In the electroplating and metal processing industries, ion exchange resins can, under certain conditions and when using suitable rinsing techniques, be used to recycle low-loaded metal-containing rinse water. In two separate in-series columns, the anions and cations present in the aqueous solution are replaced by the hydrogen or hydroxid ions of the active group of the resins using different ion-exchange materials. The so attainable water quality allows the recirculation of water in the production process. This comes along with a water savings of up to 95 %. After complete loading of the resins, they are regenerated with acids and alkalis. The resulting wastewater is fed into a wastewater treatment plant.

An accumulation of undesirable metal ions often takes place in aqueous process solutions. This often leads to negative consequences, with the result that the process solutions must be discarded. With the aid of ion exchange resins, it is possible to remove the interfering metal ions, and replace them by hydrogen ions. Thus, a considerable life extension of the process baths is achieved. The typical applications are:

1. Removal of interfering metal ions (iron, chromium, etc.) from hard chrome baths
2. Removal of iron ions from the baths of the electrolytic wide-strip galvanizing system
3. Removal of zinc and iron from thick-film passivation bath.

The use of precious metals (gold, silver and platinum group metals) is commonly found in surface technology. Due to the significant value of these metals, a complete recovery from rinse water is of particular economic interest. Using suitable ion exchangers, it is possible to ensure a secure quantitative removal from rinse water. Very low residual concentrations in the ppb range are reached. The equipment costs required for such plants are low because the loaded resins are usually not regenerated, but directly fed into a recovery system by smelting.

In times of constantly rising raw material and energy prices, recycling techniques using microfiltration are becoming increasingly interesting. A typical example is the recycling of aqueous degreasing baths. The process solution to be treated is pumped through a membrane surface where a splitting up into two partial streams occurs:

a. the permeate which has passed through the membrane and is freed from non-polar substances, for example mineral oil

and

b. the concentrate (retentate) which contains the separated non-polar substances in a concentrated form.

The permeate is directed back into the process bath, which results in a substantial life extension with the associated savings on raw materials and energy.