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Nature of flocculants
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Multivalent salts
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Polyelectrolytes/polymers
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Key characteristics of an effective flocculant
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Increasing molecular weight can increase the binding capabilities
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Flocculants that have a high charge density are therefore more effective
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Sensitivity to pH
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Coagulation using inorganic coagulants is highly sensitive to pH level
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Coagulation using organic coagulants is less sensitive to pH
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Sensitivity to biomass concentration
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Highly sensitive to concentration
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Highly sensitive to concentration
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Dosage of flocculants required
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A large concentration of inorganic flocculant is needed in order to maintain flocculation efficiency, and may contaminate the end product (e.g., addition of aluminum and iron salts)
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Lower dosages of organic flocculants are required, and less or no contamination occurs
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Applicability
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Although some coagulants may work for some microalgal species, they do not work for others
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Wide range of applications for larger number of microalgal species
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