LAUSR

Abstract Flocculation of two different fresh-water green microalgae, Chlorella vulgaris and Dictyosphaerium sp., was explored using chitosan, FeCl3 and NaOH as flocculants. The most optimal dosage of each flocculant under certain pH was determined. Both chitosan and FeCl3 gave a higher flocculation efficiency then flocculation induced by pH increase. Flocculation induced by chitosan could be achieved with lower dosage. The optimal dosages of chitosan for Chlorella vulgaris and Dictyosphaerium sp. were 10 mg/L and 5 mg/L, respectively. Furthermore, the synergy between membrane filtration and flocculation was investigated and showed a higher membrane filtration performance and harvesting efficiency compared with the filtration without flocculation in both dead-end filtration and filtration with vibration. The filtration under sub-optimal flocculation conditions also showed significant potential. Introducing such flocculation into the membrane filtration process prominently reduced both energy input and required membrane area.