Comparison of Asphalt Extraction Procedures: Implications of Hidden Environmental and Liability Costs

In the past, asphalt extractions were performed using toxic solvents; alternative, less polluting methods have been developed that can replace the traditional solvent extraction method. Accordingly, five potential asphalt extraction methods were compared for the Nebraska Department of Roads Bituminous Laboratory: solvent extraction using trichloroethylene (TCE), solvent extraction using an alternative solvent, solvent extraction using TCE and a solvent recovering reclaimer, ignition oven, and an ignition oven and solvent combination. To compare the total cost of each option, the direct capital costs, operating and maintenance costs, as well as the hidden environmental, health, and safety costs were considered. Because the hidden costs can be difficult to quantify, a total cost assessment approach was used. To represent the uncertainties in the cost and design data, fuzzy set theory was used. A traditional economic analysis, including only the capital, and operating and maintenance costs, found that the three least-cost options were within the range of uncertainty of the analysis; these three options were the ignition oven (most environmentally friendly option), ignition oven with solvents, and solvent reclaimer. However, when the hidden costs related to the environmental, health, and safety aspects for an asphalt extraction procedure were incorporated into the cost analysis, the cost comparison changed significantly; the most environmentally friendly option, ignition oven, was shown to be by far the least-cost option. Accordingly, the quantification of environmental, health, and safety costs that are difficult to assess is very important when evaluating environmentally friendly processes.