Low energy resonance vibration submerged membrane system for microalgae harvesting: Performance and feasibility

Abstract

This study investigated an energy-efficient harvesting method to collect microalgae of Chlorella Vulgaris (C. vulgaris). The method proposed in the current study was a combination of a resonance vibration submerged membrane (RVSM) system and centrifugation. The result showed that the RVSM system was able to concentrate the C. vulgaris solution by 17 times (0.61 g·L−1 to 10.4 g·L−1) without chemical cleaning during filtration with intermittent relaxation (i.e., filtration for 9 min and relaxation for 1 min) at a flux of 40 LMH (L·m−2·h−1) until the transmembrane pressure (TMP) reached 70 kPa. In addition, extracellular polymeric substances such as polysaccharides and protein were found mainly responsible for membrane fouling during the operation of concentrating C. vulgaris solution. Integrating the RVSM system with the centrifugation process required the total specific energy consumption of 0.56 kWh·m−3 (0.09 kWh·m−3 for the RVSM and 0.47 kWh·m−3 for the centrifugation). This study demonstrated the combination of the RVSM system and centrifugation to be a feasible C. vulgaris harvesting method by showing lower energy consumption than other conventional processes.