Rejection of nuclides and silicon from boron-containing radioactive waste water using reverse osmosis

•Silica and boron can be separated by RO system.•High temperature provides better separation efficiency.•Assuming reasonable system design, boron can be reused.

Reverse osmosis has been successfully utilized for waste separation across various fields. In this work, RO membrane was investigated for the separation of weakly electrolytic silica and boron, which was meaningful for potential boron reuse and waste reduction during treatment of low level radioactive waste water. The influences of temperature, pressure, and pH were tested. As the recovery rate rose to 80%, the flux decreased and the permeate concentration increased slightly. A higher temperature of 55 °C led to a higher silica and boron separation efficiency without a large loss in nuclides rejection. Under these conditions the recovery of boron is 46.58%, and the decontamination factors (DF) of silicon, Cs, Sr, and Co are 29.3, 4.54, 58.88, and 70.41, respectively. Assuming reasonable system design, the recovered water containing a high concentration of boron and a low concentration of silica is acceptable for reuse.