Enzymatic versus Nonenzymatic Conversions during the Reduction of EDTA-Chelated Fe(III) in BioDeNO<i><sub>x</sub></i> Reactors

Maas, Peter van der; Shen, Ping; Klapwijk, Bram; Lens, Piet N.L.

doi:10.1021/es049222d

Cited by 52 publications

(32 citation statements)

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“…The methanogenic 'Eerbeek' granular sludge originated from a full scale UASB reactor treating pulp and paper mill wastewater (Eerbeek, The Netherlands). Eerbeek sludge has a high Fe(III)EDTA À reducing activity (Van der Maas et al, 2005b), but no NO reducing activity (Van der Maas et al, 2003). Before use, the Eerbeek granules were mixed with the Fe(III)EDTA À medium (1/4 w/w) and crushed for 3 min with a kitchen blender.…”

Section: Sources Of Biomassmentioning

confidence: 99%

“…The volumetric Fe(II)EDTA 2À production rate was measured by monitoring the redox potential of the reactor mixed liquor, because it is a proper indicator of the Fe(II)EDTA 2À concentration (Kolthoff and Auerbach, 1952;Van der Maas et al, 2005b).…”

Section: Quantification Of the Bioreactor Regeneration Capacitymentioning

confidence: 99%

“…The NO reduction rate was quantified by measuring the N 2 O and N 2 production in the headspace of the batch vials as described previously (Van der Maas et al, 2003). The Fe(III)EDTA À reduction rate was measured by means of the redox potential as described elsewhere (Van der Maas et al, 2005b).…”

Section: Quantification Of the Bioreactor Regeneration Capacitymentioning

confidence: 99%

“…The bioreactor load, that is the amount of Fe(III)EDTA À and Fe(II)EDTA-NO 2À supplied to the bioreactor, was calculated using mass balances for O 2 and NO as described previously (Van der Maas et al, 2005b). The load of the electron acceptors (O 2 , Fe(III)EDTA À and NO) and the electron donor (ethanol) is expressed as molar electron equivalents (meq): 1 mol of ethanol, O 2 , NO, and Fe(III)EDTA À corresponds to 12, 4, 2, and 1 meq, respectively.…”

Section: Load Calculationsmentioning

confidence: 99%

“…However, not the NO reduction but Fe(III)EDTA À reduction was found to be the process rate limiting factor of BioDeNOx reactors treating flue gas with more than 1% oxygen (Van der Maas et al, 2005b (Witschel and Egli, 2001) and biological (Nörtemann, 1999) degradation of EDTA is well documented, but it is unknown to what extend these processes contribute to EDTA degradation in BioDeNOx reactors.…”

Section: Introductionmentioning

confidence: 99%

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NO removal in continuous BioDeNOx reactors: Fe(II)EDTA²⁻ regeneration, biomass growth, and EDTA degradation

Maas

Brink

Sudarno

et al. 2006

Biotech & Bioengineering

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BioDeNOx is a novel technique for NOx removal from industrial flue gases. In principle, BioDeNOx is based on NO absorption into an aqueous Fe(II)EDTA2- solution combined with biological regeneration of that scrubber liquor in a bioreactor. The technical and economical feasibility of the BioDeNOx concept is strongly determined by high rate biological regeneration of the aqueous Fe(II)EDTA2- scrubber liquor and by EDTA degradation. This investigation deals with the Fe(II)EDTA2- regeneration capacity and EDTA degradation in a lab-scale BioDeNOx reactor (10-20 mM Fe(II)EDTA2-, pH 7.2 +/- 0.2, 55 degrees C), treating an artificial flue gas (1.5 m3/h) containing 60-155 ppm NO and 3.5-3.9% O2. The results obtained show a contradiction between the optimal redox state of the aqueous FeEDTA solution for NO absorption and the biological regeneration. A low redox potential (below -150 mV vs. Ag/AgCl) is needed to obtain a maximal NO removal efficiency from the gas phase via Fe(II)EDTA2- absorption. Fe(III)EDTA- reduction was found to be too slow to keep all FeEDTA in the reduced state. Stimulation of Fe(III)EDTA- reduction via periodical sulfide additions (2 mM spikes twice a week for the conditions applied in this study) was found to be necessary to regenerate the Fe(II)EDTA2- scrubber liquor and to achieve stable operation at redox potentials below -150 mV (pH 7.2 +/- 0.2). However, redox potentials of below -200 mV should be avoided since sulfide accumulation is unwanted because it is toxic for NO reduction. Very low values for biomass growth rate and yield, respectively, 0.043/d and 0.009 mg protein per mg ethanol, were observed. This might be due to substrate limitations, that is the electron acceptors NO and presumably polysulfide, or to physiological stress conditions induced by the EDTA rich medium or by radicals formed in the scrubber upon the oxidation of Fe(II)EDTA2- by oxygen present in the flue gas. Radicals possibly also induce EDTA degradation, which occurs at a substantial rate: 2.1 (+/-0.1) mM/d under the conditions investigated.

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Section: Sources Of Biomassmentioning

confidence: 99%

Section: Quantification Of the Bioreactor Regeneration Capacitymentioning

confidence: 99%

Section: Quantification Of the Bioreactor Regeneration Capacitymentioning

confidence: 99%

Section: Load Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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NO removal in continuous BioDeNOx reactors: Fe(II)EDTA²⁻ regeneration, biomass growth, and EDTA degradation

Maas

Brink

Sudarno

et al. 2006

Biotech & Bioengineering

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Nitric oxide reduction in BioDeNOx reactors: Kinetics and mechanism

Maas

Manconi

Klapwijk

et al. 2008

Biotech & Bioengineering

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Biological reduction of nitric oxide (NO) to di-nitrogen (N(2)) gas in aqueous Fe(II)EDTA(2-) solutions is a key reaction in BioDeNOx, a novel process for NOx removal from flue gases. The mechanism and kinetics of the first step of NO reduction, that is, the conversion of NO to N(2)O, was determined in batch experiments using various types of inocula. Experiments were performed in Fe(II)EDTA(2-) medium (5-25 mM) under BioDeNOx reactor conditions (55 degrees C, pH 7.2 +/- 0.2) with ethanol as external electron donor. BioDeNOx reactor mixed liquor gave the highest NO reduction rates (+/-0.34 nmol s(-1) mg(prot)(-1)) with an estimated K(m) value for NO lower than 10 nM. The specific NO (to N(2)O) reduction rate depended on the NO (aq) and Fe(II)EDTA(2-) concentration as well as the temperature. The experimental results, complemented with kinetic and thermodynamic considerations, show that Fe(II)EDTA(2-), and not ethanol, is the primary electron donor for NO reduction, that is, the BioDeNOx reactor medium (the redox system Fe(II)EDTA(2-)/Fe(III)EDTA(-)) interferes with the NO reduction electron transfer chain and thus enhances the NO denitrification rate.

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Factors That Determine the Mechanism of NO Activation by Metal Complexes of Biological and Environmental Relevance

Franke

Eldik

2012

Eur J Inorg Chem

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This account presents a sampling of kinetic and mechanistic investigations on the activation of nitric oxide (NO) by metal complexes of biological and environmental importance. Throughout the review the main emphasis falls on the finding and characterization of factors that control the dynamics of NO-metal interactions in which the metal centers serve as coordination and electron-transfer mediators. On the basis of the systems surveyed, several important aspects concerning the mechanism of NO activation processes have been evaluated and are discussed in detail. They involve the effect of (i) chemical properties of the reaction medium, (ii) electronic

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Enzymatic versus Nonenzymatic Conversions during the Reduction of EDTA-Chelated Fe(III) in BioDeNO_x Reactors

Cited by 52 publications

References 44 publications

NO removal in continuous BioDeNOx reactors: Fe(II)EDTA²⁻ regeneration, biomass growth, and EDTA degradation

NO removal in continuous BioDeNOx reactors: Fe(II)EDTA²⁻ regeneration, biomass growth, and EDTA degradation

Nitric oxide reduction in BioDeNOx reactors: Kinetics and mechanism

Factors That Determine the Mechanism of NO Activation by Metal Complexes of Biological and Environmental Relevance

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Enzymatic versus Nonenzymatic Conversions during the Reduction of EDTA-Chelated Fe(III) in BioDeNOx Reactors

Cited by 52 publications

References 44 publications

NO removal in continuous BioDeNOx reactors: Fe(II)EDTA2− regeneration, biomass growth, and EDTA degradation

NO removal in continuous BioDeNOx reactors: Fe(II)EDTA2− regeneration, biomass growth, and EDTA degradation

Nitric oxide reduction in BioDeNOx reactors: Kinetics and mechanism

Factors That Determine the Mechanism of NO Activation by Metal Complexes of Biological and Environmental Relevance

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Product

Resources

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Enzymatic versus Nonenzymatic Conversions during the Reduction of EDTA-Chelated Fe(III) in BioDeNO_x Reactors

NO removal in continuous BioDeNOx reactors: Fe(II)EDTA²⁻ regeneration, biomass growth, and EDTA degradation

NO removal in continuous BioDeNOx reactors: Fe(II)EDTA²⁻ regeneration, biomass growth, and EDTA degradation