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Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation
Published on: July 13, 2012
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Microbial communities in anaerobic digesters change over time and sampling depth.
Adriana Giongo1, Camille E Granada2, Luiz G A Borges1
1Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Instituto do Petróleo e dos Recursos Naturais, Porto Alegre, RS, Brazil.
Summary
Psychrophilic anaerobic digestion (AD) of cattle manure produces high methane biogas and safe fertilizer. Microbial communities in the biodigester stabilized after eight days, with distinct community structures at different depths.
Area of Science:
- Microbiology
- Environmental Science
- Biotechnology
Background:
- Anaerobic digestion (AD) converts organic matter into biogas and biofertilizer using microbial consortia.
- Psychrophilic AD operates at lower temperatures (around 20°C), offering potential energy savings.
- Understanding microbial dynamics is crucial for optimizing AD efficiency and stability.
Purpose of the Study:
- To characterize microbial communities in a psychrophilic anaerobic biodigester fed with cattle manure.
- To investigate the impact of biodigester depth and incubation time on microbial community structure.
- To assess the efficacy of psychrophilic AD in pathogen removal and biogas production.
Main Methods:
- Analysis of microbial communities at three depths within a BioKöhler® biodigester over 18 days.
- Incubation under psychrophilic conditions (approximately 20°C) with cattle manure feedstock.
- High-throughput sequencing to determine microbial community composition and abundance.
- Gas chromatography to measure methane content in biogas.
- Pathogen detection (Salmonella, Escherichia) in the digestate.
Main Results:
- Maximum methane content in biogas reached 79.9%.
- Significant differences in microbial communities were observed across biodigester depths (bottom, medium, upper).
- Microbial communities stabilized by the eighth day of incubation.
- Bacteroidetes, Firmicutes, and Synergistetes were the dominant phyla.
- Specific phyla showed varying abundance related to depth, including Euryarchaeota, Actinobacteria, Crenarchaeota, and Acidobacteria.
- Pathogens such as Salmonella and Escherichia were effectively removed.
Conclusions:
- Psychrophilic anaerobic digestion of cattle manure is efficient in producing high-methane biogas and a pathogen-free, stabilized fertilizer.
- Biodigester depth significantly influences microbial community structure.
- Microbial communities achieve stability within the first week of psychrophilic digestion.
- This process offers a sustainable method for waste management and renewable energy generation.
