Abstract

Chrome-tanned solid waste emanating from leather industry is usually disposed of to the environment through landfill which not only pollutes the environment but also wastes the protein resource contained in it. Protein recovery for re-use in secondary industrial processes presents the best strategy for its re-utilisation. Dechroming by hydrolysis is the most practiced method of protein and chromium recovery from tanned solid waste. The alkali-enzyme two step hydrolysis methods are commonly utilised for improved protein recovery efficiency. However, enzyme cost and temperature dependence of the heat stable alkali enzyme has made the process economics difficult and therefore unattractive. The objective of the present study was to explore a relatively inexpensive method of recovering collagen hydrolysate through a two-step hydrolysis incorporating conventional bating enzyme. The method of treatment involved a first-step denaturation and degradation with alkali followed by inoculation with bating enzyme. The ash content, total kjeldahl nitrogen, dry matter and chromium content of the collagen hydrolysates obtained are reported. Protein recovery at 58.20% and 50.76% efficiency were obtained for the separate alkali and enzyme hydrolysis respectively. A combined protein recovery rate of 79.45% efficiency was obtained for the two-step process. The results of this study indicate that hydrolysis dechroming employing the use of conventional bating enzyme could offer a low-cost alternative for the effective treatment and reuse of chrome-tanned shaving solid waste.