Identification of methanogenesis and syntrophy as important microbial metabolic processes for optimal thermophilic anaerobic digestion of energy cane thin stillage

https://doi.org/10.1016/j.biteb.2019.100254Get rights and content
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Highlights

  • Thermophilic anaerobic digestion of thin stillage was accomplished in a CSTR.

  • Thin stillage COD was reduced by 64% and produced biogas contained 56% methane.

  • Methanogenic archaea and syntrophic bacteria were important.

  • Implies importance of biomass retention for thermophilic digestion of thin stillage

Abstract

The aim of this research was to identify key microorganisms for thermophilic (55 °C) anaerobic digestion of thin stillage derived from hydrolysis and ethanol fermentation of energy cane in a conventional stirred tank reactor with a 10-day hydraulic retention time. Efficient thermophilic anaerobic digestion with a specific methane production of 0.43 Lmethane/gtCOD used/d and biogas containing around 56% methane was accomplished. Due to an overnight temperature perturbation the specific methane production decreased to 0.16 Lmethane/gtCOD used/d. Analysis of the microbial community showed the importance of methanogenic Archaea belonging to Methanosarcina and Methanothermobacter as well as syntrophic Bacteria related to Thermacetogenium, Tepidanaerobacter and Anaerobaculum. This indicates that retention of biomass maintaining syntrophy and methanogenesis more efficiently may be useful for thermophilic anaerobic digestion of thin stillage derived from the production of energy cane ethanol.

Keywords

Anaerobic digestion
Stillage
Sugarcane
Thermophilic
Microbial community

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