Simultaneous saccharification and fermentation (SSF) with increased paper sludge organic material (PSOM) concentration (A) and the theoretical ethanol yield Y
(B), and SSF with increased inoculum size (C) and the theoretical ethanol yield Y
(D). (A, B) Initial conditions were 80 g PSOM/l and 15 FPU/g PSOM (open circles). PSOM (11 g, or 44.9 g PS) with PS cellulase 15 FPU/g PSOM was then added at 8 h (open triangles), at 8 h and 16 h (open squares), and at 8 h, 16 h and 20 h (closed squares). (C, D) Ethanol production increased inoculum size when 100 g PSOM/l and 15 FPU/g PSOM was used and with the addition of 11 g PSOM with 15 FPU/g PSOM at culture times of 8 and 16 h. Symbols: open circles = 10% v/v inoculum; closed circles = 20% v/v inoculum. Error bars in (A) denote 5% error of three repeated experiments.