REMEDIATION OF HEAVY METAL CONTAMINATED SOIL BY USING NEEM AND ALOEVERA BIOCHAR (MS Thesis)- Degree Awarded

Abstract:

Heavy metal contamination in soil is considered to be a threat towards the environmental and agricultural sustainability, especially in rapidly industrializing areas like Bangladesh. This study determined the efficiency of biochar produced from neem (Azadirachta indica) and aloevera (Aloe barbadensis miller) in immobilizing toxic metals—manganese (Mn), nickel (Ni), lead (Pb), chromium (Cr), and cadmium (Cd)—in soil that was contaminated artificially, addressing the increasing demand for sustainable heavy metal remediation methods. A fixed-bed column experiment was performed over 28 days utilizing six distinct biochar concentrations (0%, 1%, 2.5%, 5%, 10%, and 15%) to assess metal removal rate, extraction efficiency, and leaching percentages. The study identified 5% biochar concentration as the most effective and stable dosage among these concentrations for all tested metals, demonstrating high removal efficiency with delayed saturation. Pb and Cd demonstrated the highest levels of immobilization, whereas Cr exhibited moderate retention that was dependent on time. Statistical analyses involved the Kruskal–Wallis H test, and Spearman’s correlation that demonstrated that higher biochar concentrations and extended contact times significantly improved metal immobilization through mechanisms including ion exchange, surface complexation, and electrostatic attraction. The findings indicate that neem–aloe vera biochar may serve as an effective soil amendment for decreasing the mobility of heavy metals. 

• Supervision