Environmental Remediation and Sustainable Approaches to Heavy Metal Removal: A Comprehensive Review of Biosorption Techniques

Heavy metal-laden contaminated water poses a severe environmental threat due to its bioaccumulation tendency, persistent nature, and toxicity. Conventional wastewater treatment techniques, such as ion exchange, chemical precipitation, membrane separation, and electrocoagulation, can result in secondary pollutants, require high energy use, and involve high costs. This review discusses environmentally friendly methodologies for the removal of heavy metals from aqueous streams, and the biosorption process is a viable alternative to address sustainability concerns in conventional, energy-intensive industrial processes. The biosorption process utilises a wide range of natural biomasses, such as plants, fungi, algae, and bacteria, for the sequestration and removal of heavy metals from aqueous solutions. Biosorption is mediated through various mechanisms, including physical adsorption, ion exchange, complexation, precipitation, and intracellular transport. The effectiveness of a biosorbent is based on the efficiency of sequestration and removal of heavy metals under given conditions. Some important factors affecting this include pH, temperature, contact time, biomass loading, and initial heavy metal ion concentration in the solution. Additionally, the capacity for biosorption for regeneration and reuse increases its commercial viability. This work explored the sources of biosorbents and the driving forces that govern their biosorption efficiency. Furthermore, this study provides an in-depth discussion of the factors that affect the effectiveness of the process. It establishes a fundamental understanding of biosorption mechanisms and influencing factors, paving the way for future commercialisation of this promising technology