Utilization of organic waste as bio-adsorbent for the removal of heavy metals in waste water samples

Abstract

Heavy metals are elements that are naturally present in the Earth’s crust in different concentrations. Anthropogenic activities have disrupted the natural cycle and balance of certain heavy metals causing heavy metal contamination. This research was conducted to study the efficiency of different bioadsorbents viz. amaltas leaves, bar leaves, coconut husk, cow dung, jamun leaves, olive stone, maize cob, neem leaves and date stone for the removal of heavy metals from aqueous solutions as well as industrial effluents prior to optimization of conditions and various parameters. The bio adsorbents were pretreated and chemically activated. The samples were then analyzed using the atomic absorption spectrophotometer version 210VGP to check the efficiency and adsorption. The presence of metals was highest in the paper industry effluent followed by the textile industry and the car wash effluent. The results demonstrated that several low-cost agricultural and industrial waste materials exhibited substantial potential for heavy-metal removal, with almond husk and olive stone achieving consistently high removal efficiencies of 80–90% across the tested metals. Industry-specific adsorbents also showed promising performance, including 90% Cr⁶⁺ removal by maize cob from textile effluent, 85% Zn²⁺ removal by cow dung from paper-industry wastewater, and 76.2% Cr⁶⁺ removal by cow dung from car-wash effluent. Overall, the findings highlight the potential of waste-derived bio-adsorbents as economical and environmentally sustainable alternatives for heavy-metal remediation.

Bangladesh J. Sci. Ind. Res. 61(3), 89-110, 2026