| en |
Viability of adding gypsum and calcite for remediation of metal-contaminated soil: laboratory and pilot plant scales
Gonza´lez-Nu´n˜ez, R.; Alba, M. D.; Vidal, M. & Rigol, A.
Abstract
The effect of adding waste materials (gypsum
and calcite) for the remediation of a soil contaminated by
pyritic minerals was examined. Materials were characterised
in terms of their acid neutralisation capacity (ANC),
sorption capacity and structural components. Their effect
on the contaminant leaching in soil + material mixtures
over a wide range of pH was also evaluated. Results at
laboratory and pilot plant scales were compared to account
for the potential variability in the material efficiency when
applied at larger scale. The use of gypsum permitted its
valorisation, although calcite was a more effective
amendment because its addition led to a greater increase in
the pH and acid neutralisation capacity, and thus in the
sorption capacity in the resulting soil + material mixture.
In the same way, when the combination of gypsum
+ calcite was added to the soil, it led to an increase in
the pH from 2.5 to 6.9 and in the ANC from -86 to
1,513 meq/kg. As a result, the concentration of extractable
heavy metals and As was reduced, and they were successfully
immobilised both at laboratory and at pilot plant
scales. Thus, the use of these materials induced a signifi-
cant reduction in the contaminant mobility and permitted
the valorisation of waste materials.
Keywords
pHstat leaching test; Gypsum; Calcite; Metal-contaminated soil; Remediation
|
