Application of Membrane Filtration to Harvest Microalgae Cultivated from Piggery Wastewater

Abstract

      Currently, many methods such as filtration, centrifugation, flotation, and flocculation for harvesting algae for biofuel production development have been studied. In this study, application of membrane filtration to harvest microalgae was evaluated in a lab-scale system. The working volume of the system was 1 l. A hollow fiber membrane (with the surface of 0.065 m², pore size of 0.2 μm) was submerged in the system. During the experiment, the air was supplied to prevent the membrane fouling due to the attachment of the micoralgae on the membrane surface. As a result, when the air intensity increased from 0 to 0.315 l/cm².min, the flux increased and the transmembrane pressure decreased. When the air intensity was lower than 0.189 l/cm².min, the flux decreased and the transmembrane pressure increased rapidly. When the air intensity was maintained higher than 0.189 l/cm².min, the flux and the transmembrane pressure were relatively constant. Operational mode of suction pump should be maintained at 5 min on: 5 min off to keep the flux and the transmembrane pressure stable. During opertation, microalgae concentration significantly affected the flux and the transmembrane pressure. In conclusion, membrane filtration could be applied to harvest the microalgae. During operation, the air intensity should be maintained higher than 0.189 L/cm².min to help the filtration longer. Membrane filtration could be an effective method for harvesting microalgae.