Chemical forms of Zn and Cu in sewage sludge amended soil stabilized with water treatment residue

摘要

Two set of experiments were conducted to investigate the possible chemical forms transformation in sewage sludge amended soil stabilized with drinking water treatment residue (WTR). The sequential extraction method of Salas et al., 1998 was used. The chemical forms investigated were water soluble, MgCl<,2> extractable or "exchangeable" fraction, sodium acetate extractable or carbonate fraction, hydroxyl amine hydrochloride extractable or Fe-Mn oxide fraction, combination of nitric acid, peroxide and acetate extractable or organic fraction and finally, the aqua-regia or residual fraction. Water treatment residue can stabilize Cu and Zn in the sludge amended soil. However, this stability can be disrupted with the presence of plants, which exhibited a transformation from residual fraction to organic fraction.