Downstream processing of biomass produced in aquaculture wastewater for valuable pigments from the cyanobacterium Spirulina (Arthrospira) platensis : a green and sustainable approach

Aquaculture wastewater is suitable for algal growth especially due to its ammonium and nitrate content. Therefore, the wastewater can be utilized after a few amendments for algal biomass production for the recovery of valuable pigments. In the present study, aquaculture wastewater discharged from the Pangasius culture system was utilized for the production of a commercially valuable cyanobacterium Spirulina (Arthrospira) platensis with an aim to extract economically important pigments (phycocyanin and carotenoids). The aquaculture wastewater was amended with nutrients and used as a culture medium for S. platensis . The removal of nutrients from the effluent-based medium during the culture period was also monitored. A significant increase in growth rate (0.21 day −1 ), biomass productivity (23.65 mg g −1 day −1 ), and the lowest doubling time (3.37 days) was noticed in decontaminated and amended aquaculture wastewater. The biomass produced in the wastewater showed phycocyanin content (132.45 mg g −1 DW), total carotenoids (1.26 mg g −1 DW), and protein (630 mg g −1 DW). S. platensis in aquaculture wastewater showed nutrient removal up to 97.34% NH + 4 -N, 71.93% NO − 3 -N, 95.90% NO − 2 -N, and 93.39% PO 4 3− -P. The present report provides a piece of convincing evidence that S. platensis is a suitable candidate species for aquaculture wastewater utilization for cost-effective biomass production and improvement in the quality of wastewater through phycoremediation. Graphical abstract