Revisiting acetoclastic methanogens in anaerobic digestion via r/K selection-informed mathematical modeling

Chang, Huanhuan, Liu, Tingxia, Quéméner, Elie Desmond-Le, Ranjbar, Samira, & Wu, Guangxue. (2025). Revisiting acetoclastic methanogens in anaerobic digestion via r/K selection-informed mathematical modeling. Journal of Water Process Engineering, 79, 108884. https://doi.org/10.1016/j.jwpe.2025.108884

Abstract

Anaerobic digestion mathematical models (ADMMs) have been extensively employed for simulating system performance and predicting microbial community dynamics. However, accurately determining kinetic and stoichiometric parameters of specific microorganisms remains a major challenge. To simulate the competitive dynamics between two types of acetoclastic methanogens, Methanosarcina and Methanothrix, an ADMM incorporating the r/K selection theory was developed. By integrating thermodynamic analysis with metabolic pathway characterization, the kinetic parameters of the two methanogens were systematically estimated. With calibration of the maintenance coefficient and the maximum biomass specific electron-transfer rate, the thermodynamic energy dissipation approach provided a viable framework for elucidating the distinct kinetic parameters of the two methanogens. Sensitivity analysis revealed that biomass yield and acetate concentration strongly influenced Methanosarcina during the long-time operation, whereas solids retention time (SRT) was identified as the primary factor governing the dynamic of Methanothrix. Methanosarcina exhibited a higher biomass concentration under high acetate concentrations, whereas Methanothrix demonstrated a stable and sustained growth trend under extended SRTs and low acetate concentrations. Moreover, continuous flow reactor (CFR) systems exhibited a more pronounced microbial shift in response to acetate concentration variations. The stable flow and reduced substrate fluctuations of CFR systems favored the growth of Methanothrix over time.

Funder

Taighde Éireann – Research Ireland
Sustainable Energy Authority of Ireland
China Scholarship Council
Galway University Foundation

Publisher

Elsevier

Rights

CC BY

cb

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