The National Institute of Advanced Industrial Science and Technology of Japan, jointly with Mitsui Engineering & Shipbuilding Co., has successfully developed a cleanup system for soil contaminated with organic arsenic compounds, the institute announced on January 11, 2006. This technology has made it possible to remove organic arsenic from soil with nearly 100 percent efficiency. It also helps reduce costs for soil cleanup because with this technology, used cleaning agent can be recovered and reused while organic arsenic can be concentrated and thus readily recovered.
With conventional technologies, it was difficult to eliminate organic arsenic compounds from soil due to their particular characteristics--they are highly poisonous, seep easily into groundwater, are persistent once absorbed in soil, are not decomposed by microorganisms, and leave toxic inorganic arsenic compounds even after being subjected to thermal treatment or chemical decomposition. For those reasons, there was an urgent need to develop an effective soil purification technology.
The newly developed method can almost completely remove organic arsenic from soil by use of a cleaning agent made from a mixture of alcohol and low-concentrate phosphoric acid. It is thought that the agent's high effectiveness in purification is due to the fact that phosphoric acid helps separate organic arsenic from soil, and the separated arsenic dissolves in alcohol. The institute will conduct a further study on how to prevent trace amounts of organic arsenic remaining in soil from spreading further.