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Pengendalian Bioproses
Sistem pengendalian dan Multistage Chemostat Systems
Bioprocess Engineering Control - Spring 2013/2014
Dina Wahyu Indriani
Keteknikan 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
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)
Passive Immobilization: Biological Films (2/5)
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.
Passive Immobilization: Biological Films (4/5)
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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Assignments Tugas Mingguan
Q5. Paper and Resume?
Pengumpulan Paper dan Naskah Resume
Please submitted the assignments before next week, say 8 May.
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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 ini merupakan sistem pengendalian yang difokuskan kepada bioproses. Sehingga mahasiswa dapat membedakan konsep proses dan
bioproses.
E-Mail: [email protected]
