor impacto ambiental son los METland®. El término nace de la incorporación de las METs a los humedales (wetlands) construidos con el objetivo de intensificar esta tecnología; es decir, aumentar la eficiencia de tratamiento de contaminantes del agua residual por unidad de superficie. El lecho de los METland® es de material carbonoso conductor de la electricidad, lo que permite que las bacterias electroactivas, como Geobacter, lo utilicen como aceptor terminal de electrones (TEA) extracelular. Esta fuente inagotable de TEA estimula el metabolismo oxidativo de las bacterias, incrementando la oxidación de contaminantes Esta tesis ha explorado la denominada tecnología METland®, operándola siempre en condiciones de anegación, donde los procesos anaerobios cobran más importancia. Los METland® han mejorado la eficiencia en el tratamiento de las aguas residuales con respecto a los humedales construidos, pero aún es necesario determinar cómo actúan e interaccionan entre sí, cada uno de sus principales componentes: vegetación, microorganismos y material del lecho (Capítulo 2). El impacto de la vegetación en la eficiencia del tratamiento de un METland® es menor que en un humedal construido ya que, el propio material conductor actúa como TEA sustituyendo, de una forma más efectiva, al oxígeno que producen las raíces de las plantas. En este nuevo nicho ecológico, las bacterias electroactivas encontrarán una ventaja competitiva, desarrollándose en mayor medida y dando lugar a “sinergias eléctroquímicas”. Los estudios electroquímicos (Capitulo 3) de la interfase bacteria-material, permiten explicar tanto la transferencia extracelular de electrones como el mecanismo de transferencia a través del lecho conductor. Los materiales con baja resistencia eléctrica, como el coque grafitado, favorecen una transferencia continua de electrones (mecanismo tipo geoconductor). En cambio, en otros como el biochar, abundan los compuestos oxigenados que, en forma quinonas, dan lugar una transferencia discontinua (mecanismo tipo geobatería). El flujo de electrones en un METland® anegado, además de estar determinado por el material del lecho, también va a depender de la concentración y localización del TEA. Este flujo de electrones puede ser controlado gracias a un nuevo dispositivo denominado e-sink (o sumidero de electrones), inventado y patentado por el grupo de investigación de Bioe (Capítulo 4). Gracias al efecto del e-sink, las reacciones de oxidación de la materia orgánica no se verán limitadas, lo que se traduce en un aumento de la eficiencia del tratamiento. El escalado de esta tecnología es ya una realidad, existen METlands localizados en diferentes regiones climáticas de todo el mundo. Estos sistemas pueden tratar cientos de metros cúbicos de agua al día de diversa naturaleza, tanto urbanas como industriales. En este contexto, hemos explorado su uso en el tratamiento de aguas residuales de ganadería. Los experimentos a escala laboratorio sugieren un futuro prometedor en su aplicación para el tratamiento de purines (Capítulo 5). Asimismo, el proceso de escalado del sistema METland se ha completado en un entorno real (TRL8) como el Instituto de Nutrición Animal de la Estación Experimental del Zaidín en Granada (CSIC). Como conclusión, la tecnología METland® es una realidad en el mercado del tratamiento de las aguas residuales de pequeñas aglomeraciones urbanas, dada su alta eficiencia y versatilidad. Los METlands son una solución respetuosa con el medio ambiente que minimiza los costes de operación y mantenimiento, que permite un tratamiento efectivo de las aguas residuales en localizaciones descentralizadas. No obstante, se debe seguir investigando en este campo para entender mejor la interacción bacteria–lecho conductor, así como seguir innovando en aquellos aspectos de diseño (configuración, materiales) que permitan optimizar su eficiencia