The flocculation process of Chlorella sp. using chitosan as a bio-flocculant: Optimization of operating conditions by response surface methodology

Abstract

The flocculation efficiency and biomass recovery are key characteristics to consider and measure when researching solid–liquid separation during the harvesting process of Chlorella sp. microalgae. Response surface methodology (RSM) with a central composite design (CCD) is used in conjunction with chitosan as the bio-flocculant to improve the flocculation efficiency and biomass recovery parameters. The pH, bio-flocculant dosage, and cationic inducer dose are all factors that have been determined. A multiple response optimization approach was used to effectively estimate the optimal parameters, which were at pH 8, chitosan concentration of 100 mg/500 ​mL, cationic inducer concentration of 50 ​mg/L, and stirring speed of 240 ​rpm. The overall appropriateness function approach was used to effectively estimate the optimal parameters. Flocculation efficiency is 96.12%, and biomass recovery is 312.5 ​mg for the most advantageous flocculation, as well as the flocculation rate was 2.007 min−1. The RSM-CCD approach is beneficial for improving this flocculation process, which will result in a more effective and efficient water reuse process and management of the microalgae harvesting process.