was only 1.89% (w/w) of the dry cassava residues weight as shown in the Materials and Methods section, and the insoluble solids con- tent was 8.04% (w/w) in the slurry, then the total residual starch was equivalent to 1.52 g/L (starch content in cassava residues 1.89% multiplied the insoluble solids content in the slurry 8.04%). Given the total starch in the cassava residues was converted into ethanol according to the theoretical yield (0.511 g ethanol/g starch) during the Co-SSF process, the theoretical ethanol increase was only 0.77 g/L, far less than the total ethanol increase 5.5 g/L with cellulase addition. Therefore, it is reasonable to conclude that most of the ethanol increased after cellulase addition was from the glucose released from cellulose. The ethanol increased was attrib- uted to the cassava cellulose conversion was reasonable and viable.