Case study - Metal remediation in groundwater

NICKEL IN GROUNDWATER - DETOXIFICATION TEST

TREATED MATRIX

Groundwater

Contaminants

Nickel

TREATMENT TYPE

Water soluble nickel precipitation through adsorption on iron and manganese oxides and pH control

Contamination severity

Thousands of µg/l

Final goal

National legislation limit for groundwater (tab. 2 all.5 al titolo V, parte IV D.Lgs 152/06)

Site location

Milan province

The polluted site consisted of a residential area built on a plot of land formally hosting a  galvanic factory; nickel and hexavalent chromium contaminated the groundwater. Water samples were treated at Biosearch Ambiente in microcosm tests in order to evaluate the potential for detoxification.

After treating the hexavalent chromium through bioremediation, the nickel concentration has been lowered with a technique relying on its adsorption on the surface of iron oxide at high pH values.   This process allows the precipitation of the soluble metal onto soil particles, making it not bioavailable and not mobile in the aquifer.

Three samples of groundwater, containing 3100, 2950 and 515 µg/l of nickel respectively, have been treated at the 64 th day of microcosm obtaining an instant diminishing of its presence in solution. This lower concentrations have been confirmed at day 84 th of the experiment demonstrating a reduction of 99,93% (C), 64,41% (B) and 97,47% (N) respectively.

Bonifica metalli