Flocculation of microalgae using calcium oxide nanoparticles; process optimization and characterization

Abstract

The massive energy required for biomass gathering makes current commercial microalgal biofuel manufacturing economically unsustainable. A present harvesting method is provided as an inexpensive and energy-efficient way; nano-flocculation by employing nanoparticles to concentrate and flocculate microalgae of interest. In this study, we used calcium oxide nanoparticles (CaONPs) derived from waste products of the Fayoum Sugar Factory (FSF) as a low-cost flocculent for a microalgae flocculation process that was tuned using three control parameters: temperature, flocculent dose, and medium pH values. Furthermore, FSF wastewater was employed as a nourishment source for microalgae production. FT-IR, X-RD, Zeta potential, and TEM were used to further identify and characterize CaONPs. According to the current data, using CaONPs under the best conditions for algae harvesting (pH 9.8 and temperature 45 °C with 250 mg/L) resulted in 99.3% algal coagulation. The advantages of the current method are that it is safe, rapid, does not require the addition of chemicals, is simple and effective, sustainable, and is cost-efficient because there are no costs associated with pre-treatment of the biomass.