Biosorption of uranium with Sargassum filipendula - Use in treatment of effluents of laboratories

International and National Standards establish methodologies for the management of radioactive waste in order to comply with radiological protection principles. Thus, it is necessary to find alternatives with both low cost and effective results. This work studied the use of brown algae Sargassum filipendula in its ability to remove uranium in waste generated in the environmental analysis laboratories of the Institute of Radiation Protection and Dosimetry. At first, the kinetics of biosorption was studied. This experiment was conducted on a batch at concentrations of 1 mg/L and 100 mg/L. Mathematical models of the first and second order were used to fit the experimental results. In evaluating the maximum removal capacity by marine biomass on a batch, different uranium concentrations were analyzed, and isoterms of biosorption were plotted. The experimental results have been adjusted by Langmuir and Freundlich models. The Freundlich model presented the best correlation coefficients (0.99 and 0.94) for studies with an hour and three hours of contact, respectively. In order to determine the best conditions for removal of uranium using the Sargassum filipendula, it was necessary to hold experiments in a continuous flow. A study on the critical height of bed depth was carried out by filling a column with different masses of seaweed. It was obtained a lower outlet concentration of uranium (0.07 mg/L) in 40 cm bed depth. This best height of bed was applied to the waste treatment of SEANA laboratories. It was monitored the increase of retention in biomass for a known quantity of uranium. The results showed an excellent uptake of uranium (1.25 mg U/g of biomass) even in the presence of other metals and reagents. Decontamination of the effluent for uranium reached values below those set by CONAMA for water classes I and II, making it possible to reuse the water. (author)