Evaluation of Chlorella sorokiniana Biomass Recovery by Using Different Chemical-based Flocculants

Introduction: The nature and the concentration of the chemical agents responsible for cell flocculation are the bottlenecks for microalgae recovery. The aim of the present study was to evaluate different chemical-based flocculants for Chlorella sorokiniana flocculation.Materials and Methods: The biomass recovery efficiency was evaluated by comparing self-flocculation and flocculation with the ferric chloride, sodium hydroxide, aluminum sulfate, and zinc sulfate. After identifying the best flocculating agent, its concentration was varied to determine the optimal condition by rapid agitation followed by sedimentation (۰.۲۵ to ۱ g/L).Results: Zinc sulfate was unsuitable for this strain due to an efficiency lower than ۴۰%. Self-flocculation and sodium hydroxide were fairly efficient (۴۸.۶۵% and ۵۸.۰۶%, respectively). Aluminum sulfate produced moderate results (۵۶.۲۷%), but flocculation took a long time to become efficient. Ferric chloride showed the best potential for flocculation, and in the analysis of different concentrations (۰.۲۵ to ۱ g/L) showed to be fast and efficient (nearly ۸۰% of biomass recovery in ۱۰ min) at a concentration of ۰.۷۵ g/L.Conclusions: All the flocculants tested in this study can be utilized for biomass recovery, except for the zinc sulfate. The procedure was efficient, inexpensive, and contaminant-free for the recovery of C. sorokiniana biomass. 

Keywords:

Microalgae , flocculation , Sedimentation , Ferric Chloride