Optimization of an UF pilot plant for the treatment of radioactive waste

A crossflow filtration process has been developed to treat the Harwell site low level active liquid waste. A pilot plant was then constructed and operated to determine the α and βγ removal from the effluent. The unit has been used to assess the long term performance of ultrafiltration and microfiltration membranes. The reliability of the pilot plant equipment has also been demonstrated over periods of between 6,000-10,000 operating hours. Tests have shown that the process gives optimum α removal at pH5 down to 1.5 mBq/ml and that addition of copper ferrocyanide and zirconium phosphate to the effluent can significantly improve βγ removal. Direct electrical Membrane Cleaning has been shown on a laboratory scale to enhance crossflow filtration performance at conductive UF and microfiltration membranes by improving their performance at reduced crossflow velocites. Pilot scale units based on Tech Sep M4 and MA1/S sintered stainless steel membranes have been designed and constructed for longer term evaluation in the UF pilot plant. Tests on the former have recently begun. (author)