Microbial community and metabolic responses to electrical field intensity for alleviation of ammonia inhibition in an integrated bioelectrochemical system (BES)

Bioelectrochemical system (BES) is a promising solution for mitigation of ammonia inhibition in anaerobic digestion (AD) process. However, the effect of electric field intensity on microbial community changes and metabolic function prediction during the alleviation of ammonia inhibition are still missing. The results of the current study represented that the improvement of ammonia removal (20.6%) and methane production (14.6%) could both be achieved at 0.2 V while higher voltages led to reductions of methane production (more than 48.9%) compared with the control. Moreover, hydrogenotrophic methanogens (Methanobacterium) seemed to be more robust to high voltages compared with aceticlastic methanogens (Methanosaeta). Additionally, bacteria for hydrolysis and acidogenesis (Rikenellaceae and Soehngenia) were found vulnerable to external electric field intensity. Furthermore, abundances changes of metabolic pathways demonstrated that the degradation of carbohydrates, lipids and proteins during all steps (hydrolysis, acidogenesis, acetogenesis and methanogenesis) of AD process could be affected by different applied voltages.

Automated summary

The electric field intensity plays a significant role in the effectiveness of bioelectrochemical systems (BES) in alleviating ammonia inhibition, with low voltages improving ammonia removal and methane production, while high voltages leading to a significant decrease in methane production. Hydrogenotrophic methanogens show more resistance to high voltages compared to aceticlastic methanogens, and certain bacteria are vulnerable to external electric field intensity. Abundance changes in metabolic pathways demonstrate that the degradation of carbohydrates, lipids, and proteins in all steps of the anaerobic digestion process can be affected by different applied voltages.