Enzymatic hydrolysis by Trichoderma reesei of diluted acid-pretreated wastepaper for bioethanol production

Abstract Enzymatic hydrolysis of waste biomass for bioethanol production is considered a traditional, inexpensive, and energy-effective approach decades ago. In the present study, waste office paper was pretreated with diluted sulfuric acid (H2SO4) and hydrolysed with one of the most available and cost-effective enzymes, cellulase from Trichoderma reesei, under submerged static condition. Wastepaper size was reduced to 2cm2, blended with water and dry wet-blended, and pretreated with diluted H2SO4. Among different concentrations (0.5M, 1.0M, 1.5M, 2.0M) of H2SO4, the maximum glucose content was obtained at 2.0M H2SO4 at 90 min reaction time, and glucose yield was 0.11g glucose/g wastepaper. The cut paper, wet-blended, and acid-treated wastepaper was hydrolysed with cellulase enzyme for 2, 4, and 5 consecutive days with 5mg, 10mg, 15mg, and 20mg enzyme loadings. The maximum glucose content was obtained, 9.75g/l after 5 days of enzymatic hydrolysis with 20mg enzyme loading and a glucose yield of a 0.5g glucose/g wastepaper. The wastepaper hydrolysate was further fermented for 6, 8, and 10 hours continuously with Saccharomyces cerevisiae (yeast), and at 10 hours of fermentation, the maximum glucose consumption was 0.18g by yeast. Later, HPLC analysis of the fermented medium presented a strong peak of bioethanol content at 16.12min. Further, the distillation of bioethanol by rotary evaporator presented 0.79ml bioethanol/fermented solution, which indicated the conversion efficiency of 79%.