Characterization of chitosan extracted from shrimp shell waste and its utilization as a flocculant for harvesting of microalgae

Shrimp shell waste generated from shrimp processing industries is one of the leading issues contributing to environmental pollution and health hazards. The common practice for its management is disposal or burning of the waste, which is not environmentally safe due to the shells' low degradability or burning capability. In this situation, transforming the waste into a valuable product named Chitosan for application in different areas could be an effective solution for waste remediation. This study extracts Chitosan from shrimp shell waste by demineralization, deproteination, and deacetylation processes. The extracted product was characterized by different analyses such as chitosan yield, bulk density, solubility, degree of deacetylation, water binding capacity, fat binding capacity, surface morphology, and FTIR spectroscopy. The results showed that chitosan yield, bulk density, solubility, degree of deacetylation, water binding capacity, fat binding capacity were 29%, 0.27 g/cm3, 97%, 58%, 533%, 459%, respectively. Surface morphology and FTIR spectroscopy suggested that Chitosan had good adsorption capacity, making them an effective flocculant for harvesting microalgae. Microalgae harvesting was done at a mixing rate of 120 rpm, 80 rpm, and 40 rpm, respectively, with two-dose (e.g., 20 mg/L and 60 mg/L) and a single mixing time (5 min). About 100% harvesting efficiency was found at a dose of 20 mg/L with a mixing rate of 120 rpm. Hence, this study offers a waste remediation technique to manage and utilize shrimp waste to prevent deterioration of the environment and human health.