Bioremediation of petroleum hydrocarbon from soil using earthworm species Eisenia fetida in a vermiwash system

Abstract

Soil contamination by petroleum hydrocarbon based compounds continues to present an environemtal hazard in many countries. More so, in many developing countries there is a lack of proper disposal mechanisms for products such as used vehicular engine oil. The investigation and application of appropriate biological methods to mitigate and possibly irradicate the adverse effects of hydrocarbon contaminants on soil quality and productivity is critical for environmental sustainability. The study reports on the application of earthworm species Eisenia fetida in the remediation of petroleum hydrocarbons from clay loam soil and their effects on native micrbial populations under vermiwash conditions. The earthworm species were obtained from soil in the community of Nismes, Guyana. The results revealed that Eisenia fetida strived well in 5 % v/w used engine oil, 92% survival was recorded in engine oil contaminated soil. Eisenia fetida exhibited an ability to biodegrade petroleum hydrocarbon from the soil and bioaccumulate these compounds within their tissue. The results attained showed a reduction of 68.95% of TPH in contaminated soil that consisted of Eisenia fetida and a 4.50% reduction in contaminated soil without the Eisenia fetida. Further, Eisenia fetida in used engine oil contaminated soils possesd 66.9% more TPH in their tissues compared to Eisenia fetida in uncontaminated soil. Investigations revealed exemplary support for the use of Eisenia fetida in the remediation of petroleum hydrocarbon, promotion of microbial population and improvement of soil quality.