The reducing sugar yields obtained from pre-treatment 3 using ultrasonication (Fig. 1C) showed similar trends to pre-treatments 1 and 2. The dosage of 20% displayed the highest reducing sugar yield after ultrasonication for 30 min. While all other dosages reached their maximum values after 40 min. The maximum reduc- ing sugar yield increased with the dosage of WBY with values of 16.97%, 21.53% and 29.19% for 5%, 10% and 15% WBY respectively. The highest reducing sugar yield obtained from pre-treatment 3 was clearly higher than that obtained from pre-treatment 2 and similar to that obtained from pre-treatment 1.