2 - Fundamentals of aerobic membrane bioreactors

Abstract

Typical membrane bioreactors (MBRs) are essentially systems that include physical filtration into conventional biological treatment such that the liquid component can be separated from the mixed liquor. The fundamental principle of membrane application in water and wastewater treatment is in the filtration of physical or chemical components such that constituents that are wanted pass through the membrane, while others are rejected. Consistent high-water quality output is one of the MBRs main advantages and has elevated the popularity of aerobic MBRs (AeMBRs) installations worldwide. However, issues of high energy consumption and membrane fouling still need to be managed. A wide variety of materials, both organic polymeric and inorganic, have been employed to prepare membranes and a number of MBR configurations have been studied. Typical MBR processes can be categorized into two main configurations, namely (1) immersed MBR (iMBR) and (2) side-stream (sMBR). Extractive and diffusive MBRs (eMBR and dMBR) are not for the objective of separating biomass and mixed liquor, and are still largely in the developmental stages for practical applications. Regardless of the configurations, membrane fouling is an unresolved issue in MBRs. Various forms of fouling controls from physical to biological have been proposed. Physical and chemical control methods have been explored and widely applied, and research in QQ for MBRs has been steadily increasing in the past decade. This chapter provides fundamentals required for students of membrane technology and operators for a basic understanding of the physical and biological processes involved in the AeMBR technology.