Green remediation and enhanced metal accumulation using moringa oleifera leaf extracts and hydrocarbon-degrading microorganisms in crude oil-impacted soils of the niger delta, nigeria

Abstract

This emerging technology called “Phytoremediation” which uses plants to remove pollutants from the environment is preferred over traditional methods, because it offers site restoration, partial decontamination, and maintenance of biological activity and physical structure whilst being potentially cheap, visually unobtrusive and with a possibility of bio-recovery of metals. Because of these advantages, phytoremediation is considered as a 'green', sustainable pollution removal process. The present study was designed to evaluate Phytoremediation potential of Moringa oleifera leaf extract on soil contaminated with Spent Engine Oil. Top soil (0-15cm depth) was randomly collected and 5kg each of the composite samples were transferred into fifty (50) plastic buckets with drainage holes at the base, plugged with cotton wool to retain the soil. The Plastic buckets were arranged into five treatment groups with Ten (10) replicates each. The polythene bags were arranged in a completely randomized block design. Spent Engine oil obtained from mechanic shops in Bedwell Calabar, Cross River State, was applied as the pollutant. The Spent engine oil was introduced at different concentration levels (0.3, 0.5, 0.7, and 1.0 l/5kg) into the treatment groups apart from the control (0.0 l/5kg).The results across the various treatment levels where subjected to statistical analysis, using Analysis of variance (ANOVA) and the results showed that physicochemical parameters (soil pH and organic carbon), Heavy Metals present, Total Petroleum Hydrocarbon and Microbial Counts were significantly higher (P<0.05) in treatment groups than the control. The result also showed a significant reduction (P<0.05) of the Total petroleum hydrocarbon after treatment.