Kinetic Modelling and Error Analysis of the Bioremediation of Used Motor Oil Contaminated Soil Using Palm Bunch Ash as Stimulant

Abstract

The spillage of petroleum and its derivatives in soil and water has caused severe hazards to human health, led to serious environmental problems, caused economic loss and lower ground water usage. This research was conducted in order to compare the biostimulation potential of palm bunch ash (PBA) for the remediation of used motor oil contaminated soil as well as to obtain the best kinetic model that fits the experimental data in the treatment cells labelled T1 to T12. D-optimal design of response surface methodology of Design expert was used to generate ten experimental runs with PBA as numerical factor and pollution level (5% and 10%) as categorical factor. Samples were taking from each of the treatment cells for analysis of Oil and Grease Content (O&G) and Total Heterotrophic Bacteria Count (THBC) at two-week interval. After ten (10) weeks, the results showed T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, and T12 exhibited 86.5%, 100%, 79.2%, 74.5%, 95.5%, 79.2%, 100%, 99.4%, 99.0%, 63.0%, 88.0%, and 58% oil and grease degradation, respectively. The R2 values showed that the first and second order kinetic models fitted the experimental data. Comparing the results of the error analysis of the studied kinetics, it was found that the first order kinetic model best fits the degradation of used motor oil in all the treatment cells. The biodegradation rate constant values are high for the treatment cells with 5% pollution level for the zero, first and second order kinetic models. It was also observed that the THBC in all the treatment cells followed the batch growth culture of microorganisms. From the results of this work, it can be concluded that the application of PBA stimulates the growth of microorganisms that enhanced the consumption of used motor oil in the soil. Thus, can be applied to develop an environmentally safe, robust, and economically viable treatment strategy for oil contaminated soil.