Electrocoagulation reduces harvesting costs for microalgae.

Area of Science:

• Biotechnology
• Environmental Engineering
• Algal Biotechnology

Background:

• Centrifugation is the standard method for microalgae harvesting but is energy-intensive and costly.
• High energy demands of centrifugation limit the economic viability of microalgae cultivation.
• Developing cost-effective harvesting methods is crucial for scaling up microalgae production.

Purpose of the Study:

• To evaluate electrocoagulation with iron electrodes as an alternative to centrifugation for harvesting microalgae.
• To optimize electrocoagulation parameters for high harvesting efficiency and low iron contamination in biomass.
• To assess the economic feasibility of electrocoagulation in reducing microalgae harvesting costs.

Main Methods:

• Lab-scale experiments were conducted to harvest Chlorella vulgaris using electrocoagulation.
• Key parameters investigated included electric charge, biomass concentration, pH, temperature, agitation, salt content, and electrolysis time.
• Harvesting efficiency and residual iron content in biomass were measured.

Main Results:

• Electrocoagulation achieved over 95% harvesting efficiency across a wide range of experimental conditions.
• Residual iron content in the harvested microalgae biomass met food-grade legislative requirements.
• Integrating electrocoagulation as a pre-concentration step reduced total energy costs to 0.136 kWh/kg dry biomass, a significant saving.

Conclusions:

• Electrocoagulation with iron electrodes is a highly efficient method for harvesting microalgae.
• This method offers a substantial reduction in energy consumption and costs compared to centrifugation.
• Electrocoagulation presents a viable and cost-effective solution for industrial-scale microalgae harvesting.