Bioremediation of oil-contaminated soil — A rate model

Three rate equations, a modified Monod equation and two mass transfer rate equations, were used to calculate the biodegration rate, oxygen transfer rate and oil transfer rate during a bioremediation process of oil-contaminated soil. Based on experimental rate constants, these three rates were calculated and compared. It was found the bioremediation rate of oil-contaminated soil could be controlled by the mass transfer process of oil into aqueous solution (0.12 mg BOD/(1•h)). When the oil transfer rate is enhanced by at least 10 times, the oxygen transfer process (0.1–1.0 mg BOD/(1•h) becomes the rate-controlling step. For most of the cases, the biodegradation of oil in aqueous solution is not the limiting step unless the microbial population in the aqueous solution is less than 100 mg VSS/1.