Abstract

We characterized chemical and microbial responses to changes in the carbon-to-nitrogen ratio (C:N) and organic loading rate (OLR) during anaerobic codigestion (ACoD) of cattle manure digestate mixed with industrial organics. C:Ns of 25 and 35, both operating at OLRs ≤ 4 gVS L-1 d-1, sustained methane production averages of 0.36 ± 0.03 L gVS-1 d-1 and 0.32 ± 0.05 L gVS-1 d-1, respectively, throughout a 15-day period. Using 16S rRNA high-throughput sequencing coupled with PICRUSt2, taxonomy and predicted gene abundances were mapped to the major ACoD stages. C:N (25, 35) and the OLR (2, 4 gVS L-1 d-1) had minimal impacts on community structure and function, with a slight but notable increase in acetoclastic methanogens and alpha/beta diversity (Shannon and Bray-Curtis) at C:N 35. The microbial composition data indicated potential souring before the chemical data. ACoD was unsustainable at C:N 35 and OLR 6.5 gVS L-1 d-1, which was revealed by low methane production and souring. Digester failure correlated with a shift from acetoclastic to hydrogenotrophic methanogens (Methanobacteriaceae) and increased acidogenesis, driven by Provetellaceae and Lachnospiraceae. Our findings demonstrate that timely microbiome monitoring can contribute to efficient and sustained ACoD operation, especially when variable organic feedstock composition and loading rates are the norm.

Department(s)

Civil, Architectural and Environmental Engineering

Publication Status

Open Access

Comments

Iowa Economic Development Authority, Grant 20-SEPF-007

International Standard Serial Number (ISSN)

1520-5029; 0887-0624

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Chemical Society, All rights reserved.

Publication Date

07 Mar 2024

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