Aspergillus Indium LED Recovery Platform

An engineered fungal monoculture bioplatform based on Aspergillus niger for sustainable recovery of indium from waste liquid crystal display (LCD) and light-emitting diode (LED) panels through indirect bioleaching. This system represents a green alternative to conventional harsh chemical extraction methods (concentrated acids at high temperatures), utilizing fungal organic acid production to mobilize and recover critical materials from electronic waste. A. niger produces a cocktail of organic acids including oxalic acid (14.9 g/L), gluconic acid (1.2 g/L), citric acid (0.9 g/L), and malic acid (0.39 g/L) during growth on glucose-based medium. The spent culture filtrate achieves remarkable indium recovery performance: 100% indium yield from waste LCD/LED panels in just 1.5 hours at 70°C, with final indium concentration of 145.6 mg/L. The bioleaching mechanism involves H+ ions from acidic functional groups (-COOH) of organic acids and secreted proteins, which dissolve indium-tin oxide (ITO) coatings and indium-bearing components. The process operates at low pH (1.96) due to organic acid accumulation, creating optimal conditions for indium mobilization while avoiding the corrosivity, energy intensity, and hazardous waste generation of conventional acid leaching. This biotechnological approach addresses the critical need for indium recycling, as this element is essential for touchscreens, flat-panel displays, and optoelectronics, yet faces supply constraints due to limited primary resources and increasing demand from electronics manufacturing.