Ethanol production from pulp & paper sludge and monosodium glutamate waste liquor by simultaneous saccharification and fermentation in batch condition

This work examined the simultaneous saccharification and fermentation (SSF) process for the biological conversion of pulp & paper sludge (PPS) and monosodium glutamate waste liquor (MGWL) into ethanol using Saccharomyces cerevisiae CICC 1001 in batch condition. At the SSF conditions of sterilization, pH 6.0, 6% TS (total solid), and adding nutrient solution, the highest ethanol yield of 42.5 g L−1 was obtained at the enzyme loading of 40 A.U. (activity unit) g−1 VSfed (volatile solid); only if the pH value was changed to 4.5, the ethanol yield reduced by 47%; only if the TS concentration was changed to 3%, the ethanol yield decreased by 11%; only if the substrates were not sterilized, 5% decrease occurred to the ethanol production; only if no nutrient solution was added to the reactor, 97% reduction of ethanol yield happened; the extent of influence of the impact factors ranked in the order of nutrient solution > pH > TS concentration > sterilization. The Fourier Transform Infrared (FTIR) spectra of substrates after SSF further verified the results of process performances. Therefore, this SSF of PPS and MGWL reduced the residue streams and land-filling costs while benefiting in ethanol production.

► SSF for the biological conversion of PPS and MGWL to ethanol was efficient without pretreatment.
► The maximum concentrations of reducing sugar and ethanol were 57.3 g L−1 and 42.5 g L−1, respectively.
► Influence extent of factors ranked in the order of nutrients > pH value> TS concentration > sterilization.
► SSF reduced residue streams and land-filling costs while benefiting in ethanol production.