Cotton gin dust (CGD) and cotton gin waste (CGW) were provided by Hantex Textile Residues Ltd. (Gaspar, Brazil) with a 7 wt% moisture content (wet basis). The commercial enzyme preparation Cellic CTec2® was obtained from Novozymes Latin America (Araucária, Brazil) and the microorganism used in the L-690,330 experiments was the Thermosacc® Dry S. cerevisiae strain from Lallemand (Milwaukee, USA).
2.2. Pretreatment factorial design
Pretreatment of the cotton gin residues CGD and CGW was investigated through a 22 factorial design in which the macrophages following conditions were used: catalyst concentration (NaOH) of 2 and 4 wt% (0.2 and 0.4 g g−1 of dry biomass, respectively) and temperature (100 and 120 °C) (Table 1). Also, three replicates were performed at 110 °C and 3 wt% NaOH, which corresponds to the center point of the factorial design. The pretreatment TS (or the solid-to-liquid ratio in relation to the dry biomass) and the residence time at the desired temperature were established at 10 wt% and 60 min as recommended by Silverstein et al. (2007).