Denitrification and nitric oxide reduction in an aerobic toluene-treating biofilter

Abstract

The presence of significant denitrification activity in an aerobic toluene‐treating biofilter was demonstrated under batch and flow‐through conditions. N2O concentrations of 9.2 ppmv were produced by denitrifying bacteria in the presence of 15% acetylene, in a flow‐through system with a bulk gas phase O2 concentration of >17%. The carbon source for denitrification was not toluene but a byproduct or metabolite of toluene catabolism. Denitrification conditions were successfully used for the reduction of 60 ppmv nitric oxide to 15 ppmv at a flow rate of 3 L min−1 (EBRT of 3 min) in a fully aerated, 17% v/v O2 (superficially aerobic) biofilter. Higher NO removal efficiency (97%) was obtained by increasing the toluene supply to the biofilter. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:408‐415, 1998.

A Fungal Vapor-Phase Bioreactor for the Removal of Nitric Oxide from Waste Gas Streams

“…Toluene was chosen as the carbon and energy source for the system, since previous studies have used toluene as the carbon and energy source for NO removal investigations at lower NO loading rates. 5 A slightly different contaminant supply configuration ( Figure 2) was used during the periodic NO removal experiments. Each NO experiment was conducted for 12-24 hr.…”

“…[3][4][5][6][7] The main disadvantage of these bacterial systems is that they require completely anaerobic conditions to achieve NO removal. 3,4 In addition, a long residence time is usually required due to NO mass transfer limitations from the gas phase into the liquid biofilm.…”

“…3,4 In addition, a long residence time is usually required due to NO mass transfer limitations from the gas phase into the liquid biofilm. 5,7 To be competitive with conventional NO treatment processes, biofilters need to be able to operate at short residence times and under aerobic conditions (3-5% O 2 ), as typically encountered in the field.…”

“…[3][4][5] In these cases, the biofilter must be able to maintain high removal efficiencies of the carbon source as well as NO to be effective. Since fungal biofilters can achieve high removal efficiencies for VOCs, 8,9 and some strains of fungi are known to denitrify, 10 the use of a fungal biofilter for the removal of NO and VOCs from waste gas streams may be an attractive alternative to conventional treatment processes.…”

Abiotic and Biological Mechanisms of Nitric Oxide Removal from Waste Air in Biotrickling Filters

“…7,[13][14][15][16] Many researchers adopted the process to treat the nitrogen oxides (NO x )-contaminated gas via denitrification. 17,18 This process relies on the maintenance of anoxic conditions so that NO x can be converted into inert N gas. The reduction is assumed to require the elimination of oxygen from the reactor, which leads to a huge cost increase for the full-scale implementation of biofiltration in the treatment of NO x .…”