• Calvert, Giles
• Boxall, Naomi
• Van Yken, Jonovan

Abstract

Electronic waste (e-waste) refers to all electrical and electronic equipment (EEE) and its parts that have been used and discarded as waste without the intent of re-use. Globally, e-waste generation is rapidly growing at an alarming rate of approximately 2 Mt per year due to high consumption rates of EEE, short life cycles and few repair options. It is the fastest-growing part of municipal solid waste in many countries, and it has been estimated that annual global e-waste generation will reach 74.7 Mt by 2030. Along with the co-existence of various hazardous substances (e.g., heavy metals, flame retardants, persistent organic pollutants), e-waste often contains valuable and critical metals such as gold, silver, copper and other base metals, rare earth elements, lithium, and cobalt. As such, it represents a notable revenue stream, and one worth addressing to minimise the impacts associated with improper handling at the end of life. Also, considering the declining grades of primary minerals resources, developing technologies for sustainable extraction and recovery of metals from e-waste is critical to ensuring sustainable utilisation and management of resources to meet the demands of EEE. Pyrometallurgy and hydrometallurgy are conventional technology options for recovering metals from e-waste. However, pyrometallurgy is energy intensive and demands high capital investment and supplies of large e-waste feedstock volumes to justify economies of scale. On the other hand, hydrometallurgy relies heavily on the use of strongly corrosive or oxidising chemical agents for metal leaching, rendering the process eco-unfriendly. There has been a growing interest in using biotechnical processes for value recovery from e-waste. Biohydrometallurgy is a subset of hydrometallurgy that harnesses the natural ability of microorganisms, such as bacteria, archaea, and fungi, to facilitate the extraction and recovery of metals from metal-containing solid matrices (e.g., mineral ores, e-waste) in aqueous systems. It has the potential to be a greener alternative to traditional metallurgical processes with lower energy costs and environmental impacts. This presentation will give an overview of the research conducted at Australia’s National Science Agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), on the development of biotechnical processes for extracting and recovering metals from two types of e-waste, namely spent lithium-ion batteries and printed circuit boards with the view of supporting sustainable resource management and the circular economy. The processes include the extraction of metals into solution with biologically-generated leaching reagents (e.g., ferric iron and biogenic acid), as well as the recovery of metals from aqueous solutions by bioprecipitation with biogenic hydrogen sulfide.

Topics

• impedance spectroscopy
• mineral
• silver
• extraction
• gold
• Hydrogen
• copper
• leaching
• cobalt
• Lithium
• iron
• rare earth metal