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By: Ekperi Nelson Ibezim, Joseph Gana, and Okirie Faith Uchendu.
1&3Research Scholars, Department of Chemical Engineering, Rivers State University Port Harcourt, Rivers State.
2Lecturer, Department of Chemical Engineering, Federal University Otuoke, Bayelsa State.
The degradation of Total Petroleum Hydrocarbons (TPH) in petroleum-contaminated clay soil remains a major environmental concern, particularly in regions with limited remediation options. This study investigates the enzymatic kinetics of TPH biodegradation using Michaelis-Menten modeling in the presence of Bryophyllum pinnatum leaf extracts as biostimulants. Fourteen bioreactors containing 2000g of contaminated clay soil were prepared with 100ml of crude oil and treated with varying doses (100ml, 200ml, and 300ml) of ethanol- and water-based Bryophyllum pinnatum extracts. Physicochemical and microbiological analyses were performed over a 42-day period. The kinetic parameters—maximum degradation rate (Vmax) and Michaelis-Menten constant (Km)—were derived using Lineweaver-Burk plots. Results showed that ethanol extracts were more effective than water extracts in enhancing microbial degradation of TPH. The highest Vmax (4000 ppm/day) and Km (1.068 ppm⁻¹) were recorded in T11, treated with 300ml ethanol. The regression coefficients (R² values) from linearized kinetic models ranged between 0.8432 and 0.9752, indicating strong correlations and model reliability. Bacterial counts were significantly higher in ethanol-treated samples compared to controls, suggesting enhanced microbial proliferation and degradation efficiency. The study concludes that biostimulant type and dosage influence the enzymatic behavior of hydrocarbon degradation and that Michaelis-Menten modeling is a reliable tool to quantify these dynamics. This approach supports the optimization of bioremediation strategies for petroleum-contaminated clay soils.
Citation:
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