Polymeric Membranes in Membrane Bioreactors for Wastewater Reclamation

Abstract

In recent years, membrane bioreactor (MBR) process has been recognized as a promising wastewater treatment/remediation technology. In these systems, the final settling requirement in the conventional activated sludge (CAS) process is eliminated by an integrated filtration system. The MBR system consists of a combination of an activated sludge process with microfiltration (MF) or ultrafiltration (UF) technologies. Various types of materials, such as polymers, have been used to make membranes that have been used successfully in MBRs. These membranes are fabricated using various fabrication techniques including non-solvent induced phase separation (NIPS), and thermally induced phase separation (TIPS). MBRs provide high-quality effluents due to the effective removal of several pollutants including micropollutants present in wastewaters. However, the main challenge with this method is the membrane fouling in the filtration tank, which decreases the membrane performance and lifespan, causing a substantial escalation in maintenance and operation costs. This chapter discusses the applications of MBRs, and their advantages and disadvantages compared to CAS process. In addition, membrane configurations, membrane fabrication methods, MBR classifications, and membrane and bioreactor parameters as effective factors in design and operation parameters in the MBR systems are discussed. Despite more than two decades of significant advances in developing fouling mitigation methods, membrane fouling is still considered the major bottleneck limiting performance and maintenance of MBRs. Therefore, it is tried to provide an overview of affecting fouling parameters and controlling strategies. Finally, the challenges and opportunities needed to be considered to facilitate the extended use of MBRs are outlined.