A sustainable approach for cotton bioscouring: reuse of the pectate lyase containing treatment bath.

Enzymatic scouring of cotton has established itself (slowly) as a green alternative to alkaline scouring in the textile industry, mostly due to more environmentally friendly processing at lower pH and temperatures and its less aggressive action on the cotton fibers. However, among other limitations, enzyme costs have contributed to impeding its wide acceptance and use. For the first time, in this study, the recycling of the bioscouring bath was evaluated, unlike most current bioscouring that is performed using fresh enzyme solution. Bioscouring of raw knitted cotton fabric was carried out for 30 min with a commercial pectinase (BioPrep® 3000L) at 55 °C and pH 8.5. About 89% of the recovered pectate lyase-containing scouring bath was completed with 11% of fresh enzyme solution and reused in a new bioscouring process under the same conditions. Up to ten reuse cycles were possible maintaining the level of pectin removal and without significant loss in quality of subsequent dyeing. A detailed analysis of the pretreated fabrics is presented. Reusing the scouring bath, reducing the intensive consumption of input materials (enzyme, water, and chemicals) and wastewater generation can be possible, making bioscouring a more attractive and sustainable technique. The process demonstrated is promising and its industrial application is feasible.