Bark, a suitable biosorbent for the removal of uranium from wastewater-From laboratory to industry

Abstract : This paper shows that natural materials such as barks can successfully replace synthetic resins for industrial purposes. Evaluated in batch conditions, biosorption of uranium on suitably prepared Douglas fir barks took place in less than 10 min and appeared to be optimum at pH>4. The biosorption process of uranium (uranyl form UO2 2+) was characterized in the optimal physico-chemical conditions and could be mathematically modeled as a Langmuir isotherm. With a maximum uranium specific uptake qmaxvalue of 1.16 meq.g-1 (138 mgU.g-1) it was found that the sorption capability of Douglas fir barks was at least five times higher for uranium than for other heavy metals such as lead. Adsorption of uranium contained in water leached from a former uranium mine was then monitored over a one-month period in a laboratory-scale chromatography column. The fixation capacity remained fairly constant throughout the whole testing period. Water radioactivity decreased from 1500 mBq.L-1 (0.12 mgU.L-1) to <5 mBq.L-1(0.4 μ gU.L-1) at the column exit. This technology was successfully transferred and tested through a pilot project under industrial conditions with the support of AREVA