due to the algal biomolecules release (proteins and polysaccharides) produced by
ozone that assisted flocculation (Cheng et al. 2011). Proteins generated due to
ozonation from the cells probably allowed for froth formation and cell segregation.
1.3.7.5 Electrolytic Flotation
Water hydrolysis powered by electric fields generates H 2 bubble formation that
attach microalgae with each other and bring them to the upper surface to speed up
harvest process (Mollah et al. 2004). The process of electrolytic flotation was
conducted simultaneously in batch mode, and continuous mode higher power
correlated positively with improved separation of algal cells in eutrophic lake
water was reported (Alfafara et al. 2002). The benefit of this technique is that no
additional chemicals are required to induce separation.
1.3.7.6 Foam Flotation
It includes the mechanism of extracting the active surface chemicals from the water
and by drawing water from solid and liquid mixtures. Foam generation is by addition
of a surface-active chemical to the solid-liquid mixture and air bubbles injection for
creating a steady foam. Depending on the algae to be collected, bubbles may be of
various sizes, usually between 10 and 3000 mm in diameter.
1.3.8 Magnetic Separation
Magnetic algae separation was suggested in the past and is currently under investigation. The principle consists of passing algal cells that are magnetized in nature
(or aggregates magnetic in nature) through a magnet and extracting them from
culture medium directly.
The magnetite and aluminum sulfate were used in the initial magnetic separation
methods applied to the culture that is attached with the algal cells and then subsequently an electromagnet aids in extraction. In neutral and slightly acidic pH waters
they were more active (removal from 79 to 94%) but less effective with higher pH
water (55 to 64%) (Bitton et al. 1975). This method has the pH sensitivity concern,
along with the reliance on magnetic materials and flocculants added.
1.3.9 Ultrasonic Separation
Ultrasonic waves have been used to induce algae agglomeration and to improve algal
differentiation in various formats. The mechanism of separation is based on a
24
A. Shrivastava et al.
ozone that assisted flocculation (Cheng et al. 2011). Proteins generated due to
ozonation from the cells probably allowed for froth formation and cell segregation.
1.3.7.5 Electrolytic Flotation
Water hydrolysis powered by electric fields generates H 2 bubble formation that
attach microalgae with each other and bring them to the upper surface to speed up
harvest process (Mollah et al. 2004). The process of electrolytic flotation was
conducted simultaneously in batch mode, and continuous mode higher power
correlated positively with improved separation of algal cells in eutrophic lake
water was reported (Alfafara et al. 2002). The benefit of this technique is that no
additional chemicals are required to induce separation.
1.3.7.6 Foam Flotation
It includes the mechanism of extracting the active surface chemicals from the water
and by drawing water from solid and liquid mixtures. Foam generation is by addition
of a surface-active chemical to the solid-liquid mixture and air bubbles injection for
creating a steady foam. Depending on the algae to be collected, bubbles may be of
various sizes, usually between 10 and 3000 mm in diameter.
1.3.8 Magnetic Separation
Magnetic algae separation was suggested in the past and is currently under investigation. The principle consists of passing algal cells that are magnetized in nature
(or aggregates magnetic in nature) through a magnet and extracting them from
culture medium directly.
The magnetite and aluminum sulfate were used in the initial magnetic separation
methods applied to the culture that is attached with the algal cells and then subsequently an electromagnet aids in extraction. In neutral and slightly acidic pH waters
they were more active (removal from 79 to 94%) but less effective with higher pH
water (55 to 64%) (Bitton et al. 1975). This method has the pH sensitivity concern,
along with the reliance on magnetic materials and flocculants added.
1.3.9 Ultrasonic Separation
Ultrasonic waves have been used to induce algae agglomeration and to improve algal
differentiation in various formats. The mechanism of separation is based on a
24
A. Shrivastava et al.