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Removal of uranium from groundwater is of great significance as compared to in situ bioimmobilization technology. In this study, a novel direct electro-reductive method has been developed to efficiently remove and recover uranium from carbonate-containing groundwater, where U­(VI)­O2(CO3)3 4– and Ca2U­(VI)­O2(CO3)3 are the dominant U species. The transferred electron calculations and XPS, XRD analyses confirmed that U­(VI) was reduced to U­(IV)­O2 and accumulated on the surface of the Ti electrode (defined as Ti@U­(IV)­O2 electrode) with high current efficiencies (over 90.0%). Moreover, over 98.0% of the accumulated U­(IV)­O2 could be recovered by soaking the Ti@U­(IV)­O2 electrode in the dilute nitric acid. Results demonstrated that the accumulated U­(IV)­O2 on the surface of the Ti electrode played a key role in the removal of U­(VI), which can promote the electro-reduction of U­(VI). Therefore, the electrode could be used repeatedly and has a high removal capacity of U­(VI) due to the continuous accumulation of active U­(IV)­O2 on the surface of the electrode. Significantly, the uranium in both real and high salinity groundwater can be efficiently removed. This study implies that the proposed direct electro-reductive method has great potential for the removal and recovery of uranium from groundwater and uranium-containing wastewater.

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Three lipases were applied to hydrolyze the floatable grease (FG) in the food waste for eliminating FG inhibition and enhancing digestion performance in anaerobic process. Lipase-I, Lipase-II, and Lipase-III obtained from different sources were used. Animal fat (AF) and vegetable oil (VO) are major crude lipids in Chinese food waste, therefore, applied as substrates for anaerobic digestion tests. The results showed that Lipase-I and Lipase-II were capable of obviously releasing long chain fatty acid in AF, VO, and FG when hydrolyzed in the conditions of 24h, 1000-1500μL and 40-50°C. Compared to the untreated controls, the biomethane production rate were increased by 80.8-157.7%, 26.9-53.8%, and 37.0-40.7% for AF, VO, and FG, respectively, and the digestion time was shortened by 10-40d. The finding suggests that pretreating lipids with appropriate lipase could be one of effective methods for enhancing anaerobic digestion of food waste rich in crude lipid.