Study on the treatment of radioactive wastewater by non-contact membrane distillation

Conventional contact membrane distillation technology has some problems, such as membrane fouling and wetting, resulting in short membrane life, low permeate flux, and instability, which limit its industrial application. Here, a non-contact membrane distillation method is proposed for radioactive wastewater treatment. The effects of hot-side inlet temperature, hot-side flow rate, sweeping gas temperature, and cold-side flow rate on permeate flux are examined. The purification ability of this method for strontium ion in simulated radioactive wastewater and actual radioactive wastewater from uranium-containing hydrometallurgical purification plant was investigated. Under the optimized conditions, the permeate flux of non-contact membrane distillation unit reaches 24.87 kg/(m2·h), the rejection rate of Sr2+ in simulated radioactive wastewater is more than 99.99%, and the decontamination factor can reach more than 4.5 × 106. The total α and β activity concentrations in the radioactive wastewater are 21279.7 Bq/L and 17811.9 Bq/L, respectively, while the actual α and β activity concentrations of the distillate produced by the membrane distillation device are 0.205 Bq/L and 0.877 Bq/L, respectively. Overall, the proposed method has the advantages of long membrane service life, high and stable permeate flux, which can facilitate its large-scale industrial application in volume reduction and deep purification of radioactive wastewater.