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Updated: Jul 5, 2026
11:31
Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation
Published on: July 13, 2012
Methanogenesis under acidic pH conditions in a semi-continuous reactor system
Katherine A Taconi1, Mark E Zappi, W Todd French
1Department of Chemical and Materials Engineering, University of Alabama in Huntsville, 130 Engineering Building, Huntsville, AL 35899, United States. taconik@uah.edu
Bioresource Technology
|May 10, 2008
Summary
Operating anaerobic digesters at low pH can be feasible. Acclimated microbial communities can maintain methanogenesis, reducing chemical oxygen demand (COD) and producing methane comparable to neutral pH systems.
Area of Science:
- Environmental science
- Biotechnology
- Microbiology
Background:
- Wastewater streams are often acidic, necessitating costly alkalinity for neutral pH anaerobic digestion.
- Previous batch studies indicated low pH could boost methane production by 30%.
Purpose of the Study:
- To assess the feasibility of low pH methanogenesis in a semi-continuous lab-scale anaerobic digester.
- To determine if acidic conditions inhibit methane production.
Main Methods:
- Utilized a semi-continuous laboratory-scale fermentor.
- Operated the system within a pH range of approximately 4.0-5.3.
- Monitored methane production and chemical oxygen demand (COD) reduction.
Main Results:
- Significant methane production was achieved at low pH (4.0-5.3).
- Methanogenesis was sustained after microbial consortium acclimation to acidic conditions.
- Comparable COD reduction and methane yields were observed versus neutral pH systems.
Conclusions:
- Anaerobic digestion is feasible at low pH with sufficient microbial acclimation.
- Low pH operation can maintain efficient methane production and COD removal.
- This approach may reduce the need for alkalinity supplementation in acidic wastewater treatment.
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