Removal of strontium ions from simulated radioactive wastewater by vacuum membrane distillation

Highlights: • Vacuum membrane distillation was used to separate Sr²⁺ from wastewater. • Effect of operation factors on membrane flux was examined. • Pressure buildup effect would decrease membrane flux. • Dusty gas model could estimate membrane flux well. - Abstract: The removal of Sr²⁺ ions from simulated radioactive wastewater by vacuum membrane distillation (VMD) with hollow fiber membrane module was investigated. The removal efficiency of Sr²⁺ could maintain over 99.60%, and the membrane flux could maintain at 6.71 L·m⁻²·h⁻¹ when Sr²⁺ in the feed solution was about 10 mg/L. The effect of operating parameters on the membrane flux was examined, including feed temperature (30–70 °C), permeate side vacuum (0.10–0.98 atm) and feed flow velocity (10.5–41.8 L/h). Pressure buildup effect was observed during the process, which could interfere with the membrane flux. Pressure buildup effect was more serious when permeate side vacuum degree was over 0.9 atm. Considering energy consumption efficiency, the permeate side vacuum degree should be maintained at the turning point (0.9 atm) of the membrane flux. Dusty gas model could simulate the mass transfer of VMD process well with ARE (average relative error) of 5.31%. VMD is potential for the removal of Sr²⁺ ions from aqueous solution.