At electrochemical processing of high-alloyed steels and alloys, the alloying metals pass as ions to the electrolyte fluid being a neutral water solution of nitrate sodium. Thus ions of iron, nickel, titan form insoluble hydroxides and precipitate in the form of sludge.
Special problems are caused by chrome which is partially dissolved with formation of chromate-ions (Ñr+6) which do not form a sludge and, thus, can be accumulated in the electrolyte fluid. If you not take any measures after some period of time concentration of Cr+6 ions in the tank will exceed levels of permissible sanitary regulations. At excess of maximum permissible concentration, ions of hexavalent chrome can make harmful effect on health of people, therefore, it is necessary to neutralise both the electrolyte fluid, and the sludge polluted by chromate-ions.
These are only machines of the "ET" series in Russia which are equipped by the independent systems capable in the automatic mode to support permissible maximum concentration limit both in electrolyte fluid with which the operator works, and in the sludge which goes for recycling.