Chemical and enzymatic hydrolysis of chrome shavings

The recovery of chromium and protein from chrome shavings, an important sol id waste of tannery industries, were investigated. Distilled water citric a nd oxalic acids ethylenediaminetetraacetic acid, and surface-active substan ces (Triton-X-100) were used for chrome shavings washing in thermostatic ba th. After washing with oxalic acid at 50 degrees C, 68% of chromium were re covered in this step. The hydrolysis of the solid waste was studied under d ifferent conditions of temperature, shaking time, and concentration of acid , hydroxide, and enzyme. Sulfuric acid, sodium hydroxide and Alcalase, a pr oteolytic enzyme, were used for chrome shavings solubilization. Starting wi th a 26.6 g (Cr)/kg of chrome shavings sample, using the washing methods an d enzyme at 60 degrees C and 2 hours, only 4 mg/kg of chromium remained aft er protein solubilization.