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Anaerobic digestion of ammonia-pretreated corn stover

Yuan, Hairong, Li, Rongping, Zhang, Yatian, Li, Xiujin, Liu, Chunmei, Meng, Ying, Lin, Meina, Yang, Ziyi
Biosystems engineering 2015 v.129 pp. 142-148
acidification, ammonia, anaerobic digestion, biogas, cellulose, corn stover, digestion, hemicellulose, lignin, lignocellulose, water content
The effect of ammonia pretreatment on the anaerobic digestibility of corn stover was investigated. Corn stover with different moisture contents (30%, 50%, 70%, and 90%) was pretreated with three concentrations of ammonia (2%, 4%, and 6%) at 35 ± 2 °C for the following batch digestion. Results showed that the reagent of 4% ammonia and 70% moisture content could achieve the highest anaerobic digestibility. In comparison with the untreated, the time needed to produce 90% of the maximum digester gas production (T90) shortened from 52 d to 37 d. The total biogas production and the unit volatile solids (VS) biogas yield were 20,740 ml and 427.1 ml respectively, both 26.70% higher than the untreated. It was found that the digesters with high moisture contents of 70% and 90% were more stable and had shorter acidification periods relative to the low moisture contents of 30% and 50%. The decreases in cellulose, hemicelluloses and lignin indicated that ammonia pretreatment could destroy the lignocellulose (LCH) structure and furthermore enhance the biogas production. Following anaerobic digestion, 80.6% of cellulose and 68.52% of hemicelluloses were consumed where there was 4% ammonia and 70% moisture content, indicating why these conditions produced the highest level of biogas.