Main Variables Affecting a Chemical-Enzymatic Method to Obtain Protein and Amino Acids from Resistant Microalgae

he development of microalgae uses requires further investigation in cell disruption alternatives to reduce the costs associated to this processing stage. This study aimed to evaluate the main variables affecting an extraction method to obtain protein and amino acids from microalgae. The method was based on a sequential alkaline-enzymatic process, with separate extractions and noncontrolled pH, and was applied to fresh biomass of a resistant species. The processed microalgae were composed of a consortium with Nannochloropsis sp. as predominant species. After the optimization of the pH of the alkaline reaction, the effect of the time of the alkaline reaction (30-120min), the time (30-120min) and temperature (40-60 degrees C) of the enzymatic reaction, and the biomass concentration (50-150mgml(-1)), on the extraction yields of protein and free amino nitrogen (FAN) and on the final concentration of protein in the extract, was studied using a response surface methodology. Even though all the variables and some interactions among them had a significant effect, the biomass concentration was the most important factor affecting the overall process. The results showed relevant information about the different options in order to maximize not only the response variables individually but also different combinations of them. Assays with optimized values reached maximum yields of 80.3% and 1.07% of protein (% of total protein) and FAN (% of total biomass), respectively, and a protein concentration in the extract of 15.2mgml(-1). The study provided the essential information of an alternative approach to obtain protein and amino acids from fresh biomass of resistant microalgae with a high yield, also opening perspectives for further research in particular aspects

Influence of Leachate and Nitrifying Bacteria on Photosynthetic Biogas Upgrading in a Two-Stage System

Photosynthetic biogas upgrading using two-stage systems allows the absorption of carbon dioxide (CO2) in an absorption unit and its subsequent assimilation by microalgae. The production of microalgae requires large amounts of nutrients, thus making scale-up difficult and reducing economic feasibility. The photosynthetic process produces oxygen (O-2) (1 mol per mol of CO2 consumed), which can be desorbed into purified biogas. Two-stage systems reduce its impact but do not eliminate it. In this study, we test the use of landfill leachate as a nutrient source and propose a viable and economical strategy for reducing the O-2 concentration. First, the liquid/gas (L/G) ratio and flow mode of the absorber were optimized for 20% and 40% CO2 with COMBO medium, then landfill leachate was used as a nutrient source. Finally, the system was inoculated with nitrifying bacteria. Leachate was found to be suitable as a nutrient source and to result in a significant improvement in CO2 absorption, with outlet concentrations of 0.01% and 0.6% for 20% and 40% CO2, respectively, being obtained. The use of nitrifying bacteria allowed a reduction in dissolved oxygen (DO) concentration, although it also resulted in a lower pH, thus making CO2 uptake slightly more difficult

SENSADO DE ESCARCHA EN EVAPORADORES MEDIANTE CAÍDA DE PRESIÓN (FROST SENSING IN EVAPORATORS THROUGH PRESSURE DROP)

En esta investigación se presentan una serie de pruebas que se realizaron con el objetivo de relacionar la caída de presión del aire que fluye a través del evaporador de un refrigerador, con el volumen de escarcha que se acumula en él. La relación entre la caída de presión y el volumen de escarcha permitió generar un método de sensado que puede ser utilizado para formular un modelo matemático que describa el crecimiento de escarcha en función de la caída de presión. El objetivo de un refrigerador es la conservación de alimentos almacenados en su interior mediante la disminución de la temperatura del aire interno. El inconveniente es la capa de escarcha que se genera sobre el evaporador, puesto que la escarcha genera un aislamiento térmico, disminuyendo la capacidad de transferencia de calor. Medir la cantidad de escarcha formada en el evaporador trae consigo varias posibilidades de mejora para los refrigeradores, la más importante es en el sistema de refrigeración, manteniendo estable la transferencia de calor entre el aire y el evaporador; otra sería en el consumo eléctrico, si se realiza la operación de deshielo con la misma cantidad de escarcha, se puede disminuir el tiempo de deshielo reduciendo el consumo eléctrico, además de que el calor generado por la resistencia también puede disminuir llegando en menor medida a los alimentos.Palabra(s) Clave: deshielo, escarcha, presión, sensado, refrigerador.AbstractIn this research, we presented a series of tests that were conducted with the objective of the pressure drop of the air flowing through the evaporator of a refrigerator, with the volume of frost that accumulates in it. The relationship between pressure drop and clock volume can generate a detection method that can be used to formulate a mathematical model that describes frost growth as a function of pressure drop. The objective of a refrigerator is the preservation of food stored inside by reducing the temperature of the internal air. The drawback is the layer of frost that is generated on the evaporator, since the frost generates a thermal insulation, decreasing the capacity of heat transfer. Measuring the amount of frost formed in the evaporator brings several possibilities of improvement for the refrigerators, the most important is in the refrigeration system, keeping the heat transfer between the air and the evaporator stable; another would be in electricity consumption, if the de-icing operation is carried out with the same amount of frost, the melting time can be reduced by reducing the electricity consumption, besides the heat generated by the resistance can also decrease, reaching a lesser extent to the food.Keywords: De-icing, Frost, Pressure, sensed, Refrigerator

Characterization of Bacterial and Archaeal Communities by DGGE and Next Generation Sequencing (NGS) of Nitrification Bioreactors Using Two Different Intermediate Landfill Leachates as Ammonium Substrate

Nitrification-denitrification is an environmentally friendly and cost-effective way to treat landfill leachates. Special attention has been given to the nitrification step, usually the limiting one due to its special sensitivity to environmental factors. Here, the effect of the acclimatization of the nitrifying biomass to two different intermediate landfill leachates with different salt concentrations, COD and BOD5 has been studied. Despite the complete nitrification being successfully performed, the specific nitritation rates were reduced after the biomass adaptation to both landfill leachates caused by the presence of heavy metals and the high salt concentration. NGS analysis of the biomass samples revealed that Proteobacteria (48.5%), Actinobacteriota (14.4%) and Chloroflexi (9.5%) were the dominant phyla in the non-adapted biomass. The leachate feeding led to a decrease in OTU diversity and favored the growth of the phyla Bacteroidetes (27.2%), Euryarchaeota (26.6%) and Proteobacteria (20.0%) accounting for more than 70% of relative abundance. Several OTUs capable of performing the nitritation belong to the Xanthobacteraceae and the Xanthomonadaceae families, the Saccharimonadales order, and the genus Nitrosomonas, Nitrosospira and Paracoccus. In the nitratation process, the Xanthobacteraceae family and Lautropia and Nitrolancea genera were found.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The Spanish Government (Ministry of Economy and Competitiveness) and the Vice-rectorate for Research of the University of Cadiz provided financial support through the project CTM2016-79089-R "Enhancement of landfill gas by an integrated biological system (Biointegra3)" and UCA/REC01VI/2017 (Universidad de Cadiz) respectivel

Recent advances in biological technologies for anoxic biogas desulfurization.

Recovery of the energy contained in biogas will be essential in coming years to reduce greenhouse gas emissions and our current dependence on fossil fuels. The elimination of H2S is a priority to avoid equipment corrosion, poisoning of catalytic systems and SO2 emissions in combustion engines. This review describes the advances made in this technology using fixed biomass bioreactors (FBB) and suspended growth bioreactors (SGB) since the first studies in this field in 2008. Anoxic desulfurization has been studied mainly in biotrickling filters (BTF). Elimination capacities (EC) up to 287 gS m-3 h-1 have been achieved, with a removal efficiency (RE) of 99%. Both nitrate and nitrite have been successfully used as electron acceptor. SGBs can solve some operational problems present in FBBs, such as clogging or nutrient distribution issues. However, they present greater difficulties in gas-liquid mass transfer, although ECs of up to 194 gS m-3 h-1 have been reported in both gas-lift and stirred tank reactors. One of the major disadvantages of using anoxic biodesulfurization compared to aerobic biodesulfurization is the need to provide reagents (nitrates and/or nitrites), with the consequent increase in operating costs. A solution proposed in this respect is the use of nitrified effluents, some ammonium-rich effluents nitrified include landfill leachate and digested effluent from the anaerobic digester have been tested successfully. Among the microbial diversity found in the bioreactors, the genera Thiobacillus, Sulfurimonas and Sedimenticola play a key role in anoxic removal of H2S. Finally, a summary of future trends in technology is provided

Research into 3D construction and its applications.

[EN] This article intends to give an understanding of the process of research into cement materials, focussed on 3D printing. A group of four students at the Universitat Polit.cnica de Val.ncia – three architectural engineers and one electronic and automotive industrial engineer, spent three years researching and developing both a mobile 3D printing device; and a cement material to be extruded by this device and be capable of modelling any type of figure with FDM technology. The main objective of this research is the application of this new construction system to the house-building and real estate sector; reducing occupational hazards, costs and waste material.[ES] En el presente artículo se pretende dar a conocer el proceso de investigación sobre materiales cementicios enfocados a la impresión 3D. Un grupo de 4 estudiantes de la Universidad Politécnica de Valencia, 3 Ingenieros de la Edificación y 1 Ingeniero de Electrónica y automatismo Industrial, llevan 3 años investigando y desarrollando tanto un dispositivo de impresión 3D móvil como un material cementicio para ser extrusionado por dicho dispositivo y ser capaz de modelar cualquier tipo de figura con tecnología FDM(ADICIÓN DE CAPAS). El principal objetivo de esta investigación es la aplicación de este nuevo sistema constructivo al sector inmobiliario y construir vviiendas, reduciendo riesgos laborales, costes y material de residuo. Caracterizando nuevas dosificaciones cementicias, conseguimos aumentar su Trabajabilidad y Robustez frente a iclemencias metereológicas que puedan afectar a su reología y comportamiento al momento de su puesta en obra mediante bombeo y extrusión mecánica.Ramírez Collado, V.; Puchades Valencia, JL.; Martín Rodríguez, J.; Muñoz Montes, JG. (2018). Investigación sobre construcción 3D y sus aplicaciones. En CIAB 8. VIII Congreso Internacional de arquitectura blanca. Editorial Universitat Politècnica de València. 190-197. https://doi.org/10.4995/CIAB8.2018.7648OCS19019

A Non-Invasive Thermal Drift Compensation Technique Applied to a Spin-Valve Magnetoresistive Current Sensor

A compensation method for the sensitivity drift of a magnetoresistive (MR) Wheatstone bridge current sensor is proposed. The technique was carried out by placing a ruthenium temperature sensor and the MR sensor to be compensated inside a generalized impedance converter circuit (GIC). No internal modification of the sensor bridge arms is required so that the circuit is capable of compensating practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a microfabricated spin-valve MR current sensor. The temperature compensation has been solved in the interval from 0 °C to 70 °C measuring currents from −10 A to +10 A