Evaluation of Recent Advancements in Biosorption of Strategic Elements as a Non-Conventional Technique: A Review

The nuclear waste process includes a range of toxic metals as well as lanthanides and actinides. The elimination lanthanides and actinide has received a lot of attention recently for environmental reasons linked to the safe disposal of such a reduced activity wastes. These metals are very reactive at low concentrations and can accumulate in the food web, causing severe public health concerns. Remediation using conventional physical and chemical methods is uneconomical and generates large volumes of chemical waste. Biosorption is a physical process that employs ion exchange, surface complexation and precipitation to use less expensive alternative biological materials as biosorbents. Biosorption of hazardous metals has received considerable and growing interest over the years. Various biomasses including microorganisms (bacteria and fungi), algae and plant products have been used as biosorbents for metal biosorption. The use of microbial biosorbents is eco-friendly and cost effective; hence, it is an efficient alternative for the remediation of strategic metal contaminated environments. Microbes have various mechanisms of metal sequestration that hold greater metal biosorption capacities. By analyzing the mechanism of microbial metal interactions (including extracellular polymer precipitation, ion substitution reaction, ligand complexation, van der Waals force adsorption, redox transformation, inorganic microcrystalline deposition and intracellular bioaccumulation, etc.), we elucidated the influence of key factors, such as strain characteristics, initial concentration of heavy metals, contact time, coexisting ions and environmental parameters (pH, temperature, etc.), on the adsorption efficacy. The fundamental goal of this review is to offer critical information on recent advances in the field of biosorption, address the challenge of innovative strategies such as surface modification (acid-base treatment), and immobilization technology (embedding method/carrier immobilization) are proposed to enhance microbial biosorption performance.