Heavy Metal Ion Removal: A Global Review of Wastewater Treatment Technologies.

This review addresses the escalating global water crisis driven by water pollution, especially by heavy metal ions, a consequence of rapid industrialization and population growth. Due to their high toxicity, solubility, and persistence, heavy metals pose a severe threat to human health and ecosystems through bioaccumulation. The analysis highlights a strategic shift in wastewater management from simple elimination of the toxics metal ions to the recovery of metal ions with economic value. Given the increasing complexity of industrial effluents, the scientific community is intensifying its focus on evaluating the technical and financial feasibility of various treatment technologies. Significant research is being conducted to address these environmental issues, and innovative technologies are being developed to enhance the quality of water contaminated by metal ions. On the other hand, to prevent pollution, plans containing several barriers must be established, including management, economic, and technical ones. Ultimately, the reuse of treated wastewater is the only viable long-term solution for securing global drinking water supplies. A new analysis focused on the transition from traditional, inefficient, and costly wastewater treatment to advanced, resource recovery-oriented systems is essential. The current perspective shows a clear need to advance beyond synthetic laboratory studies to real-world applications while addressing operational barriers to support a circular economy based on simple disposal of the toxic metal ions to the recovery of metals with economic value (e.g., copper, gold, silver, rare metals). Also, although the field has been explored, a new review is imperative because current technologies that show high efficiency (up to 99%) in the removal of toxic metal ions (adsorption, membrane filtration, electrochemical processes) face major challenges, such as the formation of large volumes of toxic sludge, membrane fouling, and high operating costs.