ADSORPTIVE BEHAVIOUR OF RICE HUSK BIOCHAR FOR TRANSFORMING GROUNDWATER-MEDIATED FLUORIDE CYCLING IN NATURAL ENVIRONMENTS

Fluoride is a global groundwater contaminant and essential for the human body’s growth and development. Simultaneously, agricultural crop residue management is crucial for preventing mindless stubble burning. Biochar effectively controls water pollution, supports sustainable development goals, and achieves a circular economy. The study investigated the feasibility of treating fluoride-contaminated surface and groundwater using biochar from agricultural waste rice husk as a renewable, carbon-neutral material. It considered factors like contact time, initial Fˉ levels, biochar dose, pH, salt strengths, temperatures, and co-occurring ions. Real-world problems were tested using regeneration and reusability to understand potential recycling and treatment of F-contaminated surface and groundwater under various water conditions for piloting biochar production in field-scale applications. Modified biochar achieved 98.13% Fˉ removal at pH 7 for 10 mg L⁻¹. Electrostatic attraction, ion exchange, pore fills, and surface complexation are some of the Fˉ removal methods. Biochar effectively treated natural fluoride-contaminated surface and groundwater, achieving removal efficiency of 91.20% and 95.61% for 10 mg L⁻¹ Fˉ contamination, following multiple adsorption-desorption experiments. Techno-economic analysis of biochar synthesis and Fˉ treatment costs revealed worthwhile output and recommendations for future research on Fˉ adsorption using biochar.