New applications in integrated fixed film activated sludge-membrane bioreactor (IFAS-MBR) systems

Abstract

This chapter provides an overview on the development and application of integrated fixed film activated sludge-membrane bioreactor (IFAS-MBR) systems. IFAS-MBRs represent a novel configuration for advanced wastewater treatment, and only a few studies are available in literature. With this aim, the results of some studies on IFAS-MBR systems already published are discussed and compared in this chapter. Literature shows that the influent carbon to nitrogen ratio (C/N) strongly affects the biological process in IFAS-MBR. The organic matter removal efficiency (removed biologically) decreases from 60% to 23.5% with the decrease of influent C/N from 10 to 2mgCODmgTN?1. Nitrogen removal processes have good performance in IFAS-MBR treating municipal wastewater even under different operating or influent conditions. In terms of membrane fouling, the type of fouling mechanism (internal pore blocking, or superficial cake deposition) in IFAS-MBR systems strongly depends on the development and characteristics of the cake layer deposited on the membrane surface. The presence of detached biofilm in the mixed liquor favors the formation of a cake layer with a good pre-filtering action and a reduction of "pore blocking." Finally, future research perspectives are discussed, including the development of new media (i.e., sponge-based carriers) and membrane-fouling control strategies. Further, more lab-scale and pilot-scale studies are required to investigate the effects of operating conditions.