The Metamorphosis of Electroplating Wastewater

Shanghai Mint is an affiliate of the China Banknote Printing and Minting Corporation (CBPM). The environmental team at the Mint is utilising an integrated solution to remove nickel from electroplating wastewater to assist in its green commitments. The limit for nickel ion concentration in the nickel-plated steel electroplating wastewater has been set to 0.1 mg/L.

The electroplating wastewater initially has a pale turquoise hue, the distinctive colour of nickel ions. The water flows into the regulating tank which has foam floating on the water surface, or residues from cleaning agents. At the general discharge outlet, the same water runs through the Parshall flume. It turns clear, colourless, odourless and foam-free, looking identical to tap water.

After more than 10 hours of treatment, the nickel ion concentration in the nickel-plated steel electroplating wastewater is reduced from 2–3 mg/L to below 0.1 mg/L, a process that the Mint has likened to a 'metamorphosis'. To sustain stable compliance with discharge standards, the team has tapped the maximum capacity of each treatment unit, adopted targeted solutions against key challenges, and developed an efficient integrated nickel removal process to tackle technical bottlenecks.