EXTRACTION AND CHARACTERIZATION OF CHROME-FREE PROTEIN FROM CHROMIUM-CONTAINING COLLAGENOUS WASTE GENERATED IN THE LEATHER INDUSTRY

In the United States, almost 56,000 metric tons of chromium-containing solid waste are generated by the leather industry each year, and approximately ten times this amount is generated worldwide. Environmental concerns and escalating landfill costs are becoming increasingly serious problems to the leather industry and alternative disposal methods are needed. We have developed a process in which this waste is first treated with alkali to extract a high molecular weight gelable collagen protein. The sludge that remains is further treated with enzymes to recover a lower molecular weight protein hydrolyzate and a recyclable chromium product. The recovered protein fractions, practically devoid of chromium, could be used in a wide range of products, including adhesives, cosmetics, films, animal feed and fertilizer. The isolated chromium can be chemically treated and recycled into the tanning process.