Insights into the economic viability of cellulases recycling on bioethanol production from recycled paper sludge

Abstract

The economics of Recycled Paper Sludge conversion into ethanol was here assessed with emphasis on integrating a cellulase recycling system. Without cellulases recycling this process presented positive economic outputs (payback period of 7.85 years; 10.90 Million US$ of accumulated NPV) despite the modest ethanol titers. Recycling both free and solid-bound enzymes allowed considerable savings of enzyme but also an increase on annual costs (0.88%), resulting on a superior economic output: payback period decreased to 7.25 years; accumulated NPV increased to 14.44 Million US$. Recycling exclusively the liquid fraction enabled a clear costs reduction, however, also total ethanol decreased, attenuating the abovementioned benefits. Targeting higher ethanol concentrations, superior solids consistencies were also evaluated. Despite a costs reduction, total ethanol decreased due to a higher ethanol retention on the solid. A sensitivity analysis further revealed that the cost of enzymes and ultrafiltration membrane may be critical on enzyme recycling economic feasibility.

One-step purification of two novel thermotolerant β-1,4-glucosidases from a newly isolated strain of Fusarium chlamydosporum HML278 and their characterization

“…Lignocellulose is a linear polysaccharide linked by D-glucose via β-(1,4)-glycosidic bonds, and is the most abundant renewable resource on earth (Zhang et al 2010;Kovacs et al 2009;Sánchez and Cardona 2008). Lignocellulose can eventually be degraded into glucose under the synergy of the cellulase system: endoglucanase (EC 3.2.1.4) randomly acts on the noncrystalline region inside the cellulose molecule to produce glucose and short fiber oligosaccharides sugar; Exoglucanase (EC 3.2.1.91) hydrolyzes β-1,4-glycosidic bonds from outside to inside along the non-reducing end of cellulose to release cellooligosaccharides, cellobiose or glucose; β-glucosidase (EC 3.2 0.1.21) hydrolyzes cellobiose or other soluble cellobiose and cellooligosaccharides into glucose (Gomes et al 2018;Fan et al 2016;Arantes and Saddler 2010 ). β-glucosidase plays an important role in the hydrolysis of cellulose.…”

“…The intermediate products of cellulose hydrolysis, such as cellobiose, cellooligosaccharides, have a strong inhibitory activity on the activity of exoglucanase and endoglucanase. β-glucosidase hydrolyzes cellobiose and cellooligosaccharides to produce glucose, reducing the inhibitory effect of these intermediate products on exoglucanase and endoglucanase, thus improve the saccharification rate of cellulose enzymes (Gomes et al 2018;Kamila et al 2016;Chauve et al 2010;Ikeda et al 2006;Tanaka et al 2006;Wen et al 2005).…”

Paper Waste Recycling. Circular Economy Aspects

“…For this reason, research is being conducted to reduce these costs, unfortunately the number of studies on the recycling of enzymes are very few. There is also little research done to evaluate the converted paper sludge material and apply a filtration process to it, giving it even more importance, as these processes are usually costly [17]; − Hydrogen is a clean source of fuel because it does not emit contamination during combustion. Organic hydrogen production, where dark fermentation is used, is less energyintensive than conversion of hydrocarbon vapor and water hydrolysis.…”

One-step purification of two novel thermotolerant β-1,4-glucosidases from a newly isolated strain of Fusarium chlamydosporum HML278 and their characterization

“…Lignocellulose is a linear polysaccharide linked by D-glucose via β-(1,4)-glycosidic bonds, and is the most abundant renewable resource on earth (Zhang et al, 2010; Kovacs et al, 2009;Sánchez and Cardona, 2008). Lignocellulose can eventually be degraded into glucose under the synergy of the cellulase system: endoglucanase (EC 3.2.1.4) randomly acts on the non-crystalline region inside the cellulose molecule to produce glucose and short ber oligosaccharides sugar; Exoglucanase (EC 3. cellooligosaccharides to produce glucose, reducing the inhibitory effect of these intermediate products on exoglucanase and endoglucanase, thus improve the sacchari cation rate of cellulose enzymes (Gomes et al, 2018;Kamila et al, 2016;Chauve et al, 2010;Ikeda et al, 2006Tanaka et al, 2006Wen et al, 2005. β-glucosidase is an important industrial enzyme that has been used in many bioprocesses, including the processing of biofuels, paper industry, textile industry, waste, and food (Pei et al, 2012;Tian et al, 2010;Bayer et al, 2008;Han and Chen, 2008;Rubin 2008;Villena et al, 2007;Zaldivar et al, 2001).…”