In this paper, the anaerobic treatment of a high organic-strength wastewater-type feedstock, referred as the liquid fraction of pressed municipal solid waste (LPW) was studied for energy recovery and organic matter removal. The processes investigated were (i) dark fermentation to produce biohydrogen, (ii) anaerobic digestion for biogas formation and (iii) microbial fuel cells for electrical energy generation. To find a feasible alternative for LPW treatment (meeting the two-fold aims given above), various one- as well as multi-stage processes were tested. The applications were evaluated based on their (i) COD removal efficiencies and (ii) specific energy gain. As a result, considering the former aspect, the single-stage processes could be ranked as: microbial fuel cell (92.4%)> anaerobic digestion (50.2%)> hydrogen fermentation (8.8%). From the latter standpoint, an order of hydrogen fermentation (2277 J g COD d)> anaerobic digestion (205 J g COD d)> microbial fuel cell (0.43 J g COD d) was attained. The assessment showed that combined, multi-step treatment was necessary to simultaneously achieve efficient organic matter removal and energy recovery from LPW. Therefore, a three-stage system (hydrogen fermentation-biomethanation-bioelectrochemical cell in sequence) was suggested. The different approaches were characterized via the estimation of COD balance, as well.
ResumenSe analizó el comportamiento de tubos evacuados ante la acción de la radiación solar incidente en la zona ecuatorial alto andina. Las pruebas se realizaron en cuatro días diferentes con tres declinaciones solares, cubriendo la época seca y la época lluviosa. Se trabajó con dos tubos evacuados, inclinados a 15º y 60º; 20º y 45º; 30º y 60º; 10º y 50º. Las mediciones demuestran que en las primeras horas del monitoreo la temperatura más alta del agua corresponde al tubo evacuado con el ángulo mayor y al acercarse el medio día el comportamiento cambia, a la inversa. Se concluye que para optimizar la incidencia de la radiación solar directa en el calentamiento de agua en la región ecuatorial se debe emplear tubos evacuados horizontales.
Palabras clave: calentadores solares, ángulo de inclinación, colector solar, comportamiento térmico
Effect of Tilt Angle of Evacuated Tubes on the Temperature of the Water AbstractThe behavior of solar evacuated tubes under the action of solar radiation in the Equator Andean high lands is presented. The tests were performed during four different days with three solar declinations, covering the dry season and the rainy season. In this study evacuated tubes at inclinations 15º and 60º; 20º and 45º; 30º and 60º; 10º and 50º were employed. The collected data shows that at the beginning of the monitoring experiment the highest temperatures was found for larger inclination angles. At noon, the behavior changes, to the inverse. It is concluded that solar evacuated tubes in the Equator Andean high lands must be in horizontal position to optimize the use of direct solar radiation.
Se presenta el diseño y construcción de un robot didáctico interactivo cuya estructura posee tracción omnidireccional con comunicación WIFI para el envío-recepción de información entre el usuario y el robot. Su estructura está conformada por dos pantallas, una en la parte superior del robot, simulando la cabeza y otra en la parte frontal del cuerpo; dispone de una cámara para obtener “visión” y sensores de proximidad para crear una relación de simbiosis con el usuario. Para controlar los dispositivos se emplearon una Raspberry Pi 3 y una tarjeta Arduino 328 bajo un sistema maestro esclavo. La estructura del robot fue diseñada mediante modelamiento 3D y las partes fueron creadas mediante impresión 3D. Tiene las siguientes funciones: control manual, relatar un cuento, modos baile, publicitario o juego que pueden ser seleccionadas desde la interfaz de usuario. El prototipo tiene énfasis en presentar aplicaciones que estimulen aprendizaje y comprensión lógica en los niños, dejando la posibilidad de ser reprogramado para añadir funciones.
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