The Optimization of a Three-Phase Surfactant Washing System

In this analysis, the economics of MBI International’s three-phase surfactant washing system for the removal of polychlorinated biphenyls (PCBs) from sediment was optimized. The system, which consists of a screw washer, an oil/water separator, and a vacuum filter, transfers PCBs to a sacrificial oil layer through two individual two-phase partitioning steps. At the completion of the washing process, the sacrificial oil layer is incinerated. Cleaned soil is disposed of in a municipal solid waste facility, and the spent surfactant layer is recycled. The washing system was modeled using the MATLAB mathematical program and an economical analysis was conducted using the results from the program. When connecting-equipment between operating units, product maintenance, and capital depreciation are considered, the economic results were reported with a 35% confidence level. According to the cost analysis, the manufacturing cost to treat 20 tons of sediment per hour was determined to be approximately 15 million dollars. This cost includes the usage of 6% (by volume) surfactant in the aqueous phase and 375 kilograms of sacrificial oil. The net profit was calculated to be approximately 56 thousand dollars. The three-phase surfactant washing system is technically feasible and sound. It is recommended that a pilot plant investigation be initiated for the patentpending process. Work done under the direction of Blaine Severin, PhD., of MBI International in partial fulfillment of the requirements of Michigan State University MTH 844, advised by Professor J. A. Courtney.