Degradation biokinetics of used and fresh lube oils in contaminated soil environment

C. P. Ukpaka and E. N. Wami

Abstract

In order to solve the problems of the soil environment caused by the discharge of petroleum products especially oils used for lubrication, investigations were carried out to assess the degradation of fresh and used lube oil in soil environment using bacteria degraders present in the soil. This was done by introducing some quantities of the pollutant (fresh and used lubricating oils) into some soil samples obtained from the environment. The degradation pattern was studied by estimating the level of the microbial growth using culture method and the phenol content. This was done before the introduction of the pollutant and at two weekly intervals for 42days. Results show that the phenol content, microbial and micro species present in the soil rapidly increased to maximum and then declined. The specific rate, maximum specific rate and equilibrium constants were determined using Line-Weaver Burk Plots. Results obtained show that the bacteria which degraded the fresh and used lube oil were inhibited by the presence of phenol which was informed during the biodegradation reaction. Empirical equation for microbial growth rate using the data from the experiment was obtained. The degradation of the fresh lube oil occurred faster than the used lube oil. The equation is useful in monitoring and predicting the performance of microorganisms in bioreactor and predicting the performance of microorganisms in bioreactor containing used or fresh lube oil.