Novel bioaugmentation strategy boosted with biochar to alleviate ammonia toxicity in continuous biomethanation

• Published in: Bioresource technology Vol. 343; p. 126146
• Main Authors: Yan, Yixin, Yan, Miao, Ravenni, Giulia, Angelidaki, Irini, Fu, Dafang, Fotidis, Ioannis A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2022
• Subjects: Ammonia tolerance; Bioremediation; Interspecies interaction; Methanoculleus thermophilus; Methanogenesis; Methanoculleus thermophilus; Ammonia tolerance; Bioremediation; Interspecies interaction; Methanogenesis
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2021.126146

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•Ammonia tolerant methanogens stored in gel for long period and used on demand.•Bioaugmentation boosted with Biochar enhanced the methane yield by 28.6%.•A biochar and biogel synergism was found to alleviate ammonia inhibition.•Bioaugmented M. thermophilus sp. contributed largely to rapid methane recovery.•Biochar addition created a long-term ammonia tolerance of Methanosarcina spp.
This study investigated for the first time if ammonia tolerant methanogenic consortia can be stored in gel (biogel) and used in a later time on-demand as bioaugmentation inocula, to efficiently relieve ammonia inhibition in continuous biomethanation systems. Moreover, wood biochar was assessed as a potential enhancer of the novel biogel bioaugmentation process. Three thermophilic (55 °C), continuous stirred-tank reactors (RBgel, RChar and RMix), operated at 4.5 g NH4+-N L-1 were exposed to biogel, biochar and mixture of biogel and biochar, respectively, while a fourth reactor (RCtrl) was used as control. The results showed that the methane production yields of RMix, RChar and RBgel increased by 28.6%, 20.2% and 10.7%, respectively compared to RCtrl. The highest methane yield was achieved by the synergistic interaction between biogel and biochar. Additionally, biogel stimulated a rapid recovery of Methanoculleus thermophilus sp. and syntrophic acetate oxidising bacteria populations.