The recovery of alcohol and by-products from ethanol-water and methanol-wat
er pulping liquors was studied. The recovery system proposed consists of th
ree stages: black liquor flashing, lignin precipitation, and precipitation
distillation of mother liquor. At the flash stage, 47 and 51% of the alcoho
l in the black liquor are recovered for ethanol and methanol processes, res
pectively. The lignin recovery yield at the precipitation stage is 67% for
ethanol black liquor and 73% for methanol black liquor. The distillation of
precipitation mother liquors enables recovery of 98% ethanol and 96% metha
nol from this stream as distillate, whereas the distillation residue contai
ns significant amounts of sugars, furfural, and acetic acid that can be rec
overed. The study concludes with the overall mass balance for the recovery
system proposed.