Bioremediation of heavy metals in aquatic environment: A review

The pursuit of critical minerals such as lithium (Li), nickel (Ni), cobalt (Co), and rare earth elements (REE) has intensified mining, producing heavy metal waste that contaminates water bodies. Pollution from human activities and improper disposal of high-tech products containing heavy metals like Hg, Cd, Ni, Cu, Pb, and Cr has degraded surface and groundwater. These metals enter the human body via bioaccumulation in the food chain or direct consumption of contaminated water, posing health risks. There is an urgent need for cost-effective, eco-friendly methods to decontaminate water without generating additional pollutants. Conventional remediation technologies are costly and produce hazardous waste requiring disposal. In contrast, biological materials—such as bacteria, cyanobacteria, fungi, lichens, algae, and plants—offer affordable, sustainable solutions for water decontamination. Moreover, metal-rich biomass from bioremediation processes, like cyanoremediation, can be converted into valuable products, such as metal nanoparticles for pharmaceutical and industrial use, creating a closed-loop system that generates wealth instead of waste. Genetic engineering can further enhance biosorbent organisms and plants to improve heavy metal binding and accumulation. This review examines the environmental and health impacts of heavy metals, the limitations of conventional remediation methods, various bioremediation techniques, and future research directions.