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Coating metal and plastic components with nickel is widespread as it delivers improved wear resistance, hardness and corrosion protection. From microelectronics, engine parts and chemical handling equipment, to doorknobs, bathroom taps and kitchen utensils: nickel coatings help things work better, look better and last longer.
However, in Europe alone, the metal coating industry annually consumes 100 million cubic metres of water and produces over 300 000 tonnes of hazardous waste – effluent loaded with organic agents and heavy metals. But due to the EU Water Framework Directive and other legislation, it is facing pressure to implement more environmentally friendly measures.
The EU-funded ECOWAMA project has developed an innovative management model and pilot plant to help the Surface Treatment of Metals Industry (STM) overcome the challenges of waste disposal, as well as expensive water and energy usage.
“Until now, the STM sector had to pay specialist companies to dispose of their effluent, which is costly,” says project coordinator Maximilian Kotzur of Germany’s Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB.
“In ECOWAMA, we developed a closed-loop waste treatment process which recycles water and recovers energy and valuable metals from the effluent. So the STM industry can now move towards a ‘circular economy’ model where as much as possible is recovered and reused.”
Winning ways with waste
In the nickel-plating process, components are dipped into successive chemical baths to clean, prepare and coat their surfaces. These use a mix of chemicals, including nickel and phosphorous compounds. After plating, the liquid waste is rich in these compounds, in addition to organics and oils. ECOWAMA developed and demonstrated a three-stage process to recover valuable materials and energy from this waste.
First, organic matter is degraded and >99 % pure nickel is recovered for reuse in the plating process.
The next step removes the phosphorous and recovers almost pure hydrogen gas from the waste, which can be used in fuel cells – reducing the net energy usage of the recovery process by over 10 %.
In the final step, the remaining waste effluent is desalinated and purified to produce pure water that is suitable to be reused in the plating process.
ECOWAMA technology offers direct cost and environmental benefits.
Nickel is a rare metal and costly to extract – both for the STM industry and the environment. Since water is a scarce resource in much of the world, its purification and reuse has real potential in countries with dry climates. These two factors, along with the recovery of pure hydrogen for fuel cells, confirm ECOWAMA’s contribution to resource conservation and reuse and building a circular economy.
Nickel and dimes
The ECOWAMA pilot plant is receiving much attention – and visits – from companies interested in testing individual modules. For example, the nickel recovery and the water-purification technologies have generated significant interest. And one industrial partner is building the hydrogen recovery process into its next-generation technologies aimed at the glass and metal industries.
“The STM industry is a crucial player, especially for Europe’s automotive, telecommunications and manufacturing industries,” says Kotzur.
“By improving the recovery of materials, energy and water, by closing the waste effluent loop, ECOWAMA has strengthened their competitive position – for example against cheaper competitors from Asia and elsewhere.”