Harvesting microalgal biomass using submerged microfiltration membranes

Area of Science:

• Biotechnology
• Environmental Engineering
• Materials Science

Background:

• Algal biomass harvesting is crucial for biofuel and bioproduct applications.
• Efficient and cost-effective concentration methods are needed for large-scale algal cultivation.
• Submerged microfiltration offers potential for initial algal biomass concentration.

Purpose of the Study:

• To evaluate submerged microfiltration for concentrating freshwater green algae (Chlorella vulgaris) and marine diatoms (Phaeodactylum tricornutum).
• To assess filtration performance, membrane fouling, and economic feasibility of the process.
• To determine energy consumption for dewatering concentrated algal biomass.

Main Methods:

• Utilized lab-made microfiltration membranes with varying porosity.
• Employed the improved flux step method (IFM) and batch filtration for performance assessment.
• Conducted membrane fouling analysis using SEM, EDX, and FTIR.
• Performed cost analysis based on submerged membrane bioreactor (MBR) data.

Main Results:

• Submerged microfiltration demonstrated economic feasibility for algal harvesting.
• IFM indicated low membrane fouling, comparable to submerged MBRs.
• Combined microfiltration and centrifugation achieved 22% w/v concentration.
• Energy consumption for dewatering was 0.84 kW h/m³ for C. vulgaris and 0.91 kW h/m³ for P. tricornutum.

Conclusions:

• Submerged microfiltration is a viable and cost-effective initial concentration step for diverse algal species.
• The process exhibits low fouling potential, ensuring operational stability.
• Efficient dewatering is achievable, supporting the economic viability of algal biomass utilization.