Sub and Supercritical Decontamination of Oil-Based Drill Cuttings: A Review

Drill mud is a fluid which is used in oil extraction industries in order to cool and lubricate the drill bit. Due to containing numerous toxic components, it is considered as a hazardous waste which must be treated before discharging to the environment. Current separation techniques for drill cutting treatment can be categorized into three main categories of physical (dewatering), physiochemical (solvent extraction, surfactant enhanced washing, and supercritical CO2 extraction), and thermal methods (desorption and microwave heating). In this research, the effectiveness of superheated steam extraction for drill mud recovery is studied. Super-critical fluid extraction is an innovative process in the field of contaminated soil treatment. Extraction with super-critical fluid is a simple and rapid extraction process which uses supercritical fluids as solvents. In order to enhance the decomposition percentage, supercritical extraction is accompanied by oxidation process using H2O2. Using superheated steam extraction process at 2.3MPa and 225 °C, 78.56% and 83.09% of total organic carbon were removed from the drill mud sample. In the combined system of supercritical extraction and oxidation with H2O2, more than 99.9% of polycyclic hydrocarbons in the drill mud mixture were decomposed. It shows that combination of supercritical extraction with an advanced oxidation process can significantly enhance the efficiency of the remediation process. The great advantage of this hybrid process is being eco-friendly due to using water as the solvent in the extraction process.