keywords: Biodegradation, PAHs, spent engine oil, microbes, pollution
This study was conducted to assess bacterial degradation of total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAHs) contents of spent engine oil (SEO) contaminated soil through the employment of Pseudomonas aeruginosa and Alcaligenes faecalis isolated from spent engine oil polluted soil from Dutse mechanic village, Nigeria. About 1.5 kg of autoclaved soil was deliberately contaminated with SEO at three levels. The soil was then supplemented with processed compost, powdered cocoa pod husk (CPH) and powdered cow dung (CD). Successively, the soil was bio-augmented with bacterial co-culture (150 ml). TPH and PAHs were estimated at the commencement, 5th and 10th week of the study. Factorial experiment laid out in a completely randomized design (CRD) was adopted. Results indicate that all the biostimulants employed did have significant effects on bacterial degradation of TPH and PAHs (P<0.05). Compost facilitated the most TPH reductions (756 and 250 mgkg) on 5 and 10% SEO contaminated levels at 5th and 10th week, respectively (P<0.05). Powdered CPH only recorded the most significant PAHs reductions (37.7 mgkg) on 15% SEO contamination level while compost recorded the most significant PAHs reduction (29.7 mgkg) on 10% SEO contamination level compared with other biostimulants employed at the 5th week and 10th week, respectively (P<0.05). The significant feat that Pseudomonas aeruginosa and Alcaligenes faecalis co-culture recorded in this study has indicated its potential for utilization in achieving effective remediation of hydrocarbon related pollution.