Surfactant-Mediated Microalgal Flocculation: Process Efficiency and Kinetic Modelling

Area of Science:

• Biotechnology
• Chemical Engineering
• Marine Biology

Background:

• Microalgae offer valuable resources like lipids and proteins, but large-scale harvesting remains a significant challenge.
• Current harvesting methods often lack cost-effectiveness and proven efficiency.
• Flocculation presents an energy-efficient alternative, with surfactant integration potentially enhancing both harvesting and cell disruption.

Purpose of the Study:

• To evaluate the efficacy of different surfactants (CTAB, DTAB, SDS) for harvesting Tetraselmis sp. microalgae.
• To assess the impact of surfactants on harvesting efficiency and sedimentation time.
• To investigate the kinetics of the microalgal harvesting process using the modified Gompertz model.

Main Methods:

• Investigated three surfactants: cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), and sodium dodecyl sulphate (SDS).
• Tested surfactants on Tetraselmis sp. strains (75LG and 46NLG) to determine harvesting efficiency and optimal concentrations.
• Analyzed harvesting kinetics using the modified Gompertz model to determine process rates.

Main Results:

• Cetyltrimethylammonium bromide (CTAB) demonstrated superior harvesting efficiency, achieving 88% for Tetraselmis sp. 75LG and 46NLG strains.
• Optimal CTAB concentrations (1500 and 2000 mg L⁻¹) significantly reduced sedimentation time to 60 minutes.
• The modified Gompertz model best described the harvesting kinetics, with CTAB yielding the largest kinetic constants.

Conclusions:

• CTAB is a highly effective surfactant for enhancing microalgal harvesting efficiency and reducing operational time.
• The use of CTAB shows potential for optimizing microalgal harvesting processes for cost-effective, large-scale production.
• Further research incorporating CTAB could unlock the commercial viability of microalgae for applications such as biodiesel production.