Hydrogenotrophic methanogens are the key for a successful bioaugmentation to alleviate ammonia inhibition in thermophilic anaerobic digesters

Abstract

Bioaugmentation to alleviate ammonia inhibition under thermophilic anaerobic digestion has never been reported, as well as the working mechanism that allows a fast and successful bioaugmentation. Thus two bioaugmentation inocula (an enriched culture, and a mixed culture composed 50/50 by Methanoculleus thermophilus and the enriched culture) on the recovery of ammonia-inhibited thermophilic continuous reactors was assessed. The results showed that bioaugmentation improved methane yield by 11-13% and decreased the volatile fatty acids (VFA) by 45-52% compared to the control reactor (abiotic augmentation). Moreover, the importance of hydrogenotrophic methanogens to a fast and successful bioaugmentation was recognized. Specifically, the instant hydrogen partial pressure reduction by the bioaugmented hydrogenotroph created thermodynamically favourable conditions for the acetate oxidation process and consequently, the catabolism of other VFA. Highthroughput sequencing results strengthened this explanation by showing that the bioaugmented M. thermophilus stimulated the growth of syntrophic acetate oxidising bacterium Thermacetogenium phaeum, immediately after bioaugmentation.

Performance and Kinetics of Bioaugmentation, Biostimulation, and Natural Attenuation Processes for Bioremediation of Crude Oil-Contaminated Soils

“…Bioremediation is recognized as a cost-effective treatment technology for oil-contaminated soils [2]. For instance, bioaugmentation (BA) and biostimulation (BS) are the two main bioremediation technologies commonly used for soil clean-up [3][4][5][6][7][8]. Bioaugmentation works by introduction of exogenous microbial population to the contaminated environment [9][10][11].…”

Anaerobic digestion of sludge filtrate using anaerobic baffled reactor assisted by symbionts of short chain fatty acid-oxidation syntrophs and exoelectrogens: Pilot-scale verification

“…In the previous study, significant ammonia-nitrogen inhibition occurred in the microbial methanogenic consortia with NH4 + -N concentration of 1000 mg•L -1 (Zhang C. et al, 2018). The better methanogenesis of the present system with high ammonia-nitrogen concentration could be due to the enrichment of hydrogenotrophic methanogens, since hydrogenotrophic methanogens have a higher tolerance for ammonia-nitrogen concentration than aceticlastic methanogens (Tian et al, 2019). Its microbial community is analyzed as follows, and the main performance of system is summarized at Table 2, .…”

Similar Methanogenic Shift but Divergent Syntrophic Partners in Anaerobic Digesters Exposed to Direct versus Successive Ammonium Additions

“…Independently of the N-input modality, hydrogenotrophic Methanoculleus strongly dominated the active community at all N concentrations, being particularly enriched at the highest TAN levels. As a fast-growing methanogen, active at high ammonia levels, Methanoculleus bourgensis ( 27 ) was successfully used in bioaugmentation of continuous AD processes to enhance methane production at high ammonia levels (5 to 11 g N-NH 4 + liter −1 ) ( 73 , 74 ). Methanoculleus was dominant in many anaerobic digesters operated at high TAN ( 72 ) or acetate ( 75 ) levels.…”