Decontamination of uranium contained low-level radioactive wastewater from UO2 fuel element industry with vacuum membrane distillation

Abstract

The rapid development of nuclear industry has generated large quantities of low-level radioactive wastewater (LLRW) to pose a potential threat globally. In this study, the feasibility of vacuum membrane distillation (VMD) process for the decontamination of uranium contained LLRW from UO2 fuel element production has been studied using commercial PTFE hollow fiber membrane. The effects of operation conditions, such as feed temperature/pH, vacuum pressure and feed flow velocity were investigated and optimized with artificial UO2(NO3)2 solution. The real process wastewater from the UO2 fuel element factory were then treated by VMD process under the optimized conditions for 1400 min with the concentration factor up to 9. No clear evidence of membrane fouling or wetting were noticed during the VMD operation nor the membrane autopsy studies. With an average permeate flux of 7.3 L m−2 h−1, it exhibited excellent retention towards all major contaminates such as uranium, COD, and NH4+-N to meet the Integrated Wastewater Discharge Standard of China (GB 8978-1996) for direct discharge.