Novel Respirometry Measurement and Comparison of Monod Kinetic Constants and Methanogen Concentrations for 27 Full-Scale Anaerobic Bioreactors

Document Type

Article

Publication Date

7-2025

Publisher

Wiley

Source Publication

Water Environment Research

Source ISSN

1061-4303

Original Item ID

DOI: 10.1002/wer.70135

Abstract

Monod kinetic coefficient values (km and Ks) as well as methanogen concentrations (Xac and Xh2) for various anaerobic bioreactors are required to gain a deeper understanding of anaerobic biotechnology. However, there are no existing, practical methods to measure or estimate these parameters or variables in typical anaerobic digester biomass that contains mixed cultures with inert organic solids. Current measurement methods rely on pure cultures developed in the laboratory. In this work, a novel respirometric method was developed and used to determine methanogen Monod parameters and active biomass concentration for samples from 27 full-scale anaerobic reactors. Differences (one to three orders of magnitude) were observed among acetate and H2 km values and active biomass fractions for the different biomass microbial communities. Average km values for acetate and H2 were 14.6- and 48-g COD/g CODx-d, whereas average Ks values were 21.9- and 0.32-mg COD/L, respectively. Average Xac as a fraction of total VSS was 0.80% and ranged from 0.02% to 2.49%, whereas average Xh2 was 1.16% and ranged from 0.04% to 8.23%. Granular biomass km values were approximately three times greater than flocculant biomass values, indicating significant fundamental differences ostensibly exist in methanogenesis between the two process configurations. In the future, relationships may be developed to predict kinetic constant values based on microbial community composition.

Comments

Water Environment Research, Vol. 97, No. 7 (July 2025): e70135. DOI.

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