The optimum flocculant dosages required for the synthetic
coagulants PAC and AS are higher than that of chitosan pH
adjusted, although they achieve lower removal efficiencies for
P. tricornutum (Table 6). Lower concentrations of chitosan
(20 ppm) with adjusted pH (to 9.9) were found to harvest
90% of the algal cells of the P. tricornutum species with an
initial concentration of ≈3–4×106 cells mL−1. Because lower
dosages of chitosan can remove algal cells, we might
conclude that chitosan (with pH adjustment) is more
effective for harvesting P. tricornutum than PAC or AS
(without pH adjustment).