Influence of boron on rejection of trace nuclides by reverse osmosis

Reverse osmosis (RO) has been proved to be an effective technology in the treatment of low level radioactive wastewaters (LLRWs) in nuclear power plants (NPPs). However, particular attention must be paid to any possible negative influence of excessive boron on the performance of membrane units. In this paper, influence of excessive boron on trace nuclide rejection by reverse osmosis had been investigated in a laboratory-scale cross-flow membrane filtration unit. The results demonstrate a positive influence. The increase scope of 1% to 8% can be observed in the nuclide rejection with the boron concentration variation from 0 to 1000 mg · L−1. Temperature increase can improve the passage of boron to the permeate side, without obvious loss of nuclide rejection. Increasing the operation pressure or pH values, however, improves trace nuclide decontamination and boron rejection simultaneously. In general, RO unit can perform a favorable rejection of trace nuclide and a moderate rejection of boron. The membrane concentrate contains less boron, which facilitates the volume minimization by evaporation. © 2015 Elsevier B.V. All rights reserved.

Membrane technology has been proved to be an effective technology in the treatment of LLRWs in NPPS, with additional advantages coming from the low energy consumption, minimized maintenance and human exposure. However, particular attention must be paid to any possible negative influence of excessive boron on the decontamination properties of membrane units. The RO membrane can perform a favorable rejection of trace nuclide, however, with a moderate rejection of boron. The membrane concentrate contains less boron, which facilitates the volume minimization by evaporation. The existence of excessive boron can improve the nuclide rejection. The increase scope of 1% to 8% can be observed in the nuclide rejection with the boron concentration variation from 0 to 1000 mg · L−1. Temperature increase can improve the passage of boron to the permeate side, without obvious loss of nuclide rejection. Increase of operation pressure or pH values, however, improves trace nuclide decontamination and boron rejection simultaneously. Acknowledgments This research was supported by the National Energy Sci & Tech project (Grant No. NY20120102) and the National Natural Science Foundation of China (Grant No. 51238006).