Production of Bio-Ethanol from Cellulose-Containing Agricultural Residues on the Pilot Setup
A raw material of feedstock should be renewable rather than depleting, wherever technically and economically practicable. The 2nd generation bioethanol-fromagricultural-residues technology is much more energy-saving and environmentally friendly. Thereupon, the oats hulls, which constitute 28 % of the grain mass and contain up to 35 % of cellulose can be regarded as the most prospective raw material for bioethanol production. In this work, bioethanol production from the oats hulls was studied on the pilotscale setup which consisted of three main stages: (1) chemical pretreatment; (2) simultaneous saccharification and fermentation to 2,1 % crude bioethanol; (3) rectification to 92-96 % bioethanol. The pretreatment was performed in rotary pulsed apparatus (RPA) and 100 L stainless steel reactor, equipped with stirring and heating systems. The suspension of oats hulls in a 2 % alkaline solution was circulated in RPA.
Simultaneous saccharification and fermentation was performed in 63-L reactor. The concentration of reducing sugars in the enzymatic hydrolysate obtained from the oats hulls fibrous product was found to be 35.5 g/L according to spectrophotometric measurements. Bioethanol was synthesized using the Saccharomyces сerevisiae
Y-1693 producer. The mass yield of bioethanol was 94.1 % of the concentration of reducing sugars or 48.6 % of the substrate mass.
Finally, the bioethanol produced on the pilot setup was rectified and then tested in catalytic dehydration to ethylene. Overall consumption indexes obtained on the pilotscale setups were rather optimistic: 95-98 kg of anhydrous bioethanol per 1 tone of oats hulls; 1.75-1.85 kg of bioethanol per 1 kg of ethylene, or 55-60 kg of ethylene per 1 metric ton of oats hulls. These figures demonstrate that bioethanol produced by
enzymatic fermentation of the oats hulls may be successfully applied to ethylene synthesis.