An ultrasonically enhanced inclined settler for microalgae harvesting

Area of Science:

• Biotechnology
• Renewable Energy
• Environmental Engineering

Background:

• Microalgae are a promising sustainable source for biofuels and bioproducts.
• Algae dewatering remains a significant challenge for industrial-scale applications.
• Existing ultrasonic settling methods are batch-oriented and not suitable for large-scale throughput.

Purpose of the Study:

• To introduce a novel continuous acoustic harvesting device for microalgae.
• To evaluate the device's performance in terms of filtration efficiency and concentration factor.
• To investigate the influence of operational parameters on harvesting performance.

Main Methods:

• The device integrates acoustophoretic force, acoustic transparent materials, and inclined settling.
• Experiments were conducted to determine filtration efficiency and concentration factor.
• Key parameters investigated include applied power, flow rate, inlet cell concentration, and inclination angle.

Main Results:

• Achieved a filtration efficiency of 70% ± 5% and a concentration factor of 11.6 ± 2.2 at 25 mL·min⁻¹.
• Energy consumption was measured at 3.6 ± 0.9 kWh·m⁻³.
• Filtration efficiency plateaued at 100 W L⁻¹ power density, increased with cell concentration, and decreased with flow rate.
• Optimal concentration factor was achieved at a 50° ± 5° settling angle.

Conclusions:

• The novel acoustic harvesting device offers a scalable solution for microalgae concentration.
• The device demonstrates superior filtration efficiency compared to existing literature methods.
• This technology advances the potential for large-scale algal biofuel and bioproduct industries.