Enhancing Biogas Production from Anaerobically Digested Wheat Straw Through Ammonia Pretreatment

• Published in: Chinese journal of chemical engineering Vol. 22; no. 5; pp. 576 - 582
• Main Authors: YANG, Dongyan, PANG, Yunzhi, YUAN, Hairong, CHEN, Shulin, MA, Jingwei, YU, Liang, LI, Xiujin
• Format: Journal Article
• Language: English
• Published: 01.01.2014
• Subjects: Ammonia; Biodegradability; Biogas; Drying; Loading rate; Moisture content; Straw; Wheat
• ISSN: 1004-9541
• DOI: 10.106/S1004-9541(14)60075-6

Abstract Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia (2%, 4%, and 6%, dry matter) and three moisture contents (30%, 60%, and 80%, dry matter) were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates (50, 65, and 80 g[middot]L super(-1)) to produce biogas. The results indicated that the wheat straw pretreated with 80% moisture content and 4% ammonia achieved the highest methane yield of 199.7 ml[middot]g super(-1) (based on per unit volatile solids loaded), with shorter digestion time (T sub(80)) of 25 days at the loading rate of 65 g[middot]L super(-1) compared to untreated one. The main chemical compositions of wheat straw were also analyzed. The cellulose and hemicellulose contents were decomposed by 2%-20% and 26%-42%, respectively, while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and 12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.