Recycling the liquid fraction of alkaline hydrogen peroxide in the pretreatment of corn stover

Abstract

The aim of this study was to evaluate the influence of recycling the liquid fraction of pretreatment with alkaline hydrogen peroxide (AHP) on the hydrolysis of corn stover. Corn stover was pretreated in the traditional condition with 7.5% v/v HO. After pretreatment, the solids were separated from the liquid fraction and five successive reuse cycles of the liquid fraction were tested. The solid fraction from pretreatment in each recycle was submitted to enzymatic hydrolysis. The number of recycles had a linear negative effect (R=0.98) on biomass delignification efficiency and also affected negatively the enzymatic conversion efficiency. Despite the decrease in efficiency after each recycling step, reuse of the liquid fraction leads to reduction in water, HO and NaOH consumption of up to 57.6%, 59.6% and 57.6%, respectively. These findings point to an efficient recycling technology, which may reduce costs and save water.

Reduction of the environmental footprint of thermo‐alkali pretreatment by reusing black liquor during anaerobic digestion of lignocellulosic biomasses

“…These results are in accord with a previous study where, Alencar et al . reported a decrease in pH value by 2.7 after five recycling stages 18 . In the present study, the pH decreased by 3.1 after four cycles.…”

“…For instance, cellulose, hemicelluloses and lignin content for three different manures, viz., chicken, dairy and swine manure were reported to be in the range of 11–20% for cellulose, 15–28% for hemicelluloses and 2–17% for lignin 43 . In comparison, the average content of these components in lignocellulosic biomass ranged from 30% to 60% for cellulose, 20% to 40% for hemicelluloses and 15% to 30% for lignin 18 . On the other hand, the C, H, N, and S content in HM were similar to the values reported for lignocellulosic biomasses 44 …”

“…Depending upon the chemical composition of the feedstock, different pretreatments, such as biological, physical, and chemical pretreatments, and combinations of them, are used. Among them, chemical and thermo‐chemical pretreatments have been shown to be the best in terms of improved methane yields from various lignocellulosic biomasses 13,14,18–21 . Previously, thermo‐alkaline pretreatments have shown to improve methane yields by 32% with sorghum forage (10% NaOH at 40 °C), 22 55% with wheat straw (8% NaOH at 75 °C for 60 min), 14 and by a threefold increase with pine wood (8% NaOH at 100 °C after 45 days) 21 …”

“…Black liquor recycling after alkaline pretreatment allowed 38%, 33 45%, 29 and 68% of NaOH 28 to be saved and reduced 65% of the water used 33 (in v/v) in the lignocellulosic bioethanol production. However, recycling of black liquor for successive pretreatment runs have been poorly investigated for anaerobic digestion, 19,31,34 and a loss of the efficiency is assessed after two successive steps 18,20,29 . For instance, Kabir et al .…”

Insight into Pretreatment Methods of Lignocellulosic Biomass to Increase Biogas Yield: Current State, Challenges, and Opportunities

“…On the other hand, Alencar et al [128] evaluated the H 2 O 2 recycling strategy and tested the efficiency of recycled H 2 O 2 in five successive reuse cycles and reported a decrease in efficiency at each cycle of reuse than the previous.…”