A Study on the Performance of Vacuum Membrane Distillation in Treating Acidic, Simulated, Low-Level Radioactive...

Area of Science:

• Environmental Science
• Chemical Engineering
• Materials Science

Background:

• Radioactive liquid waste poses significant environmental and health risks.
• Effective treatment methods are crucial for nuclear waste management.
• Vacuum membrane distillation (VMD) is a promising technology for wastewater treatment.

Purpose of the Study:

• To evaluate the performance of a VMD system with PTFE hollow fiber membranes for treating simulated acidic radioactive liquid waste.
• To determine optimal operational parameters for VMD treatment.
• To investigate the impact of nuclide and tributyl phosphate (TBP) concentrations on VMD performance.

Main Methods:

• An orthogonal experimental design was employed to optimize key parameters: feed temperature, vacuum pressure, and flow velocity.
• Simulated radioactive liquid waste with varying nuclide and TBP concentrations was treated.
• Permeate flux, nuclide rejection, and nitric acid rejection were measured.

Main Results:

• Optimal VMD parameters were identified as 70 °C feed temperature, 90 kPa vacuum pressure, and 500 L·h⁻¹ flow rate.
• The system achieved a maximum permeate flux of 0.9 L·m⁻²·h⁻¹, with >99.9% nuclide rejection and 99.4% nitric acid rejection.
• High nuclide concentrations (>50 mg·L⁻¹) negatively correlated with permeate flux. TBP caused membrane fouling and reduced efficiency.

Conclusions:

• The VMD system with PTFE membranes is highly effective for treating acidic radioactive wastewater.
• The process simultaneously removes nuclides and concentrates nitric acid.
• VMD shows significant potential for application in nuclear wastewater treatment, with performance affected by feed composition and fouling.