Authors: Nikitha B
Abstract: Fluoride-rich industrial effluents originating from sectors such as metal smelting, fertilizer production, glass manufacturing, and battery industries pose significant environmental and public-health concerns due to the risk of dental and skeletal fluorosis. Precipitation, ion-exchange, and membrane filtration are examples of conventional treatment techniques that are less appropriate for large-volume or variable-composition industrial wastewaters due to their high operating costs, sludge production, fouling, or poor selectivity. Biosorption, which uses natural, waste-derived, or biologically modified materials, has become a viable, affordable, and sustainable method of removing fluoride. This review offers an extensive review of biosorbents reported for fluoride remediation, including engineered bio-chars, metal-loaded bio-composites, raw biomass (plant fibers, algae, and agricultural waste), and advanced hybrid materials like MOF-based bio-adsorbents. The majority of research reports Langmuir-type monolayer adsorption behavior, with pseudo-second-order kinetics suggesting chemisorption, particularly for biosorbents impregnated with metals. High removal efficiencies (up to ~90%) and significant adsorption capacities have been attained under ideal laboratory conditions, but problems still exist, including limited regeneration data, narrow effective pH ranges, high adsorbent modification costs, and a lack of validation using actual industrial effluents containing competing ions. This review identifies these knowledge gaps and makes recommendations for future research, such as mechanistic evaluation under actual wastewater matrices, pilot-scale continuous-flow studies, hybrid treatment processes, and regeneration optimization. As long as future studies concentrate on scalability, long-term stability, and practical application, biosorption has great potential as a cost-effective and ecologically friendly technique for fluoride removal.
DOI: https://doi.org/10.5281/zenodo.17962912
