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Reduction of the environmental footprint of thermo‐alkali pretreatment by reusing black liquor during anaerobic digestion of lignocellulosic biomasses
Author(s) -
Peyrelasse Christine,
Kaparaju Prasad,
Lallement Audrey,
Marques Melissa,
Monlau Florian
Publication year - 2021
Publication title -
biofuels, bioproducts and biorefining
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.931
H-Index - 83
eISSN - 1932-1031
pISSN - 1932-104X
DOI - 10.1002/bbb.2208
Subject(s) - chemistry , black liquor , manure , anaerobic digestion , pulp and paper industry , cow dung , cellulose , fraction (chemistry) , methane , biomass (ecology) , chicken manure , organic matter , waste management , lignin , chromatography , fertilizer , organic chemistry , agronomy , biology , engineering
In this study, the effect of thermo‐alkaline pretreatment and recycling of the liquid fraction (black liquor) for successive pretreatment steps on chemical composition and methane yields from horse manure was investigated. At first, horse manure was subjected to alkaline pretreatment at 70 °C for 1 h (8.6 g NaOH/100 g total solids). Pretreated biomass was then separated into solid and liquid fractions (black liquor). In the subsequent stages, black liquor was mixed with 20% (v/v) of fresh NaOH and was reused to pretreat subsequent batches of horse manure (cycles 1–4). Chemical analyses showed that thermo‐alkaline pretreatment was effective in the delignification and solubilization of organic matter and thereby increased the holocellulose (cellulose and hemicelluloses) content in the solid fraction of horse manure. On comparison with untreated horse manure methane yields (225 ± 1 L CH 4 kg −1 VS added ), thermo‐alkaline pretreatment improved the methane yields of horse manure by 39% (313 ± 16 L CH 4 kg −1 VS added ). However, the effectiveness of black liquor recycling on methane production decreased (from 39 to 12%) with an increase in the number of recycling steps (from 1 to 4). Nevertheless, recycling of black liquor reduced the consumption of NaOH (40%) and water use (60%). Thus, thermo‐alkaline pretreatment with liquor recycling was found to be an effective pretreatment with an economic gain of 2.4 to 10.4 compared to pretreatment without recycling. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd