Harnessing the Capabilities of Microorganisms for the Valorisation of Coal Fly Ash Waste through Biometallurgy

Coal fly ash (CFA) is a highly versatile raw material that has the potential to yield multiple value-added products, including cenospheres, zeolites, carbon nanotubes, and fertiliser substrates. Despite its versatility, a majority of these components are often overlooked, and CFA is primarily used for construction. Conventional processing methods of CFA are known to pose significant environmental challenges, including the leaching of hazardous materials, emission of toxic gases, and the high energy consumption needed to extract the value-added components. Herein, we explore the potential of biometallurgical approaches as an eco-friendly alternative to conventional processing methods for the comprehensive utilisation of CFA. Our focus is on the application of different microorganisms to CFA, the domestication of microorganisms, preprocessing of CFA to facilitate effective biometallurgical processes, the use of bioreactors, and synthesis of nano silica particles. We also propose a novel method for extracting the value-added components from CFA using a preprocessing technique (i.e., washing cycle), combined with multiple interactions with biometallurgical processes. Adopting this approach, we not only enhance environmental stewardship but also improve the circular economic aspects of multi-component utilisation, while providing valuable insights for the development of sustainable techniques for utilising CFA.

Automated summary

Coal fly ash (CFA) is a versatile raw material that can be used to produce various value-added products, but its potential is often overlooked. Conventional processing methods for CFA pose environmental challenges and require high energy consumption. This study explores the use of biometallurgical approaches as an eco-friendly alternative, focusing on microorganism applications, CFA preprocessing, bioreactors, and synthesis of nano silica particles. A novel method utilizing preprocessing and biometallurgical processes is proposed to extract value-added components from CFA, promoting environmental stewardship and circular economy.