Nanoparticle-assisted microbial remediation as a potential approach to groundwater fluoride contamination

Fluoride (F⁻) contamination in groundwater poses a critical threat to global public health, particularly in regions reliant on untreated aquifers for drinking water. While conventional defluoridation methods such as precipitation, coagulation, reverse osmosis, and ion exchange have shown effectiveness, their limitations in cost, efficiency, and sustainability necessitate alternative solutions. This review explores nanoparticle-assisted microbial remediation as a promising hybrid approach for fluoride removal. The integration of nanomaterials with microbial systems enhances defluoridation efficiency by combining high surface area adsorption, targeted pollutant interaction, and bioactivity. Nanomaterials such as carbon nanotubes, graphene oxide, and metal oxides (e.g., Fe₃O₄, MgO, ZrO₂) offer high fluoride affinity, tunable surface properties, and reusability. When coupled with microbial agents like Bacillus spp., these systems demonstrate synergistic activity under optimal pH conditions (6.5-7.5), improving biofilm formation, ion transport, and F⁻ adsorption. This review highlights the physicochemical interactions between fluoride ions and engineered nanostructures, evaluates microbial metabolic contributions to fluoride detoxification, and addresses key challenges such as nanoparticle toxicity, environmental persistence, and scale-up feasibility. Emphasis is placed on surface functionalization, magnetic recovery, and the development of biodegradable nanomaterials. The findings suggest that nanobioremediation holds strong potential as a scalable, eco-friendly, and cost-effective strategy for groundwater F^- mitigation.