The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Eliminating boron in waste water

New regulations for waste water set a limits for boron to less then 1.5 mgr/liter.

We currently plate bright nickel in our electroplating on plastics plant.
(boron comes from the boric acid in the Ni bath).

Is there any way to cope with this regulation ?

Thank you for any information.

Daniel Livshitz
plating on plastics - Tel Aviv, Israel
2006

---

2006

This is a difficult problem because, as far as I know, there is no effective way to precipitate boric acid to this concentration or below it.

There are very expensive Ion Exchange resins that can selectively remove boron from wastewater. These have very low capacity, but can reduce boron to < 1 mg/L.

Your best course of action is to minimize this boron containing waste flow at the source, before it mixes with other rinses. My advice is to recycle your nickel rinses using a combination of dragout recovery rinses and supplemental evaporation. This also concentrates impurities in the bath, so it is not a perfect solution.

Another potential solution is to use the dragout recovery method for 80-90% recovery, and then to recycle the final one or two rinses with Ion Exchange. The anion resin regenerations will contain the borates, so they must be hauled off site for disposal somewhere where they don't have the same boron limit.

Lyle Kirman
consultant - Cleveland Heights, Ohio