A nickel plating solution hardly undergoes an entire renewal, so that the COD can reach an abnormally high level. In such a condition the plating may be too hard and low in quality. Permanganate and activated carbon may be useful to remove the COD substances. Sulfamic acid has a low pH and is oxidized into sulfuric acid under high temperature and at the anode, shortening solution life.
Wastewater resulting from an entire solution renewal includes a great amount of nickel and nitrogen.