La lluita biològica contra l'eutrofització

La presència de nitrogen i fòsfor a les aigües residuals afavoreix l'eutrofització, que genera un excessiu creixement d'algues, provocant una situació de limitació d'oxigen i la mort de gran part dels éssers vius. Actualment, el fòsfor s'elimina majoritàriament de manera físico-química, en les estacions depuradores d'aigües residuals. Una alternativa més eficient i sostenible és el procés d'eliminació biològica de fòsfor, que consisteix en afavorir el creixement d'uns bacteris capaços d'acumular fòsfor en quantitats superiors a les normals. El present treball arriba a unes sorprenents conclusions sobre la capacitat d'aquests bacteris per eliminar el fòsfor usant els nitritis o els nitrats com a acceptors d'electrons.La presencia de nitrógeno y fósforo en las aguas residuales favorece la eutrofización, que genera un excesivo crecimiento de algas, provocando una situación de limitación de oxígeno y la muerte de gran parte de los seres vivos. Actualmente, el fósforo se elimina mayoritariamente de manera físico-química, en las estaciones depuradoras de aguas residuales. Una alternativa más eficiente y sostenible es el proceso de eliminación biológica del fósforo, que conssite en favorecer el crecimiento de unas bacterias capaces de acumular fósforo en cantidades superiores a las normales. El presente trabajo llega a unas sorprendentes conclusiones sobre la capacidad de estas bacterias para eliminar el fósforo usando los nitritos o los nitratos como aceptores de electrones

Magnetic-Responsive Release Controlled by Hot Spot Effect

Magnetically triggered drug delivery nanodevices have attracted great attention in nanomedicine, as they can feature as smart carriers releasing their payload at clinician's will. The key principle of these devices is based on the properties of magnetic cores to generate thermal energy in the presence of an alternating magnetic field. Then, the temperature increase triggers the drug release. Despite this potential, the rapid heat dissipation in living tissues is a serious hindrance for their clinical application. It is hypothesized that magnetic cores could act as hot spots, this is, produce enough heat to trigger the release without the necessity to increase the global temperature. Herein, a nanocarrier has been designed to respond when the temperature reaches 43 degrees C. This material has been able to release its payload under an alternating magnetic field without the need of increasing the global temperature of the environment, proving the efficacy of the hot spot mechanism in magnetic-responsive drug delivery devices

Producció biològica d'hidrogen i energia a partir d'aigües residuals

Investigadors del Departament d'Enginyeria Química de la UAB han aconseguit obtenir energia elèctrica i hidrogen de manera eficient a partir del procés de depuració d'aigües residuals. El sistema proposat utilitza bacteris que consumeixen la matèria orgànica i produeixen un corrent elèctric que permet la producció d'hidrogen, el vector energètic del futur. Els resultats apunten cap a un desenvolupament a escala industrial d'aquesta tecnologia, si bé abans cal afrontar alguns obstacles tècnics.Investigadores del Departamento de Ingeniería Química de la UAB han logrado obtener energía eléctrica e hidrógeno de manera eficiente a partir del proceso de depuración de aguas residuales. El sistema propuesto, publicado en Water Research, utiliza bacterias que consumen la materia orgánica y producen una corriente eléctrica que permite la producción de hidrógeno, el vector energético del futuro. Los resultados apuntan hacia un desarrollo a escala industrial de esta tecnología, si bien antes hay que afrontar algunos obstáculos técnicos.Researchers from the Department of Chemical Engineering at the UAB have managed to produce electrical energy and hydrogen efficiently from the sewage treatment process. The proposed system, published in Water Research, uses bacteria which consume organic matter and produce electric current, thereby enabling the production of hydrogen, the energy of the future. The results point to an industrial scale development of this technology, although some technical obstacles must be overcome first

The influence of gravimetric moisture content on studded shoe–surface interactions in soccer

It is desirable for the studs of a soccer shoe to penetrate the sport surface and provide the player with sufficient traction when accelerating. Mechanical tests are often used to measure the traction of shoe–surface combinations. Mechanical testing offers a repeatable measure of shoe–surface traction, eliminating the inherent uncertainties that exist when human participant testing is employed, and are hence used to directly compare the performance of shoe–surface combinations. However, the influence specific surface characteristics has on traction is often overlooked. Examining the influence of surface characteristics on mechanical test results improves the understanding of the traction mechanisms at the shoe–surface interface. This allows footwear developers to make informed decisions on the design of studded outsoles. The aim of this paper is to understand the effect gravimetric moisture content has on the tribological mechanisms at play during stud–surface interaction. This study investigates the relationships between: the gravimetric moisture content of a natural sand-based soccer surface; surface stiffness measured via a bespoke impact test device; and surface traction measured via a bespoke mechanical test device. Regression analysis revealed that surface stiffness decreases linearly with increased gravimetric moisture content (p = 0.04). Traction was found to initially increase and then decrease with gravimetric moisture content. It was observed that: a surface of low moisture content provides low stud penetration and therefore reduced traction; a surface of high moisture content provides high stud penetration but also reduced traction due to a lubricating effect; and surfaces with moisture content in between the two extremes provide increased traction. In this study a standard commercially available stud was used and other studs may provide slightly different results. The results provide insight into the traction mechanisms at the stud–surface interface which are described in the paper. The variation between traction measurements shows the influence gravimetric moisture content will have on player performance. This highlights the requirement to understand surface conditions prior to making comparative shoe–surface traction studies and the importance of using a studded outsole that is appropriate to the surface condition during play

Obtaining microbial communities with exoelectrogenic activity from anaerobic sludge using a simplified procedure

BACKGROUND: The microbial fuel cell (MFC) technology transforms the chemical energy present in substrates into electricity. Starting-up these systems, i.e. enriching the anodic community in exoelectrogenic bacteria, is a lengthy process or requires expensive equipment. - RESULTS: An easy and low-cost procedure based on a sediment MFC was developed to select microbial communities with exoelectrogenic activity from the anaerobic sludge of a waste water treatment plant (WWTP). The configuration was based on a simple vessel working as a single chamber MFC with a cathode of stainless steel wool in the liquid surface and a submerged graphite fibre brush as anode. In 30 days of operation, a biofilm with remarkable exoelectrogenic activity was grown on the anode of the MFC. This graphite fibre brush anode was able to supply 0.9Wm-2 when working in an air-cathode MFC (AC-MFC) for 45 days. - CONCLUSION:The procedure presented was demonstrated to be a successful, low-costandlow-maintenance procedure to obtain exoelectrogenic activity and had performances comparable with other more costly and complex inoculation procedures. The Sed-MFC does not require a potentiostat, external aeration, stirring, membranes or an enriched inoculum in the exoelectrogenic biomass

Kinetic and stoichiometric characterization of anoxic sulfideoxidation by SO-NR mixed cultures from anoxic biotrickling filters.

Monitoring the biological activity in biotrickling filters is difficult since it implies estimating biomass concentration and its growth yield, which can hardly be measured in immobilized biomass systems. In this study, the characterization of a sulfide-oxidizing nitrate-reducing biomass obtained from an anoxic biotrickling filter was performed through the application of respirometric and titrimetric techniques. Previously, the biomass was maintained in a continuous stirred tank reactor under steady-state conditions resulting in a growth yield of 0.328±0.045 g VSS/g S. To properly assess biological activity in respirometric tests, abiotic assays were conducted to characterize the stripping of CO2 and sulfide. The global mass transfer coefficient for both processes was estimated. Subsequently, different respirometric tests were performed: (1) to solve the stoichiometry related to the autotrophic denitrification of sulfide using either nitrate or nitrite as electron acceptors, (2) to evaluate the inhibition caused by nitrite and sulfide on sulfide oxidation, and (3) to propose, calibrate, and validate a kinetic model considering both electron acceptors in the overall anoxic biodesulfurization process. The kinetic model considered a Haldane-type equation to describe sulfide and nitrite inhibitions, a non-competitive inhibition to reflect the effect of sulfide on the elemental sulfur oxidation besides single-step denitrification since no nitrite was produced during the biological assays