A method of processing an etching waste medium from circuit board and/or substrate manufacture

It is described a method of processing an etching waste medium from circuit board and/or substrate manufacture, the method comprising: i) providing a medium to be processed (11), being the etching waste medium, in particular from an etching process (150), wherein the medium to be processed (11) comprises a metal salt to be processed and an acid (15); ii) processing the medium to be processed (11) in an ion exchange process (145), so that the metal salt to be processed is exchanged by a metal salt, and a metal salt containing medium (10) is obtained from the medium to be processed (11); hereby a) streaming a first process cycle (170) through the ion exchange process (145), wherein the first process cycle (170) is a first closed loop that yields substantially only elementary metal (50); and b) streaming a second process cycle (180) through the ion exchange process (140), wherein the second process cycle (180) is a second closed loop that yields substantially only purified water (188) and/or a metal-depleted sal