Enhanced Anaerobic Bioremediation of Oil-Contaminated Intertidal Sediment with a Combination of Self-Synthesized Rhamnolipids and Sulfate

Abstract

Oil pollution in intertidal sediment is a severe environmental issue. The anoxic environment of the sediment makes it difficult for hydrophobic organic pollutants to decompose. Therefore, accelerative measures such as the addition of biosurfactants (rhamnolipids) are required to improve their bioavailability. Herein, the combination of self-synthesized rhamnolipids and electron acceptor on bioremediation of oil-polluted sediment was evaluated. After the bioremediation, the combination of rhamnolipids and sulfate significantly enhanced the removal of polycyclic aromatic hydrocarbons (74.8±1.4%). The bamA/16S rRNA ratio of sulfate with rhamnolipids treatment was the highest one (4.3±0.8%) among all treatments. On day 270, the polyphenol oxidase activity of rhamnolipids and sulfate with rhamnolipids treatments was up to 20870.1±1988.7 mg/(kg·h), 22373.8±970.1 mg/(kg·h), which was significantly higher (P<0.05) than other treatments. The results revealed that the addition of rhamnolipids favored the growth of microorganisms and promoted S cycling, and the combination with sulfate dramatically enhanced the removal of PAHs. Additionally, it was found that the petroleum hydrocarbon degradation process governed changes in microorganisms and led to microbial community shifts in different treatments. This study proved that the combination of sulfate and rhamnolipids exhibits great potential on the remediation of oil-contaminated intertidal zone.

Keywords: Intertidal sediment, oil pollution, Anaerobic bioremediation, Electron acceptor, CNPS cycling