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

A sample of used, highly saline diesel invert drilling mud (DIDM), artifici ally contaminated with lead, was tested for remediation using ICPET/NRC's S olvent Extraction Soil Remediation (SESR) process. The work comprised inves tigation of the concurrent solvent extraction of diesel oil and fixation of lead by co-agglomeration of metal binding agents. Feet, soluble and insolu ble phosphates, coal combustion fly ashes, and flue gas desulfurization scr ubber sludge were tested as lead fixation agents. Virtually complete extrac tion of diesel oil was achieved in a five-step extraction process using tol uene, trichloroethylene, or hexane as solvents. The effect of the metal fix ation agents on solvent extraction efficiency was also investigated After r emediation to remove hydrocarbons and fix heavy metals, the DIDM sample rem ained saline. Successful leaching of brine from the dried agglomerates was accomplished by wafer percolation through a fixed bed or the dried, agglome rated soil. The cleaned DIDM was evaluated for resistance to acid leaching of lead using the U.S.-EPA's toxicity test method 1310A and Toxicity Charac teristics Leaching Procedure method 1311. Longterm stability or the treated solids to acid leaching was tested using the U.S.EPA's multiple extraction procedure method 1320. Bioavailability of fixed lead to barley plants grow n on synthetic soils prepared from remediated DIDM was determined by analyz ing the roots and shoots for lead content Acid phosphatase, peroxidase, and protein levels were determined in plant roots and soil leachates by bioche mical analysis methods. These results were used to assess the effect of enz ymes produced by plant root systems, or soil associated microorganisms, on the stability of fixed lead. The presence of fixation agents reduced the bi oavailability of lead to the plants.