For the coagulating agent, i.e., ferric chloride, the highest efficiency
over 5 min of sedimentation was more than 60% achieved
at 500 mg/l concentration (Fig. 3a). However, note that this is a
very high concentration, so it may have unfavorable effects on subsequent
biomass processing. Further increase of the above-given
coagulating agent concentration did not result in higher flocculation
efficiency.