Métodos de concentración de biomasa de microalga Scenedesmus sp. cultivada en un biorreactor piloto
Loading...
Date
2011
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
Se procesó en laboratorio las muestras de una cosecha de Scenedesmus spinosus cultivadas en un biorreactor piloto utilizando el medio de nutrición Bristol las que se trataron mediante floculación y centrifugación para evaluar la eficiencia en la concentración de sólidos. Se utilizó tres floculantes, sulfato ferroso (FeSO4), cloruro férrico (FeCl3) y sulfato de aluminio (Al2(SO4)3) con concentraciones de 0,05; 0,2; 0,8; 1,5; 3,0 y 7,0 g L-1 y un rango de pH entre 4,0 y 11,0 aplicado a la mejor respuesta de concentración para cada floculante. Para obtener la mejor combinación de concentración y pH, se realizó pruebas adicionales de floculación para medir la velocidad de sedimentación de la capa superior de la biomasa. Todos estos ensayos se realizaron en un equipo floculador empleando muestras de cultivo de 800 cm3 con 11 minutos de agitación y 10 minutos de sedimentación, con tres repeticiones. En el caso de la centrifugación, el control se realizó utilizando una centrífuga de tubos a las velocidades de 1500, 1800 y 2200 rpm empleando cuatro muestras de 75 cm3 de cultivo y un tiempo de centrifugación de 15 minutos con tres repeticiones. Con el fin de cuantificar la eficiencia de la separación, se midió la turbidez inicial de la muestra y la turbidez final del clarificado y del concentrado. Los ensayos mostraron que para la floculación se obtuvo una eficiencia máxima de 97,9% para la concentración de 1,5 g L-1 de Al2(SO4)3 a pH 8,5 y una velocidad de sedimentación promedio aproximada de 2,7 cm min-1. Las pruebas también demostraron que FeSO4 es el menos eficiente de los tres floculantes en el rango de prueba. Con respecto a las pruebas de centrifugación, en una centrífuga experimental de tubos la eficiencia de concentración de sólidos varió de 95,2% a la velocidad de 1500 rpm hasta 96,0% en la velocidad de 2200 rpm; mientras que en una centrífuga de boquillas tipo industrial se obtuvo una eficiencia promedio de 85% a 5500 rpm.
Samples of a harvested culture of Scenedesmus sp. grown in a pilot raceway photobioreactor with Bristol media for nutrition were processed in the laboratory by flocculation and centrifugation to assess the efficiency of solid concentration achieved by both methods. Three flocculation agents were tested, ferrous sulphate (FeSO4), ferric chloride (FeCl3) and aluminium sulphate Al2( SO4)3 using concentrations of 0.05, 0.2, 0.8, 1.5, 3.0 y 7.0 g L 1 and a pH range between 4.0 and 11.0 applied to the better concentration response of each flocculant. For the best combination of concentration and pH, additional flocculation tests were carried out to measure the sedimentation velocity of the upper layer of biomass. All these tests were performed in initially stirred glasses with culture samples of 800 cm3 for 12 min of stirring and 10 min of sedimentation with three repetitions. In the case of centrifugation the testing was carried out using a tube laboratory centrifuge run at speeds of 1500, 1800 and 2200 rpm with culture samples of 300 cm3 for 15 min and three repetitions. In order to quantify the efficiency of the concentration, initial turbidity of the sample and final turbidity of the cleared water and of concentrated pulp was measured. The flocculation experiments showed that a limit of maximum concentration efficiency of 97.9 % that was reached with 1.5 g L-1 of Al2(SO4)3 at pH of 8.5 and an average sedimentation velocity of about 2.7 cm min-1. Testing also showed that FeSO4 was the worst of the three flocculant agents in the range tested. With respect to the 4 centrifugation test the solid concentration efficiency varied from 95.2 % at speed of 1500 rpm up to 96.0 % at speed of 2200 rpm.
Samples of a harvested culture of Scenedesmus sp. grown in a pilot raceway photobioreactor with Bristol media for nutrition were processed in the laboratory by flocculation and centrifugation to assess the efficiency of solid concentration achieved by both methods. Three flocculation agents were tested, ferrous sulphate (FeSO4), ferric chloride (FeCl3) and aluminium sulphate Al2( SO4)3 using concentrations of 0.05, 0.2, 0.8, 1.5, 3.0 y 7.0 g L 1 and a pH range between 4.0 and 11.0 applied to the better concentration response of each flocculant. For the best combination of concentration and pH, additional flocculation tests were carried out to measure the sedimentation velocity of the upper layer of biomass. All these tests were performed in initially stirred glasses with culture samples of 800 cm3 for 12 min of stirring and 10 min of sedimentation with three repetitions. In the case of centrifugation the testing was carried out using a tube laboratory centrifuge run at speeds of 1500, 1800 and 2200 rpm with culture samples of 300 cm3 for 15 min and three repetitions. In order to quantify the efficiency of the concentration, initial turbidity of the sample and final turbidity of the cleared water and of concentrated pulp was measured. The flocculation experiments showed that a limit of maximum concentration efficiency of 97.9 % that was reached with 1.5 g L-1 of Al2(SO4)3 at pH of 8.5 and an average sedimentation velocity of about 2.7 cm min-1. Testing also showed that FeSO4 was the worst of the three flocculant agents in the range tested. With respect to the 4 centrifugation test the solid concentration efficiency varied from 95.2 % at speed of 1500 rpm up to 96.0 % at speed of 2200 rpm.
Description
Tesis presentada para optar al título de Ingeniero Civil Agrícola
Keywords
Centrifugación, Floculación, Biomasa - Chile