Recovery and reuse of chemicals in unhairing, degreasing and chromium tanning processes by membranes

Membrane operations such as ultrafiltration, nanofiltration and reverse osmosis, properly integrated among them and/or with other conventional separation processes, have proven to be clean chemical processes. The study of a tanning process showed that many operations can be improved integrating them with membrane operations. The steps studied in this work were: enzymatic skins unhairing, degreasing of pickled sheepskins and chromium tanning; furthermore, the recovery and reuse of salts contained in the solution coming from chromium (III) precipitation were studied. The obtained results realize a reduction in environmental impact, a simplification of depuration processes of waste water, an easy reuse of sludge, a decrease of disposal costs and a saving of chemicals and water.