The water hyacinth's uptake of 137Cs and 90Sr and its decontamination potential as an approach to the zero-release concept

The decontamination potential of water hyacinths (Eichhornia crassipes) is discussed in the context of the concept of zero release of radioactivity to the aquatic environment. A series of static 24-hour laboratory experiments was conducted with 137Cs and 90Sr, which are the two principal long-lived and hazardous radionuclides of concern in waste management. Uptake characteristics were delineated for both the radionuclides as functions of contact time, specific activities and pH. Absorption was found to increase with increasing specific activities, with a higher percentage removal at lower specific activities. The decontamination features for the radionuclides are presented under varying parameters. The response of the biomass to a mixed system of 137Cs and 90Sr was studied as well as to radioactive liquid effluent specimens. The distribution of radionuclides in the biomass was determined in translocation studies. Most of the radioactivity was localized in the roots with marginal translocation to leaves in the case of 90Sr. The studies demonstrated water hyacinths to be a potential sorption matrix with significant decontamination properties, volume reduction characteristics and tolerance to pH variation. (author)