Experimental study demonstrates optimized ethanol yields from waste paper using fed-batch bioprocessing, indicating reduced enzyme requirements for bioethanol production.
Key Points
To optimize high-solids simultaneous saccharification and co-fermentation of paper wastes using advanced cellulase-producing yeast strains to minimize enzyme dosage and improve ethanol yields.
Compared lab-scale fed-batch vertical and batch horizontal bioreactor configurations using three untreated paper wastes: label backing, multilayer packaging, and potato paper sacks.
Evaluated cellulase-producing consolidated bioprocessing Saccharomyces cerevisiae strains (Cellusec 2.0, 3.3, or 4.0) at 20% and 30% (w/w) solid loadings with 2 FPU/g dry solids enzyme dosage.
In fed-batch bioreactors at 20% solid loading, enzyme efficiencies reached 0.109, 0.078, and 0.067 g ethanol/FPU, yielding ethanol titres of 59.3, 45.2, and 38.2 g/L (58.5%, 43.9%, and 57.1% of theoretical maximum) for label backing, potato paper sacks, and multilayer packaging, respectively.
Batch fermentation at 30% solid loading produced higher titres (65.6, 50.7, and 54.3 g/L) but markedly lower ethanol yields (36.7%, 28.0%, and 52.1% of theoretical maximum) and reduced enzyme efficiencies (0.069, 0.050, and 0.062 g ethanol/FPU).