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Table 1 Comparison of inorganic and organic flocculants for microalgal biomass harvesting [25]

From: Microalgae Chlorella vulgaris biomass harvesting by natural flocculant: effects on biomass sedimentation, spent medium recycling and lipid extraction

Parameters Inorganic flocculants Organic flocculants
Nature of flocculants Multivalent salts Polyelectrolytes/polymers
Key characteristics of an effective flocculant Increasing molecular weight can increase the binding capabilities Flocculants that have a high charge density are therefore more effective
Sensitivity to pH Coagulation using inorganic coagulants is highly sensitive to pH level Coagulation using organic coagulants is less sensitive to pH
Sensitivity to biomass concentration Highly sensitive to concentration Highly sensitive to concentration
Dosage of flocculants required 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) Lower dosages of organic flocculants are required, and less or no contamination occurs
Applicability Although some coagulants may work for some microalgal species, they do not work for others Wide range of applications for larger number of microalgal species