Effect of biostimulation on community level physiological profiles of microorganisms in field-scale biopiles composed of aged oil sludge

Four biopiles were constructed for the bioremediation of total petroleum hydrocarbons (TPHs) in aged oily sludge by indigenous microorganisms. Three biopiles were treated with bulking agent, nutrients or their combination with the fourth pile serving as the control. Responses of microbial community level physiological profiles (CLPPs) to these biostimulation strategies were estimated, and variances among three layers within each biopile were evaluated. Microbial metabolic activity and diversity and the numbers of two species of bacteria were significantly enhanced by the addition of bulking agent, which also made the layers more homogeneous. In contrast, the application of large amounts of nutrients had a suppressing effect on the microbes. After 220 days, 49.62% of TPHs were removed from the middle layer of the bulking agent pile, whereas only 20.44% were removed from the inner layer of the control. This study aims to provide experience to improve the remediation efficiency of future investigations.