A Comparative phycoremediation study of aquaculture wastewater treatment by Chlorella sp. immobilized in different hybrid-alginate matrices

The management of aquaculture wastewater presents notable environmental challenges, requiring efficient remediation techniques. This study explores the use of naturally derived immobilization materials (starch, cellulose, and bacterial cellulose) for microalgal-based phycoremediation, by utilising immobilized Chlorella sp. and offers an eco-friendly alternative to conventional synthetic matrices. The study aimed to evaluate the best immobilized carrier, and to assess the effectiveness of immobilized microalgae in removing nutrients such as chemical oxygen demand (COD), biological oxygen demand (BOD), and total nitrogen (TN) from aquaculture, along with biomass and lipid productivity. In this study, the phycoremediation using microalgae immobilized with different carrier including starch, cellulose and bacterial cellulose were evaluated within 12 days treatment. The results indicated that Chlorella sp. immobilized in starch beads demonstrated higher phycoremediation efficiency by reducing the level of COD from 96 to 10.25 (mg/L), and BOD from 24 to 3.4 (mg/L), and TN level from 43 to 4 (mg/L). Cellulose beads also showed the highest lipid content (26.76 %). While bacterial-cellulose carrier showed higher biomass production at 39.38 mg/L and lipid productivity 38.33 mg/L/day This suggests that immobilized Chlorella sp. in bacterial-cellulose beads can effectively treat aquaculture wastewater and biofuel production. This study makes a significant contribution to the field of environmental biotechnology by providing a detailed analysis of the utilization of immobilized microalgae for sustainable waste management in aquaculture systems.