Bioremediation of heavy oil-contaminated intertidal zones using slow-release nutrients and rhamnolipid biosurfactants

The decontamination of heavy oil from intertidal sediments requires a green and economic approach. Herein, the effect of a combination of natural mineral slow-release nutrients and rhamnolipid biosurfactants on the biore-mediation of a heavy oil-contaminated intertidal zone was studied. Slow-release nutrients had a good extended time performance and resisted seawater dilution. The concentrations of total nitrogen and total phosphorus after 100 days of treatment were 680.5 mg/L and 25.4 mg/L, respectively. The combined application of slow-release nutrients with rhamnolipid biosurfactants effectively improved the metabolic activity of indigenous microor-ganisms and the biodegradation efficiency of heavy oil. The combined application reduced heavy oil by 39.4%, which was 17.0% higher than the natural attenuation. In addition, we found that n-alkanes and polycyclic ar-omatic hydrocarbons in heavy oil could be reduced simultaneously. Bacterial community analysis showed that slow-release nutrients and rhamnolipid biosurfactants enriched oil-degrading bacteria, enhanced heavy oil biodegradation. Overall, our findings demonstrated that the combination of slow-release nutrients and rham-nolipid biosurfactants is an effective intertidal oil remediation treatment.