Galvanising company

Off-spec production reduced by 60% with diffusion dialysis and reverse osmosis

A galvanising company in the Netherlands continuously cleans its anodizing baths containing sulphuric acid with a combination of diffusion dialysis and reverse osmosis.

Different baths contain different levels of sulphuric acid. It is important that the quality of the anodizing bath and the rinse water is constant. Paques’ IONPAQ® technology enables this.

In 2000 a water treatment system was installed in combination with the aluminium anodizing line that consists of three baths. The anodizing bath contains 250-300 g/l sulphuric acid and its wastewater is treated with diffusion dialysis. This recovers a large percentage of the sulphuric acid. The waste from the second rinsing bath (1.5-3 g/l sulphuric acid) is treated with reverse osmosis.

The combination of these technologies

  • Decreases off-spec production with 60% (by constant anodizing bath quality)
  • Recovers 80% of the sulphuric acid
  • Reduces the necessary intake of demineralised water

The initial investment earned itself back within three years.