The authoritative public forum
  for Metal Finishing since 1989
-----

Ni elimination from waste water

April 6, 2009

I have waste water from chemical plant. The initial Ni concentration 1s 1-5 mg/l and I have to go down to 0.02 mg/l. What is the best way to do it? Is it possible to reach this limit? If not what is the lowest possible.
Regards
Yitzik

Yitzhak Marcus
ecology manager - Petah tiqva, Israel

---

Hi, Yitzhak. It's possible to get to zero with distillation or mixed-bed ion exchange. But whether it's practical to get to 0.02 mg/l may depend on the source of the nickel (electrolytic plating, electroless plating, nickel cyanide) and what else is in it. Can we have some particulars? Thanks.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 13, 2009

---

First of two simultaneous responses --

The 0.02 mg/L limit will be extremely difficult to meet on a consistent basis.

When faced with a limit like this it is usually best to locate the source(s) where nickel enters the wastewater, and to treat them there so you have some other flows to dilute it. Ion selective IX is particularly effective in this type of application, with batch treatment of the regenerations.

Alternatively, you could investigate recycling the dilute nickel flows with an RO or DI and, again, batch treat concentrates separate from other flows.

Good Luck!

Lyle Kirman
consultant - Cleveland Heights, Ohio
April 16, 2009

---

Second of two simultaneous responses --

That is a very tough limit.

If ammonia and other complexants are absent, add a few pounds of ferrous sulfate ⇦this on eBay or Amazon [affil links] /1000 gal water, then a few pounds of magnesium sulphate, then raise the pH to 10.5 - 11 with sodium hydroxide. Mg is a good coprecipitant for Ni.

If that doesn't work, try adding in some sulfur based precipitant, like sodium sulfide or DTC, after the ferrous add, and after adjusting the pH to about 9.

Dave Wichern
Consultant - The Bronx, New York
April 16, 2009