Kyoto University Succeeds in Removing PCBs from Contaminated Riverbed

A Kyoto University research team led by Associate Professor Masaki Takaoka and Assistant Professor Kazuyuki Oshita announced on November 12, 2007, that it had successfully removed 99.1 percent of polychlorinated biphenyls (PCB), a class of hazardous, man-made substances that pollute urban riverbeds in Japan, at normal temperatures without the use of heat.

Although the solvent extraction method used to process contaminated soil or riverbed sediment has several merits, such as low energy consumption and no need for a large scale treatment device, it still leaves organic solvents in the processed soil or riverbed sediment, making it necessary to further separate and refine the solvent with a sophisticated heating device.

The research team, in cooperation with Japan's Central Research Institute of Electric Power Industry, applied the liquefied dimethyl ether (DME) dehydration method to remove PCBs from a polluted riverbed. The liquefied DME dehydration method was developed by the institute to dehydrate solvents at normal temperatures by using the water absorbability of liquefied DME. The method considerably reduces energy requirements compared to the conventional method of evaporating water at high temperatures, and it can remove PCBs simultaneously during dehydration when applied to a contaminated riverbed.

The team intends to build a framework of the total process that includes decomposition and detoxifying of PCBs extracted from riverbeds, and recycling and reuse of the DME. It also plans to investigate other potential applications of the DME dehydration process and develop a scaled-up version of the method.

http://www.kyoto-u.ac.jp/index-e.html

Posted: 2008/03/27 01:33:11 PM