Effect of alginate concentration in wastewater nutrient removal using alginate-immobilized microalgae beads: Uptake kinetics and adsorption studies

• Published in: Biochemical engineering journal 2019-09, Vol.149, p.107241, Article 107241
• Main Authors: Banerjee, Shantanu, Tiwade, Palas Balakdas, Sambhav, Kumar, Banerjee, Chiranjib, Bhaumik, Soubhik Kumar
• Format: Article
• Language: English
• Subjects: Adsorption; Alginate concentration; Charge-interaction; Nutrient removal; Pore morphology; Uptake kinetics
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2019.107241

•Effect of alginate concentration on nutrient removal was investigated.•Uptake kinetics and adsorption of nutrients onto alginate beads was evaluated.•3% alginate concentration optimal both for nutrient removal and adsorption.•Adsorption of NH4+ and PO43−- P onto alginate matrix through hydrogen bonding.•3% alginate concentration bear optimal pore size for nutrient access. Effect of alginate concentration on wastewater nutrient removal by alginate-immobilized microalgae bead systems (AIMS) of Chlorella vulgaris was investigated to delineate the underlying role of alginate matrix in the removal process. The study includes kinetic evaluation of nutrient removal in AIMS of different alginate concentration (1.5–4.5% w/v%) followed by an assessment of abiotic adsorption characteristics of blank alginate beads systems (BABS) of same alginate concentrations. Results establish 3% alginate concentration as optimal both for nutrient removal in AIMS and adsorption in BABS. The adsorption data in the latter fitted well with Langmuir isotherms, suggesting monolayer physisorption, which was later corroborated through Fourier-Transform Infrared Spectroscopy (FTIR) and Energy Dispersive X-ray (EDX) analysis. A scheme for adsorption of NH4+ - N and PO43−- P on alginate matrix through hydrogen bonding was illustrated. The optimal trends were explained based on pore morphology and bead structural integrity.