Membrane bioreactor mechanisms

Lyko, S., Al-Halbouni, D., Wintgens, T., Janot, A., HoUender, J., Dott, W., et al. (2007). Polymeric compounds in activated sludge supernatant-characterisation and retention mechanisms at full scale-scale municipal membrane bioreactor. Water Research, 41(11), 3894-3902. 

Bioreactors. Bioreactors that utilize hving cells are typically called fermenters. There are several different types of bioreactors mechanically stirred or agitated tanks bubble columns (cylindrical tanks that are not stirred but through which gas is bubbled) loop reactors, which have forced circulation packed-bed reactors membrane reactors microreactors and a variety of different types of reactors that are not easily classified (such as gas-Uquid reactors and rotating-disk reactors). Biochemical engineers must choose the best bioreactor type for the desired purpose and outfit it with the right instrumentation and other features. 

Figure 5.1. Schematic diagram of the ion transport mechanism in the ion-exchange membrane bioreactor (lEMB). (a) for removal of cationic and (b) anionic micropolutants.

Lv, W, X. Zheng, M. Yang, Y. Zhang, Y. Liu, and J. Liu. 2006. Virus removal performance and mechanism of a submerged membrane bioreactor. Process Biochem. 41 299-304. 

Poly(vinylidene fluoride) (PVDF) is one of the promising polymeric materials that has prominently emerged in membrane research and development (R D) due to its excellent chemical and physical properties such as highly hydrophobic nature, robust mechanical strength, good thermal stability, and superior chemical resistance. To date, PVDF hollow-fiber membranes have dominated the production of modem microfiltration (MF) ultrafiltration (UF) membrane bioreactor (MBR) membranes for municipal water and wastewater treatment and separation in food, beverage, dairy, and wine industries. In the last two decades, increasing effort has been made in the development of PVDF hollow fibers in other separation applications such as membrane contractors [6,7], membrane distillation (MD) [8-11], and pervaporation [12,13]. 

Fig. 1. Different types of bioreactors for plant cell, tissue and organs. (A) mechanically-agitated bioreactors, a aeration-agitation, b rotating drum, c spin filter. (B) air-driven bioreactors, a bubble column, b draft tube, c external loop, (C) non-agitated bioreactors, a gaseous phase (mist), b oxygen permeable membrane aerator, c surface aeration, (D) light emitting draft tube...

The most suitable driving force in BI is the reduction of the diffusion path that already operates in transport processes across biological bilayers. Consequently, biocatalyst membranes and specially designed bioreactors, such as jet loop and membrane reactors, are available to intensify biochemical reactions. " " Supported biocatalysts are often employed to enhance catalytic activity and stability and to protect enzymes/ microorganisms from mechanical degradation and deactivation.f Immobilization of the cells is one of the techniques employed to improve the productivity of bioreactors. 

Membrane reactors were classically grouped according to the hydrodynam-ics/configuration of the system in CSTR and PFR types [106]. However, this proved vmable to comprise some commonly used types in UF, such as flat membranes or dead-end operated modules and multiphase bioreactors. A classification based on the contact mechanisms that bring together substrate and biocatalyst was thus proposed [110]. Thus, membrane reactors could be divided into direct contact, diffusion contact, and interfacial contact reactors. 

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