Table 2
Harvesting technologies, adapted from Barros et al. (2015) and Gerardo et al. (2015)
Technology
Function
Advantages
Difficulties
Primary step:
pre-concentration
Sedimentation
Based on gravity for the cell to freely settle
No energy needed
Very low cost
Slow process that can affect
biomass, relatively high
superficies required to treat
high volume
Final concentration still
very low
Coagulation–flocculation
(electro)
Use of a chemical or bioflocculants that use
the electrostatic properties of a microalgae cell
to make it aggregate in larger
flocs to enhance
settling velocity
Simple, better, and faster
sedimentation as
microalgae forms
aggregates
No energy use if not
electro-coagulation
Use of additives which can
be expensive and toxic
And/or high additional
energy for
electro-coagulation
Recycling of culture
medium is limited
Flotation
Gas vesicles are used to help microalgae
going upward and
float near the surface; a
surfactant can be aggregated
Low cost
Low space required
Short operation times
Use of additives to make
flocculates
Inapplicable in case of
marine microalgae
Secondary step:
biomass recovery
or dewatering
Centrifugation
Based on centrifugal force
High efficiency
Fast
Almost any microalgae
can be centrifuge
Expensive as it requires
high quantity of energy
Viable only for recovery of
high-value products
Possible cell damage
Filtration
Filtration with membranes
High efficiency
Free of any additive
chemical hazardous
Fouling/clogging which
increases operational cost
Membranes must be
cleaned regularly
Relatively high cost due to
pumping and membrane
replacement
(continued)
100
P.-L. Gorry et al.
Harvesting technologies, adapted from Barros et al. (2015) and Gerardo et al. (2015)
Technology
Function
Advantages
Difficulties
Primary step:
pre-concentration
Sedimentation
Based on gravity for the cell to freely settle
No energy needed
Very low cost
Slow process that can affect
biomass, relatively high
superficies required to treat
high volume
Final concentration still
very low
Coagulation–flocculation
(electro)
Use of a chemical or bioflocculants that use
the electrostatic properties of a microalgae cell
to make it aggregate in larger
flocs to enhance
settling velocity
Simple, better, and faster
sedimentation as
microalgae forms
aggregates
No energy use if not
electro-coagulation
Use of additives which can
be expensive and toxic
And/or high additional
energy for
electro-coagulation
Recycling of culture
medium is limited
Flotation
Gas vesicles are used to help microalgae
going upward and
float near the surface; a
surfactant can be aggregated
Low cost
Low space required
Short operation times
Use of additives to make
flocculates
Inapplicable in case of
marine microalgae
Secondary step:
biomass recovery
or dewatering
Centrifugation
Based on centrifugal force
High efficiency
Fast
Almost any microalgae
can be centrifuge
Expensive as it requires
high quantity of energy
Viable only for recovery of
high-value products
Possible cell damage
Filtration
Filtration with membranes
High efficiency
Free of any additive
chemical hazardous
Fouling/clogging which
increases operational cost
Membranes must be
cleaned regularly
Relatively high cost due to
pumping and membrane
replacement
(continued)
100
P.-L. Gorry et al.