Radioactive wastes ultrafiltration

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]. 

One of the current researches devoted to membrane treatment of radioactive waste is directed toward seeded ultrafiltration and all methods, which combined with ultrafiltration, give considerable enhancement of separation (Table 30.6). 

Harasimowicz, M., Application of ultrafiltration and hiperfiltration for concentration of liquid radioactive wastes, PhD thesis. University of Mining and Metallurgy, Krakow, 1995. 

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. 

Kichik, V.A. et al., Method for complex treatment of laundry liquid radioactive wastes by ultrafiltration. At. Energ., 63, 2, 130, 1987, (in Russian). 

Hooper, E.W., Activity removal from aqueous waste streams by seeded ultrafiltration, in Use of inorganic sorbents for treatment of liquid radioactive waste and backfill of underground repositories, in Proceedings of Final Research Co-ordination Meeting, Rez, Czechoslovakia, 408 November 1991, IAEA-TECDOC-675, International Atomic Energy Agency, 1992. 

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. 

Rao, S.V.S. et ah. Effective removal of cesium and strontium from radioactive wastes using chemical treatment followed by ultrafiltration, J. Radioanal. Nucl. Chem. 246(2), 413, 2000. 

Foust, H., Ghosehajra, M., Sizing an ultrafiltration process that will treat radioactive waste, Sep. Sci. Technol. 45, 1025, 2010. 

Zakrzewska-Trznadel, G., Harasimowicz, M., Miskiewicz, A., Jaworska, A., Dluska, E. and Wronski, S. 2009. Reducing fouling and boundary-layer by application of helical flow in ultrafiltration module employed for radioactive wastes processing. 240 ... 

Original radioactive liquid waste from the storage tank in nuclear center was treated in the process UF/complexation. The main radioactive components of the waste sample were °Co, Zn, " Cs, Cs, Eu, and Am. When ultrafiltration... 

This section describes some case studies carried out by the authors, which are related to radioactive liquid waste treatment using membrane processes a study about the influence of radiation on reverse osmosis membranes, a practical case about concentration of I radioactive liquid wastes by ultrafiltration and reverse osmosis processes, and a practical experience about decontamination of Cs liquid waste by reverse osmosis, including a study of radiological protection during the treatment. 

Ultrafiltration membranes are suitable for the treatment of radioactive liquid wastes, especially as reverse osmosis pretreatment [6]. Therefore, ultrafiltration is used for the removal of the radioactivity associated with the proteins and high-molecular-weight organic compounds, as these species can reduce reverse osmosis performance. 

The final concentrate, which includes UF and RO concentrates, should be disposed of by an authorized company, considering not only waste radioactivity levels but also chemical and biological contaminations, specially in the ultrafiltration concentrate since it contains most of the pathogens of the original waste. 

In this type of extraction, micellar structures are retained by correctly selecting the ultrafiltration (UF) membrane (Scamehorn et al., 1988). Hydrophobic species are solubilized within the micelles, but surfactant monomers in equilibrium with the micelles can penetrate the membrane along with the free solutes in equilibrium with those solubilized in the micelles. Whereas several uses for this technique have been suggested, such as the collection of radioactive uranium and plutonium present in acid wastes during nuclear plant decommissioning, from our point of view its principal use is in enantiomeric separation (Overdevest et al., 1998). 

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