Characterisation of an attrition scrubber for the removal of high molecular weight contaminants in sand

According to a recent paper published in The Chemical Engineer, there is an estimated 200,000 ha of contaminated land in the U.K. [C. Cunningham, J. Philip, Partners in grime, Chem. Eng. 378/379 (2002) 34-36]. Due to the requirement to remediate this land to reduce the levels of toxins, there is a need for simple transportable remediation techniques. One possible technique is the attrition scrubber. Investigations into the parameters that affect the efficiency of an attrition scrubber at removing high concentration, high molecular weight hydrocarbons from well defined silica sand medium are described. Mineral oil (Catenex S341) and unrefined bees wax were used as the contaminants. A number of parameters including liquid-solid ratio, power input, contaminant type and concentration, were experimentally tested for their effects on contaminant removal efficiencies. Repeatable experimental results were successfully obtained for all parameters tested. Mixing vessel design, power input into the system, contaminant type and concentration all had significant effects on the removal of contaminants. Maximum removal efficiencies of 21.3 and 96.7% where achieved for bee's wax and S341 respectively. These results show that an attrition scrubber can be used to remediate contaminated silica media and that remediation of soils is possible. This is the focus of the future studies. (c) 2005 Elsevier B.V. All rights reserved.