Cyclic Filtration-Cleaning of Chlorella vulgaris Using Surface-Modified Hydrophilic Polytetrafluoroethylene Membrane with Polyaluminum Chloride as Coagulant

Abstract

Membrane filtration can efficiently harvest microalgae from culture broth. The performances of cyclic filtration and cleaning tests on Chlorella vulgaris were evaluated with polyaluminum chloride (PACl) coagulation and with a surface-modified hydrophilic polytetrafluoroethylene (PTFE) membrane under 1 bar pressure drop. Filtration of the original algal suspension without PACl coagulation could lead to severe irreversible fouling on the PTFE membrane. Coagulation using 10 mgl⁻¹ PACl can mitigate pore blocking but cannot enhance filtration flux. With 500 mgl⁻¹ PACl, most fines were incorporated into large flocs to build up cakes of low resistance and protect membrane pores from severe blocking. Flux recovery all exceeded 95% with ≥10 mgl⁻¹ PACl dosage. The PACl-coagulation and surface modified PFTE membrane are feasible to dehydrate Chlorella vulgaris ESP-6 isolate using cyclic filtration-cleaning process.

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Keywords:

• Algae
• Cyclic operations
• Harvesting
• Membrane filtration

ACKNOWLEDGMENTS

The authors gratefully acknowledge funding from Project NSFC 51176037 and the support from the National Science Council.