Microbial community dynamics of a sequentially fed anaerobic digester treating solid organic waste

Area of Science:

• Biotechnology
• Environmental Science
• Microbiology

Background:

• High solids anaerobic digestion (AD) is a promising technology for waste management and energy recovery.
• Previous studies demonstrated enhanced methane production from fiber when co-digested with food waste (FW).

Purpose of the Study:

• To investigate the relationship between process parameters and microbial community dynamics in a high solids AD system.
• To identify microbial indicators associated with enhanced methane production from the fiber fraction.

Main Methods:

• Operation of a 50-kg scale, six-stage leach bed anaerobic digester at 37°C for 88 weeks.
• Analysis of microbial communities using 16S rRNA gene amplicon sequencing in leachate.
• Correlation of microbial abundance and composition with process parameters like FW proportion and methane yield.

Main Results:

• Increased FW proportion led to higher absolute microbial abundance in leachate.
• Clostridium butyricum abundance correlated with FW and overall methane yield.
• Candidatus Roizmanbacteria and Spirochaetaceae showed specific correlation with enhanced fiber methane production.
• Hydraulic channeling due to bulking agent issues temporarily altered microbial profiles.

Conclusions:

• The microbial community composition in AD leachate is strongly influenced by feedstock composition, particularly FW content.
• Specific microbial groups, Candidatus Roizmanbacteria and Spirochaetaceae, are linked to improved methane generation from fiber.
• The AD system demonstrated robustness and rapid recovery of performance and microbial community after addressing operational issues.