Once the ferric chloride concentration
was taken equal to 100 mg/l, the biomass harvested has a less concentration
of Fe than in the case where FeCl3, was solely used,
whose maximum of efficiency was achieved at 500 mg/l concentration.
By the reason of such effective action mixture of coagulant
and flocculant it was interesting reduce the dosage for lower costs.
Fig. 3c shows the dependence of the flocculation efficiency from
the mixing ratio of the coagulant and flocculant. It found that the
reduction of iron concentration to 50 mg/l and flocculant to
7.5 mg/l does not affect on flocculation efficiency (approximately
90% within 5 min of sedimentation), while further diminishing of
concentrations reduce flocculation efficiency of C. vulgaris.