Microalgae have potential for biodiesel production as they can grow rapidly, use non-arable land and non-potable water, and consume CO2. Microalgae can be cultivated in open ponds or photobioreactors, then dried and extracted for oil via methods like solvent extraction. The oil can then be transesterified to biodiesel using processes like reactive distillation to help shift the equilibrium. A variety of reactor designs exist to improve mass transfer and reaction rates for transesterification.

1. Ángel Darío González-Delgado
Biodiesel from miroalgae: A chemical process
approach

2. • Produced from microorganisms (yeast,
fungi and microalgae).
• Can avoid competition food vs. Fuel.
• Can avoid competition in use of arable
farmlands.
• Can avoid the increase of food prices.
Source: cmg1632.wordpress.com, 2013

3. Source: pacificjunction.com, 2014
• High photosynthetic efficiency and CO2
consumption rate (183 Ton CO2/Ton
microalgae) (Razzak et al., 2013).
• Can grow in different kinds of water
(Komolafe et al., 2014).
• Can duplicate their population in one day
(Noazami et al., 2011).
• Up to 8 times more biomass productivity
per area unit than terrestrial plants (UIS-
ICP-Morrosquillo, 2011).
• Up to 20 times more lipid productivity per
area unit than palm (Mata et al., 2010).

4. Biomass rich in
carbohydrates and
protein
Oil Extraction
Oil Transesterification
Final Use
CO2 Sunlight
H2O
Nutrients
Algae Cultivation
Grown
Photobioreactor
Grown
Open Pond
Algae Drying
H2O
StorageTransportDistribution
Algae Harvesting
Biodiesel from microalgae production chain

5. Scaling up

6. • The growth of microorganisms in photobioreactors is very
complex due to the effects of photosynthesis, the dynamics of
the environment and the distribution of irradiance within the
photobioreactor.
• First the walls of the reactor acts as a transparent way which
allows the photons to reach the middle without being
retained.
• second cell concentration and turbulence are achived by the
excitement generated by the entry of the gas phase, which
prevents the cell sedimentation and cell adhesion to the
reactor walls.

7. Microalgae Cultivation
• Open Ponds •Photobioreactor
•Harvesting 365 days of the year
•Under optimal conditions, microalgae can duplicate its population in one day
•Only is necessary nutrients, CO2 and a light source.
•Microalgae can be cultivations in mediums (i.e domestic wastewater) non usable for food crops

8. Microalgae cultivation: Open Ponds
•Used since50’s
•Lower cultivation costs
•Low species selectivity
•Lower control of environmental variables
•Ideal for massive scale cultivation

9. Bioprospecting of Colombian microalgae for biodiesel production MC

10. Bioprospecting of Colombian microalgae for biodiesel production MC

11. Microalgae cultivation: Open ponds

12. TYPES OF OPEN PONDS

13. • Open ponds resemble most closely the natural milieu of
microalgae.
• most common technical design for open pond systems
are raceway cultivators driven by paddle wheels and
usually operating at water depths of 15–20 cm (Pulz
2001).
• circular ponds which are common in Asia and the Ukraine
(Becker 1994).
• biomass concentrations of up to 1,000 mg/l and
productivities of 60–100 mg/(l day–1), i.e., 10–25 g/(m2
day–1)

14. Drawbacks
• Significant evaporative
losses.
• diffusion of CO2 to the
atmosphere.
• permanent threat of
contamination and
pollution.
• large area required.
• light limitation in the high
layer thickness.

15. Microalgae cultivation: PBR
•Higher production costs
•cultivation area optimization
•Controlled environment for optimizing growth and
oil content
•Better gas exchange

16. Microalgae cultivation: Flat plate

17. Microalgae cultivation: PBR

18. Microalgae cultivation: PBR

19. TYPES OF CLOSED PHOTOBIOREACTORS

20. Closed PBRs are characterized by the regulation and
control of nearly all the biotechnologically important
parameters as well as by the following fundamental
benefits (Pulz 1992).
– a reduced contamination risk
– no CO2 losses
– reproducible cultivation conditions,
– controllable hydrodynamics and temperature
– Flexible technical design.

21. Labscale photobioreactor form Colorado State University

22. Outdoor scale photobioreactor form Arizona State University

23. Outdoor scale photobioreactor form University of Almeria, Spain

24. Outdoor scale photobioreactor form University Ben Gurion, Israel

25. Outdoor scale photobioreactors from a plant in germany.
CO2 utilization for microalgae growth from a coal
plant (Germany)

26. Outdoor scale photobioreactor form University of Almeria, Spain

27. Outdoor scale photobioreactor form Subitec

28. Outdoor scale photobioreactor form University of South Bohemia, Czech Republic

29. Source: Borowitzka 1999.

30. Microalgae Drying

31. Microalgae Drying
•Sun Drying
93% of net solar radiation received on a wet
surface goes to vaporization of water.
The remaining 7% goes to heating the air

32. Microalgae Drying
•lyophilization
75% of strains remains viable
Energy intensive
With low temperature in operation , it can retain color, fragrance,
shape and nutritious of dried food in a more efficient way than any
other traditional equipment.

33. Microalgae Drying
•Spray Drying
After spraying of the material liquid, the surface area
will be increased greatly.
In the hot air flow, 95%-98% of water can be
evaporated at a moment.
The time of completing the drying needs only
several seconds.

34. Microalgae Drying
•Drum Drying
High thermal efficiency(≥ 60%)
Medium temperature in outlets(80 degree-120
degree)
Good dry effect (≤ 10% after drying)

35. Microalgae Drying
•Oven
Heating source: electricity, steam,
far infrared, or steam+electricity.
Drying temperature is about 50 ~
300 °C, electric heater will be
15kw
Steam heating type: The normal
pressure of steam will be 0.02-
0.8MPa (0.2-8kg/cm 2)
D
rying temperature: 50 ~ 140 °C,
maximum temperature will be
150 °C.

36. Microalgae Drying
Refractance Membrane
https://www.youtube.com/watch?v=CgBMK6DMheQ

37. Microalgae oil Extraction
Dryed Algae
Oil Extraction
Process
Biocrude Oil
•Expeller/Press
•Solvent Extraction
•Supercritical Fluid
•Enzymatic
•Ultrasonic
•Osmotic Shock
•Microwaves

38. Solvent-Based extraction
•Lipid extraction with chemical solvents traditionally been used for animal and plant
lipids sources.
•for the case of microalgae, the solvent is usually added to the dried biomass but in
some cases is used in biomass with some water.
•A variety of organic solvents typically used in extraction of oil from microalgae
•Hexane-ethanol mixture
•Methanol-chloroform (Folch method)
•The method of Bligh & Dyer

39. Soxhlet extraction system
has been widely used in the extraction of microalgae
oil.
A large amount of solvents have been used as
extraction solvent in the Soxhlet method
Petroleum ether
ethyl ether
hexane
Hexane
Dichloromethane-methanol mixture
Solvent-Based extraction

40. Microwave-assisted extraction
•Uses the polarity of the molecules that make up the structure of the microalgae.
•Is characterized by a technique that reduces the time and increases the efficiency of
the process.
•Satisfactory results in the species Chlorella vulgaris, Scenedesmus sp. and
Botryococcus sp.

41. Ultrasound-assisted extraction
•Consists in microalgae exposure to acoustic waves of a certain frequency.
•Applying low frequency ultrasound to cause a strong cell killing even greater
when high frequency waves are applied.
https://www.youtube.com/watch?v=4Q5NeiUhlPs

42. Supercritical fluid extraction
•These methods emerged as an alternative
to the traditional use of large amounts of
solvents
•This type of processes, the most promising
are the supercritical fluid extraction (SFE),
and extraction with subcritical water (SWE)
•Have the possibility of coupling the system
of extraction and characterization systems
such as gas chromatography or supercritical
fluid chromatography.
•Results in microalgae

43. Subcritical water extraction (SWE)
•It has the advantage of being
environmentally friendly.
•It is a highly efficient technique when
solid samples extraction is done.
•Microalgal biomass utilization

44. Osmotic Shock
•Is a sudden reduction in
osmotic pressure.
•It is a relatively easy method
of using

45. Enzymatic extraction
•Cell walls of microalgae is degraded
by the use of enzymes.
•The enzyme activity is affected by
many variables.
•Enzymes can also be used for
transforming fatty acids present in the
microalgae.

46. Mechanical disruption
•It covers various kinds of mechanical devices (cell homogenizer, ball mills, press
systems).
•Have the disadvantage of difficult to recover oil extracted.

47. Microalgae Oil Transesterification

48. Oscillatory flow reactors are
tubular reactors in which orifice
plate baffles are equally spaced
and produce oscillatory flow
using a piston drive. When a bulk
fluid is introduced into the
reactor, an oscillatory motion
interacts with it and intensifies
radial mixing, with enhancements
in mass and heat transfer whilst
maintaining plug flow (Qiu et al,
2010)
Configuration of an oscillatory flow reactor
(Harvey et al, 2003)
Oscillatory flow reactors

49. Oscillatory flow reactors
Schematic of an oscillatory flow
reactor (Harvey et al, 2003). The
reactor consisted of two vertically
positioned jacketed tubes of 1.5m
length and 25mm internal
diameter, with equally spaced
orifice plates 1.5 tube diameters
apart of 0.25 fractional open cross
sectional area

50. Micro-channel reactors
Representative configuration of a zigzag
micro-channel reactor (Wen et al, 2009)
Micro-channel reactors are a device that has a very small channel (generally nanometer to
micrometer range in width and depth and centimeter to meter range in length) etched in a
solid material and achieve rapid reaction rates by improving the efficiency of heat and mass
transfer and utilizing high surface area/volume ratio and short diffusion distance
(Kobayashi et al, 2006)

51. Static mixers consist of specially designed motionless geometric elements enclosed within a
pipe or a column and create effective radial mixing of two immiscible liquids as they flow
through the mixer (Qiu et al, 2010)
Static mixers
Experimental setup developed by
Thompson and He (2007). The system is
composed of two stainless steel static
reactors including 34 fixed right- and left-
hand helical mixing elements. a) static
mixer closed-loop system, and (b) internal
structure of static mixers

52. Diagram of a laminar flow
reactor/separator (Boucher et al, 2009).
Reactants flowed into a reaction chamber
through a mixer with decreasing bulk
velocity and separated into two phases
under laminar flow conditions in the main
body of the reactor: a less dense biodiesel
phase separated and the glycerol phase

53. The rotating, or spinning tube reactor is a shear reactor consisting of two tubes. Once
reactants are introduced into the gap, Couette flow is induced and the two liquids are mixed
instantaneously and move through the gap as a coherent thin film due to the high shear
rate. Couette flow leads to high mass transfer rate and very short mixing time. The thin film
presents a very large interfacial contact area (Qiu et al, 2010)
Schematic of how a spinning tube reactor works
(from http://www.rccostello.com/STT.html.). There
is a very narrow annular gap between the outer
tube and the inner tube
Rotating/spinning tube reactors

54. Image of a Spinning Tube in a Tube
(STTTM) system reactor developed
by Kreido Laboratories. (from
http://www.kreido.com/downloads/ps
_stt_tech.pdf.)
Schematic of the STTTM system
developed by Kreido Laboratories (from
http://www.kreido.com/downloads/ps_stt
_tech.pdf.)

55. Diagram of a typical STTTM reactor.
Reactant fluid A is instantaneously
mixed with reactant fluid B in the
STTTM reactor with zero eddy decay.
This can be accompanied with an
optional gas or catalyst to complete
or accelerate the reaction. The
necessary residence time is
controlled by the reactants' feed
rates, as well as by the rotor speed.
Separate temperature zones allow
unprecedented temperature control
of the reaction, including staging
different temperature profiles for the
complete reaction. (from
http://www.rccostello.com/STT.html.)

56. Microwave reactors utilize microwave irradiation to transfer energy directly into reactants and
thus accelerate the rate of chemical reaction
Microwave reactors
In this commercially available reactor,
reagents are pumped in through a
tube located near the bottom of the
vessel and out at the top; the
temperature can be measured using
a fiber-optic probe and microwave
power is automatically controlled to
hold the contents of the reactor at the
same temperature (Barnard et al,
2007)

57. Cavitational reactors use acoustic energy or flow energy to generate cavitation phenomena.
During the violent collapse of the cavities produced by the pressure changes from sound
and flow energy releases large magnitude of energy over a small location, and brings about
very high temperatures and pressures; cavitation also intensifies the mass transfer rate by
generation of local turbulence and liquid micro-circulation in the reactor (Qiu et al, 2010)
Cavitational reactors
Detailed scheme of a new pilot flow reactor
for high-intensity ultrasound irradiation
(Cintas et al, 2010)

58. Schematic diagram of a hydrodynamic cavitation
system setup developed by : 1) tank; 2) cold
water; 3) pump; 4) orifice plate (Wang et al,
2006)
Schematic diagram of an ultrasonic cavitation
system setup: 1) condensator; 2) transducer; 3)
ultrasonic reactor; 4) stand support; 5)
thermometer; 6) ultrasonic generator (Wang et al,
2006)

59. Reactive distillation (RD) combines chemical reactions and product separations in one unit
Reactive distillation
General setup of RD in a trayed-column.
The feed stream of oil and
methanol/catalyst is introduced at the
upper tray of the column and flows
downward while the methanol vapors
from the reboiler flask rises upwards
causing a counter-current gas-liquid
contact (He et al, 2004)

60. In the esterification of high acid value
feeds (microalgae and waste oils), the
reaction equilibrium can be shifted
toward the key product (ester) by
continuous removal of byproduct (water),
instead of using an excess of reactant
(Kiss et at, 2008)
FAMEs production by esterification with
methanol in a reactive distillation column (Kiss
et at, 2008)

61. Membrane reactors integrate reaction and membrane-based separation into a single
process. They can increase the conversion of equilibrium-limited reactions by removing
some products from the reactants stream via membrane
Membrane reactors
Due to the immiscibility of oil and alcohol, and
due to various surface forces, the oil will exist in
the form of an emulsion. In the presence of a
permeable membrane, the oil droplets are too
large to pass through the pores of the
membrane. However, FAAEs will pass through
the membrane pores along with the alcohol,
glycerol and catalyst, due to smaller molecular
size (Dube et al, 2007)
Schematic of biodiesel production in a
membrane reactor (Dube et al, 2007)

62. General setup of a membrane reactor
(Cao et al, 2009). The membrane reactor
employs a continuous feed of oil and
methanol, and the product are
continuously removed from the reaction
zone simultaneously.

63. Centrifugal contactors integrate reaction and centrifugal separation into a unit
Centrifugal contactors
The immiscible liquid phases are
introduced in the annular mixing zone
between the outside of the rotor and the
inside of the outer housing. The
dispersion is then sucked inside the
centrifuge, where the two phases are
gradually separated whilst moving
upwards, after which they leave the
device through separate exits (Kraai et
al, 2008)
Schematic cross-section of a centrifugal contact
separator (Kraai et al, 2008)

64. Residence
time
Current
status
Advantages
Oscillatory flow
reactor
30 min Pilot plant Molar ratios applied are lower than the stoichiometric
ratio, reducing operational cost
The short length-to-diameter decreases capital cost and
allows it to be scaleable
Micro-channel
reactor (MCR)
28s to
several
minutes
Lab scale Its smaller size offers reductions in footprint requirements,
construction and operating costs
MCR can be scaled up readily by adding more reactors of
the same proven dimensions in parallel (“numbering up”)
Static mixer (SM) ∼30 min Lab scale SM require low maintenance and space due to it has no
moving parts
Rotating/spinning
tube reactor
< 1 min Commercial
scale
Less reaction time and mixing power input are required
compared to conventional reactors
The short residence time allows this reactor to handle
feedstocks with high free fatty acid content
Summary
Adapted from Qiu et al (2010 )

65. Residence time Current
status
Advantages
Microwave
reactor
Several minutes Lab scale Conversions are achieved in less time compared with
similar reactors using conventional thermal heating
Cavitational
reactor (CR)
Microseconds to
several seconds
Commercial
scale
CR is 160–400 times more efficient than conventional
mixing methods, from the point of view of energy
efficiency of mixing
Reactive
distillation
Several minutes Pilot plant Conversion limitation is avoided by continuous in situ
product removal for equilibrium-controlled reactions
Integration of reaction and separation reduces capital
investment and operating costs
Membrane
reactors
1 – 3 h Pilot plant Conversion limitation is avoided by continuous separation
of reaction products
Summary
Adapted from Qiu et al (2010 )

66. 66
Thank you!
E-Mail: agonzalezd1@unicartagena.edu.co
Researchgate: Angel Gonzalez-Delgado
Canal Youtube: Ingeniería Química Fácil