A New Technique for Measurement of Oil Biodegradation

Abstract

An active strain of anaerobic thermophilic bacteria was isolated from the environment of the United Arab Emirates. The strain, identified as Bacillus species, consists of two types—round and rod-shaped bacteria. This project studied the possibility of using these two types of bacteria for biodegradation of oil under elevated temperature conditions using a new method of measurement. Chemical and physical techniques were used previously to estimate the degradation rate of oil by microbes. In this project, a technique is was used to provide more accurate and reliable measurements. Visual inspection and measurements of oil drop size as a function of time were conducted. A computer image analyzer was used in this study to track bacterial growth and capacity to survive under different environmental conditions.

The temperature of the studied systems varied between 25°C and 70°C, and salt (sodium chloride (NaCl)) concentration varied between 0 and 50,000 ppm NaCl. The temperatures were selected to include typical sea water and reservoir temperatures in the Persian Gulf region. The average bacterial concentration used in this study was 182 × 10³ cells/mL. Experimental results indicated that the bacteria have the capacity to survive in saline and high temperature environments. The maximum oil degradation was observed at 70°C for all tested salinities. The degradation rate can be maximized by lowering the salinity and increasing the temperature of the studied systems. At a high temperature of 70°C, bacterial growth tends to improve at a low salt concentration, with a maximum oil degradation rate obtained at 10,000 ppm NaCl.

Keywords:

• bioremediation
• crude oil
• degradation
• microbial enhanced oil recover
• salinity
• temperature
• thermophilic-bacteria

ACKNOWLEDGMENTS

Experimental work was conducted by the students of Safety and Environmental Impact Course. Many thanks are due to Mr. Ibrahim Almagrabi and Engineer Tariq Mohammed Alansari for repeating the experimental work and for conducting image analyzer tests.