ream would significantly reduce the required size of the EASW processing facility. First the soil to be treated is mixed with recycled water, plus any make-up chemicals required to adjust the pH and electrical conductivity. The soil slurry then flows through the EASW unit where it efficiently scrubbed by the mechanism described in the previous paragraphs. The resulting steam is condensed and volatile contaminants separated. The soil slurry continues to a separator unit where free water is separated from the slurry. A centrifuge was used in the laboratory investigation, but a settler may be desirable for large scale operations. The soil is then rinsed with water. This rinsing should be accomplished in a counter-flow mode so that the soil leaving the rinse unit only contains uncontaminated rinse water. The contaminated water stream is treated to remove the bulk of the contaminants. A variety of options are available to treat the contaminated water. These include decanting of oil phases, biological treatment to destroy organics, precipitation of soluble materials, etc. The resulting recycle water does not have to be treated to discharge standards. The water treatment process just has to be adequate to prevent excessive build-up of contaminants in the process streams. Cost of using the EASW process It has been found based on their research experiment that the cost of commercial electric power for the EASW process would be about $15 per ton of soil. This price is based on experimental data and confirmed with heat-balance calculations. The amount of electrical energy might be further reduced by efforts to conserve energy and to optimize the apparatus. The incremental capital investment is estimated as 10 to 20 percent over that for conventional soil washing. (2) On this basis the EASW would be the least costly remediation technology for soils which can not be washed with existing processes. Future OutlookA computer simulation of the EASW soil...
