Chemically enhanced biological NOx removal from flue gases : nitric oxide and ferric EDTA reduction in BioDeNox reactors

摘要: The emission of nitrogen oxides (NOx) to the atmosphere is a major environmental problem. To abate NOx emissions from industrial flue gases, date, mainly chemical processes like selective catalytic reduction (SCR) are applied. All these require high temperatures (>300 °C) and expensive catalysts. Therefore, biological removal techniques using denitrification may represent promising alternatives for conventional SCR techniques. However, water based biofiltration requires relatively long scrubber/bioreactor retention times, i.e. big reactor volumes, due slow mass transfer NO gas into liquid phase. BioDeNOx in principle welcome alternative water-based biofiltration, since it does not need catalysts, while scrubber times can be very short (<10 seconds) chemically enhanced absorption. In this thesis, concept was investigated with special attention bioreactor key conversions: Fe(III)EDTA- reduction. This study showed stable phase efficiencies up 80 %. It found that primary determined by absorption kinetics. Fe(II)EDTA2- concentration required, FeEDTA liquor should reduced state. totally system avoided, will induce sulfide accumulation. latter process unwanted, already low concentrations an incomplete inhibition N2O N2. achieve satisfying avoid sulfdogenic conditions, redox potential reactors steered between -180 -200 mV versus Ag/AgCl (pH 7.2±0.2). An ethanol dosing controlled signal shown proper manner do so