An explanation of the methanogenic pathway for methane production in anaerobic digestion of nitrogen-rich materials under mesophilic and thermophilic conditions

• DOI: 10.1016/j.biortech.2018.05.062
• Publication Date: 2018-05-18T02:39:31Z
• Authors: Dong-Min Yin; Maria Westerholm; Wei Qiao; Shao-Jie Bi; Simon M. Wandera; Run Fan; Meng-Meng Jiang; Ren-Jie Dong
• Keywords: Bioreactors; Ammonia; Nitrogen; 13. Climate action; Temperature; 0202 electrical engineering, electronic engineering, information engineering; Anaerobiosis; 02 engineering and technology; Euryarchaeota; Methane; 7. Clean energy

The impact of temperature on the anaerobic digestion of chicken manure was investigated by studying the process performance and pathway for continuously-fed digesters under mesophilic and thermophilic conditions. The mesophilic digester obtained a 15% higher methane yield compared with the thermophilic digester. Mesophilic and thermophilic digester had free ammonia of 31 and 145 mg/L, respectively. The stable carbon isotope analysis indicated that 41% and 50% of acetate was converted to methane through the syntrophic acetate oxidation and hydrogenotrophic methanogenesis (SAO-HM) pathway under mesophilic and thermophilic conditions, respectively. The genus Pseudomonas represented 10% and 16% under mesophilic and thermophilic conditions, respectively. A high abundance of the methanogens genus Methanoculleus (94% of total methanogens) in mesophilic and the genus Methanothermobacter (96%) in thermophilic digesters indicated they were the main hydrogenotrophic partners in SAO. The present study therefore illustrated that methanogenic pathway shifting, induced by free ammonia, closely correlated to the process performance.