Predicting selected kinetic parameters of hydrocarbon interactions with alum-based water treatment residuals

Abstract

Kinetic parameters of hydrocarbon interactions with alum-based water treatment residuals (WTR) in the biostimulation of crude oil-polluted soil are very important because they reveal how long the WTR bind with the hydrocarbon to control its fate and transport in the soil. In this study, we used Michaelis-Menten biokinetic model to determine two important kinetic parameters, the maximum specific rate constant (μmax) and Michaelis-Menten constant (Km), as well as total petroleum hydrocarbon (TPH) degradation rate equation in the biostimulation of crude oil-polluted Niger Delta Oxisols using WTR synthesized from local fishpond effluents. Using the completely randomized design, the experimental setup consisted of 6-duplicate reactors including the control (labelled A to F) containing mixtures of soil, crude oil, and WTR in the ratios of 4:1:0, 4:1:1, 4:1:1.5, 4:1:2, 4:1:2.5, and 4:1:3, respectively. Treatment lasted for 70 days and TPH concentration was determined by gas chromatography-mass spectrometry (GC-MS). Results showed that a rounded average of 51% TPH reduction was achieved after 70 days of treatment. The rounded average of μmax was 0.5 mg/kg-day and Km was 270 mg/kg, while the TPH degradation rate equation was deduced as r=−0.5S/(270+S) at any TPH concentration, S. With an average root-mean-square error of 4.998 mg/kg, residual prediction deviation of 18.08, and corresponding validation r2 of over 99%, the model prediction was categorized as excellent with an error of only 1%. This shows the potential of the model to predict TPH in the biostimulation of crude oil-polluted Niger Delta Oxisols with alum-based WTR.