Due to water shortage and increased water pollution, various methods are being explored to improve water quality by treating contaminants. Sonophotocatalysis is a combination of two individual water treatment processes i.e., photocatalysis and sonocatalysis. With advantages including shorter reaction times and enhanced activity, this technique shows possible futuristic applications as an efficient water treatment technology. Herein, background insight on sonophotocalysis as a water and wastewater treatment technique as well as the general mechanism of activity is explained. The commonly used catalysts for sonophotocatalytic applications as well as their synthesis pathways are also briefly discussed. Additionally, the utilisation of sonophotocatalysis for the disinfection of various microbial species as well as treatment of wastewater pollutants including organic (dyes, pharmaceuticals and pesticides) and inorganic species (heavy metals) is deliberated. This review also gives a critical analysis of the efficiency, enhancement strategies as well as challenges and outlooks in this field. It is thus intended to give insight to researchers in the context of facilitating future developments in the field of water treatment, and advancing sonophotocatalysis towards large-scale implementation and commercialization.

The heightened occurrence of emerging organic pollutants (EOPs) in aquatic bodies has been the subject of global apprehension due to the toxicity they pose to the environment, humans and animals alike. The presence of EOPs has soared due to industrialization and is further exacerbated by human activities like the overuse and poor disposal of dyes, pesticides, pharmaceuticals, surfactants, personal care products and food additives. The complete treatment and removal of EOPs from industrial wastewater and sewage has remained a challenge because of their pseudo-persistence and resistance to degradation. Due to their impressive light absorption properties, high surface-area-to-volume ratio, high porosity, superior mechanical strength, electrospun titanium dioxide (TiO₂) and zinc oxide (ZnO) nanofibers have been proposed for the photocatalytic treatment of EOPs. Therefore, this review first highlights the fabrication and modification methods of TiO₂ and ZnO nanofibers. A systematic survey of the latest progress in the application of TiO₂ and ZnO nanofibers for the degradation of EOPs is then elaborated. Thus, the main goal is to shed light and give insight to researchers on the possibilities surrounding the elimination of EOPs by applying electrospun TiO₂ and ZnO semiconductor materials. In addition, the loopholes associated with fabrication and modification processes are discussed with the aim of encouraging innovation for prospective technology advancement and commercialization, as well as to enhance research efforts in wastewater treatment and environmental sustainability.

Although mining plays a vital role in the economic development of many countries, devastating environmental repercussions are associated with it. The extraction of mineral resources inevitably results in the generation of acid mine drainage (AMD), which entails intricate oxidation interactions that occur under ambient conditions in abandoned and active mines. The arbitrary release of AMD can lead to a series of long-term environmental problems, degradation of aquatic habitats and health complications. Over the years, extensive progress has been made in the prevention and treatment of AMD, with some processes even progressing as far as the commercialisation level. This chapter therefore discusses the process of AMD formation, preventative and control measures and AMD treatment options applicable to both operating and developed mines, as well as to researchers interested in environmental remediation and rehabilitation. Advances in mineral beneficiation and water reclamation strategies employed in the AMD treatment processes are highlighted to shed light on strides being made towards promoting a circular economy in mining industries. The featured work therefore demonstrates the global progress towards environmental protection and water resource management. The challenges and loopholes associated with the current AMD treatment methods are deliberated and possible future prospects in the field are proposed.

Heavy metal mining and industrial waste contamination are significant environmental issues that modern civilization has been grappling with for some time. In geological ores, nickel (Ni) fire assay fusion (Ni-FA) and lead (Pb) fire assay fusion (Pb-FA) are the most crucial classical analytical chemistry methodologies used for the collection and determination of platinum group elements (PGEs) and gold (Au) from PGE ore. These classical experiments involve the pre-concentration of PGEs and Au and separation into metallic and silicate phases, which offer high accuracy and high precision with a low limit of detection. Industrial metallurgical and FA processes produce lead-contaminated cupels with high Pb concentrations, posing health risks and environmental pollution if not retrieved. In this study, we discuss waste generated during the PGE separation method, particularly from FA processes. The study explores classical methods and analytical techniques for removing and quantifying Pb, Ni, and other critical minerals from lead and nickel waste streams, considering their potential levels in different environments. The chapter provides an overview of fire assay methods for PGM preparation, current quantification trends, potential environmental impacts, energy storage options, production effort, and hazards. In comparison with the pyrometallurgy approach, studies indicate that hydrometallurgical processing is a more effective way of recovering value-added metals. Lastly, the current status and future perspective on the application of critical minerals, and repurposing for a circular economy have been outlined, indicating the economic viability of recycling.