A waste-to-wealth initiative exploiting the potential of Anabaena variabilis for designing an integrated biorefinery

Abstract

The current research work was an innovative approach providing dual advantages of waste bioremediation and an effective biorefinery. The study attempted to exploit wastewater like aqua discharge and solid wastes like poultry litter/cow dung for cyanobacterial cultivation. Aqua discharge appended with 7.5 g L−1 poultry litter turned out as the best combination generating 46% higher carbohydrate yield than BG-11 control. A. variabilis cultivation in this waste-utilized medium also revealed its excellent bioremediation ability. While 100% removal was observed for nitrite, nitrate, and orthophosphate, a respective 74% and 81% reduction was noted for ammonium and total organic carbon. Chemical and biological oxygen demands were also reduced by 90%. This work was also novel in developing a sequential design for the production of bioethanol and co-products like exopolysaccharides, sodium copper chlorophyllin, C-phycocyanin, and poly-β-hydroxybutyrate from the same cyanobacterial biomass. The developed biorefinery implementing the waste-utilized medium was one of its kind, enabling biomass valorization of 61%. Therefore, the present study would provide a leading-edge for tackling the high production costs that limit the practical viability of biorefinery projects. The recyclability of the bioremediated wastewater would not only curtail freshwater usage, the waste disposal concerns would also be mitigated to a great extent.

Comparative Evaluation of Chlorella vulgaris and Anabaena variabilis for Phycoremediation of Polluted River Water: Spotlighting Heavy Metals Detoxification

“…C. vulgaris and A. variabilis were substantially able to grow and remediate the polluted water collected from the Dhaleswari river. The growth profiles of C. vulgaris and A. variabilis were identical to each other in both river water and wastewater environments as observed in this study and other studies by Kumar et al [45] and Deb et al [46]. As the experiment progressed, both microalgae-and cyanobacteria-treated samples showed an increase in water pH (Figure 1a), which could be attributed to the photosynthetic CO 2 assimilation [47].…”