60 research outputs found
Un equip de la UAB, al concurs de biologia sintètica del MIT
Un equip de 8 estudiants -5 de la UAB, 1 de la Universitat Santiago de Compostela i 2 de la Universitat de Granada-, coordinats per tres professors del Departament d'Enginyeria Química -Juan Antonio Baeza Labat, Joan Albiol Sala i Pau Ferrer Alegre-, participen en l'edició 2009 d'iGEM, la prestigiosa competició de biologia sintètica organitzada pel MIT (Massachusets Institute of Technology). Es tracta del primer projecte que presenta una universitat catalana a aquest concurs. Els estudiants desenvoluparan un biosensor per al control de qualitat en el procés de potabilització d'aigües.Un equipo de 8 estudiantes -5 de la UAB, 1 de la Universidad Santiago de Compostela y 2 de la Universidad de Granada-, coordinados por tres profesores del Departamento de Ingeniería Química -Juan Antonio Baeza Labat, Joan Albiol Sala y Pau Ferrer Alegre-, participan en la edición 2009 de iGEM, la prestigiosa competición de biología sintética organizada por el MIT (Massachusets Institute of Technology). Se trata del primer proyecto que presenta una universidad catalana a este concurso. Los estudiantes desarrollarán un biosensor para el control de calidad en el proceso de potabilización de aguas
Productes biodegradables més econòmics
Davant la necessitat de produir productes biodegradables que respectin el nostre entorn, els polihidroxialcanoats (PHA) compleixen la funció amb escreix, però també presenten algun problema. Sobretot, pel que fa al seu alt cost de producció. Són plàstics sintetitzats per bacteris que basen la seva producció en cultius purs -aquells que subministren al bacteri nutrients adeqüats i en condicions ambientals concretes-, la qual cosa dificulta la seva posició comercial en comparació amb altres productes sintètics més econòmics, però no biodegradables. Amb la voluntat de solventar aquest hàndicap, l'article següent avalua la possibilitat de treballar amb cultius mixtes enriquits en microorganismes PAO i utilitzant subproductes orgànics. Els microorganismes PAO acumulen matèria orgànica en forma de PHA en ambients sense oxigen. En aquesta línia de treball amb cultius no exènics, es podrà saber si és factible la producció de bioplàstics més econòmics estudiant la composició resultant dels PHA i comparant la quantitat obtinguda amb diferents fonts de carboni. Els resultats semblen positius.Ante la necesidad de producir productos biodegradables que respeten nuestro entorno, los polihidroxialcanoats (PHA) cumplen la función con creces, pero también presentan algun problema. Sobre todo, en cuanto a su alto coste de producción. Son plásticos sintetizados por bacterias que basan su producción en cultivos puros -aquellos que suministran a la bacteria nutrientes adecuados y en condiciones ambientales concretas-, lo que dificulta su posición comercial en comparación con otros productos sintéticos más económicos, pero no biodegradables. Con el objetivo de solventar este handicap, el siguiente artículo evalúa la posibilidad de trabajar con cultivos mixtos enriquecidos en microorganismos PAO y utilizando subproductos orgánicos. Estos microorganismos acumulan materia orgánica en forma de PHA en ambientes sin oxígeno. En esta línea de trabajo con cultivos no exénicos, se podrá saber si es factible la producción de bioplásticos más económicos estudiando la composición resultante de los PHA y comparando la cantidad obtenida con diferentes fuentes de carbono. Los resultados parecen positivos
Augment del rendiment de les depuradores d'aigues
Les depuradores d'aigues residuals són actualment un dels sistemes existents més importants per reduir al mínim l'abocament de contaminants al medi ambient. Un dels processos que es fan servir en aquestes instal·lacions es el denominat EBPR (Enhanced Biological Phosphorus Removal, "Eliminació Biològica de Fòsfor"), encara que, de vegades, poden sorgir dificultats que afectin el rendiment de l'eliminació dels contaminants. Investigadors del Departament d'Enginyeria Química han estudiat a fons aquesta problemàtica, aportant nous coneixements sobre el procés EBPR.Las depuradoras de aguas residuales son actualmente uno de lossistemas existentes más importantes para reducir al mínimo el vertido decontaminantes al medio ambiente. Uno de los procesos que se utilizanen estas instalaciones es el denominado EBPR (Enhanced BiologicalPhosphorus Removal, "Eliminación Biológica de Fósforo"), aunque, enocasiones, pueden surgir dificultades que afectan al rendimiento de laeliminación de los contaminantes. Investigadores del Departamentd'Enginyeria Química de la UAB han estudiado a fondo estaproblemática, aportando nuevos conocimientos sobre el proceso EBPR.Wastewater treatment plants are currently one of the most importantsystems at hand to minimise the dumping of pollutants into theenvironment. One of the processes, which are used in these facilities, iswhat is known as EBPR (Enhanced Biological Phosphorus Removal),although, on occasions, difficulties may arise which hinder theperformance of pollutant elimination. Researchers at the Department ofChemical Engineering have studied this problem in depth, providing newknowledge about the EBPR process
Desarrollo e implementación de un sistema supervisor para la gestión y control de EDAR
Descripció del recurs: el 19-08-2008Consultable des del TDXTítol obtingut de la portada digitalitzadaEn la presente tesis se desarrolla y optimiza un conjunto de metodologias que permiten la construccion de un sistema de control supervisor basado en el conocimiento, para la gestión y control de Estaciones Depuradoras de Aguas Residuales(EDAR). Para demostrar la aplicabilidad de este tipo de tecnicas, asi como incrementar el conocimiento del proceso y desarrollar nuevas tecnicas de control, se ha aplicado el sistema desarrollado a una planta piloto y a una EDAR real. En estas aplicaciones, se ha demostrado como una herramienta valida para el control y gestion en tiempo real de plantas depuradoras, que permite la mejora de los procesos de depuracion biologica, en cuanto a fiabilidad de operación, mejora del rendimiento de eliminacion y reducción del coste energetico necesario para obtener un determinado grado de depuración. Para la implementación del sistema, se ha construido una planta piloto altamente instrumentalizada y con gran versatilidad, que permite la eliminación simultanea de carbono, nitrogeno y fosforo. Toda la instrumentación disponible esta gestionada por un sistema de control y adquisición de datos (SCADA), diseñado siguiendo un esquema distribuido. Este sistema desarrollado e implementado en la planta piloto, ha permitido el funcionamiento autonomo de un proceso de depuracion biologica con eliminacion de nutrientes durante más de cuatro años. Por encima del sistema SCADA se ha implementado un Sistema Basado en el Conocimiento(SBC) que hace posible el control del rendimiento del proceso en conjunto. Este sistema permite el control de situaciones anormales y el cumplimiento de restricciones legales en el efluente en una planta depuradora(piloto o real). Para la validación de todo el sistema supervisor se han realizado una serie de experimentos en planta piloto para optimizar la eliminación de nitrogeno en condiciones de entrada constante y dinamicas. Los objetivos principales han sido la obtención de la eliminación de nitrogeno prefijada y la utilización de los minimos recursos posibles, manteniendo, a su vez, una adecuada eliminación de materia organica y fosforo. Utilizando distintas estrategias de operación se han obtenido mejoras en el proceso: un aumento de eliminacion por unidad de biomasa superior al 16% y una disminución en el vertido de nitrogeno superior al 46%
Exploring key operational factors for improving hydrogen production in a pilot-scale microbial electrolysis cell treating urban wastewater
Altres ajuts: acords transformatius de la UABBioelectrochemical systems (BES) are becoming popular technologies with a plethora of applications in the environmental field. However, research on the scale-up of these systems is scarce. To understand the limiting factors of hydrogen production in microbial electrolysis cell (MEC) at pilot-scale, a 135 L MEC was operated for six months under a wide range of operational conditions: applied potential [0.8-1.1 V], hydraulic residence time [1.1-3.9 d], and temperature [18-30 °C], using three types of wastewater; synthetic (900 mg CODs L−1), raw urban wastewater (200 mg CODs L−1) and urban wastewater amended with acetate (1000 mg CODs L−1). The synthetic wastewater yielded the maximum current density (1.23 A m−2) and hydrogen production (0.1 m3 m−3 d−1) ever reported in a pilot scale MEC, with a cathodic recovery of 70% and a coulombic efficiency of 27%. In contrast, the use of low COD urban wastewater limited the plant performance. Interestingly, it was possible to improve hydrogen production by reducing the hydraulic residence time, finding the optimal applied potential or increasing the temperature. Further, the pilot plant demonstrated a robust capacity to remove the organic matter present in the wastewater under different conditions, with removal efficiencies above 70%. This study shows improved results compared to similar MEC pilot plants treating domestic wastewater in terms of hydrogen production and treatment efficiency and also compares its performance against conventional activated sludge processes
A review on the integration of mainstream P-recovery strategies with enhanced biological phosphorus removal
Acord transformatiu CRUE-CSICPhosphorus (P), an essential nutrient for all organisms, urgently needs to be recovered due to the increasing demand and scarcity of this natural resource. Recovering P from wastewater is a feasible and promising way widely studied nowadays due to the need to remove P in wastewater treatment plants (WWTPs). When enhanced biological P removal (EBPR) is implemented, an innovative option is to recover P from the supernatant streams obtained in the mainstream water line, and then combine it with liquor-crystallisation recovery processes, being the final recovered product struvite, vivianite or hydroxyapatite. The basic idea of these mainstream P-recovery strategies is to take advantage of the ability of polyphosphate accumulating organisms (PAO) to increase P concentration under anaerobic conditions when some carbon source is available. This work shows the mainstream P-recovery technologies reported so far, both in continuous and sequenced batch reactors (SBR) based configurations. The amount of extraction, as a key parameter to balance the recovery efficiency and the maintenance of the EBPR of the system, should be the first design criterion. The maximum value of P-recovery efficiency for long-term operation with an adequate extraction ratio would be around 60%. Other relevant factors (e.g. COD/P ratio of the influent, need for an additional carbon source) and operational parameters (e.g. aeration, SRT, HRT) are also reported and discussed
Benefits and drawbacks of integrating a side-stream sludge fermenter into an A2O system under limited COD conditions
Altres ajuts: acords transformatius de la UABThe implementation of a side-stream sludge fermenter (SSSF) has been identified as a possible solution to improve the performance of an anaerobic/anoxic/aerobic (A2O) configuration when treating low COD wastewater. This study systematically evaluated the effects of incorporating a SSSF into an A2O configuration (side-stream enhanced biological phosphorus removal, S2EBPR) for P/N/COD removal under a limited influent COD (CODINF) condition. The performance of the S2EBPR (with the SSSF receiving 6% of the recycled activated sludge and operating with a hydraulic retention time (HRT) of 2.4 d) and A2O were compared under the same limited CODINF (350 mg/L) condition. S2EBPR improved the amount of P removed (26.6%) under a low influent COD/P of only 26.3 compared with A2O of 32.6, and enhanced denitrification (11%) without compromising full ammonium and COD removal. However, the PLOAD to the plant increased due to the P-release in SSSF, resulting in higher effluent P concentration. The methane and energy recovery indexes were around 45% lower than those of A2O. Sequencing analysis revealed a high abundance of PAO in accordance to its higher P removal. This study represents a comprehensive evaluation of the S2EBPR configuration and provides an assessment of its suitability
Revealing the proliferation of hydrogen scavengers in a single-chamber microbial electrolysis cell using electron balances
The bioelectrochemical generation of hydrogen in microbial electrolysis cells (MECs) is a promising technology with many bottlenecks to be solved. Among them, the proliferation of hydrogen scavengers drastically reduces the cell efficiency leading to unrealistic coulombic efficiencies (CE) and cathodic gas recoveries (rCAT). This work provides a novel theoretical approach to understand, through electron equivalent balances, the fate of hydrogen in these systems. It was validated with a long term operated single-chamber membrane-less MEC. In the short term, H2-recycling (i.e. hydrogen being derived to the anode) resulted in rCAT of only 4% and in CE up to 463%. The 80.5% of the current intensity came from H₂-recycling and only the 19.5% from substrate oxidation. In the long term, methane was produced from hydrogen, thus decreasing rCAT to 0 (rCAT ¼ 94.5% when considering methane production). CE was 74.5% suggesting that H₂-recycling only took place when methanogenic activity was marginal
Less is more : a comprehensive study on the effects of the unmber of gas diffusion layers on air-cathode microbial fuel cells
Altres ajuts: Acord transformatiu CRUE-CSICAir-cathode microbial fuel cells (AC-MFC) use a gas-diffusion-layer (GDL) coating based on polytetrafluoroethylene applied to the cathode to prevent electrolyte leakage. However, this type of GDL can also lead to a decrease in MFC performance due to electron-transfer limitation, mass-transfer limitation or catalyst availability. This study provides a comprehensive understanding of the significance of the GDL coating, demonstrating the interaction between the number of GDL coatings and the external resistance (Rext) used. An experimental design in 28 mL AC-MFCs was prepared and conducted using two different Rext (10 and 249 Ω) and four different GDL coatings (1 to 4 layers). The coating effect was not significant when operating with a high Rext, where the electron transfer was the limiting process. However, when the Rext was low, the amount of polytetrafluoroethylene limited the cathode performance due to a significant decrease in the Pt availability on the catalytic surface. Thus, GDL-1 with 10 Ω as Rext reached 0.96 mA/cm2, 3-fold higher than that obtained with 249 Ω as Rext (ca. 0.30 mA/cm2). Besides, the current density did not vary noticeably in the other cathodes with 249 Ω as Rext. Contrarily, the current density with 10 Ω as Rext decreased as the number of GDL increased (0.74, 0.57 and 0.37 for GDL-2, GDL-3 and GDL-4 respectively). These values agreed with those of the polarization curve. Furthermore, limitations were also observed in electrochemical impedance spectroscopy measurements: the charge resistance increased with the number of GDL, related to the ease of electron flow. These values were18 Ω, 22 Ω, 53 Ω and 58 Ω for GDL-1, GDL-2, GDL-3 and GDL-4, respectively, for both 10 and 249 Ω cathodes
The selective role of nitrite in the PAO/GAO competition
Proliferation of Glycogen Accumulating Organisms (GAOs) accounts as one of the major bottlenecks in biological phosphorus removal systems. GAO outcompeting polyphosphate accumulating organisms (PAOs) results in lower P-removal. Thus, finding optimal conditions that favour PAO in front of GAO is a current focus of research. This work shows how nitrite can provide a novel strategy for PAO enrichment. A propionate-fed GAO- nriched biomass (70% Defluviicoccus I, 18% Defluviicoccus II and 10% PAO) was subjected more than 50 d under anaerobic-anoxic conditions with nitrite as electron acceptor. These operational conditions led to a PAO-enriched sludge (85%) where GAO were washed out of the system (<10%), demonstrating the validity of the new approach for PAO enrichment. In addition, the presented suppression of Defluviicocus GAO with nitrite represents an add-on benefit to the nitrite-based systems since the proliferation of non-desirable GAO can be easily ruled out and added to the other benefits (i.e. lower aeration and COD requirements)
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