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Creating anoxic and microaerobic conditions in sequencing batch reactors treating volatile BTX compounds
1Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, 418 New Engineering Building, Blacksburg, VA 24061, USA.
Summary
This study introduces a novel reactor strategy for degrading volatile contaminants like benzene, toluene, and xylene (BTX) in wastewater. It found that anoxic conditions degrade some BTX compounds, while microaerobic conditions degrade others, enhancing biodegradation.
Area of Science:
- Environmental Microbiology
- Biotechnology
- Wastewater Treatment
Background:
- Volatile organic compounds (VOCs) in wastewater pose environmental challenges.
- Stripping of volatile contaminants limits biodegradation efficiency in conventional systems.
- Sequencing batch reactors (SBRs) offer flexibility in managing wastewater treatment processes.
Purpose of the Study:
- To develop an experimental strategy for studying volatile contaminant biodegradation in wastewater.
- To investigate the biodegradation of benzene, toluene, and xylene isomers (BTX) under alternating anoxic and microaerobic conditions.
- To assess the effectiveness of a novel reactor configuration in preventing contaminant stripping and promoting biodegradation.
Main Methods:
- Utilized an alternating anoxic/microaerobic sequencing batch reactor (SBR) for wastewater treatment.
- Employed benzene, toluene, and xylene isomers (BTX) as model volatile contaminants.
- Implemented a novel laboratory reactor configuration to establish oxygen-free anoxic and microaerobic (< 0.2 mg/L dissolved oxygen) conditions.
- Used oxidation-reduction potential (ORP) to monitor electron acceptor conditions within the SBR.
Main Results:
- Demonstrated that toluene and m-xylene are biodegradable under anoxic (denitrifying) conditions.
- Showed that benzene, o-xylene, and p-xylene are biodegradable under microaerobic conditions.
- Successfully prevented the stripping of volatile BTX compounds into the atmosphere.
- ORP effectively monitored different electron acceptor conditions in the SBR.
Conclusions:
- Establishing microaerobic conditions in full-scale bioreactors can enhance the biodegradation of aerobically biodegradable volatile contaminants.
- The developed laboratory reactor configuration is suitable for studying microaerobic metabolism and volatile contaminant biodegradation.
- Alternating anoxic and microaerobic conditions provide a viable strategy for comprehensive BTX biodegradation in wastewater.