Flocculants used in large scale
should be inexpensive, non-toxic and effective (Grima et al., 2003).
Chitosan is a cationic polyelectrolyte obtained by deacetylation of
chitin, which is the second most abundant biopolymer in the world
(Renault et al., 2009) and has been proved highly effective in
removing both freshwater algae and marine algae from water
(Divakaran and Sivasankara Pillai, 2002). Unlike the metal salts,
chitosan is non-toxic, biodegradable, renewable and ecologically
acceptable (Renault et al., 2009). Its use therefore causes little
problems in the subsequent application of the recovered biomass
as a biofuel and the recycling of the culture medium. However,
though extensively studied, the mechanism of chitosan flocculation
of algal cells is still not well understood, and the process efficiency
depends on the algal properties and culture conditions used
in each study (Cheng et al., 2011).