NO production in the Fe(EDTA)-NO reduction process: the effects of carbon source and pH.

Chemical absorption-biological reduction (BioDeNO), which uses Fe(EDTA) as a complexing agent for promoting the mass transfer efficiency of NO from gas to water, is a promising technology for removing nitric oxide (NO) from flue gases. The carbon source and pH are important parameters for Fe(EDTA)-NO (the production of absorption) reduction and NO emissions from BioDeNO systems. Batch tests were performed to evaluate the effects of four different carbon sources (i.e., methanol, ethanol, sodium acetate, and glucose) on Fe(EDTA)-NO reduction and NO emissions at an initial pH of 7.2 ± 0.2. The removal efficiency of Fe(EDTA)-NO was 93.9 %, with a theoretical rate of 0.77 mmol L h after 24 h of operation. The highest NO production was 0.025 mmol L after 3 h when glucose was used as the carbon source. The capacities of the carbon sources to enhance the activity of the Fe(EDTA)-NO reductase enzyme decreased in the following order based on the C/N ratio: glucose > ethanol > sodium acetate > methanol. Over the investigated pH range of 5.5-8.5, the Fe(EDTA)-NO removal efficiency was highest at a pH of 7.5, with a theoretical rate of 0.88 mmol L h. However, the NO production was lowest at a pH of 8.5. The primary effect of pH on denitrification resulted from the inhibition of nosZ in acidic conditions. [ABSTRACT FROM AUTHOR]