Comparison of the fixed-bed and batch leaching characteristics of aromaticcompounds in residually trapped crude oils and oily wastes

The fixed-bed dissolution characteristics were characterized for five aroma tic components in two crude oils residually trapped in glass beads and two refinery residuals containing an oily phase. Good agreement between predict ed and experimental results for the fixed-bed dissolution of benzene, tolue ne, ethylbenzene, p- and m-xylenes, and naphthalene (BTEXN) from the two cr ude oils was observed over a wide range (three to four orders of magnitude) in aqueous effluent concentrations. The partition coefficients used to des cribe the experimental leaching curves agreed well with those independently measured from multiple-batch aqueous extractions. For the two refinery res iduals, good agreement between predicted and experimental fixed-bed dissolu tion was also observed for a one- to two-orders of magnitude range in leach ate concentrations. These results illustrate a methodology for predicting t ime-dependent leaching behavior for an oily residual using partition coeffi cients measured from batch leaching tests. In addition, it was found that w hen the oil content of the oily residuals was accounted for, the partition coefficients measured for BTEXN for the oily residuals were similar to thos e for the crude oils. In the absence of batch measurements for a given oily residual, this latter result suggests that the time-dependent leaching beh avior, under local equilibrium conditions, can be estimated from measuremen ts of only the contaminant concentrations in the waste and the oil content. (C) 1999 Elsevier Science B.V. All rights reserved.