Towards high recovery in water reclamation processes : high performance NF-MBR+RO hybrid system

• Main Author: Laopipatpinyo, Tanchanok
• Other Authors: Chong Tzyy Haur
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Environmental engineering
• Online Access: https://hdl.handle.net/10356/150448
• Institution: Nanyang Technological University

Rising water demand due to population growth has driven the development of water technology with the objective to sufficiently provide water for the population. Water reclamation has been a promising process to increase the amount of water supply without stressing natural sources of water. Wastewater treatment technology such as membrane bioreactors (MBRs) have demonstrated high efficiency in certain micropollutants removal, especially those installed with high-retention membranes. Therefore, MBR systems equipped with NF membrane (NF-MBR) and UF membrane (UF-MBR) are examined in this study to observe their potential in removing perfluorooctane sulfonic acid (PFOS). As salinity build-up has been a frequent occurrence in NF-MBR, the study also explores the effects of high salt accumulation on the microbial community as well as fouling in NF-MBR in comparison to UF-MBR. The results had shown superior performance of NF-MBR over UF-MBR in removing PFOS. Also, high COD removal rates (>90%), comparable amount of biofilm, slightly higher amounts of bound and soluble EPS, and total ATP in NF-MBR in relative to UF-MBR delineate no negative effect of salt accumulation on microbial growth. A more rapid rise in TMP was also observed in NF-MBR in comparison to UF-MBR. With the presence of organic foulants and high concentrations of multivalent ions on the NF membrane, cake formation of suspended and colloidal particles and microbial products as well as build-up of rejected salts could possibly be the cause of a more rapid TMP rise in NF-MBR.