The pickling process is used to remove a thin layer of metal off of the stainless steel part. Acids are commonly used in the metal finishing and metal processing industry in a variety of ways. In order to maintain an acceptable process, the metal concentration must be controlled within a specific rang. The most common method of controlling the metal concentration is decanting or dumping the acid and making up with fresh acid. This results in cost of acid disposal or treatment, cost of replacement acid and product quality or productivity variation.

With hundreds of systems installed all over the world, Eco-Tec acid purification units (APU) have evolved to be reliable and maintenance free.