The Effect of Nitrate, Salinity, Pollutant Concentration and Cell Mass on BTEX Degradation in Microaerophilic Environment

Despite of numerous studies on BTEX biodegradation, a few researches has been conducted to optimize the environmental conditions for biodegradation of this pollutant considering the effective factors. The objective of this study was to investigate the effect of environmental factors such as nitrate, salinity and cell mass (the isolated bacterium from the soil) on BTEX degradation and to optimize the environmental conditions for biodegradation. In order to identify the appropriate microorganism for BTEX degradation, isolation of the bacterium from the oil contaminated soil was performed firstly. Then the nitrate, salinity, cell mass and BTEX concentrations were considered as independent variables to optimize BTEX degradation conditions by the isolated bacterium. Finally, a quadratic polynomial mathematical model was suggested by the Design Expert software (R2=0.85). This research showed that the isolated bacterium is able to degrade BTEX and the proper condition for degradation can be achieved by applying the above-mentioned model. Results showed that the effect of BTEX and Nitrate concentration on BTEX degradation is significant. So that increasing BTEX concentration to the extent of 200 ppm and decreasing nitrate concentration to the extent of 400 ppm reduced BTEX degradation to 4.2% and 9%, respectively.