Bioreactor Types in Detail with Diagrams

Bioreactor Engineering

1. TYPES OF BIOREACTOR
Dr Bhavesh Patel
Principal
V P & R P T P Science College, Vallabh Vidyanagar

2. Back ground
ABioreactorisoneinwhichbiologicalreactionstakes
place.
Bioreactorisalsoknownasfermentor
Fermentationisanimportantreactioncarriedoutby
biologicalsystem,importantlybymicroorganisms.
Fermentationcanbedefinedasanoxidationreduction
energyyieldingprocesswherebothoxidizingandreducing
agentsareorganiccompound.
TheprocessoffermentationwasfirstobservedbyLouis
Pasteurwhogavetheconceptof“Germtheoryof
fermentation”.Accordingtohimthefermentationis
mediatedbygermsi.e.microorganism.(theprocesswas
originallyconsideredasachemicalprocess)

3. Back ground
Previouslytheprocessoffermentationwasconsideredas
ananaerobicprocesswhereasugarorstarchcontaining
substrateisconvertedintoalcoholwiththehelpofyeast.
Presentdefinitionofindustrialfermentationis
“Bioconversionofanysubstrateintoitsproduct”
Hence,anyprocessthatismediatedbybiologicalsystemis
knownasfermentation.
Presentlyweareproducingmanyproductsatindustrial
scalelikealcohol,aminoacids,vitamins,antibiotics,organic
acidsetc.(studentsmusttrytoprepareacomprehensive
listofproductsproducealongwithproducerorganisms)

4. Types of Fermentation
Fermentationisoftwotypesnamely,Surfaceand
submerged
Asthenameindicateinsurfacefermentationtheorganisms
tendstogrowonsurfaces.Thistypeofprocessismainly
applicabletofungiandinvolvetheuseofsolidorsemisolid
substrate.Thepresentdayprocesswhichinvolvesthe
conceptofsurfacefermentationissolidstatefermentation.
Theothertypeoffermentationinvolvesthecultivationof
organismsbeneaththesurface(submerged).Suchprocess
mainlyinvolvescultivationofbacteriausingliquidmedia.
Submergedcultivationcanbecarriedoutbytwowaysi.e.
BatchcultivationandContinuouscultivation.

5. Typical Batch Reactor

6. Continuous fermenter

7. Continuous fermenter
Continuousfermentationrepresentsanopensystemi.e.the
systemwherenutrientadditionandproductharvestingisa
continuousprocess.Asagainstthisbatchcultivationrepresents
aclosedsystem,whereeverythingisaddedonceandonlygases
areallowedtoexchangefromenvironmentinbetween.
Continuousfermentationisalsoasubmergedkindofprocess
whereorganismpresentinasteadystatei.e.logphase.Thiscan
beachievedbycontinuousadditionoffreshnutrientsand
harvestingthefermentedbrothatthesametime.
TheaboveprocesscanbehandledusingChemostatand
Turbidostat

8. Advantages of Continuous fermenter
Sizeofthefermenterreducedandhenceestablishment
expenditure.
Inoculumistobedevelopedonce
Lowshutdownperiod
Productismoreuniform
Usefulwherehighnutrientsorhighproductaccumulationis
inhibitoryforthegrowth
Effectiveuseofmanpower

9. Tubular fermenter/ Packed bed reactor
The performance of Batch & CSTF is dominated by suspended
microbes. They often occur as large flocs.
In tubular fermenter the microorganisms exists as flocks or
films.
Process with microorganisms adhering to support surface are
chiefly used in the waste water treatment industry under the
name “Trickling Filter”.
Vinegar, waste water treatment

10. Tubular fermenter

11. The Fluidized Bed Fermenter
It represents particulate fluidization.
This is a characteristic of beds of regular particles suspended in
an up flowing liquid stream.
It has increase in porosity from bottom to top of the bed &
decreased particle movement when compared with beds
containing particles of constant size.
Used for Beer & Cider production.
Flow rate limited by wash out.

12. Fluidized Bed Fermenter

13. Tower fermenter/ Air lift fermenter
It is developed for continuous production of beer.
The fermenter consists of a vertical cylinder with an aspect ratio
of approx.10:1
The significant feature of tower is the progressive & continuous
fall in the specific gravity of the nutrient medium between the
bottom & top of tower.
It is difficult to control microbial hold up.

14. Tower fermenter/ Air lift fermenter

15. Tray fermenter

16. Solid substrate fermentation (SSF)
Fermentation process occurring in the absence or near-absence of
free water.
SSF processes generally employ a natural raw material as carbon
and energy source.
Solid substrate (matrix), however, must contain enough moisture.
Mostly used with fungi.
Examples of products of solid state fermentation include industrial
enzymes, fuels and nutrient enriched animal feeds, Bioleaching,
Bioremediation, Bio pulping etc

17. Advantages of Solid State Fermentation (SSF)
over Submerged Liquid Fermentation (SLF)
The low availability of water reduces the possibilities of
contamination by bacteria and yeast.
High level of aeration can be maintained
Provides natural environment for the growth of Fungi, which is
the main candidate for SSF
The inoculation with spores (fungi) facilitates its uniform
dispersion through the medium
Reactor with simple design is in use
SSF in most cases require low energy

18. Advantages of Solid State Fermentation (SSF)
over Submerged Liquid Fermentation (SLF)
Polluting effluents volume are generally low
The product obtained in SSF have slightly different properties
(thermo tolerance)
Easy downstream processing

20. Disadvantages of Solid State Fermentation (SSF)
over Submerged Liquid Fermentation (SLF)
The substrate in most cases require pre treatment such as size
reduction by grinding, physical, chemical or enzymatic hydrolysis,
cooking and vapour treatment.
Bacteria are poor performer in SSF because of low free water
Monitoring of process parameters such as pH, moisture content,
substrate oxygen and biomass concentration becomes a problem
Agitation is not possible. Aeration is also difficult
Possibilities of contamination with other fungal spp. is always
there

21. Main groups of microorganisms involved in SSF
Bacteria
Clostridium sp. –Ensiling, Food
Lactobacillus sp. –Ensiling, Food
Streptococcus sp. –Composting
Pseudomonas sp. –Composting
Serratia sp. –Composting
Bacillus sp. –Composting, Natto, amylase
Yeast
Endomicopsis burtonii –Tape, cassava, rice
Schwanniomyces castelli –Ethanol, Amylase
Saccharomyces cerevisiae –Food, Ethanol

22. Main groups of microorganisms involved in SSF
Fungi
Alternaria sp. –Composting
Penicillium notatum, roquefortii –Penicillin, Cheese
Lentinus edodes –Shii-take mushroom
Plurotus oestretus, sajor-caju –Mushroom
Aspergillus niger –Feed, Proteins, Amylase, Citric acid
Rhizopus oligosporus –Tempeh, soybean, amylase, lipase
Aspergillus oryzae –Koji, food, citric acid
Amylomyces rouxii –Tape, casava, rice
Beauveria sp., Metharizium sp. –Bioinsecticide
Rhizopus sp. –Composting, food, enzymes, organic acids
Mucor sp. –Composting, food, enzyme

23. Application areas of SSF
Economic SectorApplication Examples
Industrial
Fermentation
EnzymesproductionAmylases, amyloglucosidase, cellulases,
proteases, pectinases. Xylanases, glucoamylases
Bioactive productsMycotoxins, gibberellins, alkaloids, antibiotics,
hormones
Organic acid Citric acid, fumericacid, itaconicacid,lactic acid
Bio fuel Ethanol
Miscellaneous Pigments, bio surfactants, vitamins, xanthan
Agro-Food
Industry
BiotransformationTraditional fermented food (Koji, sake, ragi,
tempeh), Protein enrichment and single cell
protein production, mushroom
Food additives Aroma compounds, dyestuffs, essential fat and
organic acids
Environmental
control
Bioremediation and
Biodegradation
Caffeinated residues, pesticides, poly chlorinated
bisphenyls(PCBs)
Biological
detoxification of
agro waste
Coffee pulp, cassava peels, canola meal, coffee
husk