Nitric oxide removal from flue gas with a biotrickling filter using Pseudomonas putida

The development of an effective biotrickling filter (BF) system to inoculate a newly isolated strain of Pseudomonas putida SB1 for the effective treatment of nitric oxide (NO) is described. The experiments were carried out in a bench-scale BF under high concentrations of O-2 and NO in simulated flue gas. A method including alternating aeration in screening and rescreening based on the pH changes for cultivating natural aerobic denitrifying bacteria was employed. The SB1 showed a denitrifying capability of 95% nitrate removal rate over a 24 h period in an aerobic environment. with no nitrite accumulation. The BF system was able to consistently remove 82.9-94.2% NO when the inlet NO was 400 ppm in an enriched oxygen stream of 2-20%. The oxygen had no negative effect on the aerobic denitrifier SB1, but rather enhanced the total efficiency in part by chemical oxidation and in part by the strain activities. A kinetic relation between the oxygen concentration and biological NO removal was developed to confirm that the microbial metabolism played the main role. 79.3% of the total NO removal can be attributed to bio-denitrifying at 20% oxygen, and most chemical oxidation occurred concurrently. Overall, the study demonstrates that NO removal by the aerobic denitrifying process in BF is feasible in flue gas. (C) 2008 Elsevier B.V. All rights reserved.