Population dynamics during startup of thermophilic anaerobic digesters: The mixing factor

Sophia A. Ghanimeh, Pascal E. Saikaly, Dong Li, Mutasem El-Fadel

    Research output: Contribution to journalArticlepeer-review

    12 Scopus citations

    Abstract

    Two thermophilic digesters were inoculated with manure and started-up under mixed and stagnant conditions. The Archaea in the mixed digester (A) were dominated by hydrogenotrophic Methanobateriaceae (61%) with most of the methane being produced via syntrophic pathways. Methanosarcinales (35%) were the only acetoclastic methanogens present. Acetate dissipation seems to depend on balanced hydrogenotrophic-to-acetotrophic abundance, which in turn was statistically correlated to free ammonia levels. Relative abundance of bacterial community was associated with the loading rate. However, in the absence of mixing (digester B), the relationship between microbial composition and operating parameters was not discernible. This was attributed to the development of microenvironments where environmental conditions are significantly different from average measured parameters. The impact of microenvironments was accentuated by the use of a non-acclimated seed that lacks adequate propionate degraders. Failure to disperse the accumulated propionate, and other organics, created high concentration niches where competitive and inhibiting conditions developed and favored undesired genera, such as Halobacteria (65% in B). As a result, digester B experienced higher acid levels and lower allowable loading rate. Mixing was found necessary to dissipate potential inhibitors, and improve stability and loading capacity, particularly when a non-acclimated seed, often lacking balanced thermophilic microflora, is used.

    Original languageBritish English
    Pages (from-to)2211-2218
    Number of pages8
    JournalWaste Management
    Volume33
    Issue number11
    DOIs
    StatePublished - Nov 2013

    Keywords

    • 16S rRNA gene pyrosequencing
    • Microbial dynamics
    • Mixing
    • Startup
    • Thermophilic anaerobic digestion

    Fingerprint

    Dive into the research topics of 'Population dynamics during startup of thermophilic anaerobic digesters: The mixing factor'. Together they form a unique fingerprint.

    Cite this