Biosorption and Ecological Risk Mitigation of Heavy Metals in Adire Textile Effluent Using Low-Cost Agricultural Adsorbents

This study evaluated the effectiveness of locally available agricultural wastes such as sawdust, rice husk, sugarcane bagasse, and their combinationfor the remediation of heavy metals and physicochemical pollutants in Adire (tie-and-dye) textile wastewater. The adsorption experiments were conducted under batch conditions, and the treated effluents were analyzed for Pb, Cu, Cr, Ni, Zn, Fe, and key water quality parameters including BOD, COD, TDS, turbidity, and conductivity. Removal efficiencies ranged from 26% to 61%, with sawdust achieving the highest performance in terms of heavy metal reduction. Pollution Load Index (PLI) and Geoaccumulation Index (Igeo) showed significant decreases post-treatment, suggesting reduced ecological risk. Additionally, Hazard Quotients (HQs) were computed to evaluate residual environmental toxicity, revealing that all treated effluents still exceeded ecological safety thresholds (HQ > 1), particularly for lead and zinc. These findings demonstrate that biosorbents can significantly reduce pollution levels but may require polishing treatments or blending strategies to meet discharge standards. The study highlights the viability of waste-to-resource technologies for decentralized wastewater management in lowincome and artisanal industrial contexts.