Amalgamation of electrocoagulation-flotation and membrane technology: Rapid and efficient microalgal biomass recovery and fouling mitigation

Abstract

This study presents an innovative microalgae recovery and fouling mitigation technology that combines electrocoagulation-flotation (ECF) and membrane processes to achieve a rapid and efficient microalgae recovery while mitigating fouling. Under the same conditions, applying 1.5 A current significantly improved the average water flux (from 480 to 1455 LMH) and membrane rejection rate (from 93 % to 98 %) compared to the membrane filtration process without ECF. The total fouling resistances also decreased by approximately 67 % (from 0.17 × 10¹⁰ to 0.055 × 10¹⁰ m⁻¹). The molecular dynamic simulation, along with chemical and imaging analyses, revealed that the Al³⁺ ions (37 mg/L) released from the aluminum anode, combined with the bubbles generated from the cathode, effectively coagulated and floated the microalgal biomass on the suspension surface. This process significantly reduced cake formation on the membrane. Furthermore, the fouling model simulations indicated that ECF could change the fouling mechanism, shifting from cake filtration to an intermediate standard model. The findings suggested that integrating ECF with membrane filtration could reduce the operational time from 10 to 3.3 min, which resulted in a significant reduction in energy consumption from 19.71 to 9.14 kWh/kg biomass (approximately to half). This study offers a promising approach for rapid and efficient microalgae harvesting through the membrane filtration process.