INTEGRATION OF ULTRAFILTRATION INTO UNHAIRING AND DEGREASING OPERATIONS

A study of some wet processing steps in the tanning industry was carri ed out in order to improve their efficiency and save raw materials. Ul trafiltration was integrated in the unhairing and degreasing steps to carry out a continuous separation of some species during operation. Re sults showed that by combining the enzyme unhairing reaction with simu ltaneous separation of products, better control of the unhairing opera tion was obtained. Ultrafiltration of the bath during the aqueous degr easing step permitted the recovery of fatty substances and the recycli ng of the surfactant. Physical and chemical analyses on samples of ski ns treated in these new processes showed similar characteristics with respect to the traditional ones. On the basis of the experimental resu lts, cleaner processes were obtained thanks to the use of less harmful solvents; a reduction of the environmental impact, a simplification o f water purification processes, a convenient re-use of sludges, a decr ease of disposal costs and a saving of chemicals and water, without ch ange of the final product, are other important advantages.