Introduction. In the galvanoplasty sector, the aluminium anodizing process is one of the
most critical in environmental impact terms.
Objective. To describe the opportunities of cleaner production for the aluminium anodizing
process.
Materials and Methods.To recover NaOH we analyzed three technologies: Ionic exchange,
crystallization and precipitation, which were all taken into account due to past international
successful experiences. Pilot tests and laboratory tests were made, determining that ionic
exchange does not offer technical satisfactory results and that feasible options are crystallization
and aluminium precipitation. To recover H2SO4 from the anodizing bath, ionic exchange
was explored as an alternative, obtaining technical and economical satisfactory results.
Results. The economical benefits of implementing these technologies are related to diminishing
the costs generated by the consuming of caustic soda and sulphuric acid, a better control
of processes, constant operation conditions and a longer time of usefulness of the baths.
Environmental benefits are the optimization of the use of caustic soda, a lower sulphate
discharging less consuming of water and energy and a better generation of the metallic mud
coming from the waste water treatment done after the process.
Conclusion. The proposed system provides a potential save of water which can be gradually
increased if the appropriate acid concentrations in the bath are kept.
