Study On The Biosorption Of Uranium-containing Wastewater

Rhizopus arrhizus was chosed to treat uranium-containing wastewater in the study. A series of factors, such as the reaction time, pH, temperature and concentration etc, which might influence the biosorption, were studied systematically. Its uranium-uptaking capacity was up to 162.3mg/g dry weight (25@, reaction time 30minutes) when the initial pH was 4. The adsorption capabilities were improved greatly by the pre-treatment of Rhizopus arrhizus with NaOH.When the initial pH was 4 at 251, the uranium-uptaking capacity was up to 216.5mg/g dry weight. The optium pH was 4-5, Fe3+, Cu2+, Zn2+, CO32- and F- could affect uranium adsorption respectively,but K+, Na+, NH4+, Cl- NO3- had no affect to the uranium adsorption. Rhizopus arrhizus could be used in column adsorption directly, and thepolyurethane foam could immobilized the cells effectively. The adsorption rate could be up to 98% using the immobilized cells by pretreating with NaOH. The adsorbed uranium could be eluted quantitively with Na2CO3 and NaHCO3.The elution rate was up to 94%. Rhizopus arrhizus could be used repeatly. It exhibited higher uptake capabilities when the adsorption-elution cycles was up to 6 times.The surface analysis of Rhizopus arrhizus showed that - NH2 and -NHCOCH3 groups in cell wall might complex uranim ion in the solution. The cell shrinked after pretreatment with NaOH and then exposed more actived groups, whichresulted in the increase of the adsorption capacity.The adsorption capabilities of Rhizopus arrhizus improved higher when used the polyurethane foam immobilized cells by pretreating with NaOH. It was found ideal results by treating uranium-containing wastewater. This research is valuable in uranium-containing wastewater treatment field.