Biodegradation of heavy crude oil in wastewater by an efficient strain, ERCPPI-1

The potential biodegradation of heavy crude oil from wastewater was assessed based on the development of a fermentative process with a new strain of Enterobacter cloacea (ERCPPI-1) which was isolated from heavy crude oil in south of Iran, when cultured in a basal mineral medium using heavy crude oil as the sole carbon source. The effects of heavy crude oil concentration, temperature, pressure, pH and salinity on the growth rate of ERCPPI-1 in the presence of heavy crude oil as the sole carbon source were investigated. The results showed that ERCPPI-1 has a good potential for biodegradation of heavy crude oil in the concentration ranges of 0.25-10%, temperatures up to 70 degrees C, pressures up to 6000 psia, pH ranges of 4-10, and salinity up to 15%. However, as the concentration of heavy crude oil is increased from 0.25% to 10%, the percentage of degradation by the strain is decreased from 76.3% to 19.1%. Temperature of 40 degrees C and pH of 7.0 were found to be the optimum conditions for maximum biodegradation rate. The experiments also showed that the strain ERCPPI-1 was able to produce a type of biosurfactant, using heavy crude oil as the sole carbon source, with high oil spreading and emulsification properties. The experiments performed in piston-cylinder systems demonstrated that the efficiencies of oil recovery and biodegradation of hydrocarbons are at a reasonable rate. These results suggest that strain ERCPPI-1 has the ability to degrade heavy crude oil under ex situ and in situ conditions.