Abstract:
Sustainable recovery of valuable metals from primary and secondary wastes are essential for circular economy and critical metal conservation. In this study, a bio-based ecofriendly method for metal recovery is demonstrated using a natural biopolymer, extracellular polymeric substance (EPS) produced by the cyanobacteria Synechocystis sp. IMMT47. EPS, was used to recover manganese and iron from low-pH leach liquor derived from bioleaching of polymetallic nodules (PMNs). The influence of pH, EPS dosage, and metal concentration on recovery efficiency was evaluated. High recovery rates of manganese (85.18%) and iron (99.73%) were achieved even at low pH of 2, eliminating the need for neutralization-a major cost and environmental constraint in conventional hydrometallurgy. This study is first to report application of cyanobacterial EPS for direct metal recovery under acidic conditions, offering a sustainable and low-impact alternative to traditional chemical processes such as precipitation and solvent extraction. This approach aligns with green extraction technologies and zero-waste resource management principles.
