Adsorption of Acid Extractable Oil Sands Tailings Organics onto Raw and Activated Oil Sands Coke

Abstract

The accumulation of organic contaminants in process-affected (PA) water represents an environmental liability for oil sands operators. Oil sands coke is a promising adsorbent for removing dissolved organic carbon (DOC), which includes toxic acid-extractable oil sands tailings organics (AEOSTO) found in PA water. The ability of raw and activated delayed and fluid coke to remove DOC and AEOSTO from PA water was assessed. Treatment with 5 g/L of activated delayed and fluid coke removed 91% of DOC and 92% of AEOSTO at levels of 36 mg/L and 60 mg/L, respectively. Heavy metal leaching of vanadium at 5.9 mg/L was observed for a 5 g/L application of activated delayed coke, representing a challenge to the approach. Microtox testing indicated that higher carbon doses of activated cokes were effective in reducing toxic the biological response caused by organic compounds; however, exposure to heavy metals increased the toxic effect with time. The proposed methodology should be coupled with an inorganic treatment technique for complete oil sands tailings water treatment.