Remediation of weathered petroleum oil-contaminated soil using a combination of biostimulation and modified Fenton oxidation

In this work, remediation of weathered crude oil-contaminated soil by biostimulation of indigenous microbes through addition of peanut hull as bulking agent was conducted in laboratory. A modified Fenton oxidation, using Fe(III) chelated with nitrilotriacetic acid in a molar ratio of 1:1 as a catalyst, was applied to the bioremediation. The results showed that, after bioremediation for 20 weeks, reduction of total petroleum hydrocarbons (TPHs) by 88.9% was observed in the combined treatment compared with 55.1% in the biological treatment alone. The Microtox® toxicity of treated soil extract was reduced greatly after the chemical oxidation process. Biostimulation with inorganic nitrogen and phosphorus increased TPH degraders in the treated soil by two orders of magnitude. The activity of microbial communities also increased markedly in the treated soil compared with that in the control.

► We use a two-stage remedial system to remediate weathered crude oil-contaminated soil.
► Toxic metabolites were removed by the modified Fenton reactions.
► Biostimulation can enhance microbial activity, biodiversity, and pollutant removal.