Potential use of feedlot cattle manure for bioethanol production.
This paper reports on processing options for the conversion of feedlot cattle manures into composite sugars for ethanol fermentation. Small-scale anaerobic digestion trials revealed that the process significantly reduces the content of glucan and xylan (ca. 70%) without effecting lignin. Moreover, anaerobic digestate (AD) fibres were poor substrates for cellulase (Cellic® CTec 2) saccharification, generating a maximum combined sugar yield of ca. 12% per original dry weight. Dilute acid pretreatment and enzyme saccharification of raw manures significantly improved total sugar recoveries, totalling 264 mg/g (79% theoretical). This was attained when manures were pretreated with 2.5% H2SO4 for 90 min at 121°C and saccharified with 50 FPU CTec 2/g glucan. Saccharomyces cerevisiae efficiently fermented crude hydrolysates within 6 h, yielding 7.3 g/L ethanol, representing glucose to ethanol conversion rate of 70%. With further developments (i.e., fermentation of xylose), this process could deliver greater yields, reinforcing its potential as a biofuel feedstock.
NSW Department of Primary Industries, Wollongbar Primary Industries Institute, NSW, Australia. Electronic address: tony.vancov@dpi.nsw.gov.au.
T
T
Vancov
Chemistry and Physics Department, University of Santa Cruz do Sul, 2293 Avenida Independência, Santa Cruz do Sul 96815-900, RS, Brazil.
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RC
Schneider
NSW Department of Primary Industries, Wollongbar Primary Industries Institute, NSW, Australia.
J
J
Palmer
NSW Department of Primary Industries, Wollongbar Primary Industries Institute, NSW, Australia.
S
S
McIntosh
School of Civil and Environmental Engineering, University of New South Wales, NSW, Australia.
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R
Stuetz
D000693:Anaerobiosis / Q000187:drug effects; D000818:Animals; D061249:Batch Cell Culture Techniques; D056804:Biofuels; D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D002241:Carbohydrates / Q000032:analysis; D002417:Cattle; D002480:Cellulase / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects; D005947:Glucose / Q000032:analysis; D006868:Hydrolysis; D008372:Manure / Q000032:analysis*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D013464:Sulfuric Acids / Q000494:pharmacology; D013997:Time Factors; D014994:Xylose / Q000032:analysis
D056804:Biofuels; D002241:Carbohydrates; D008372:Manure; D013464:Sulfuric Acids; D000431:Ethanol; D014994:Xylose; D002480:Cellulase; D005947:Glucose; C033158:sulfuric acid
Anaerobic digestate; Cellic® CTec 2 saccharification; Dilute-acid pretreatment; Ethanol fermentation; Feedlot cattle manure