The search for alternative methodologies for industrial scale production of metabolites has paved way for the Rotary Disc Bioreactors (RDB). In this presentation, the analysis of the available methodologies is being defined for the production of commercially relevant products. Also, the critical factors and operational parameters are also being discussed for the design of RDB. It was found that to this date, the use of RDB is limited to production of Microbial Cellulose and Lipopeptides.

1. Rotary Disc Bioreactors- Design and
Application
Compiled by – Prashant Pokhriyal
M.Tech
(BioProcess Technology)
Institute of Chemical Technology,
Mumbai

2. TYPES OF BIOREACTOR
Bubble Column Reactor Fed- batch Reactor Continuous Stirred Tank Reactor

3. Rotating Biological Contactors
• First introduced in Germany in 1960s
• Became popular in US in 1970s.
• Biological growth is attached to the surface of the disc and forms a slime layer.
• The discs contact the wastewater with the atmospheric air for oxidation as it rotates.
• The discs are submerged in waste water to about 40% of their diameter.
• Initial use didn’t proved to be economically justifiable compared to its cost.

4. Static vs RDR Fermentation

5. Motivation for Process Development
• Tyagi et al (1992) made observations in the process involving
biodegradation of petroleum refinery wastewater in a polyurethane foam
attached RBC revealed the ability of RBC to retain the considerable
amounts of attached biomass, in conjugation with proper oxygen transfer
rate environment.
• The need to produce microbial cellulose in 1990s.
• Conventional production methods proved to be difficult because of
scaling up.
uncontrollable foaming
necessity of intense washing or cooling

6. Literature Survey
S.No Author(s) Publication/Patent
1
Norhayati, 2009 Rotary discs reactor for enhanced production of
microbial cellulose
2
Kim et al., 2007 Bacterial Cellulose Production by
Gluconacetobacter sp. RKY5 in a Rotary
Biofilm Contactor
3
Chtioui et al., 2012 Rotating discs bioreactor, a new tool for lipopeptides
production
4
Bungay, III et al., 1995 Production of microbial cellulose using a rotating disk
film bioreactor
5
Lin et al., 2014 Semi-continuous bacterial cellulose production in a
rotating disk bioreactor and its materials properties
analysis

7. Physical Design
• 10-Reactor as a whole
• 12-Rotary Discs
• 14-Shaft
• G-Distance between two discs (should be as small
as possible)
• 16-biological medium required to wet the rotating
disk during rotation
• 18-Externally positioned rotating device
• 20-Cylinderical Trough
• 22-Hermetically sealing bearing which serves to
connect the shaft to an externally positioned
• rotating device
• 24-Openings for measurement of Probes
• 26-Probes
• 28-Sampling and Draining Points

8. Disc
Discs Diameter Characterization
PMMA 7 cm Drill with 0.3 cm
holes, 0.3 cm
thickness
Stainless Steel 7 cm 0.3 cm mesh sizes,
0.05 cm thickness
Polyethylene 7 cm 0.3 cm mesh sizes,
0.05 cm thickness
Polyethylene 7 cm 0.6 cm mesh sizes,
0.1 cm thickness

9. Comparison of Various Physical Designs in available Literature
Design
Parameters
Norhayati, 2009 Kim et al., 2007
Chitoui et
al., 2012
Serafica et al.,
2002
Bungay, III
et al., 1995
Krystynowicz
et al., 2002
Lin et al., 2013
Material of
Construction
(PMMA)Poly-methyl
metacrylate
Polypropylene
Glass
cylinder
equipped
with
stainless
steel discs
Clear plastic
cylinders with
stainless steel
center shafts and
polyethylene Disc
Made up of
stainless steel
or
polymeric
materials With
suffcient
rigidity
-
Plastic
composite
support (PCS),
a composite
Material
Disc Diameter 7 cm 12 cm 9.4 cm -
80-90% of
diameter of
Cylindrical
Trough
- -
Disc Thickness - 0.3 cm 1.5 mm - - - -
Submergence of
Disc in the
Media(%)
39 34 ~50 - - - 50
Number of Discs 8 8 7 and 14 - - 24 -
Rotational Speed
per minute
15-35 30 12 6-12 6 5
Volume of Trough 2 Litres 3.54*10-3 L 0.05 L 2 L 1 L 2 L and 11 L

10. Critical Factors affecting the operation of RDB
• Fermentation conditions, which include the
composition of the media that is the carbon, nitrogen and mineral
composition
microbe used.
• Operating Conditions, such as
dissolved oxygen
pH
inoculation ratio
inoculation age.

11. Critical Factors affecting the operation of RDB
Parameters Norhayati, 2009 Kim et al., 2007 Chitoui
et al.,
2012
Serafica et
al., 2002
Bungay, III
et al., 1995
Krystynowi
cz
et al., 2002
Lin et al.,
2013
Microbe Acetobacter
xylinum
Gluconacetobacter Bacillus
subtilis
ATCC
21332
Acetobacter
xylinum
Acetobacter
xylinum
Acetobac
ter
xylinum
E25
Glucon
acetob
acter
xylinum
Media
Composition
Shigeru
Yamanaka
Medium
Modified HS
medium
Landy
medium
Media used
by Hestrin
and
Schramm
(1954)
GYP medium Schramm
and
Hestrin
medium
CSL-Fru
mediu
m
Temperature 26 30 30 25-35 30 28
pH 5 6 7 4 4.5-5.5 3-5

12. Design Considerations
• Steady State Model regarding effluent substrate effluent concentrations-
• 𝑐 𝐵 =
𝐹𝑐0
𝐹+𝐹 𝑓 1+𝑏11+
𝑏12
1+𝑘1
+𝑘 𝐿 𝐴 𝑠
𝑘1
1+𝑘1
; 𝑘1 = µ
𝑋
𝐾 𝐶 𝑌
𝐾𝐿
• cB = Substrate concentration in the bulk of the liquid in the trough
• Ff = Volumetric flow rate of liquid film
• F = Flow rate of feed per single disc face
• c0 = Concentration of substrate in the feed
• b11 and b12, are elements of the matrix (bij) = exp(Aβ), the solution matrix
of equation c(θ) = exp(Aβ)c(0)
• kL = Mass transfer coefficient between liquid film and biofilm
• As = Area of the disc submerged in the trough

13. Mass Balances
•
𝑑𝑉
𝑑𝑡
= 𝐹 𝐻 + 𝐹 𝐷 + 𝐹𝑂 ; Overall Mass Balance
•
𝑑𝑥 𝑝
𝑑𝑡
=
1
𝑉
(𝐹 𝐻 𝑥 𝑝𝑓 − 𝐹 𝐻 𝑥 𝑃 − 𝐹 𝐷 𝑥 𝑃 − 𝑘 𝑝 𝐴 𝑑 𝑥 𝑃) ; Overall Particle Balance
•
𝑑𝑥 𝑔
𝑑𝑡
=
1
𝑉
(𝐹 𝐷 𝑥 𝑔𝑓 − 𝐹 𝐷 𝑥 𝑔 − 𝐹 𝐻 𝑥 𝑔 −
µ 𝑚𝑎𝑥 𝑚𝐴 𝑑
𝑌 𝑏𝑚/𝑔
); Overall Glucose Balance, assuming lag phase has
completed.
• V is the liquid volume
• xp is the particle concentration in solution,
• kp is a particle uptake rate constant
• Ad is the total disk area
• FH, FD and FO are the volumetric flow rates of the concentrated particle
• feed, dilute sugar feed and outlet streams respectively
• 𝑘 𝑝 𝐴 𝑑 𝑥 𝑃 accounts for the uptake of particles in the growing cellulose gel
• µ 𝑚𝑎𝑥 is the specific growth rate,
• m is the mass of active biomass per unit disk area (assumed to be
• constant at a quasi-steady state value)
• 𝑌𝑏𝑚/𝑔 is the yield of biomass from glucose

14. Power Requirements
• General Power Number Calculation
• 𝑁𝑝 =
𝑃
ρLN3 𝐷5
• Power Number calculated per unit surface area
•
𝑃
𝐴
= λ1N2 𝐷2 ; 𝜆1 = 4𝛼µ/𝜋𝑑 (Laminar Conditions)
•
𝑃
𝐴
= λ2 𝑁3 𝐷3; 𝜆2 =
4NpρL
𝜋
(Turbulent Conditions)

15. Critical Factors affecting the operation of RDB
Microbial cellulose weight versus pH
after 5 days fermentation in RDR
Microbial Cellulose Fermantation in RDR
after 5 days fermentation
𝑑𝑀𝑐
𝑑𝑡
=
µ 𝑚𝑎𝑥 𝑚𝐴 𝑑
𝑌𝑐 𝑔
𝑑𝑀 𝑃
𝑑𝑡
= 𝑘 𝑝 𝐴 𝑑 𝑥 𝑃
mass of dry cellulose Particle mass in
growing gel

16. Potential Applications
• The sequential bioreactions, where enzyme immobilization can prove
to be beneficial.
• Controlling of permeability gels formed with embedded particles.
• Wound dressings or artificial skin with time release particles.
• Manufacture of elegant grade paper.
• Conductive paper containing metallic particles.
• Abrasive Papers with particles inside instead of glued to the surface.

17. Advantages of Rotary Disc Bioreactors
• Simple Design.
• Relatively low energy consumption.
• Easy maintenance.
• Easy to scale-up.
• No problem of foaming, especially in the production of lipopeptides and surfactants.
• Proper aeration.
• Higher Production yield.
• Ability to combine two unit operations.
• Can use waste organic waste as substrate.
• Larger area available for production of molecule of interest.
• Capability to change the media conditions during the fermentation process.

18. Comparative assessment
Strains Static
Culture/BCel(g /L/day)
PCS-
RDB/BCel(g /L/day)
G. xylinum 23769 0.3 ± 0.025 0.148 ± 0.047
G. xylinum 700178 0.24 ± 0.009 0.21 ± 0.044

19. Conclusions and future work
• The Rotary Disc Reactors are an effective, yet still unexplored
methodology for the production of cellular metabolites.
• The production in RDB is affected by the design as well as the
operational parameter like rotational speed, air flow rate etc.
• More research work is needed to be done for their more diverse
applications.

20. References
• Bungay, Henry R., Serafica, Gonzalo C., Production of Microbial Cellulose using Rotating Disc Film Bioreactor, 1999. U.S. Patent
5,955,326
• Chtioui, Omar, Dimitrov, Krasimir, Gancel, Frédérique, Dhulster, Pascal, Nikov, Iordan, 2012. Rotating discs bioreactor, a new tool for
lipopeptides production. Process Biochemistry 47 (2012) 2020–2024
• Hansford, G. S., Andrews,J. F., GRIEVES, C. G., Carr, A. D., 1978, A steady-state model for the Rotating Biological Disc Reactor. Water
Research vol 12 pp. 855-868.
• Kinsey, Matthew Kuure, Weber, Dale, Bungay, Henry R., Plawsky, Joel L., Bequette, B. Wayne,2005. Modeling and Predictive Control
of a Rotating Disk Bioreactor. American Control Conference June 8-10, 2005. Portland, OR, USA
• Lin, Shin-Ping, Hsieh, Shu-Chen, Chen, Kuan-I, Demirci, Ali, Cheng, Kuan-Chen, 2013. Semi-continuous bacterial cellulose
production in a rotating disk bioreactor and its materials properties analysis. Cellulose (2014) 21:835–844
• Pa’e, Norhayati Binti, 2009. Rotary Discs Reactor for enhanced production of microbial cellulose. Faculty of Chemical and Natural
Resources Engineering Universiti Teknologi Malaysia.
• Karmanev, D. G., 1991. Model of the biofilm structure of Thiobacillus ferrooxidans. Journal of Biotechnology 20 (1991) 51-64.
• Kim, Yong-Jun, Kim, Jin-Nam, Wee, Young-Jung, Park, Don-Hee, Ryu, Hwa-Won, 2007. Bacterial Cellulose Production by
Gluconacetobacter sp. RKY5 in a Rotary Biofilm Contactor. Applied Biochemistry and Biotechnology 529 Vol. 136–140, 2007.
• Krystynowicz, A, Czaja, W, Wiktorowska ,A Jezierska, Miskiewicz, M Goncalves, Turkiewicz, M, Bielecki, S., 2002. Factors affecting
the yield and properties of bacterial cellulose. Journal of Industrial Microbiology & Biotechnology (2002) 29, 189 – 195
• Lin, JP, Chen, B, Wu, JP, Cen, PL, 1997. L-Lactic acid fermentation in a rotating-disc contactor with simultaneous product separation
by ion-exchange. Chinese Journal of Chemical Engineering, Vol.5, No.1, 49-55, 1997.
• Mormino, R., Bungay, H., 2003. Composites of bacterial cellulose and paper made with a rotating disk bioreactor. Appl Microbiol
Biotechnol (2003) 62:503–506 DOI 10.1007/s00253-003-1377-5.
• Serafica, G., Mormino, R., Bungay, H.,2002. Inclusion of solid particles in bacterial cellulose. Appl Microbiol Biotechnol (2002)
58:756–760 DOI 10.1007/s00253-002-0978-8
• Tyagi, R.D., Tran, F. T., Chowdhury, A. K. M. M.,1991. Performance of RBC coupled to a polyurethane foam to biodegrade petroleum
refinery wastewater. Environmental Pollution 76 (1992) 61-70.

21. 21