Radioactive wastes microfiltration

Sengupta, S.K., Slade, J.A., and Tulk, W.S., Fiquid radioactive waste processing with crossflow microfiltration and spiral wound reverse osmosis, Report AECL-11270, Chalk River, Ontario, Febmary, 1995. 

Laboratory and pilot plant experiments carried out at INCT showed that reverse osmosis is very useful for the treatment of liquid low-level radioactive wastes from Polish nuclear laboratories. However, to reach high decontamination the process should be arranged as a multistage operation with microfiltration or ultrafiltration pretreatment [32,33]. 

Reverse osmosis preceded by microfiltration or ultrafiltration is considered as an option for the treatment of radioactive wastes from Romanian nuclear centers. Effective studies are carried on at Research Center for Macromolecular Materials and Membranes, Bucharest and at Institute of Nuclear Research, Pitesti aiming in employing these pressure-driven techniques for cleaning the wastes from decontamination of nuclear installations and reactor primary circuit [34,35]. 

In nuclear technology, microfiltration is used either for pretreatment purposes or for concentration of coarse particles after precipitation process. For high-level radioactive wastes the ceramic filters are used, giving for some types of effluents high decontamination and concentration factors. The MF facilities used in nuclear industry to treat liquid radioactive wastes are summarized in Table 30.12. 

Dulama, M., Deneanu, N., and Popescu, IV., Liquid radwaste treatment hy microfiltration, ultrafiltration and reverse osmosis, in Book of extended synopses, Int. Conf on management of radioactive waste from non-power applications—sharing the experience St. Paul s Bay (Malta) 5-9 Nov. 2001, IAEA, 187, 168-169, 2001. 

Some areas of application are the nuclear industry and the treatment of radioactive liquid wastes, with two main purposes reduction in the waste volume for further disposal, and reuse of decontaminated water. Pressure-driven membrane processes (microfiltration, ultrafiltration, nanofiltration, and reverse osmosis [RO]) are widely used for the treatment of radioactive waste. 

Membrane technologies have a great potential in the treatment of radioactive liquid wastes, as it has been proved throughout this chapter. In this sense, it is expected a growing use of the membrane processes in the radioactive field, with different possibilities alone, combined between them (microfiltration or ultrafiltration and reverse osmosis) or combined with other conventional processes like evaporation or ion exchange. Furthermore, some special membrane processes, like membrane distillation or liquid membranes, could be applied for the specific treatment of radioactive wastes. 

For radioactive effluent treatment, the relevant membrane processes are microfiltration, ulfrafiltration (UF), reverse osmosis, electrodialysis, diffusion, and Donnan dialysis and liquid membrane processes and they can be used either alone or in conjunction with any of the conventional processes. The actual process selected would depend on the physical, physicochemical, and radiochemical nature of the effluents. The basic factors which help in the design of an appropriate system are permeate quality, decontamination, and VRFs, disposal methods available for secondary wastes generated, and the permeate. 

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