Abstract

Heavy metal pollution in wastewater is increasingly becoming an urgent problem, mainly due to its persistence, toxicity, and threat to ecosystems and human health. This review largely evaluates different treatment technologies designed to minimize heavy metal contaminants originating from industrial and municipal wastewater. From traditional techniques (such as ion exchange, membrane filtering, coagulation- flocculation, chemical precipitation, electrochemical, etc.), we assessed their efficiencies and drawbacks, especially cost, selectivity, and sludge production. New technologies in nanotechnology such as oxide nanoparticles, carbon nanotubes, and nano membranes come with new possibilities for increasing surface area and adsorption efficiency. Furthermore, biological processes such as bioleaching, phytostabilization, rhizofiltration, and bacteria bioremediation promote more environmentally acceptable solutions. Artificial intelligence and machine learning are becoming more prevalent in treatment systems and can help with predictive maintenance, process modifications, and real-time monitoring. Nonetheless, much still needs to be done to tackle the real life challenges such as, affordability of scaling up; selectivity for metal recovery; and proper waste management. In conclusion, there is room for both conventional and modern technologies, augmented by evidence-based solutions and green technologies.