Optimization of Alkaline Hydrolysis of Chrome Shavings to Recover Collagen Hydrolysate and Chromium Hydroxide

The tanning industry uses skins and hides from cattle, sheep, among others, which are a byproduct of the meat industry. In their production process, they generate wastewater and solid wastes in significant quantities, that require alternatives for their adequate treatment. The present research was developed to optimize the alkaline hydrolysis process of chrome leather shavings to recover collagen hydrolysate and chromium salts, and to identify the relation between the response variables and hydrolysis conditions. For this purpose, a preliminary study was carried out, where alkaline hydrolysis conditions were adjusted, then these were optimized through a factorial design and scaled up the process to a pilot level. The preliminary study of alkaline hydrolysis of the sample was performed, where reaction time and sodium hydroxide concentration were established as factors to adjust the process. The optimization of this method was developed through a factorial design with two response variables: percentage of recovered collagen protein (PRCP) and percentage of residual chromium (PRC) present in the collagen hydrolysate. Thus, the optimum alkaline hydrolysis conditions were obtained: 70C, 0.47 M NaOH and 90 minutes for the reaction, and the relation between the response variables. Finally, the process was carried out in a pilot scale in which 45 L of collagen hydrolysate was recovered, with 87.16% of recovered collagen protein and 1.17% of residual chromium.