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Pengendalian BioprosesSistem pengendalian dan Multistage ChemostatSystems

Bioprocess Engineering Control - Spring 2013/2014

Dina Wahyu IndrianiKeteknikan Pertanian- Mei 2013

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Materi Kuliah

No Materi Submateri Waktu

8 Mengetahui pengendalian bioproses dalam berbagai macam aplikasi/ penelitian

Contoh-contoh pengendalian dalam Bioproses April (3)

9 Sistem Pengendalian konsentrasi pada bioreaktor fermentasi (2)

Konsep Pengendalian pada sistem fermentasi April (4)

10 Sistem pengendalian pada bioreaktor pada berbagai tipe bioreaktor

Pemodelan pengendalian pada Bioreaktor fermentasi May (1)

11 Resume dan Persiapan Presentasi Contoh aplikasi pengendalian konsentrasi, suhu dan pH dalam penelitian

May (2)

12 Sistem Pengendalian Chemical Compund, Multistage Chemostat Systems.

Sistem pengendalian dalam mengetahui jumlah bakteri , Total Organic Compund, dalam bioreaktor fermentasi

May (3)

13 Sistem Pengendalian dalam aliran (Group Presentation)

Pengendalian aliran dalam bioreaktor fermentasi May (4)

14 Presentasi Paper (Group Presentation) May (5)

Jadwal dan materi

IMMOBILIZED CELL SYSTEMS

Introduction (1/2)Immobilization is the restriction of cell mobility within a defined space. Immobilized-cell cultures have the following potential advantages over suspension cultures.

1. Immobilization provides high cell concentrations.2. Immobilization provides cell reuse and eliminates the costly

processes of cell recovery and cell recycle. 3. Immobilization eliminates cell washout problems at high

dilution rates.4. The combination of high cell concentrations and high flow

rates (no washout restrictions) allows high volumetric productivities.

Introduction (2/2)

5. Immobilization may also provide favorable microenvironmental conditions (i.e., cell-cell contact, nutrient-product gradients, pH gradients) for cells, resulting in better performance of the biocatalysts (e.g., higher product yields and rates).

6. In some cases, immobilization improves genetic stability.7. For some cells, protection against shear damage is

important.

The major limitation on immobilization is that the product of interest should be excreted by the cells.A further complication is that immobilization often leads to systems for which diffusional limitations are important.

Active Immobilization of Cells (1/5)

Active immobilization is entrapment or binding of cells by physical or chemical forces.

Physical entrapment within porous matrices is the most widely used method of cell immobilization. Polymer beads are usually formed in the presence of cells and can be prepared by one of the following methods:

1. Gelation of polymers: Gelatin and agar beads may be prepared by mixing the liquid form of these polymers with cell suspensions and using a template to form beads.

Active Immobilization of Cells (2/5)

2. Precipitation of polymers: Cells are dispersed in a polymer solution, and by changing the pH or the solvent, the polymer can be precipitated.

3. Ion-exchange gelation: Ion-exchange gelation takes place when a water-soluble polyelectrolyte is mixed with a salt solution.

4. Polycondensation: Epoxy resins are prepared by polycondensation and can be used for cell immobilization.

5. Polymerization: Polymeric networks can be prepared by cross-linking copolymers of a vinyl group containing monomers. Polyacrylamide beads are the most widely used polymer beads.

Active Immobilization of Cells (3/5)Immobilization by polymerization is a simple method.

Encapsulation is another method of cell entrapment. Various polymers can be used as capsule membranes.

Another form of entrapment is the use of macroscopic membrane-based reactors.The simplest of these is the hollow-fiber reactor.

In addition to entrapment or encapsulation, cells can be bound directly to a support.

Adsorption of cells on inert support surfaces has been widely used for cell immobilization.

Active Immobilization of Cells (4/5)The major advantage of immobilization by adsorption is direct contact between nutrient and support materials.Also, the control of microenvironmental conditions is a problem with porous support materials.

Adsorption capacity and strength of binding are the two major factors that affect the selection of a suitable support material.The binding forces between the cell and support surfaces may vary, depending on the surface properties of the support material and the type of cells.

However, limited cell loadings and rather weak binding forces reduce the attractiveness of adsorption method.

Active Immobilization of Cells (5/5)Covalent binding is the most widely used method for enzyme immobilization.However, if is not as widely used for cell immobilization.

Covalent binding forces are stronger than adsorption forces, resulting in more stable binding.

Cross-linking by glutaraldehyde may adversely affect the cell's metabolic activity and may also cause severe diffusion limitations.

In the case of gel entrapment, gels should be porous enough and particle size should be small enough to avoid intraparticle diffusion limitations.

Passive Immobilization: Biological Films (1/5)

Figure 9.11


Biological films are the multilayer growth of cells on solid support surfaces.

In mixed-culture microbial films, the presence of some polymer-producing organisms facilitates biofilm formation and enhances the stability of the biofilms.

In a stagnant biological film, nutrient and product profiles within the biofilm are important factors affecting cellular physiology and metabolism.



Thin biofilms will have low rates of conversion due to low biomass concentration, and thick biofilms may experience diffusionally limited growth, which may or may not be beneficial depending on the cellular system and. objectives.

Usually, the, most sparingly soluble nutrient, such as dissolved oxygen, is the rate-limiting nutrient within the biofilm.


Diffusional Limitations in Immobilized Cell Systems (1/11)

The presence and significance of diffusional limitations depend on the relative rates of bioconversion and diffusion, which can be described by the Damkohler number (Da) (see eq. 3.52 also).

It is desirable to keep Da < 1 to eliminate diffusion limitations when the productivity of a cell population does not improve upon immobilization due to cell-cell contact and nutrient gradients.

Figure 3.12


Diffusional limitations may be external (that is, between fluid and support surface in adsorption and covalent binding), intraparticle (i.e., inside particles in entrapment, encapsulation, or immobilization in porous particles), or both.

These models apply directly to immobilized cells when the kinetics of bioconversion are described by a Michaelis-Mentent type of kinetic expression.

Models for immobilized enzymes have no terms for biocatalyst replication, so this case presents a new problem.


A microbial floc is an aggregation of many cells, and in some processes these aggregates can be more than 1 mm in diameter. The simplest case is to assume that the system is at quasi-steady state and all the cells inside the biofilm are in the same physiological state.

A differential material balance for the rate-limiting substrate within the biofilm (see Fig. 3.11) yields at steady state

(3.49)


Bioprocess Control Application

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AssignmentsTugas Mingguan

Q5. Paper and Resume?

Pengumpulan Paper dan Naskah Resume

Please submitted the assignments before next week, say 8May.

At class’s leader

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Universitas Brawijaya – Malang Join UB be The Best

Keteknikan Pertanian Fakultas Teknologi Pertanian

Pengukuran dan pengendalian bioproses merupakan matakuliah terapan dari Elektronika dan Intrumentasi, Sistem Kontrol, Matetmatika Terapan, Fisika serta Kinia dasar.

Sistem Pengendalian Bioproses lebih difokuskan kepada arahan dan bimbingan kepada mahasiswa yang akan melakukan pengendalian bioproses dalam penelitian sehingga dasar serta konsep pengendalian yang diajarkan dalam matakuliah ini teraplikasikan.

Selain itu sistem pengndalian yang terdapat dalam matakuliah inimerupakan sistem pengendalian yang difokuskan kepada bioproses. Sehingga mahasiswa dapat membedakan konsep proses dan bioproses.

E-Mail: [email protected]

Rumusan Perkuliahan Pengendalian Bioproses

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