*3.10. Analytical Methods*

Quantification of glucose in the hydrolysates was performed upon enzymatic hydrolysis using the glucose oxidase/peroxidase (GOPOD) method (K-GLUC, Megazyme, Ireland), while that of reducing sugars was performed using the DNS method with glucose as a suitable standard as described previously [26,53].

Paper sludge *saccharification yield* from all the enzymatic hydrolysis reactions was calculated using the following equation:

$$Sacchariification\text{ }yield\left(\%\right) = \frac{Glucose\text{ }released \times 0.9}{Glucam\text{ } content} \times 100\tag{3}$$

#### *3.11. Scanning Electron Microscopy (SEM)*

Prior to scanning electron microscopy (SEM), paper sludge samples before and after enzymatichydrolysis were mounted on a metal stub, dried using critical point-drying process and coated with a thin layer of gold prior to SEM analysis. The diameters and lengths of the paper sludge microfibrils from SEM images were quantified using the imaging software Image J. Approximately 30 microfibrils representing each sample were randomly and manually picked for diameter and length analysis.
