Feasibility studies on in‐situ biological treatment of drilling muds at an abandoned site in Sicily

Abstract

AbstractThe ongoing production and bioaccumulation of drilling fluids and muds has resulted in an increased concern for reducing the environmental impact of contaminated sites. The use of bioremediation as a treatment option is an important focus of research. Objectives of this study were: (i) to assess initial toxicity of drilling mud from an agricultural setting in Galliano, Sicily (Italy) and (ii) to develop a low intervention bioremediation approach to ensure that US and international soil/ground water quality standards have been met. Total petroleum hydrocarbon content of the drilling mud was reduced to 617.0 ± 176.0, 446.0 ± 195.0, and 533.0 ± 138.0 mg kg−1, respectively, from 5000.0 ± 530.0 mg kg−1 after treatment via conventional ex‐situ soil slurry reactor mixing (84.2–95% reduction). Using an in‐situ approach with bioreactors placed vertically into the zone of contamination, hydrocarbon concentrations went from 217.12 ± 43.38 and 149.68 ± 45.51 mg kg−1 to 15.16 ± 3.35 and 34.27 ± 15.86 mg kg−1 for control test beds (85.1 ± 11.2% reduction), and from 89.20 ± 67.42, 141.71 ± 64.80, and 197.87 ± 77.38 mg kg−1 to 5.24 ± 6.15, 15.02 ± 10.20, and 9.65 ± 9.37 mg kg−1 for experimental test beds (92.9 ± 3.0% reduction), respectively. Cadmium (Cd) and Selenium (Se) had exceeded Italian and state soil leachability standards (0.005 mg dm−3 Cd) and (0.010, 0.050 mg dm−3 Se), at the conclusion of the study. In‐situ treatment of drilling mud provided a framework for monitoring the fate of organic and residual metals toxicity in soils. Copyright © 2003 Society of Chemical Industry