Combined ethanol and methane production from switchgrass (Panicum virgatum L.) impregnated with lime prior to steam explosion
Capecchi, Lorenzo ; Galbe, Mats LU ; Wallberg, Ola LU
; Mattarelli, Paola
and Barbanti, Lorenzo
(2016)
In Biomass & Bioenergy
90.
p.22-31
- Abstract
Pretreatments are crucial to achieve efficient conversion of lignocellulosic biomass to soluble sugars. In this light, switchgrass was subjected to 13 pretreatments including steam explosion alone (195 °C for 5, 10 and 15 min) and after impregnation with the following catalysts: Ca(OH)2 at low (0.4%) and high (0.7%) concentration; Ca(OH)2 at high concentration and higher temperature (205 °C for 5, 10 and 15 min); H2SO4 (0.2% at 195 °C for 10 min) as reference acid catalyst before steam explosion. Enzymatic hydrolysis was carried out to assess pretreatment efficiency in both solid and liquid fraction. Thereafter, in selected pretreatments the solid fraction was subjected to simultaneous... (More)
Pretreatments are crucial to achieve efficient conversion of lignocellulosic biomass to soluble sugars. In this light, switchgrass was subjected to 13 pretreatments including steam explosion alone (195 °C for 5, 10 and 15 min) and after impregnation with the following catalysts: Ca(OH)2 at low (0.4%) and high (0.7%) concentration; Ca(OH)2 at high concentration and higher temperature (205 °C for 5, 10 and 15 min); H2SO4 (0.2% at 195 °C for 10 min) as reference acid catalyst before steam explosion. Enzymatic hydrolysis was carried out to assess pretreatment efficiency in both solid and liquid fraction. Thereafter, in selected pretreatments the solid fraction was subjected to simultaneous saccharification and fermentation (SSF), while the liquid fraction underwent anaerobic digestion (AD). Lignin removal was lowest (12%) and highest (35%) with steam alone and 0.7% lime, respectively. In general, higher cellulose degradation and lower hemicellulose hydrolysis were observed in this study compared to others, depending on lower biomass hydration during steam explosion. Mild lime addition (0.4% at 195 °C) enhanced ethanol in SSF (+28% than steam alone), while H2SO4 boosted methane in AD (+110%). However, methane represented a lesser component in combined energy yield (ethanol, methane and energy content of residual solid). Mild lime addition was also shown less aggressive and secured more residual solid after SSF, resulting in higher energy yield per unit raw biomass. Decreased water consumption, avoidance of toxic compounds in downstream effluents, and post process recovery of Ca(OH)2 as CaCO3 represent further advantages of pretreatments involving mild lime addition before steam explosion.
(Less)
- author
- Capecchi, Lorenzo
; Galbe, Mats
LU
; Wallberg, Ola
LU
; Mattarelli, Paola
and Barbanti, Lorenzo
- organization
- publishing date
- 2016-07-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Anaerobic digestion, Energy yield, Lime, Simultaneous saccharification and fermentation, Steam explosion, Switchgrass
- in
- Biomass & Bioenergy
- volume
- 90
- pages
- 10 pages
- publisher
- Elsevier
- external identifiers
-
- scopus:84963864011
- wos:000377740200004
- ISSN
- 0961-9534
- DOI
- 10.1016/j.biombioe.2016.03.035
- language
- English
- LU publication?
- yes
- id
- 84356c92-14d6-4892-be6f-46e1eaf9e1a7
- date added to LUP
- 2016-05-10 07:34:03
- date last changed
- 2024-01-04 03:08:26
@article{84356c92-14d6-4892-be6f-46e1eaf9e1a7,
abstract = {{<p>Pretreatments are crucial to achieve efficient conversion of lignocellulosic biomass to soluble sugars. In this light, switchgrass was subjected to 13 pretreatments including steam explosion alone (195 °C for 5, 10 and 15 min) and after impregnation with the following catalysts: Ca(OH)<sub>2</sub> at low (0.4%) and high (0.7%) concentration; Ca(OH)<sub>2</sub> at high concentration and higher temperature (205 °C for 5, 10 and 15 min); H<sub>2</sub>SO<sub>4</sub> (0.2% at 195 °C for 10 min) as reference acid catalyst before steam explosion. Enzymatic hydrolysis was carried out to assess pretreatment efficiency in both solid and liquid fraction. Thereafter, in selected pretreatments the solid fraction was subjected to simultaneous saccharification and fermentation (SSF), while the liquid fraction underwent anaerobic digestion (AD). Lignin removal was lowest (12%) and highest (35%) with steam alone and 0.7% lime, respectively. In general, higher cellulose degradation and lower hemicellulose hydrolysis were observed in this study compared to others, depending on lower biomass hydration during steam explosion. Mild lime addition (0.4% at 195 °C) enhanced ethanol in SSF (+28% than steam alone), while H<sub>2</sub>SO<sub>4</sub> boosted methane in AD (+110%). However, methane represented a lesser component in combined energy yield (ethanol, methane and energy content of residual solid). Mild lime addition was also shown less aggressive and secured more residual solid after SSF, resulting in higher energy yield per unit raw biomass. Decreased water consumption, avoidance of toxic compounds in downstream effluents, and post process recovery of Ca(OH)<sub>2</sub> as CaCO<sub>3</sub> represent further advantages of pretreatments involving mild lime addition before steam explosion.</p>}},
author = {{Capecchi, Lorenzo and Galbe, Mats and Wallberg, Ola and Mattarelli, Paola and Barbanti, Lorenzo}},
issn = {{0961-9534}},
keywords = {{Anaerobic digestion; Energy yield; Lime; Simultaneous saccharification and fermentation; Steam explosion; Switchgrass}},
language = {{eng}},
month = {{07}},
pages = {{22--31}},
publisher = {{Elsevier}},
series = {{Biomass & Bioenergy}},
title = {{Combined ethanol and methane production from switchgrass (Panicum virgatum L.) impregnated with lime prior to steam explosion}},
url = {{http://dx.doi.org/10.1016/j.biombioe.2016.03.035}},
doi = {{10.1016/j.biombioe.2016.03.035}},
volume = {{90}},
year = {{2016}},
}