Simultaneous saccharification and fermentation with Weizmannia coagulans for recovery of synthetic fibers and production of lactic acid from blended textile waste

Textile waste is still mostly landfilled or incinerated while a lot of fabrics consist of blended fibers that represent a challenge for recycling. In this study, enzymes were used to specifically decompose cellulose from blends for recovery of synthetic fibers and microbial conversion of resulting glucose into lactic acid (LA) as a building block of the biobased polyester PLA. To overcome enzyme inhibition by glucose and to reduce process cost, simultaneous saccharification and fermentation (SSF) by Weizmannia coagulans in presence of cellulolytic enzymes were investigated. Indeed, viscose fibers in blends were completely hydrolyzed according to weight loss and HPLC quantification of formed glucose which was converted into pure l-LA (25.6 g/L). In parallel, pure synthetic fibers (polyester and polyamide) were recovered as confirmed by SEM, FTIR, and TGA analyses. This approach represents a circular economy concept to recycle and simultaneously valorize each component of a blended textile waste stream.