In thefirst batch of ethanol fermentation, tap water was used to
make mash. At the end of the fermentation, the“beer’’ was trans-ferred into a distillation column and distilled. The distillage was
centrifuged (4000gfor 30 min) to obtain the supernatant (thin
stillage). Next, 40% of the thin stillage was stored at20
C before
use. The residual was fed into the anaerobic digester. The digestate
was then mixed with the thin stillage and recycled to make mash
for the following batch of ethanol fermentation