Chitosan is one of the first compounds of biological origin that
was considered for use as a flocculant. This compound had been
also considered earlier as a flocculant for treating different sorts
of wastewater. When it appeared, the microalgae harvest problem
had once again excited interest in this compound (Chang and Lee,
2012). The main difficulty with chitosan use to harvest microalgae
is that this compound is efficient at low pH values, whereas the
microalgal cultures are on the contrary characterized by pH above
7 (Chang and Lee, 2012). What should be also noted is poor solubility
of chitosan in water, which necessitates intensive stirring of the
medium earlier in floccule formation. The latter, in turn, would
result in more power consumed for flocculation process as compared
with traditional polymer-based flocculants.