Maas Peter van der, Brink Paula van den, Klapwijk Bram, Lens Piet
Sub-department of Environmental Technology, Wageningen University, The Netherlands.
Chemosphere. 2009 Apr;75(2):243-9. doi: 10.1016/j.chemosphere.2008.04.043. Epub 2008 Jun 17.
BioDeNO(x), a novel technique to remove NO(x) from industrial flue gases, is based on absorption of gaseous nitric oxide into an aqueous Fe(II)EDTA(2-) solution, followed by the biological reduction of Fe(II)EDTA(2-) complexed NO to N(2). Besides NO reduction, high rate biological Fe(III)EDTA(-) reduction is a crucial factor for a succesful application of the BioDeNO(x) technology, as it determines the Fe(II)EDTA(2-) concentration in the scrubber liquor and thus the efficiency of NO removal from the gas phase. This paper investigates the mechanism and kinetics of biological Fe(III)EDTA(-) reduction by unadapted anaerobic methanogenic sludge and BioDeNO(x) reactor mixed liquor. The influence of different electron donors, electron mediating compounds and CaSO(3) on the Fe(III)EDTA(-) reduction rate was determined in batch experiments (21mM Fe(III)EDTA(-), 55 degrees C, pH 7.2+/-0.2). The Fe(III)EDTA(-) reduction rate depended on the type of electron donor, the highest rate (13.9mMh(-1)) was observed with glucose, followed by ethanol, acetate and hydrogen. Fe(III)EDTA(-) reduction occurred at a relatively slow (4.1mMh(-1)) rate with methanol as the electron donor. Small amounts (0.5mM) of sulfide, cysteine or elemental sulfur accelerated the Fe(III)EDTA(-) reduction. The amount of iron reduced significantly exceeded the amount that can be formed by the chemical reaction of sulfide with Fe(III)EDTA(-), suggesting that the Fe(III)EDTA(-) reduction was accelerated via an auto-catalytic process with an unidentified electron mediating compound, presumably polysulfides, formed out of the sulfur additives. Using ethanol as electron donor, the specific Fe(III)EDTA(-) reduction rate was linearly related to the amount of sulfide supplied. CaSO(3) (0.5-100mM) inhibited Fe(III)EDTA(-) reduction, probably because SO(3)(2-) scavenged the electron mediating compound.
BioDeNO(x)是一种从工业烟道气中去除氮氧化物的新技术，它基于将气态一氧化氮吸收到Fe(II)EDTA(2-)水溶液中，随后将与Fe(II)EDTA(2-)络合的NO生物还原为N(2)。除了NO还原外，高速率的生物Fe(III)EDTA(-)还原是BioDeNO(x)技术成功应用的关键因素，因为它决定了洗涤液中Fe(II)EDTA(2-)的浓度，从而决定了从气相中去除NO的效率。本文研究了未适应的厌氧产甲烷污泥和BioDeNO(x)反应器混合液对生物Fe(III)EDTA(-)还原的机理和动力学。在批次实验（21mM Fe(III)EDTA(-)，55℃，pH 7.2±0.2）中确定了不同电子供体、电子介导化合物和CaSO(3)对Fe(III)EDTA(-)还原速率的影响。Fe(III)EDTA(-)还原速率取决于电子供体的类型，以葡萄糖为电子供体时观察到最高速率（13.9mM h(-1)），其次是乙醇、乙酸盐和氢气。以甲醇为电子供体时，Fe(III)EDTA(-)还原速率相对较慢（4.1mM h(-1)）。少量（0.5mM）的硫化物、半胱氨酸或元素硫加速了Fe(III)EDTA(-)的还原。还原的铁量显著超过了硫化物与Fe(III)EDTA(-)化学反应所能形成的量，这表明Fe(III)EDTA(-)的还原是通过一种自动催化过程加速的，该过程中由硫添加剂形成了一种未确定的电子介导化合物，可能是多硫化物。以乙醇为电子供体时，特定的Fe(III)EDTA(-)还原速率与供应的硫化物量呈线性关系。CaSO(3)（0.5-100mM）抑制了Fe(III)EDTA(-)的还原，可能是因为SO(3)(2-)清除了电子介导化合物。
