Enzymatic processing of materials containing chromium and protein

Abstract

Materials containing both chromium and protein and treated by processes which include the steps of: combining a material to be treated (i.e. containing both chromium and protein) with sufficient water to produce a mixture having from about 75 wt. % water to about 95 wt. % water, and an additive which both provides an alkaline pH and provides calcium or magnesium as an enzyme cofactor. The mixture is thereafter held at a temperature of from about 60.degree. C. to about 75.degree. C. for a period of time of from about 0.5 hour to about 4 hours. Subsequently, at least one enzyme is utilized to hydrolyze the protein, thus producing a product containing solubilized hydrolyzed protein and insoluble chromium. After separation of the soluble fraction from the insoluble fraction, the chrome in the insoluble residue may be recycled into the pickling or tanning process, and the essentially chrome-free protein hydrolyzate is potentially useful as an ingredient in feeds, fertilizers, and cosmetics. The processes of the present invention are used to particular advantage to treat wastes from the leather tanning industry, for example, material such as blue stock, chrome shavings, chrome buffing dust, chrome cakes and chrome sludges.