Effect of bacteria augmentation on aromatic and asphaltenic fraction removal in solid culture

Bioaugmented-assisted remediation of a hydrocarbon-polluted soil was performed in sealed serum bottles using a native and well adapted mixed culture consisting on S. liquefaciens and B. coagulans. The soil for this study was acidic (pH 3.8) with a total petroleum hydrocarbon (TPH) concentration of 220,000 mg/kg soil and a native microbial population of 2.0×10⁵ CFU/g soil. This study examines a biological treatment to clean up petroleum-polluted soil using a mixed culture composed by S. liquefaciens and B. coagulans. C/N/P ratio, moisture and pH were adjusted to appropriate values to assist the biodegradation process. Results demonstrated that heterotrophic activity in microcosms was higher (1.9 mg/g) in bioaugmented microcosms compared with non-bioaugmented (1.3 mg/g). During all the incubation period only three strains were cultivated S. liquefaciens, B. coagulans and a non-identified yellow bacteria. The TPHs removal increased 12% in bioaugmented microcosms at the end of 74 days of treatment. In the case of aromatic and asphaltenic fractions the removals increased 12 and 10% respectively. During the first 35 days of incubation, TPHs removal correlates with the exponential phase of microbial growth. Our results showed that bioaugmented-assisted remediation of hydrocarbon-polluted soils in highly polluted and weathered sites are feasible.