PROCESSING OF LEATHER WASTE - PILOT-SCALE STUDIES ON CHROME SHAVINGS - PART I - ISOLATION AND CHARACTERIZATION OF PROTEIN PRODUCTS AND SEPARATION OF CHROME CAKE

During the past years, we have demonstrated that it is possible to iso late protein products from chrome shavings, a waste from the tannery i ndustry, using alkaline protease under mild conditions. This process h as been patented and broadly described, though the treatment of the ch rome cake has not been described in detail. The objective of this pres ent work was to isolate protein products from chrome shavings, treat a nd purify the remaining chrome cake and tan hides with the recovered c hromium. This first part discusses the digestion of commercial chrome shavings - with an alkali in a first step and with an alkaline proteas e in a second step - to isolate two different protein products: gelati n and hydrolysate. Chemical and physical properties of these samples w ere studied. Gelatin samples were deionized and chemical and physical analyses performed. Also, chemical properties of the solid residue fro m each step of the process were evaluated.