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Updated: May 12, 2026
11:31
Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation
Published on: July 13, 2012
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High-solid digestion - A comparison of completely stirred and plug-flow reactor systems
Ebba Perman1, Anna Karlsson2, Maria Westerholm1
1Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden; Biogas Solutions Research Center, Linköping, Sweden.
Waste Management (New York, N.Y.)
|September 1, 2024
Summary
High-solid digestion (HSD) using plug-flow reactors (PFRs) showed improved methane production and nutrient recovery compared to continuously stirred-tank reactors (CSTRs). Both reactor types, however, achieved stable digestion of organic waste.
Area of Science:
- Biotechnology
- Environmental Science
- Waste Management
Background:
- High-solid digestion (HSD) offers a sustainable method for treating organic waste and producing biogas.
- HSD utilizes a lower dilution rate than conventional wet digestion, making it resource-efficient.
- This study investigates reactor type as a key factor influencing HSD performance.
Purpose of the Study:
- To compare the performance of plug-flow reactors (PFRs) and continuously stirred-tank reactors (CSTRs) in high-solid digestion.
- To evaluate the impact of reactor type on biogas production, nutrient recovery, and microbial community structure.
- To assess the stability and efficiency of HSD under thermophilic conditions.
Main Methods:
- HSD was conducted in thermophilic conditions (52°C) using a mixture of household, garden, and agricultural wastes.
- Plug-flow reactors (PFRs) and continuously stirred-tank reactors (CSTRs) were compared for their effectiveness.
- Microbial community analysis was performed using 16S rRNA gene sequencing.
Main Results:
- PFRs demonstrated higher specific methane production and nitrogen mineralization compared to CSTRs.
- Volatile solids reduction was comparable between PFRs and CSTRs.
- Significant differences in bacterial and archaeal communities were observed, correlated with stirring speeds (1 rpm in PFRs vs. 70-150 rpm in CSTRs).
Conclusions:
- Both PFRs and CSTRs can achieve stable high-solid digestion, indicating process flexibility.
- PFRs offer slight advantages in methane yield and nutrient recovery for HSD.
- Reactor design significantly influences the microbial consortia involved in high-solid digestion.
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