Advanced membrane technology for biomass separation

• Main Author: Lau, Adrian Chee Yang
• Other Authors: Wang Rong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; Membrane; Biomass
• Online Access: https://hdl.handle.net/10356/176234
• Institution: Nanyang Technological University

Single cell proteins (SCP) are becoming increasingly popular today as an alternative source of protein, given that current sources of protein are largely unsustainable. SCPs are derived mainly from microorganisms that undergo fermentation to produce products that have a solids content of under 5%. To extract the pure SCPs, further separation techniques are required which include coagulation and flocculation, sedimentation, floatation, centrifugation, and membrane filtration. Among these methods, membrane separation is most favored due to its advantages such as carrying out separation processes without the need for additives, relatively low energy consumption, and continuous separation at mild conditions. In this study, multibore ceramic microfiltration membranes were employed to apply in biomass harvest for protein extraction. However, the membrane performance was retained by the membrane fouling of organic matter in the biomass suspension, which would be significantly affected by many parameters, such as membrane pore size, membrane configuration, shear force on the membrane, etc. As such, this study aims to evaluate and compare the filtration performance between (1) different ceramic membranes of pore sizes 200 and 500 nm; (2) membrane configurations with 2 and 4 membrane modules; and (3) membrane systems operating under different crossflow velocities of 0.1 m/s and 0.2 m/s. The results obtained suggest that membranes with larger pore sizes (500 nm) were overall more susceptible to membrane fouling, especially with regards to irreversible fouling as compared to membranes with smaller pore sizes (200 nm). In addition, the data suggests that overall concentration performances of membrane configurations with 2 and 4 membrane modules were about the same, which indicates a promising potential for seamless scalability of the membrane system. Furthermore, membrane operation under higher cross flow velocities is likely to lead to greater shear stress applied onto the membrane surface, which inhibits cake layer formation and reduces membrane fouling. However, operating at higher cross flow velocities could translate to greater energy costs. Considering the energy consumption together with the comparable membrane performance, a cross flow velocity of 0.1 m/s was more suitable for the long-term PPB concentration process. This study paved the way for applying membrane technology in biomass harvest for further scale-up.