Abstract: A new process for removal of a metal ion from an anionic complex, including a first chelating agent and a metal ion, such as copper, nickel or cobalt ion, in electroless plating bath rinse streams utilizes a cation exchange resin to extract the metal ion from the rinse stream after the metal ion has been removed from the anionic complex and complexed with a second chelating agent.In another embodiment, a competing chelating agent is not added to the electroless plating bath waste stream, but rather, another metal ion (B), which has a higher affinity for the chelating agent than the metal ion (A) of interest and which is nontoxic, is added to the waste stream. Metal ion B is selected so that under predetermined conditions, metal ion B forms a stronger complex with the chelating agent than does metal ion A. Also, the complex of the chelating agent and nontoxic metal ion B is anionic. A cation exchange resin is used to extract metal ion A from the treated waste stream.

Abstract: The present invention relates to a method for the selective extraction of the metals gold, silver, platinum or mercury ions or colloidal gold, from an aqueous solution containing at least one of these metal ions which comprises contacting the solution, at a pH of 2 or less, with cells or cell extracts of a microorganism capable of binding these metals for a period of time and under conditions sufficient to allow binding of the metals to the cells or cell extracts.