Earnest efforts are being made to develop radioactive decontamination technologies in Japan, which suffered serious damage from the accident at the Fukushima I nuclear power station. A joint research team consisting of the University of Tsukuba and other institutions has been developing an algal culture plant that uses sunlight, with the aim of using the algae to remove radioactive material released into water. The team has been working to establish a technology that takes advantage of a property of phytoplankton—which absorbs cesium into its body by confusing the element with potassium—to remove radioactivity from reservoirs, the ocean, lakes, paddy fields and other water bodies.
The team has conducted an experiment where it cultured several types of algae with high levels of radioactivity removal capability for 14 days, and succeeded in removing about 70 per cent of cesium in water. The algae that have absorbed cesium will be collected by a filter and incinerated.
The University of Tsukuba and other participating institutions have grown 189 species of algae and plants in a culture solution mixed with radioactive material, and examined the radioactivity removal rate of each species. The result included identification of three species of algae capable of removing cesium-137 by 40 per cent or more. The algal culture plant used by the team is designed to provide a stable culture condition by collecting sunlight with its newly developed Fresnel lens. The team plans to continue their research by carrying out verification tests in a large pool and other environments.
