Biological Removal of Gaseous Ammonia in Biofilters: Space Travel and Earth-Based Applications

• Published in: Journal of the Air & Waste Management Association (1995) 2000-09, Vol.50 (9), p.1647-1654
• Main Authors: Joshi, Jitendra A., Hogan, John A., Cowan, Robert M., Strom, Peter F., Finstein, Melvin S.
• Format: Article
• Language: English
• Subjects: Air Pollution - prevention & control; Air Pollution, Indoor - prevention & control; Aluminum Oxide; Ammonia - metabolism; Applied sciences; Atmospheric pollution; Biological and medical sciences; Biological treatment of gaseous effluents; Bioreactors; Biotechnology; Environment and pollution; Environment Pollution; Exact sciences and technology; Filtration - instrumentation; Fundamental and applied biological sciences. Psychology; General processes of purification and dust removal; Industrial applications and implications. Economical aspects; Models, Theoretical; Nitrogen - analysis; Nitrogen - metabolism; Pollution; Prevention and purification methods; Research Design; Silicon Dioxide; Space Flight; Sterilization; Time Factors; United States; United States National Aeronautics and Space Administration
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10473289.2000.10464189

Gaseous NH 3 removal was studied in laboratory-scale biofilters (14-L reactor volume) containing perlite inoculated with a nitrifying enrichment culture. These biofilters received 6 L/min of airflow with inlet NH 3 concentrations of 20 or 50 ppm, and removed more than 99.99% of the NH 3 for the period of operation (101, 102 days). Comparison between an active reactor and an autoclaved control indicated that NH 3 removal resulted from nitrification directly, as well as from enhanced absorption resulting from acidity produced by nitrification. Spatial distribution studies (20 ppm only) after 8 days of operation showed that nearly 95% of the NH 3 could be accounted for in the lower 25% of the biofilter matrix, proximate to the port of entry. Periodic analysis of the biofilter material (20 and 50 ppm) showed accumulation of the nitrification product NO 3 - early in the operation, but later both NO 2 - and NO 3 - accumulated. Additionally, the N-mass balance accountability dropped from near 100% early in the experiments to ~95 and 75% for the 20- and 50-ppm biofilters, respectively. A partial contributing factor to this drop in mass balance accountability was the production of NO and N 2 O, which were detected in the biofilter exhaust.