Bioremediation of crude oil by indigenous species isolated from oil sludge contaminated soil. A case study: Karun Gas Oil Production Company, (IRAN)

The present study aimed to investigate the biodegradability of the native species isolated from a site contaminated with crude oil (Karun Gas Oil Production Company, Iran). According to the findings, the species isolated from bacillus could grow at the concentrations of 1 and 3% of crude oil within the pH range of 3-5 and at various temperatures. Bacillus sonorensis had higher efficiency at the concentration of 1%, temperature of 30 °C, and near-neutral pH compared to the second species. Therefore, it could be used in biological remediation processes through the reduction of biosurfactant and surface tension to a certain extent (24.87 mN/m) compared to the control samples (59 mN/m). Furthermore, the chemical analysis showed that the bioremediation efficiency of chrysene, fluorene, naphthalene, dibenz(a, h)anthracene, and pyrene was 35.85, 39.56, 27.14, 28.45, and 27.5% within four days, respectively. With the reduction of the surface tension, aromatic compounds could be better decomposed compared to aliphatic compounds