Wastewater treatment process using immobilized microalgae

• Published in: Water science and technology Vol. 90; no. 4; pp. 1306 - 1320
• Main Authors: Aguiar Severo, Ihana, Azevedo, Otto Gustavo de Avila, da Silva, Paulo Alexandre Silveira, Jacob-Furlan, Beatriz, Mariano, André Bellin, Ordonez, Juan C, Vargas, José Viriato Coelho
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01.08.2024
• Subjects: Algae; Alginates - chemistry; Alginic acid; Alternative energy sources; Animals; Aquatic microorganisms; Biological Oxygen Demand Analysis; Biomass; Cell culture; Cells, Immobilized - metabolism; Chemical oxygen demand; Costs; Culture media; Energy industry; Immobilization; Immobilized cells; Manure; Manures; Microalgae; Microalgae - growth & development; Microalgae - metabolism; Microscopic analysis; Nitrogen; Nutrient removal; Nutrients; Organic carbon; Oxygen requirement; Phosphorus; Phytoplankton; Pig manure; Pollutants; Seaweed meal; Sodium; Sodium alginate; Substrates; Swine; Waste Disposal, Fluid - methods; Wastewater - chemistry; Wastewater treatment; Water Purification - methods; Water treatment; Brazil; alginate; cell immobilization; nutrient removal; biodigested swine manure
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2024.283

Microalgae biomass products are gaining popularity due to their diverse applications in various sectors. However, the costs associated with media ingredients and cell harvesting pose challenges to the scale-up of microalgae cultivation. This study evaluated the growth and nutrient removal efficiency (RE) of immobilized microalgae in sodium alginate beads cultivated in swine manure-based wastewater compared to free cells. The main findings of this research include (i) immobilized cells outperformed free cells, showing approximately 2.3 times higher biomass production, especially at 10% effluent concentration; (ii) enhanced organic carbon removal was observed, with a significant 62% reduction in chemical oxygen demand (383.46-144.84 mg L ) within 48 h for immobilized cells compared to 6% in free culture; (iii) both immobilized and free cells exhibited efficient removal of total nitrogen and total phosphorus, with high REs exceeding 99% for phosphorus. In addition, microscopic analysis confirmed successful cell dispersion within the alginate beads, ensuring efficient light and substrate transfer. Overall, the results highlight the potential of immobilization techniques and alternative media, such as biodigested swine manure, to enhance microalgal growth and nutrient RE, offering promising prospects for sustainable wastewater treatment processes