Solubilization of Copper, Nickel and Zinc from Electronics Waste Using Providencia and Pseudomonas Species

Abstract

The role of microbes in solubilization of e-waste metals offers an eco-friendlier and cost-effective alternative to traditional metal recovery methods. Pseudomonas aeruginosa, Providencia. manganoxydans and Pseudomonas fluorescens isolated from soil obtained from an e-waste dump site in Owerri and water from coal mines in Enugu, were used to solubilize copper, nickel and zinc from printed circuit boards of discarded electronics devices. The solubilization assessment was carried out for 24 days with two particles sizes of the printed circuit boards (50 µm and 950 µm), single and mixed cultures of the organisms and three added nitrogen sources (NPK, organic manure and (NH4)2SO4). The result obtained showed that the three organisms can solubilize multiple metals simultaneously, the single cultures of P. manganoxydans and P. fluorescens performed better than the different mixed cultures of the organism based on the concentration of the metals in solution after the solubilization. The solubilization rate for the powdered printed circuit boards particle size (ps) 50 µm were better when compared to the particle size (ps) 950 µm across the three isolates. At the end of the 24th day, cultures with NPK and (NH4)2SO4 as nitrogen sources performed better than those with organic manure. P. manganoxydans and P. fluorescens had a better metal solubilization concentration than P. aeruginosa. P. fluorescens with (NH4)2SO4 and particle size (ps) 50 µm showed a solubilization rate of 68% for copper, 67% for nickel and 64% for zinc, the metal solubilization rate of P. manganoxydans with (NH4)2SO4 was 86% for copper, 68% for nickel and 70% for zinc while the metal solubilization rate of P. aeruginosa with (NH4)2SO4 was 37% for copper, 62% for nickel and 32% for zinc. P. fluorescens with NPK and particle size (ps) 50 µm showed a solubilization rate of 72% for copper, 80% for nickel and 72% for zinc. Microbial solubilization presents a transformative approach to metal extraction, by offering a greener, cost-effective, and efficient alternative to conventional methods, it holds great promise for the future of metal resource recovery. Research development in microbial solubilization should include the use of genetically engineered microorganisms or novel microbial solubilization techniques to further enhance the efficiency and selectivity of the process. As such, microbial solubilization may continue to evolve as a cutting-edge method/technology for sustainable metal extraction.