TOKYO -- Shimizu has developed an efficient and cost-effective way to clean soil in Vietnam that remains contaminated to this day with toxic dioxins from the Vietnam War.
The Japanese civil engineering company will propose to Hanoi that it install a large-scale pilot plant to test the technology. If that proves successful, prospects are high that Shimizu will become involved in soil remediation work in Vietnam. The company is already the leader in Japan with a 20% share of the domestic soil remediation market.
In Shimizu's soil washing technology, dirt sorted by granular size is rinsed with water and subjected to a process where dioxins adhere to the surface of air bubbles. Any contaminants that remain are burned off by heating to high temperature.
Shimizu used this process on soil contaminated by Agent Orange -- a defoliant used by the U.S. military on large swaths of land during the war -- and showed that 95% of all dioxins could be removed.
The company estimates that 70% of Vietnam's contaminated soil could be treated this way, allowing the dirt to be returned and reused. Furthermore, it calculates that the process would cost only around half that of conventional incineration of soil to remove dioxins.
Within three or four years Shimizu hopes to construct a large pilot plant in Vietnam costing about 2 billion yen ($19 million) to prove the technology. The plan is to get funding from the Vietnamese government and from sources such as the Japan International Cooperation Agency.