A new process, namely, IERECHROM (Ion exchange REcovery of CHROMmium), has been developed for removal of Cr(III) ionic complex from segregated wastewaters (10% of the overall wastewaters discharged from tanning operations). The process is based on a macroporous carboxylic resin (i.e., Purolite C106) retaining the metal of reference, together with other trace metals, including aluminum and iron. In a first regeneration step, alkaline hydrogen peroxide (pH 12) is used. The anionic species formed (Chromate and aluminate) are quantitatively eluted from the cation resin and separated. In a second polishing step of the resin, ferric species are eluted with 1 M sulfuric acid. The resulting ferric and aluminum sulfate solutions are recycled as flocculating agents. The residual Chromate solution is directly reused in the plating industry or, after reduction to Cr(III), in the same tannery. Before the new exhaustion cycle, the resin is reactivated by elution of 1 M NaOH followed by hydrolysis with softened water. A 10 m3/day fully automated pilot plant was assembled, and process reliability and cost benefits were demonstrated.
|Titolo:||Ion Exchange Process for Chromium Removal and Recovery from Tannery Wastes|
|Data di pubblicazione:||1995|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1021/ie00047a009|
|Appare nelle tipologie:||1.1 Articolo in rivista|