Evaluation of Neem (Azadirachta indica) as a Bioremediation Agent in Waste Oil-polluted Swampy Soil

Abstract

This study examined the effectiveness of neem (Azadirachta indica) leaf powder in the bioremediation of waste-oil-contaminated loamy soil. The concentrations of selected hydrocarbon markers—n-octane (C8), n-icosane (C20), and n-triacontane (C30)—were monitored every 7 days over a 42-day remediation period. The remediation agents were sourced from Ohiauga Community in Ogba/Egbema/Ndoni Local Government Area, Rivers State, Nigeria. The leaves were sun-dried and ground into powder, then later applied to the contaminated soil at four dosage levels: 5g, 10 g, 15g and 20g. Hydrocarbon characterization was conducted on both the waste oil and the treated soil samples. Results showed a consistent decline in total petroleum hydrocarbon (TPH) levels with an increase in Neem dosage and curing time. The highest remediation efficiency was recorded in samples treated with 20g of neem powder, indicating its strong hydrocarbon-reducing potential. The results indicate that neem serves as an efficient, affordable, and eco-friendly material for rehabilitating loamy soils contaminated with waste oil. The study recommends the use of neem-based treatments for oil-polluted sites and encourages government authorities to promote the production of neem powder as part of sustainable pollution management efforts.