Membrane bioreactor modules

It is significant that the reaction mixture was worked up by removal of the unreacted ester by hexane extraction and concentration of the aqueous layer to obtain the desired (i )-amino acid. The process has a high throughput and was easy to handle on a large scale. However, because of the nature of a batch process, the enzyme catalyst could not be effectively recovered, adding significantly to the cost of the product. In the further scale up to 100-kg quantity productions, the resolution process was performed using Sepracor s membrane bioreactor module. The enzyme was immobilized by entrapment into the interlayer of the hollow-fiber membrane. Water and the substrate amino ester as a neat oil or hexane solution were circulated on each side of the membrane. The ester was hydrolyzed enantioselectively by the enzyme at the membrane interface, and the chiral acid product... 

Fig. 3.96. Schematic figure of membrane sampling modules from bioreactor coupled to HPLC-DAD. Reprinted with permission from A. Plum et al. [156].

Bader et al. [35] and De Bartolo et al. [36] developed the flat membrane bioreactor which consists of a multitude of stackable flat membrane modules as shown in Fig. 5. Each module has an oxygenating surface area of 1150 cm. Up to 50 modules can presently be run in parallel mode. Isolated hepatocytes are co-cultured with non-parenchymal cells. Liver cells are located of a distance of 20 pm of extracellular matrix from a supported polytetrafluorethylene (PTFE) film. Medium and cells in the modules are oxygenated in the incubator by molecular diffusion of air across the non-porous PTFE membrane. The design of the bioreactor is also the basis for its proven potential for cryostorage with fully differentiated adult primary human liver cells. 

Membrane bioreactors are composed of two fundamentals parts, the biological reactor in which the reaction occurs (active sludge containing purifying bacteria) and the membrane module for the separation of the different compounds. 

Membrane bioreactors can be classified into two main groups according to their configuration. The first group is commonly known as recirculated or external MBR and involves the recirculation of the solution through a membrane module that is outside the bioreactor. Both inner-skin and outer-skin membranes can be used in this... 

In recent years, membrane bioreactors, bioreactors combined with membrane separation unit have established themselves as an alternative configuration for traditional bioreactors. The important advantages offered by membrane bioreactors are the several different types of membrane modules, membrane structures, materials commercially available. Membrane bioreactors seem particularly suited to carry out complex enzymatic/microbial reactions and/or to separate, in situ, the product in order to increase the reaction efficiency. The membrane bioreactor is a new generation of the biochemical/chemical reactors that offer a wide variety of applications for producing new chemical compounds, for treatment of wastewater, and so on. 

The major market for membrane bioreactors is represented by wastewater treatment with the use of submerged modules configuration. These are considered among the best available technologies by the European Directives on Environment. Membrane bioreactors are also applied in food, red and white biotechnology. In these cases, the external loop configuration is used. 

FIG. 22-45 Membrane bioreactor configurations for wastewater treatment, (a) With sidestream module (b) with submerged module. 

FIGURE 6.24 Membrane bioreactors configurations, (a) Internal outer-skin membranes and (b) outside membrane module. 

The treatment and safe disposal of waste is equally important whether it be waste generated by the pulp and paper industry, by the leather industry or gaseous waste. Recently, in addition to other membrane-based processes, demand has grown in the wastewater treatment industry for a process that uses both a biological stage and a membrane module, known as the membrane bioreactor (MBR) process. The bioreactor and membrane module each have a specific function (1) the biological degradation... 

Fig. 7 (A) Overview of the module (B) close-up of the module and (C) close-up of the hollow fiber membrane used in a membrane bioreactor for wastewater treatment. (Courtesy of CH2M Hill.)...

Because a blocatalyst-blndlng membrane works as a specific, heterogeneous catalyst that can be used repeatedly. It finds many applications In chemical processes. Several types of reactors have been designed to Incorporate blocatalyst-blndlng membranes. A spiral module reactor has an advantage that pressure-drop Is extremely retarded (22)- The chemical engineering of membrane bioreactors has been reviewed elsewhere (30,31). 

The specific applications section is classified and grouped according to the type of solutes separated gas mixtures, conversion, degradation, separation, and purification of biochemical products (membrane bioreactors) at wastewater treatment, types of module tested and types of carrier used. 

Membrane bioreactors have been modelled using approaches that have proven successful in the more conventional catalytic membrane reactor applications. The simplest membrane bioreactor system, as noted in Chapter 4, consists of two separate units, a bioreactor (typically a well-stirred batch reactor) coupled with an external hollow fiber or tubular or flat membrane module. These reactors have been modelled by coupling the classical equations of stirred tank reactors with the mathematical expressions describing membrane permeation. What makes this type of modelling unique is the complexity of the mecha-... 

Microfiltration plants are also being installed in membrane bioreactors to treat municipal and industrial sewage water. Two types of systems that can be used are illustrated in Fig. 7.6. The design shown in Fig. 7.6(a), using a crossflow filtration module, was developed as early as 1966 by Okey and Stavenger at Dorr-Oliver [17]. The process was not commercialized for another 30 years for lack of suitable membrane technology. In the 1990s, workers at Zenon [15,16] in Canada and... 

As an immobilization method, both for whole cells or enzymes, membrane bioreactors provide the advantages and drawbacks common to entrapment or adsorption methods. They nevertheless present particular assets. Mass transfer in the porous supports generally used (alginate, k-carrageenan, zeolites, silica) is a diffusion-controlled process, often becoming the overall rate-limiting step. This maybe overcome by the use of membrane modules. This equipment also avoids... 

Hai, F I., Yamamoto, K., Nakajima, F. and Fukushi, K. 2011. Application of a GAC-coated hollow fiber module to couple enzymatic degradation of dye on membrane to whole cell biodegradation within a membrane bioreactor./oitrna/ of Membrane Science, 389,67-75. 

Barancewicz, M., Gryta, M. (2012). Ethanol production in a bioreactor with an integrated membrane distillation module. Chemical Papers, 66, 85—91. 

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