PHOSPHATE RECOVERY FROM EUTROPHIC WATER USING IRON MODIFIED SUGARCANE BAGASSE BIOCHAR: ADSORPTION PERFORMANCE AND FERTILIZER REUSE

Abstract

Iron-modified sugarcane bagasse biochar was synthesized and evaluated for phosphate recovery from eutrophic water, as well as its potential reapplication as a phosphate-based soil fertilizer. Biochar dosage, contact time, temperature, pH, and initial phosphate concentration influence the phosphate removal, as shown by batch adsorption experiments. Under acidic conditions, the material achieved 98.5% removal, and under near-neutral conditions at 4 g/L, it achieved 80.3% removal. Iron incorporation was confirmed by SEM-EDS, and after iron modification, changes in pore structure and surface area were observed by BET analysis. According to the equilibrium data, the Langmuir model fitted better than the Freundlich model, and the kinetic data, based on adsorption modelling, followed the pseudo-second-order model, suggesting that phosphate uptake was governed by chemisorption and surface binding. After the application of the Fe-modified phosphate-loaded biochar, the improvement in shoot and root growth was indicated by the preliminary mustard pot test. The results indicated that the iron-modified sugarcane bagasse biochar has the potential for circular phosphate recovery. However, replications of plant growth experiments and actual eutrophic water are needed for validation.