Treatment of used diesel invert drilling mud to remove hydrocarbons, fix lead, and leach brine.

摘要

A sample of used, highly saline diesel invert drilling mud (DIDM), artificially contaminated with lead, was tested for remediation using a soil remediation process. Peat, soluble and insoluble phosphates, coal combustion fly ashes, and flue gas desulfurization scrubber sludge were tested as lead fixation agents. Virtually complete extraction of diesel oil was achieved in a five-step extraction process using toluene, trichloroethylene, or hexane as solvents. The effect of the metal fixation agents on solvent extraction efficiency was also investigated. After remediation to remove hydrocarbons and fix heavy metals, the DIDM sample remained saline. Successful leaching of brine from the dried agglomerates was accomplished by water percolation througha fixed bed of the dried, agglomerated soil. The cleaned DIDM was evaluated for resistance to acid leaching of lead. Long-term stability of the treated solids to acid leaching was tested. Bioavailability of fixed lead to barley plants grown on syntheticsoils prepared from remediated DIDM was determined by analysing the roots and shoots for lead content. Acid phosphatase, peroxidase, and protein levels were determined in plant roots and soil leachates by biochemical analysis methods. These results wereused to assess the effect of enzymes produced by plant root systems, or soil associated microorganisms, on the stability of fixed lead. The presence of fixation agents reduced the bioavailability of lead to the plants.