This work was carried out at the Laboratory of Radiochemistry between 1991-1999.

Since 1978 in the Laboratory of Radiochemistry has been a working research group for solidification of liquid nuclear wastes. From the very beginning the main research area has been the separation of radionuclides with ion exchangers. Successful R&D work with inorganic ion exchangers led to industrial applications at several nuclear plants all over the world. From the beginning of 1990ís, the knowledge and skills obtained in the field of nuclear waste purification were applied to new research in the area of the removal of toxic metals from metallurgical waste effluents.

I wish to express my warmest gratitude to Dr. Jukka Lehto for his guidance, support and forbearance during the past years of research. I am also grateful to Professor Timo Jaakkola for his encouragement in this study.

I would like to thank all my colleagues at the Laboratory of Radiochemistry and especially the members of the ion exchange research group for their help. I wish to thank Donald Smart for revising the language of this thesis and I owe many thanks to Jyrki Vähätalo and Kimmo Suominen for the inspiration they gave me at the very beginning of my scientific career.

Finally, my warmest thanks and love go to my family Pia, Aleksi and Suvi for their important support.

Funding was received from the National Technology Agency, the European Commission funded project BRPR-CT96-0158, the Jenny and Antti Wihuri Fund, the Magnus Ehrnrooth Fund, and the Kemira Oyj Fund.