The United States of America As Represented by the Secretary of

Edward J Diefendorf

Maryann M Taylor

William N Marmer

George C Na

Eleanor M Brown

Willian N Marmer

Chromium containing protein materials are treated by processes which include the steps of: combining the material to be treated with sufficient water to effect the solubilization of the gelable protein recovered therefrom, and an alkali additive. The mixture is thereafter held at a temperature of from about 60.degree. C. to about 85.degree. C. for a period of time of from about 0.5 hour to about 8 hours. The mixture is then filtered to remove the aqueous phase, which contains solubilized gelable protein. Subsequently, water is again added to the resultant chrome-containing proteinaceous cake and at least one enzyme is utilized to hydrolyze the remaining protein thus producing a product containing solubilized partially hydrolyzed protein and insoluble chromium. After separation, the chrome in the insoluble residue may be recycled into the pickling or tanning process, and the essentially chrome-free protein components may be used as ingredients in feeds, fertilizers, and cosmetics. The processes of the present invention are used to particular advantage to treat wastes from the leather tanning industry including blue stock, chrome shavings, chrome buffing dust, chrome cakes and chrome sludges.

Enzymatic processing of materials containing chromium and protein

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.

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Audubon, NJ, United States of America

Edward J Diefendorf