Optimization of shrimp and crab shell as bio-flocculant for Chlorella pyrenoidosa harvesting using response surface methodology

Abstract

The use of bio-flocculants in flocculation processes offers a feasible approach for separating solid and liquid phases, with a particular focus on microalgae harvesting. Critical parameters such as the dose of bio-flocculant, pH level, and dose of cationic inducer significantly impact the success of microalgae harvesting. This study aims to examine the efficacy of chitosan derived from shrimp shells and crab shells as bio-flocculants in microalgae harvesting, specifically Chlorella pyrenoidosa. Central Composite Design (CCD) and Response Surface Methodology (RSM) were employed in this study to attain optimal flocculation conditions, characterized by high flocculation efficiency and short settling time. The optimal harvesting condition using chitosan derived from shrimp shells was achieved at 0.499 g/L of bio-flocculant, pH 9.09, and 0.172 g/L of cationic inducer with 92.58% efficiency and 133.49 s settling time. Meanwhile, The optimal harvesting condition with chitosan derived from crab shells was achieved at 0.434 g/L of bio-flocculant, pH 8.96, and 0.168 g/L of cationic inducer. This resulted in an efficiency of 93.72% and a settling time of 117 s. Based on this fact, the potential of shrimp shells and crab shells as bio-flocculants for Chlorella pyrenoidosa harvesting is evident. Furthermore, the efficacy of flocculation and settling time are significantly influenced by variables such as the concentration of cationic inducers, the levels of bio-flocculants, and pH.