Remediation of Fuel Oil-Contaminated Soils by a Three-Stage Treatment System

The objective of this study was to develop a three-stage treatment train system to remediate fuel oil-contaminated soils. The treatment system included the first stage of biodegradable surfactant and groundwater flushing followed by the second stage of Fenton-like oxidation. The third stage was the application of enhanced bioremediation for the removal of residual total petroleum hydrocarbon (TPH) after the first two treatment processes. Three different surfactants [Simple Green (TM) (SG), Triton X-100, and Tween 80] were evaluated in batch experiments for their feasibility on TPH removal. Results from the surfactant biodegradation and microbial enumeration study indicate that SG was more biodegradable and enhanced the microbial activity of the intrinsic micro-organisms. Thus, SG was applied in the following column experiment. Results from the column study indicate that approximately 80% of TPH in soil (with initial concentration of 50,000 mg kg(-1)) could be removed after the SG [50 pore volumes (PVs)] followed by groundwater (30 PVs) flushing. The Fenton-like oxidation (with 6% of H2O2 addition) was able to remove another 15% of TPH. Observed first-order reaction rate constant of TPH oxidation was 2.74 x 10(-2) min(-1), and the half-life was 25 min during the first 40 min of reaction. The residual 5% of the TPH could be further remediated via the aerobic bioremediation process. Thus, complete TPH removal was obtained in this study using the three-stage treatment scheme. The proposed treatment system would be expected to provide a more efficient and cost-effective alternative to remediate fuel oil-contaminated sites.