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Effects of nitrogen and oxygen on biofilter performance
He Yang1, Beatrice Minuth, D Grant Allen
1Department of Chemical Engineering and Applied Chemistry, University of Toronto, Ontario, Canada.
Journal of the Air & Waste Management Association (1995)
|April 2, 2002
Summary
This study investigated nitrogen and oxygen needs for methanol biofiltration. Optimal nitrogen levels boosted removal rates, while high oxygen concentrations improved performance up to a point, indicating other factors may limit efficiency.
Area of Science:
- Environmental biotechnology
- Biochemical engineering
- Microbial degradation
Background:
- Biofiltration is a key technology for removing volatile organic compounds (VOCs) like methanol from industrial emissions.
- Optimizing biofilter performance requires understanding the influence of essential nutrients and operating conditions, such as nitrogen availability and oxygen supply.
Purpose of the Study:
- To determine the nitrogen (ammonia and nitrate) and oxygen requirements for efficient biofiltration of methanol.
- To investigate the impact of varying nitrogen-to-carbon (N:C) ratios and oxygen concentrations on methanol removal rates.
Main Methods:
- Laboratory-scale biofilters packed with inert material were utilized.
- Methanol was supplied with inorganic nitrogen sources (NH3 or NO3) at diverse N:C ratios (0.015–0.4).
- Gas streams with varying oxygen content (air to 80% oxygen) were tested.
Main Results:
- Methanol removal rates increased with N:C ratio at low nitrogen levels for both NH3 and NO3.
- High NH3 concentrations inhibited biodegradation, while high NO3 concentrations led to a plateau in removal rates.
- Increasing oxygen content to 63% enhanced the maximum removal rate from 120 to 145 g/m3/hr.
- Further increases in oxygen beyond 63% did not significantly improve performance.
Conclusions:
- Nitrogen availability is crucial for methanol biofiltration, with optimal N:C ratios enhancing removal.
- Ammonia can be inhibitory at high concentrations, whereas nitrate shows a saturation effect.
- Oxygen supply is important, but its benefits plateau, suggesting that biofilm thickness and oxygen transfer limitations become critical at higher loadings.