Tackling membrane fouling in microalgae filtration using nylon 6,6 nanofiber membrane

Area of Science:

• Biotechnology and Bioengineering
• Materials Science
• Environmental Engineering

Background:

• Microalgae cultivation is crucial for the food-water-energy nexus but faces high cultivation and harvesting costs.
• Membrane processes are promising for microalgae harvesting but are hindered by membrane fouling.
• Conventional polyvinylidene fluoride phase inverted membranes (PVDF PIM) are susceptible to fouling, limiting their efficiency.

Purpose of the Study:

• To evaluate the performance of nylon 6,6 nanofiber membrane (NFM) against PVDF PIM for microalgae (Chlorella vulgaris) filtration.
• To assess fouling resistance and filtration efficiency of NFM compared to PVDF PIM.
• To explore the impact of relaxation cycles on NFM performance.

Main Methods:

• Comparative filtration experiments using Chlorella vulgaris.
• Characterization of membrane properties: hydrophilicity, pore size, and pore density.
• Measurement of permeance and biomass retention under different operational conditions, including varying relaxation cycles.

Main Results:

• Nylon 6,6 NFM exhibited superhydrophilicity, larger pore opening size (0.22 vs 0.18 μm), and higher pore density (23 vs 18 pores/μm²).
• NFM demonstrated significantly higher initial permeance (1018 vs 493 L/m²hbar) and steady-state permeance (286 vs 120 L/m²hbar) with comparable biomass retention.
• Longer relaxation cycles enhanced NFM performance (178 L/m²hbar for 0.5 min, 236 L/m²hbar for 5 min), unlike PVDF PIM.

Conclusions:

• Nylon 6,6 NFM significantly outperforms PVDF PIM in microalgae filtration due to superior fouling resistance and higher flux.
• The enhanced performance of NFM can reduce membrane area requirements and aeration demand, lowering operational costs.
• Further research into NFM material properties and operational parameters can optimize its competitiveness for microalgae harvesting.