A research team at the Tokyo Institute of Technology (TIT) has developed technology for purification of water contaminated with radioactivity, and is pursuing studies toward its practical utilization. The technology was developed for the purpose of supporting efforts to mop up the troubles at the stricken Fukushima I nuclear power station, and succeeded on an experimental basis in lowering the concentration of cesium to one-ten-thousandth of the input level.
The technology combines iron ferrocyanide, which acts to adsorb cesium and can be procured at a low cost, with an independently developed coagulation-sedimentation agent. The process begins with the input of powder-form iron ferrocyanide into the contaminated water, where it adsorbs the cesium. Next, the coagulation-sedimentation agent is mixed in, so as to divide the contaminated water into supernatant and thickened, contaminated mire. The technology is capable of removing 99.8% of the cesium within 30 minutes after input, and has a throughput of up to 20-30 tons of water per hour. As compared with the process applying zeolite, which is in widespread use, the new technology offers a substantial contraction of the treatment time.
According to Professor Masanori Aritomi of the research team, there is still room for improvement as regards adjustment of the blend of the coagulation-sedimentation agent. The team also sees a need for cooperation by concerned institutions for treatment of high-level radioactive waste, which could not be handled by a university organization working alone.
